DESCRIPTION
[Title of Invention]
RECORDING MEDIUM, PLAYBACK APPARATUS, RECORDING APPARATUS,
PLAYBACK METHOD, AND RECORDING METHOD
[Technical Field]
The present invention relates to an information
recording medium, a playback method thereof, and a recording
method thereof, in particular, to a technology for realizing
special playback such as fast-forward/rewind. Here, the
information recording medium is a BD-ROM or the like having
recorded thereon contents such as video and audio, with
copyright protection.
[Background Art]
Special playback functions such as fast-forward/rewind
are indispensable functions for playing back an AV stream
recorded on a BD-ROM, DVD, or the like.
In general, a player can perform special functions such
as fast-forward/rewind by executing reading of a disc,
decoding of the read data, and the like at a speed faster
than a normal playback speed, and then playing it back. However,
this method places burden on the player, causing the player
to be unable to perform processing at the speed required for
high-speed playback such as 10x for fast-forward/rewind.
Accordingly, in order to realize special playback such
as fast-forward/rewind, the player needs to read and decode
part of the AV stream while making temporal skips . For example,
the player may select intra-frame encoded images (hereinafter,
referred to as "I-pictures") in video included in an AV stream
in accordance with the speed of fast-forward/rewind, and
performs reading and decoding. However, an AV stream on a
BD-ROM or DVD contains various streams such as video, audio,
and subtitles multiplexed into the AV stream. Besides,
pictures vary in size in a case where the video is encoded
using variable length encoding. Accordingly, identifying an
I-picture pertaining to a desired time requires analysis
processing of the AV stream, thereby consuming a large amount
of processing time.
Thus, BD-ROMs use entry maps to realize
fast-forward/rewind. An entry map is composed of a list of
multiple entry points each indicating an access position in
an AV stream. Each entry point is information in which a file
position within the AV stream corresponds to a playback time
of data located at the file position. For example, an entry
map including entry points each composed of a starting file
position of an I-picture included in an AV stream on an
information recording medium and the presentation time of
the I-picture allows the playback apparatus to identify the
position, of the I-picture, corresponding to the playback
time without analyzing the AV stream, by referring to the
entry map. As a result, the playback apparatus is able to
perform partial playback of the AV stream, thereby realizing
efficient fast-forward/rewind without burden. Patent
Document 1 discloses a data structure and a creation method
of an entry map for identifying positions of I-pictures.
[Citation List]
[Patent Literature]
[Patent Literature 1]
Patent Document 1: Japanese Laid-Open Patent
Application Publication No. 2000-228656
[Summary of Invention]
[Technical Problem]
In manufacturing BD-ROM playback apparatuses which
handle HDTV contents, demand for copyright protection at the
level of TS packets constituting the AV stream is high. However,
in order to realize copyright protection using such as special
encryption and transformation at the TS packet level, it is
required to perform decryption processing, restoration
processing or the like in real time at the uppermost stream
when reading from the BD-ROM. Especially if the AV stream
is provided for a high-speed special playback such as over
10x, such real time processing will incur a large burden.
In addition, multiple video streams may be multiplexed
into an AV stream in a BD-ROM to realize Picture-in-Picture
playback or 3D playback.
If TS packets constituting two video streams in an AV
stream are transformed and the AV stream is provided for a
high-speed special playback such as lOx, simultaneous
restoration of the transformed TS packets of these multiple
video streams need to be realized at 10x. If the BD-ROM playback
apparatus is to be designed assuming such a worst-case scenario,
it will inevitably require addition of special hardware,
increase in operation clock speed, and the like. This will
necessitate further modification and improvement of the
present BD-ROM players, which goes against the idea of
encouraging broad use of the playback apparatuses through
standardization.
The present invention was conceived in view of the above
problem and aims to provide a recording medium, a recording
method, and a playback apparatus and a playback method for
playing back the recording medium, which are able to prevent
increase in processing load due to realization of copyright
protection at the TS packet level.
[Solution to Problem]
In order to achieve the stated aim, the recording medium
of the present invention is a recording medium having recorded
thereon an AV stream and stream information. Here, the AV
stream includes (a) TS packets composing a primary video stream
and (b) TS packets composing a secondary video stream, the
stream information includes: a first entry map indicating
a plurality of associations each associating (a) a start
position of, among the TS packets composing the primary video
stream, a group of TS packets which constitute an entry unit
with (b) a presentation time stamp of the group of TS packets;
and a second entry map indicating a plurality of associations
each associating (a) a start position of, among the TS packets
composing the secondary video stream, a group of TS packets
which constitute an entry unit with (b) a presentation time
stamp of the group of TS packets of the secondary video stream,
each group of TS packets constituting an entry unit stores
an intra-frame encoded image therein, among the TS packets
composing the primary video stream, one or more TS packets
have been transformed and TS packets which constitute every
N-th entry unit, in an order of the start position, are
untransformed, N being an integer of 2 or more, and each TS
packet which constitutes one of the entry units of the secondary
video stream and whose presentation time stamp is in a
predetermined relationship with a presentation time stamp
of the every N-th entry unit, is untransformed.
[Advantageous Effects of Invention]
According to the stated structure, transformation for
the purpose of copyright protection is not executed on (a)
TS packets which constitute one of every N-th entry unit of
the primary video stream and (b) TS packets which constitute
an entry unit of the secondary video stream and whose
presentation time stamp attached thereto is in a predetermined
relationship with the one of every N-th entry unit of the
primary video stream. Consequently, selectively using entry
units stored in these TS packets eliminates the need for
restoring the transformed TS packets constituting the primary-
video stream and TS packets constituting the secondary video
stream. As a result, increase in processing load during
high-speed fast-forward/rewind playback can be prevented,
thereby realizing the copyright protection using
transformation of the TS packets within a permissible range
of the processing capability of a standard-model BD-ROM player,
without adding special hardware or increasing operation clock
speed.
Accordingly, copyright protection is realized by
transforming part of the AV stream and recording the
post-transformation AV stream, and at the same time,
high-speed and simultaneous fast-forward/rewind of the
primary video stream and secondary video stream can be
performed.
Here, among the TS packets of the secondary video stream,
TS packets constituting the entry units closest to every N-th
entry unit of the primary video stream are chosen to be
untransformed, thereby realizing fast-forward/rewind of the
primary video stream and secondary video stream in an as closely
synchronized manner as possible.
[Brief Description of Drawings]
FIG. 1 shows a use form of a recording medium of the
present invention;
FIG. 2 shows an internal structure of a BD-ROM;
FIG. 3 shows an internal structure of IndexFile;
FIG. 4 shows an internal structure of a Movie Object
file;
FIG. 5 shows a structure of an AV stream;
FIG. 6 shows an example of Picture in Picture;
FIG. 7 schematically shows how streams are multiplexed
into an AV stream;
FIG. 8 shows further details on how a video stream and
an audio stream are stored into a PES packet string;
FIG. 9 shows a structure of a TS packet and a source
packet in an AV stream;
FIG. 10 shows a data structure of PMT;
FIG. 11 shows an internal structure of a stream
information file;
FIG. 12 shows an internal structure of stream attribute
information;
FIG. 13 shows an internal structure of an entry map;
FIG. 14 shows an internal structure of a PlayList;
FIG. 15 shows an internal structure of a Playltem;
FIG. 16 shows relationship between restoration segments
and restoration parameters with respect to an AV stream;
FIG. 17 shows a function of restoration byte code data;
FIG. 18 shows a structure of a restoration entry with
respect to transformed data in an AV stream and how the
restoration entry, as a restoration descriptor, is stored
into the AV stream;
FIG. 19 shows untransformable ranges which are not
allowed to be transformed, in a video stream included in an
AV stream;
FIG. 20 shows video frame strings in video streams
included in an AV stream;
FIG. 21 shows PTS positions of entry points of a primary-
video and a secondary video with respect to STC which is a
playback time axis of the AV stream, and entry points indicating
untransformable I-pictures in the entry map of the secondary-
video ;
FIG. 22 shows relationship between untransformable TS
packets of the primary video stream and secondary video stream,
using frames constituting each video stream;
FIG. 23 shows SPN positions of the entry points of the
primary video and secondary video with respect to file position
of the AV stream, and entry points indicating untransformable
I-pictures in the entry map of the secondary video in a first
modification;
FIG. 24 shows SPN positions of entry points of the primary
video with respect to the file position of the AV stream,
and untransformable I-pictures of the secondary video in a
second modification;
FIG. 25 shows the PTS positions of the entry points of
the primary video and the secondary video with respect to
STC which is the playback time axis of the AV stream, and
entry points indicating untransformable I-pictures in the
entry map of the secondary video in a third modification;
FIG. 2 6 shows the SPN positions of the entry points of
the primary video and secondary video with respect to the
file position of the AV stream, and entry points indicating
untransformable I-pictures in the entry map of the secondary
video in a fourth modification;
FIG. 2 7 shows the PTS positions of the entry points
indicating untransformable I-pictures, in a fifth
modification, with respect to STC which is the playback time
axis of the AV stream;
FIG. 28 shows the PTS position of the entry points
indicating untransformable I-pictures, in a sixth
modification, with respect to STC which is the playback time
axis of the AV stream;
FIG. 29 shows the PTS positions of the entry points
indicating untransformable I-pictures, in a seventh
modification, with respect to STC which is the playback time
axis of the AV stream;
FIG. 3 0 shows the PTS positions of the entry points
indicating untransformable I-pictures, in an eighth
modification, with respect to STC which is the playback time
axis of the AV stream;
FIG. 31 shows an inner structure of a playback apparatus ;
FIG. 32 shows an inner structure of a system target
decoder;
FIG. 33 is a flowchart showing processing by a data
analysis execution unit 17;
FIG. 34 is a flowchart showing processing steps of
playback entry point selection processing;
FIG. 35 shows an inner structure of a recording
apparatus;
FIG. 36 shows a flowchart of a recording method;
FIG. 37 is a flowchart showing processing steps of
untransformable packet specification processing; and
FIG. 38 shows a structure of a restoration entry with
respect to transformed data in an AV stream in a modification,
and how the restoration entry, as a restoration entry packet,
is stored into the AV stream.
[Reference Signs List]
11 BD-ROM drive
12 Read buffer
13 System target decoder
14 Data restoration processing unit
15 restoration entry generation unit
16 restoration byte code data execution unit
17 data analysis execution unit
18 user event processing unit
21 Source depacketizer
22 ATC counter
23 PID filter
24 Primary video decoder
25 Secondary video decoder
26 IG decoder
2 7 PG decoder
28 Audio decoder
29 System packet decoder
30, 36, 39 TransportStreamBuffer
31 Multiplexing Buffer
32 ElementaryStreamBuffer
33 Compression video decoder
34 Re-order Buffer
35 Switch
37, 40 Buffer
38 Compression video decoder
41 System packet analysis unit
42, 43, 44, 45 Plain memory
46 Addition unit
100 BD-ROM
200 Playback apparatus
201 Material production unit
202 Scenario generation unit
203 Multiplexing processing unit
204 Restoration entry generation unit
205 Restoration byte code generation unit
206 Transformation processing unit
207 Format processing unit
208 Master production unit
300 Television
501 Playltem
5 02 PlayList mark
503 Stream information file
504 AV stream
601 AV stream to be referred to
602 AV stream playback start time
603 AV stream playback end time
604 User operation control information
605 Stream selection table
701 Video frame string
704 Audio frame string
707 Presentation graphics stream
710 Interactive graphics stream
702, 705, 708, 711 PES packet string
703, 706, 709, 712 TS packet string
713 AV stream
[Description of Embodiments]
[First Embodiment]
The following describes a first embodiment of a recording
medium of the present invention. First, among various aspects
of the recording medium of the present invention, a use form
is described. FIG. 1 shows the use form of the recording medium
of the present invention. In FIG. 1, the recording medium
of the present invention is a BD-ROM 100 which is used to
supply a motion picture to a home theater system further
composed of a playback apparatus 200, a remote controller
300, and a television 400.
The BD-ROM 100 is a recording medium having recorded
thereon a motion picture.
The playback apparatus 2 00 is an Internet-compliant
digital home appliance, and is capable of playing back the
BD-ROM 100 . The playback apparatus 200 downloads content from
a server of a film distributor via a network and stores the
downloaded content into a local storage thereof. This way,
the playback apparatus 200 is able to expand/update the content
of the BD-ROM 100 by combining the content stored in the local
storage and the content recorded on the BD-ROM 100. The
technology which handles data not recorded on the BD-ROM 100
as if the data is recorded on the BD-ROM 100, by combining
the content of the BD-ROM 100 and the content of the local
storage, is called "virtual package".
Described above is the use form of the recording medium
of the present invention.
Next, description is given on a production form of the
recording medium of the present invention. The recording
medium of the present invention can be realized by modifying
a file system.

FIG. 2 shows a structure of the BD-ROM. The fourth row
in the figure shows the BD-ROM 100, while the third row shows
a track on the BD-ROM. In the figure, the track is stretched
out horizontally, although in reality it spirals from the
inner periphery to the outer periphery of the BD-ROM 100.
The BD-ROM 100, like other optical discs such as DVDs and
CDs, has a recording area formed spirally from the inner
periphery to the outer periphery therein, and has, between
the lead-in of the inner periphery and the lead-out of the
outer periphery, a logical address space capable of recording
logical data. Additionally, inside the lead-in, there is a
special area called BCA (Burst Cutting Area) which can be
read only by drives. Being unreadable by applications, this
area is often used for copyright protection technology.
In the logical address space, volume information of a
file system is recorded from the beginning thereof, and
subsequently, application data such as video data is recorded.
The file system is a structure which represents data on a
disc in units of directories or files, and in the BD-ROM 100,
UDF (Universal Disc Format) is used. PCs (Personal Computers)
for everyday use also use a file system called FAT or NTFS
and present, on computer, data stored in a hard disc in a
structure of directories and files, thereby increasing
usability. The use of file system enables the BD-ROM 100 to
read logical data, which is stored in the same manner as in
a general purpose PC, using the directory and file structure.
With use of the directory and file structure, the
application layer format (application format) of the BD-ROM
100 is presented as the first row of the figure. According
to the directory and file structure of the BD-ROM 100, there
is a BDMV directory directly under the root directory (ROOT) .
The BDMV directory records data processed by the BD-ROM 100,
such as AV contents and management information. Under the
BDMV directory, there are IndexFile (index.bdmv), a Movie
Object file (MovieObject.bdmv), a PLAYLIST directory, a
CLIPINF directory, and a STREAM directory. The IndexFile
defines an IndexTable constituting Titles, and the Movie
Object file defines a dynamic scenario. The STREAM directory,
CLIPINF directory, and PLAYLIST directory include AV streams
(XXX.M2TS) storing AV contents such as video and audio which
are multiplexed, stream information files (XXX.CLPI) storing
management information of the AV streams, and PlayList files
(YYY.MPLS) defining logical playback paths of the AV streams,
respectively.
Directly under the root directory (ROOT) , there is also
a BDPLS directory which records restoration byte code data
(ZZZ.BDP). In a BD-ROM including the BDPLS directory, an AV
stream is partially transformed at the TS packet level in
advance. The restoration byte code data is an execution program,
and when executed, generates restoration parameters to
restore the transformed AV stream. Prior to playing back the
AV stream, the playback apparatus generates restoration
parameters by executing the restoration byte code data,
restores the transformed AV stream using the generated
restoration parameters, and plays back the re stored AV stream.
It should be noted that these directory names and file
names are defined for the purpose of explaining the present
embodiment, and accordingly, different names can be applied
when put to practical use.
In the following, description is given on the data
structure of each file under the BDMV directory.

First, the IndexFile (Index.bdmv) is described. The
IndexFile includes IndexTable shown in FIG. 3 . The IndexTable
is a table of the highest layer and defines the title structure
of all the Titles, TopMenu, FirstPlay and the like stored
in the BD-ROM. This table specifies Movie Objects included
in the Movie Object file which are first executed by all the
Titles, TopMenu, and FirstPlay. Each time a Title or a Menu
is invoked, the playback apparatus of the BD-ROM refers to
the IndexTable and executes a predetermined Movie Object.
Here, the FirstPlay is set by a content provider and has been
set to a Movie Object that is automatically executed when
the disc is inserted. The TopMenu specifies a Movie Object
invoked when a command such as "return to menu" is executed
by user operation of the remote controller.

Next, the Movie Object file (MovieObject.bdmv) is
described.
As shown in FIG. 4, multiple Movie Objects are defined
in the Movie Object file, and each Movie Object is identified
by a Movie Object ID. Each Movie Object includes one or more
navigation commands instructing a playback of a PlayList,
transition to another Movie Object or Title, and the like,
and the playback apparatus sequentially executes the string
of navigation commands. For example, when "PlayPL#N" is
described, the playback apparatus selects a file name of a
PlayList corresponding to "PlayPL#N" from the PlayList
directory and plays back the selected PlayList. Also, for
example, when "JumpObject#N" is described, the playback
apparatus selects the corresponding Movie Object from the
Movie Object file and executes the selected Movie Object.
Next, the AV stream file (XXX.M2TS) and stream
information file (XXX.CLPI) are described.

The AV stream is a digital stream of MPEG-2 transport
stream format.
FIG. 5 shows a structure of the AV stream. As shown in
FIG. 5, the AV stream is obtained by multiplexing one or more
among video streams, audio streams, presentation graphics
streams, and interactive graphics streams. The video stream
indicates a primary video or a secondary video of a motion
picture, the audio stream indicates audio part of a motion
picture, and the presentation graphics stream indicates
subtitles of a motion picture. Here, when the AV stream stores
Picture-in-Picture video, as shown in FIG. 6, the primary
video constitutes ordinary video displayed in a screen, while
the secondary video constitutes a small screen within the
primary video. If the AV stream is of three-dimensional images,
the primary video is for right-eye image, and the secondary
video is for left-eye image. The interactive graphics stream
indicates a dialogue screen created by placing GUI parts on
a screen. Each stream included in the AV stream is identified
by PID. For example, a video stream used for the primary video
of a motion picture is allocated 0x1011, an audio stream is
allocated 0x1100 to OxlllF, a presentation graphics stream
is allocated 0x1200 to 0xl21F, an interactive graphics stream
is allocated 0x1400 to 0xl41F, and a video stream used for
the secondary video of a motion picture is allocated OxlBOO
to 0x1B1F.
FIG. 7 is a schematic diagram showing how the AV stream
is multiplexed. First, a video stream 701 composed of multiple
video frames, and an audio stream 704 composed of multiple
audio frames are converted to PES packet strings 7 02 and 7 05,
respectively, and further converted to TS packets 703 and
706, respectively. Similarly, data of a presentation graphics
stream 707 and of an interactive graphics 710 are converted
to PES packet strings 708 and 711, respectively, and further
converted to TS packets 7 09 and 712, respectively. An AV stream
713 is formed by multiplexing these TS packets into one stream.
[0030]
FIG. 8 gives further details on how a video stream is
stored into an PES packet string. The first row of the figure
indicates the video frame string of the video stream. The
second row indicates the PES packet string. As shown by arrows
yy1, yy2, yy3 , and yy4 in the figure, I-pictures, B-pictures,
and P-pictures which are multiple Video Presentation Units
in the video stream are divided into units of pictures and
stored into payloads of PES packets separately. Each PES packet
has a PES header storing therein PTS (Presentation Time-Stamp)
which is a presentation time of the picture, DTS (Decoding
Time-Stamp) which is a decoding time of the picture, and the
like.
FIG. 9 shows the final format used for TS packets to
be written into an AV stream. Each TS packet is a fixed-length
packet composed of a 4-byte TS header and a 184-byte TSpayload.
The TS header includes information such as PID identifying
a stream, and the TS payload stores data. Each PES packet
is divided and stored into TS payloads. In a BD-ROM, each
TS packet has a 4-byte TP_Extra_Header attached thereto and
accordingly, is written into an AV stream as a 192-byte source
packet. The TP_Extra_Header includes information such as ATS
(Arrival_Time_Stamp). ATS shows the transfer starting time
of the TS packet to a PID filter. Source packets are arranged
in the AV stream as shown in the lower level of FIG. 8, and
the number which is incremented from the beginning of the
AV stream is called SPN (Source Packet Number).
Furthermore, inaddition to the streams for video, audio,
subtitles, and the like, TS packets in an AV stream include
PAT (Program Association Table), PMT (Program Map Table),
PCR (Program Clock Reference) and the like. PAT indicates
the PID of the PMT used in the AV stream, and the PID of the
PAT itself is registered as "0". PMT includes (i) PIDs of
streams such as for video, audio, subtitles and others, (ii)
attribute information corresponding to each PID, and (iii)
descriptors related to the AV stream. The descriptors include
such as copy control information which instructs copying of
the AV stream to be permitted or rejected. In order to
synchronize ATC (Arrival Time Clock) which is the time-axis
of ATS, with STC (System Time Clock) which is the time-axis
of PTS and DTS, PCR has information on STC time corresponding
to ATS at which the PCR packet is transferred to a decoder.
FIG. 10 shows details of the data structure of PMT. At
the beginning of PMT, a PMT header describing the length of
data included in PMT is arranged. Subsequent to that, multiple
descriptors regarding the AV stream are arranged. The
descriptors describe such as the above-mentioned copy control
information. In addition, with respect to the AV stream of
the present embodiment, transformation is performed at the
TS packet level using a transformation method described later,
and a restoration descriptor used for restoring the
transformation is described as a descriptor of PMT.
After the descriptors, multiple pieces of stream
information regarding the streams included in the AV stream
are arranged. Each piece of stream information includes a
stream type for identifying compression codec or the like
of the stream, PID of the stream, and stream descriptors
describing attribute information of the stream (frame rate,
aspect ratio, etc.). The number of the stream descriptors
is equivalent to the number of the streams included in the
AV stream.

Next, description is given on the stream information
file.
The stream information file, which is management
information of an AV stream, as shown in FIG. 11, corresponds
one-to-one with an AV stream, and includes stream attribute
information and entry maps.
The stream attribute information, as shown in FIG. 12,
includes pieces of attribute information which correspond
one-to-one to the streams included in the AV stream and which
are registered for each PID. The video stream, audio stream,
presentation graphics stream, and interactive graphics stream
each have its own attribute information. The video stream
attribute information includes information on what kind of
compression codec is used to compress the video stream, what
the resolution of each picture data constituting the video
stream is, what the aspect ratio is, what the frame rate is,
and the like . The audio stream attribute information includes
information on what kind of compression codec is used to
compress the audio stream, how many channels the audio stream
has, to which languages the audio stream corresponds, how
many sampling frequencies there are, and the like. These
information are used for initialization of the decoder and
the like before the playback apparatus performs a playback.
The entry map, as shown in FIG. 13, is table information
which describes PTS indicating presentation time of each
intra-frame encoded image (hereinafter, referred to as
"I-picture") in a video stream included in the AV stream,
and SPN of the AV stream at which each I-picture starts.
In the present embodiment, information composed of a
set of PTS and SPN indicated in one row of the table is called
"entry point", and a group of TS packets storing an I-picture
indicatedby an entry point is called "entry unit" . In addition,
a value which starts with "0" and is incremented by one at
each entry point is called "entry point ID" (hereinafter,
referred to as "EP_ID") . By using this entry map, the playback
apparatus is able to specify, in the AV stream, file positions
which correspond one-to-one with arbitrary positions on the
time-axis of the video stream. For example, when performing
special playback such as fast-forward/rewind, the playback
apparatus is able to perform processing efficiently without
analyzing the AV stream by specifying I-pictures registered
in the entry map and selectively playing back the specified
I-pictures. The entry map is created for each video stream
multiplexed into the AV stream, and is managed by PID.

Next, the PlayList file (YYY.MPLS) is described.
A PlayList indicates a playback path of an AV stream.
As shown in FIG. 14, a PlayList includes one or more PlayItems
501, and each PlayItem indicates a playback section with
respect to the AV stream. Each Playltem 501 is identified
by a Playltem ID and is described in order of playback within
the PlayList. The PlayList includes entry marks 502 each
indicates a playback start point. Each entry mark 502 can
be assigned in a playback section defined by a Playltem, and
as shown in FIG. 14, is assigned to a position which can be
a playback start point with respect to the Playltem and is
used for a playback from a specified time. For example, a
motion picture Title can be played back in units of chapters
by assigning the entry marks 502 to positions where chapters
start.
Content of a Playltem is described with reference to
FIG. 15. The Playltem includes information on stream
information to be referred to 601, a playback start time 602,
a playback end time 603, and a stream selection table 605.
Since the playback start time and playback end time are time
information, the playback apparatus performs playback
processing after (a) obtaining SPN corresponding to the
specified playback start time and SPN corresponding to the
specified playback end time by referring to the entry map
of the stream information file and (b) specifying the read
start position.
The stream selection table 605 is a table indicating
whether each stream multiplexed into the AV stream to be
referred to is valid or invalid when playing the Playltem.
Specifically, according to the example shown in FIG. 15, the
AV stream includes one video stream, three audio streams,
four presentation graphics streams, and three interactive
graphics streams. According to the stream selection table
605, among these streams, video, audio 1, audio 2, presentation
graphics 1, presentation graphics 2, and interactive graphics
1 are valid. Accordingly, in this PlayItem, the
above-mentioned valid elementary streams are playable, while
the other elementary streams are not allowed to play. The
stream selection table 605 also stores attribute information
of each stream. Here, the attribute information is information
indicating characteristics of each stream. For example, audio,
presentation graphics, and interactive graphics include
language attribute and the like.

Next, description is given on restoration byte code data
under the BDPLS directory, and the transformation method and
data structure, of the AV stream, required to implement
copyright protection using the restoration byte code data.
Described below are the transformation method and data
structure of the AV stream.
First, the restoration segment and restoration
parameter are described. As shown in FIG. 16, the AV stream
is divided into multiple restoration segments based on the
entry map. Every 25 entry points from the beginning, the AV
stream is divided to a restoration segment. However, it should
be noted that the final restoration segment includes between
25 to 49 entry points so as not to be of less than 25 entry
points. A restoration segment ID (SG_ID) starts from "0" at
the beginning of the restoration segment, and is incremented
by one. A restoration parameter which is a byte string having
a constant length is defined for each restoration segment.
When transformed data in the AV stream is to be restored,
the restoration parameter defined by the restoration segment
to which the transformed data belongs is used.
Next, the restoration byte code data is described with
reference to FIG. 17. The restoration byte code data is a
program code executable by a virtual operation means such
as JAVA, and, when executed given the number of the AV stream
and restoration segment ID, generates a restoration parameter
corresponding thereto. The restoration byte code data can
be arbitrarily created by a content provider. Accordingly,
for example, the content provider is requested to make efforts
such as, with use of a key on the BD-ROM disc or in the playback
apparatus, allowing only the playback apparatus having the
correct key to generate the restoration parameter, thereby
preventing an illegal playback apparatus from performing
playback, or obfuscating program codes to prevent the program
itself from being illegally analyzed.

The transformation method of an AV stream is described
in detail in the following.
FIG. 18 shows how an AV stream is transformed. The AV
stream is transformed by steps of selecting
pre-transformation data, creating a restoration entry,
recording a restoration descriptor into PMT, and overwriting
the pre-transformation data with post-transformation data.
The pre-transformation data indicates original data
before part of a video stream, audio stream and the like which
are multiplexed into the AV stream is transformed. The
pre-transformation data which is of a constant length can
be selected at an arbitrary position in the payload of a TS
packet. Further, in the present embodiment, some of the TS
packets are protected as untransformable packets, and the
pre-transformation data cannot be selected from the
untransformable packets.
The restoration entry is created using the
pre-transformation data. The restoration entry includes the
following fields: a transformation instruction flag, a
relative packet count, an intra-packet position, and an
overwrite value. The overwrite value is set to the
pre-transformation data. The intra-packet position describes
a byte offset from the beginning of the source packet V
including the pre-transformation data. The relative packet
count contains the number of packets from the source packet
V of PMT which exists prior to the pre-transformation data
to the source packet including the pre-transformation data.
The transformation instruction flag contains at least either
"restoration not required" or "restoration required". When
transformation processing has been performed with respect
to data included in the AV stream, "restoration required"
is contained. For each restoration entry which is created
as mentioned above, a mask restoration entry is created by
performing an XOR operation on the restoration entry and the
restoration parameter corresponding to the restoration
segment including the pre-transformation data. It should be
noted that while masking is performed by an XOR operation
here, other invertible logical operations or encryption
processing can be used instead.
The mask restoration entry is included in a restoration
descriptor which is recorded in PMT as the descriptor thereof.
Here, the restoration descriptor is registered as the first
descriptor of PMT so as to enable the playback apparatus to
perform analysis processing of PMT efficiently.
Finally, the position of the pre-transformation data
in the AV stream is overwritten by the post-transformation
data such as a random value.
Even in a case where the transformation processing has
not been performed in one or more of the restoration segments
of the data of the AV stream, a restoration entry is created
with the transformation instruction flag set to "restoration
not required", and a restoration descriptor is created by
masking the created restoration entry with the restoration
parameter and is recorded in PMT. It should be noted that
while a piece of pre-transformation data is stored in one
restoration entry here, multiple pieces of pre-transformation
datacanbe stored in one restoration entry. With this structure,
the number of PMT can be reduced with respect to the
pre-transformation data.

Next, description is given on untransformable ranges
in a video stream included in the AV stream, in which the
TS packets are not allowed to be transformed. First,
description is given with respect to the primary video stream.
FIG. 19 shows, in a primary video stream included in
the AV stream, the untransformable ranges not allowed to be
transformed. The first row of FIG. 19 indicates the data
structure of the pictures in the primary video stream, and
the second row of FIG. 19 indicates the TS packets storing
the AV stream. Arrows indicate positions of the source packets
containing the beginning of the pictures (shaded areas in
the second row) . The third row of FIG. 19 indicates an entry
map corresponding to the primary video stream, and each entry
point indicates the first packet among the TS packets storing
an I-picture. Here, each I-picture indicated by an entry point
whose EP_ID is a multiple of four is rendered untransformable,
and each entry unit, in the AV stream, composed of the TS
packets storing the I-picture becomes an untransformable
range. The example in FIG. 19 shows that the I-pictures
indicated by the first entry point (EP_ID=0) and the fourth
entry point (EP_ID=4) counting from the first entry point
are untransformable. If, for example, the AV stream in FIG.
19 further continues, the I-pictures indicated by the entry
points such as EP_ID=8, EP_ID=12, EP_ID=16... are
untransformable. Here, the I-pictures indicated by the entry
points whose EP_ID is a multiple of four are untransformable.
Thus, by cyclically rendering part of the TS packets
untransformable so as to ensure that the part is not transformed,
the playback apparatus which plays back the recording medium
of the present embodiment is able to specify I-pictures which
are not transformed, in a video stream in the entry map.
Consequently, the playback apparatus can perform, by
selecting and playing the untrans formed I-pictures, special
playback such as fast-forward/rewind without executing
restoration processing which causes a load on the apparatus
playback.

Next, description is given on untransformable ranges
in the secondary video stream.
FIG. 2 0 shows video frame strings of video streams
included in the AV stream. The upper row of FIG. 2 0 shows
a video frame string of a video stream which is a primary
video and has PID of 0x1011, while the lower row of FIG. 20
shows a video frame string of a video stream which is the
secondary video and has PID of OxlBOO. As shown in FIG. 20,
intervals between an I-picture and the next I-picture may
differ between the primary video and the secondary video.
Here, if it is assumed that I-pictures indicated by the entry
points whose EP_ID is a multiple of four are untransformable
for the entry maps of both the primary video and secondary
video, then when the playback apparatus plays back the
I-pictures indicated by the entry points whose EP_ID is a
multiple of four, for both the primary video and secondary
video, while performing special playback such as
fast-forward/rewind, it may result in playing pictures whose
PTSs are considerably distant between the primary video and
the secondary video in terms of time.
Thus, entry points indicating untransformable
I-pictures in the entry map of the secondary video are
determined as shown in FIG. 21. FIG. 21 shows PTS positions
of entry points with respect to STC which is a playback time
axis of the AV stream. Arrows shown in the second row of FIG.
21 indicate PTS positions of entry points of the primary video
having PID of 0x1011. EP_ID of each of these entry points
is a multiple of four, and the I-pictures indicated by these
entry points are untransf ormable. Arrows shown in the third
row of FIG. 21 indicate PTS positions of entry points of the
secondary video having PID of 0x1B00. Here, with respect to
each PTS position of an entry point whose PID is 0x1011 and
EP_ID is a multiple of four, an I-picture indicated by, among
the entry points having PID of OxlBOO, an entry point whose
PTS is closest to the PTS position is rendered untransformable,
and the entry unit storing this I-picture in the secondary
stream is rendered untransformable. For example, among the
entry points having PID of 0x1B00, an entry point having EP_ID
of B is closest to the PTS of the entry point whose PID is
0x1011 and EP_ID is 4N. Accordingly, the I-picture indicated
by this entry point is rendered untransformable. Similarly,
among the entry points having PID of OxlBOO, the entry point
having EP_ID of C is closest to the PTS of the entry point
whose PID is 0x1011 and EP_ID is 4(N+1). Accordingly, the
I-picture indicated by this entry point is rendered
untransformable. Furthermore, among the entry points having
PID of OxlBOO, the entry point having EP_ID of E and the entry
point having EP_ID of F are closest to the PTS of the entry
point whose PID 0x1011 and EP_ID is 4(N+2). In this case,
both I-pictures indicated by these two entry points are
rendered untransformable.
The I-pictures rendered untransformable are shaded
pictures in the picture strings in the video streams shown
in FIG. 22. With the AV stream having this data structure,
when performing fast-forward/rewind of the primary and
secondary videos, the playback apparatus can play I-pictures
which are closest to each other in terms of presentation time,
using the I-pictures rendered untransformable . This realizes
the synchronized playback of the primary and secondary videos
as a result. Here, if the AV stream recorded on the BD-ROM
100 is of three-dimensional images, where the primary video
is for right-eye image and the secondary video is for left-eye
image, the shaded I-pictures in the right-eye and left-eye
images are closest to each other in terms of presentation
time, that is to say, the right-eye and left-eye pictures
constituting a three-dimensional frame. This enables natural
three-dimensional playback when performing
fast-forward/rewind playback using only these I-pictures.
It should be noted that in FIG. 21, a modification can
be made such that when the difference between PTS of an entry
point of the primary video whose PID is 0x1011 and EP_ID is
a multiple of four, and PTS of an entry point of the secondary
video whose PID is 0x1B00 and which is closest to the
aforementioned PTS is more than half of the maximum value
of the interval of I-pictures set by the BD-ROM format, the
I-picture indicated by the entry point having PID of 0x1B00
does not need to be rendered untransformable. As a result,
when playing back an I-picture of an entry point whose PID
is 0x1011 and EP_ID is a multiple of four, the playback
apparatus is not required to play back a part unnecessarily
further away to play back an untransformable I-picture of
an entry point having PID of 0x1B00. This reduces the load
on the playback apparatus.
Also, a modification can be made as in the following:
in a case where there are two entry points, among the entry
points of the secondary video having PID of 0x1B00, whose
PTSs are equally closest to the PTS of an entry point of the
primary video whose PID is 0x1011 and EP_ID is a multiple
of four, the I-picture indicated by one of the two entry points
with PTS which is positioned posterior to the other is rendered
untransformable, and the I-picture indicated by the other
which is positioned anterior is not rendered untransformable .
For example, in FIG. 21, among the entry points having PID
of 0x1B00, the entry point having EP_ID of E and the entry
point having EP_ID of F are closest to the PTS of the entry
point whose PID is 0x1011 and EP_ID is 4 (N+2) . In accordance
with the modification, only the I-picture indicated by the
posteriorly positioned entry point having EP_ID of F is
rendered untransformable.
Up to this point, the data structure of the BD-ROM which
is the recording medium of the present invention has been
described.

As described above, according to the present invention,
the following two aspects can be achieved: (i) copyright
protection at the TS packets level is realized by transforming
part of the AV stream; and (ii) because every fourth entry
unit in the primary video stream and entry units, in the
secondary video stream, each storing Presentation Time Stamp
(PTS) closest to the every fourth entry unit in the primary
video stream are ensured to be untransformed, by selectively
using these untransformed entry units, it is not necessary
to execute transform restoration processing when performing
high-speed fast-forward/rewind playback, thereby preventing
increase of processing load.
Here, in particular, the TS packets in the secondary
video stream which are ensured to be untransformed constitute
entry units closest, in terms of time, to the every fourth
entry unit in the primary video stream. Accordingly, even
selective use of the entry units constituted by these
untransformed TS packets also enables fast-forward/rewind
where the primary video stream and the secondary video stream
are as closely synchronized as possible.

The following describes modifications of the present
embodiment, with respect to the selection of the I-pictures
to be rendered untranformable in the secondary video.
(1) It should be noted that the untransformable
I-pictures in the secondary video may be determined as shown
in FIG. 23. FIG. 23 shows SPN positions of entry points with
respect to the AV stream file. Arrows shown in the second
row of FIG. 23 indicate SPN positions of the entry points
having PID of 0x1011. EP_ID of each of these entry points
is a multiple of four, and the I-pictures indicated by these
entry points are untransformable. Arrows shown in the third
row of FIG. 23 indicate SPN positions of the entry points
having PID of 0x1B00. Here, with respect to each SPN position
of an entry point with EP_ID of a multiple of four, in the
primary video stream having PID of 0x1011, an I-picture
indicated by, among the entry points of the secondary video
stream having PID of 0x1B00, an entry point whose SPN is closest
to the SPN position is rendered untransformable.
For example, among the entry points having PID of 0x1B00,
an entry point having EP_ID of B is closest to the SPN of
the entry point whose PID is 0x1011 and EP_ID is 4N. Accordingly,
the I-picture indicated by this entry point is rendered
untransformable. Similarly, among the entry points having
PID of 0x1B00, the entry point having EP_ID of C is closest
to the SPN of the entry point whose PID is 0x1011 and EP_ID
is 4 (N+l) . Accordingly, the I-picture indicated by this entry
point is rendered untransformable. Furthermore, among the
entry points whose PID is 0x1B00, the entry point having EP_ID
of E and the entry point having EP_ID of F are closest to
the SPN of the entry point whose PID is 0x1011 and EP_ID is
4 (N+2) . In this case, both I-pictures indicated by these two
entry points are rendered untransformable.
In the present modification, untransformable
I-pictures of the primary and secondary videos are stored
at positions close to each other in the packet sequences of
the AV stream. With the AV stream having this data structure,
when performing fast-forward/rewind of the primary and
secondary videos, the playback apparatus uses I-pictures
which are close to each other in terms of storage position
in the file for playback, thereby reducing the load of BD-ROM
drive reading processing.
It should be noted that in FIG. 23, a modification can
be made such that when the difference between (a) SPN of an
entry point having EP_ID of a multiple of four, of the primary
video stream having PID of 0x1011, and (b) SPN of, among entry
points of the secondary video whose PID is 0x1B00, an entry
point whose SPN is closest to the SPN pertaining to PID of
0x1011 is more than a size determined by (half of the maximum
temporal interval between I -pictures set by the BD-ROM format)
* (bitrate size of the AV stream), the I-picture pertaining
to PID of 0x1B00 does not need to be rendered untransf ormable .
As a result, when playing an I-picture of the entry point
having EP_ID of a multiple of four, of the primary video stream
having PID of 0x1011, the playback apparatus is not required
to play back a part unnecessarily further away to play back
an untransf ormable I-picture of an entry point of the secondary
video having PID of 0x1B00, thereby reducing the load on the
playback apparatus.
(2) As another modification, the untransformable
I-pictures in the secondary video may be determined as shown
in FIG. 24. FIG. 24 shows SPN positions of entry points with
respect to the AV stream file. Arrows shown in the second
row of FIG. 24 indicate SPN positions of the entry points
having PID of 0x1011. EP_ID of each of these entry points
is a multiple of four, and the I-pictures indicated by these
entry points are untransf ormable. Arrows shown in the third
row of FIG. 24 indicate SPN positions where beginnings of
the I-pictures of the secondary video having PID of 0x1B00
exist. Here, the first I-picture among I-pictures of the
secondary video positioned posterior to the entry point having
EP_ID of a multiple of four, of the primary video having PID
of 0x1011, are rendered untransformable. In other words, in
the secondary video, an entry unit storing the first I-picture,
among the I-pictures whose SPN are positioned posterior to
the entry point, of the primary video, having EP_ID of a
multiple of four, becomes a untransformable range.
For example, in FIG. 24, among the I-pictures whose PID
is 0x1B00 and which are positioned posterior to the SPN
indicated by the entry point whose PID is 0x1011 and EP_ID
is 4N, the I-picture#B is the beginning of the picture closest
to the SPN pertaining to PID of 0x1011. Accordingly, this
I-picture is rendered untransformable. Similarly, among the
I-pictures positioned posterior to the SPN of the entry point
whose PID is 0x1011 and whose EP_ID is 4 (N+1), the I-picture#E
is the beginning of the picture closest to the SPN of the
entrypoint whose PID is 0x1011 andEP_ID is 4 (N+l) . Accordingly,
this I-picture is rendered untransformable. With this
structure, untransformed I-pictures of the secondary video
can be specif ied using only the entry map of the primary video,
thereby reducing the load of implementation of the playback
apparatus.
It should be noted that this can be modified such that
when the difference between SPN of an entry point whose PID
is 0x1011 and EP_ID is a multiple of four, and SPN of, among
each beginning of pictures whose PID is 0x1B00 and SPN is
positioned posterior to the SPN pertaining to PID of 0x1011,
the beginning of a picture whose SPN is closest to the SPN
pertaining to PID of 0x1011 is more than a size determined
by (the maximum temporal interval between I-pictures set by
the BD-ROM format) * (bitrate size of the AV stream), the
I-picture pertaining to PID of 0x1B00 does not need to be
rendered untransformable. As a result, when playing an
I-picture of an entry point whose PID is 0x1011 and EP_ID
is a multiple of four, the playback apparatus is not required
to play back a part unnecessarily further away to play back
an untransformable I-picture of an entry point having PID
of 0x1B00, thereby reducing the load on the playback apparatus.
(3) As another modification, the untransformable
I-pictures in the secondary video may be determined as shown
in FIG. 25. FIG. 25 shows PTS positions of entry points with
respect to the STC which is the playback time axis of the
AV stream. Arrows shown in the second row of FIG. 25 indicate
the PTS positions of the entry points having PID of 0x1011.
EP_ID of each of these entry points is a multiple of four,
and the I-pictures indicated by these entry points are
untransformable. Arrows shown in the third row of FIG. 25
indicate the PTS positions of the entry points having PID
of 0x1B00. Here, with respect to each PTS position whose PID
is 0x1011 and EP_ID is a multiple of four, an I-picture
indicated by, among the entry points whose PID is 0x1B00 and
which are positioned posterior to the PTS position, an entry
point whose PTS is closest to the PTS position is rendered
untransformable.
For example, among the entry points whose PID is 0x1B00
and which are positioned posterior to the PTS of the entry-
point whose PID is 0x1011 and EP_ID is 4N, the entry point
having EP_ID of B is closest to the PTS of the entry point
whose PID is 0x1011 and EP_ID is 4N. Accordingly, the I-picture
indicated by this entry point is rendered untransformable.
Similarly, among the entry points whose PID is 0x1B00 and
which are positioned posterior to the PTS of the entry point
whose PID is 0x1011 and EP_ID is 4 (N+1), the entry point having
EP_ID of C is closest to the PTS of the entry point whose
PID is 0x1011 and EP_ID is 4 (N+l) . Accordingly, the I-picture
indicated by this entry point is rendered untransformable.
With this data structure, when performing fast-forward/rewind
of primary and secondary videos, the playback apparatus can
easily search I-pictures which are close to each other in
terms of presentation time, thereby realizing efficient
fast-forward/rewind of the primary and secondary videos by
the playback apparatus as a result.
It should be noted that this can be modified such that
when the difference between PTS of an entry point whose PID
is 0x1011 and EP_ID is a multiple of four, and PTS of an entry
point whose PID is 0x1B00 and which is closest to the
aforementioned PTS is more than the maximum value of the
interval of I-pictures set by the format, the I-picture
indicated by the entry point having PID of 0x1B00 does not
need to be rendered untransformable . As a result, when playing
back an I-picture of an entry point whose PID is 0x1011 and
EP_ID is a multiple of four, the playback apparatus is not
required to play back a part unnecessarily further away to
play back an untransformable I-picture of an entry point having
PID of 0x1B00 . This reduces the load on the playback apparatus.
(4) As another modification, the untransformable
I-pictures in the the secondary video may be determined as
shown in FIG. 26. FIG. 26 shows SPN positions of entry points
with respect to the AV stream file. Arrows shown in the second
row of FIG. 26 indicate the SPN positions of the entry points
having PID of 0x1011. EP_ID of each of these entry points
is a multiple of four, and the I-pictures indicated by these
entry points are untransformable. Arrows shown in the third
row of FIG. 2 6 indicate SPN positions where beginnings of
the I-pictures of the secondary video having PID of 0x1B00
exist. Here, with respect to each SPN position whose PID is
0x1011 and EP_ID is a multiple of four, an I-picture, of the
secondary video having PID of 0x1B00, whose SPN at the beginning
thereof is closest to the SPN position is rendered
untransformable.
For example, in FIG. 26, among the I-pictures having
PID of 0x1B00, the I-picture#B is the beginning of the picture
closest to the SPN indicated by the entry point whose PID
is 0x1011 and EP_ID is 4N. Accordingly, this I-picture is
rendered untransformable. Similarly, among the I-pictures
having PID of 0x1B00, the I-picture#c is the beginning of
the picture closest to the SPN of the entry point whose PID
is 0x1011 and EP_ID is 4(N+1). Accordingly, this I-picture
is rendered untransformable. With this data structure, when
performing fast-forward/rewind of primary and secondary
videos, the playback apparatus can easily search and play
I-pictures which are close to each other in terms of file
position, thereby realizing efficient fast-forward/rewind
of the primary and secondary videos by the playback apparatus
as a result.
It should be noted that this can be modified such that
when the difference between SPN of an entry point whose PID
is 0x1011 and EP_ID is a multiple of four, and SPN of, among
I-pictures having PID of 0x1B00, an I-picture whose SPN is
closest to the SPN pertaining to PID of 0x1011 is more than
the size determined by (the maximum temporal interval between
I-pictures set by the format) * (bitrate size of the AVclip) ,
the I-picture pertaining to PID of 0x1B00 does not need to
be rendered untransformable. As a result, when playing an
I-picture of the entry point whose PID is 0x1011 and EP_ID
is a multiple of four, the playback apparatus is not required
to play back a part unnecessarily further away to play back
an untransformable I-picture of an entry point having PID
of 0x1B00, thereby reducing the load on the playback apparatus.
(5) As another modification, the untransformable
I-pictures in the secondary video may be determined as shown
in FIG. 27.
FIG. 2 7 shows PTS positions of entry points with respect
to the STC which is the playback time axis of the AV stream.
Arrows shown in the second row of FIG. 27 indicate the PTS
positions of the entry points having PID of 0x1011. EP_ID
of each of these entry points is a multiple of four, and the
I-pictures indicated by these entry points are
untransformable. Arrows shown in the third row of FIG. 27
indicate the PTS positions of the entry points having PID
of 0x1B00. Here, with respect to each PTS position whose PID
is 0x1011 and EP_ID is a multiple of four, part of the stream
from SPN of, among the entry points whose PID is 0x1B00 and
whose PTS is equivalent to or positioned anterior to the PTS
position, an entry point whose PTS is closest to the PTS
position, to SPN of the next entry point having PID of 0x1B00
is rendered untransformable.
For example, among the entry points whose PID is 0x1B00
and PTS is equivalent to or positioned anterior to PTS of
the entry point whose PID is 0x1011 and EP_ID is 4N, the entry
point having EP_ID of A is closest to the PTS of the entry
point whose PID is 0x1011 and EP_ID is 4N. And the next entry
point having PID of 0x1B00 is the entry point having EP_ID
of B. Accordingly, the secondary video stream between SPNs
of these two entry points is rendered untransformable.
Similarly, among the entry points whose PID is 0x1B00 and
whose PTS is equivalent to or positioned anterior to PTS of
the entry point whose PID is 0x1011 and EP_ID is 4 (N+1), the
entry point having EP_ID of C is closest to the PTS of the
entry point whose PID is 0x1011 and EP_ID is 4 (N+1). And the
next entry point having PID of 0x1B00 is the entry point having
EP_ID of D. Accordingly, the secondary video stream between
SPNs of these two entry points is rendered untransf ormable.
[0071]
With this data structure, when performing
fast-forward/rewind of primary and secondary videos, the
playback apparatus can easily search the secondary video
stream which has the same PTS as the presentation time, thereby
realizing efficient fast-forward/rewind of the primary and
secondary videos by the playback apparatus as a result.
(6) As another modification, the untransformable
I-pictures in the secondary video may be determined as shown
in FIG. 28.
FIG. 2 8 shows PTS positions of entry points with respect
to the STC which is the playback time axis of the AV stream.
The arrows shown in the second row of FIG. 28 indicate the
PTS positions of the entry points having PID of 0x1011. EP_ID
of each of these entry points is a multiple of four, and the
I-pictures indicated by these entry points are
untransformable. Arrows shown in the third row of FIG. 28
indicate the PTS positions of the entry points having PID
of 0x1B00. Here, with respect to each PTS position whose PID
is 0x1011 and whose EP_ID is a multiple of four, part of the
stream from SPN of, among the entry points whose PID is 0x1B00
and whose PTSs are positioned anterior to the PTS position,
an entry point whose PTS is closest to the PTS position, to
SPN of the next entry point having PID of 0x1B00 is rendered
untransformable. However, it should be noted, with respect
to each PTS position whose PID is 0x1011 and whose EP_ID is
a multiple of four, if an entry point whose PID is 0x1B00
and whose PTS is equivalent to the PTS position exists, an
I-picture indicated by this entry point is rendered
untransformable.
For example, among the entry points whose PID is 0x1B00
and whose PTSs are positioned anterior to PTS of the entry
point whose PID is 0x1011 and EP_ID is 4N, the entry point
having EP_ID of A is closest to the PTS of the entry point
whose PID is 0x1011 and EP_ID is 4N. And the next entry point
having PID of 0x1B00 is the entry point having EP_ID of B.
Accordingly, the secondary video stream between SPNs of these
two entry points is rendered untransformable. Further, among
the entry points whose PID is 0x1B00, PTS of the entry point
having EP_ID of C is equivalent to the PTS of the entry point
whose PID is 0x1011 and EP_ID is 4(N+1). Accordingly, the
I-picture indicated by this entry point is rendered
untransformable.
With this data structure, when performing
fast-forward/rewind of primary and secondary videos, the
playback apparatus can easily search the secondary video
stream which has the same PTS as the presentation time, thereby
realizing efficient fast-forward/rewind of the primary and
secondary videos by the playback apparatus as a result.
(7) As another modification, the untransformable
I-pictures in the secondary video may be determined as shown
in FIG. 29.
FIG. 2 9 shows PTS positions of entry points with respect
to the STC which is the playback time axis of the AV stream.
Arrows shown in the second row of FIG. 2 9 indicate the PTS
positions of the entry points having PID of 0x1011. EP_ID
of each of these entry points is a multiple of four, and the
I-pictures indicated by these entry points are
untransformable. Arrows shown in the third row of FIG. 29
indicate the PTS positions of the entry points having PID
of 0x1B00. Here, with respect to each PTS position whose PID
is 0x1011 and EP_ID is a multiple of four, part of the stream
from SPN of, among the entry points whose PID is 0x1B00 and
PTSs are equivalent to or positioned anterior to the PTS
position, an entry point whose PTS is closest to the PTS
position, to the I-picture of the next entry point having
PID of 0x1B00 is rendered untransformable.
For example, among the entry points whose PID is 0x1B00
and PTSs are equivalent to or positioned anterior to PTS of
the entry point whose PID is 0x1011 and EP_ID is 4N, the entry
point having EP_ID of A is closest to the PTS of the entry
point whose PID is 0x1011 and EP_ID is 4N. And the I-picture
indicated by the next entry point having PID of 0x1B00 is
the entry point having EP_ID of B. Accordingly, the secondary
video stream from SPN of this entry point having EP_ID of
A to the I-picture indicated by the entry point having EP_ID
of B is rendered untransformable. Similarly, among the entry
points whose PID is 0x1B00 and whose PTSs are equivalent to
or positioned anterior to PTS of the entry point whose PID
is 0x1011 and EP_ID is 4(N+1) , the entry point having EP_ID
of C is closest to the PTS of the entry point whose PID is
0x1011 and EP_ID is 4(N+1) . And the next entry point having
PID of 0x1B00 is the entry point having EP_ID of D. Accordingly,
the secondary video stream from SPN of this entry point having
EP_ID of C to the I-picture indicated by the entry point having
EP_ID of D is rendered untransformable.
With this data structure, when performing
fast-forward/rewind of primary and secondary videos, the
playback apparatus can easily search the picture of the
secondary video stream which has the same PTS as the
presentation time of the primary video, while at the same
time being able to easily search, the I-picture of the secondary
video being closest to the presentation time of the primary
video, thereby realizing efficient fast-forward/rewind of
the primary and secondary videos by the playback apparatus
as a result.
(8) As another modification, the untransformable
I-pictures in the secondary video may be determined as shown
in FIG. 30.
FIG. 3 0 shows PTS positions of entry points with respect
to the STC which is the playback time axis of the AV stream.
Arrows shown in the second row of FIG. 30 indicate the PTS
positions of the entry points having PID of 0x1011. EP_ID
of each of these entry points is a multiple of four, and the
I-pictures indicated by these entry points are
untransformable. Arrows shown in the third row of FIG. 30
indicate the PTS positions of the entry points having PID
of 0x1B00. Here, with respect to each PTS position whose PID
is 0x1011 and EP_ID is a multiple of four, part of the stream
from SPN of, among the entry points whose PID is 0x1B00 and
whose PTS is positioned anterior to the PTS position, an entry
point whose PTS is closest to the PTS position, to the I-picture
indicated by the next entry point having PID of 0x1B00 is
rendered untransformable. However, it should be noted, with
respect to each PTS position whose PID is 0x1011 and EP_ID
is a multiple of four, if an entry point whose PID is 0x1B00
and PTS is equivalent to the PTS position exists, an I-picture,
in the secondary video, indicated by this entry point is
rendered untransformable.
For example, among the entry points whose PID is 0x1B00
and whose PTSs are positioned equivalent to or anterior to
PTS of the entry point whose PID is 0x1011 and EP_ID is 4N,
the entry point having EP_ID of A is closest to the PTS of
the entry point whose PID is 0x1011 and EP_ID is 4N. And the
next entry point having PID of 0x1B00 is the entry point having
EP_ID of B. Accordingly, the secondary video stream from SPN
of this entry point having EP_ID of A to the I-picture
indicated by the entry point having EP_ID of B is rendered
untransformable. Further, among the entry points whose PID
is 0x1B00, PTS of the entry point having EP_ID of C is equivalent
to the PTS of the entry point whose PID is 0x1011 and EP_ID
is 4 (N+l) . Accordingly, the I-picture indicated by this entry
point is rendered untransformable.
With this data structure, when performing
fast-forward/rewind of primary and secondary videos, the
playback apparatus can easily search the picture of the
secondary video stream which has the same PTS as the
presentation time of the primary video, while at the same
time being able to easily search the I-picture of the secondary
video being closest to the presentation time of the primary
video, thereby realizing efficient fast-forward/rewind of
the primary and secondary videos by the playback apparatus
as a result.
It should be noted that when the pictures to be rendered
untransf ormable, indicated by the entry points of the entry
maps of the primary and secondary videos, are of a field
structure and the picture of the second field is inter-frame
encoded (for example, Predictive method) , both the first and
second fields can be rendered untransformable. With this
structure, when executing special playback without restoring
the stream, the playback apparatus is able to play back data
in both of the first and second fields of the picture, which
are to be rendered untransformable, indicated by the entry
map.
[Second Embodiment]
In the second embodiment, the playback apparatus of the
present invention is described.
FIG. 31 shows a structure of a playback apparatus 200.
The playback apparatus 200 includes a BD-ROM drive 11, a read
buffer 12, a system target decoder 13, a data restoration
processing unit 14, a restoration entry generation unit 15,
a restoration byte code data execution unit 16, a data analysis
execution unit 17, and a user event processing unit 18.
The BD-ROM drive 11 reads data from the BD-ROM disc based
on commands from the data analysis execution unit 17 and stores
the read data into the read buffer 12. The data read from
the BD-ROM disc includes the Index File, Movie Object file,
and PlayList file in addition to the AV stream. When a command
to read restoration byte code data is generated by the
restoration byte code data execution unit 16 , the BD-ROM drive
11 reads the restoration byte code data from the BD-ROM disc
and transmits it to the restoration byte code data execution
unit 16.
The read buffer 12 is a buffer composed of a memory or
the like temporarily storing the data read using the BD-ROM
driver.
The system target decoder 13 performs demultiplexing
processing on source packets read by the read buffer 12, and
decodes and plays back each stream. When data of PMT is
transferred from the read buffer 12 and a system target decoder
in the system target decoder 13 detects a restoration
descriptor, the system target decoder 13 transfers to the
restoration entry generation unit 15 the restoration
descriptor and SPN of the PMT packet in which the restoration
descriptor is described. Details of the system target decoder
13 are described later.
The user event processing unit 18 responds to user
operations via the remote controller and requests the data
analysis execution unit 13 to execute processing. For example,
when a button on the remote controller is pressed, the user
event processing unit 18 requests the data analysis execution
unit 13 to execute the command contained in the button. For
example, when the fast-forward/rewind button on the remote
controller is pressed, the user event processing unit 18
instructs the data analysis execution unit 13 to execute
fast-forward/rewind processing on the AV stream of the
PlayList currently being played back.
The restoration byte code data execution unit 16, upon
receiving an execution command from the data analysis
execution unit 17, receives the number of the AV stream and
the restoration segment ID from the data analysis execution
unit 17, acquires the restoration byte code data 16 from the
BD-ROM drive 11, and executes processing. A restoration
parameter generated from the restoration byte code data is
passed on to the restoration entry generation unit.
The restoration entry generation unit 15 generates a
restoration entry by executing, on the mask restoration entry
included in the restoration descriptor transferred from the
system target decoder 13, XOR operation processing of the
restoration parameter transferred from the restoration byte
code data execution unit 16. The restoration entry generation
unit 15 transfers SPN of a PMT packet corresponding to the
generated restoration entry, to the data restoration
processing unit 14.
The data restoration processing unit 14 receives the
SPN of the PMT packet corresponding to the restoration entry
transferred from the restoration entry generation unit 15
and executes restoration processing. When the transformation
instruction flag of the restoration entry is "restoration
not required" , the data restoration processing unit 14 ignores
the restoration entry and performs no processing. When the
transformation instruction flag of the restoration entry is
"restoration required" , the data restoration processing unit
14 identifies a source packet, which is the restoration target,
based on the relative packet count and the SPN of the PMT
packet, and finds the identified source packet in the read
buffer 12. The data restoration processing unit 14 identifies
an overwrite position in the source packet based on the
intra-packet position of the restoration entry, and
overwrites it with the overwrite value.
The data analysis execution unit 17 includes a command
processor executing navigation commands which constitute a
Movie Object, and a playback control engine. The playback
control engine plays back the AV stream, via the PlayList
information, based on an execution result of PlayPL command
by the command processor, API calls by a platform unit, and
the like. The data analysis execution unit 17 manages how
far the AV stream has been played back, and prior to changing
of the restoration segment in the AV stream, instructs the
restoration byte code data execution unit 16 to execute the
restoration byte code data to generate the next restoration
parameter.
The data analysis execution unit 17 , uponbeing notified,
by the restoration byte code data execution unit 16, of an
execution command of special playback which is high-speed
fast-forward/rewind, analyzes the entry map in which PID in
the stream information file of the AV stream to be played
back indicates the primary video, and identifies entry points
whose EP_ID is a multiple of four. Next, the data analysis
execution unit 17 analyzes the entry map in which PID in the
stream information file of the AV stream to be played back
indicates the secondary video. After selecting the entry point
of the primary video to be played back first, the data analysis
execution unit 17 selects, in the entry map of the secondary
video, an entry point whose PTS is close to the PTS of the
entry point of the primary video. Following that, the data
analysis execution unit 17 realizes high-speed
fast-forward/rewind by repeating the following processing
(1) to (4). (1) The data analysis execution unit 17 notifies
the BD-ROM drive 11 of the smallest SPN among the selected
entry points of the primary video and secondary video, and
requests the BD-ROM drive 11 to start reading from the notified
SPN. (2) The data analysis execution unit 17 provides
information on the entry points of the primary video and
secondary video to the system target decoder 13 , and instructs
the system target decoder 13 to play back only I-pictures
therein. (3) The data analysis execution unit 17 receives
notification of playback completion of the I-pictures of the
primary video and secondary video from the system target
decoder 13. (4) The data analysis execution unit 17 selects,
in the entry map of the primary video, an entry point to be
played back next whose EP_ID is a multiple of four, and selects,
in the entry map of the secondary video, an entry point whose
PTS is closest to the PTS of the selected entry point of the
primary video. Note that obviously, not all of the entry points
in the primary video with a multiple of four need to be played
back, and the entry points are selected and played back in
accordance with the speed of fast-forward/rewind specified
by the user.

Next, the system target decoder 13 is described with
reference to FIG. 32.
A source packetizer 21 interprets source packets
transferred to the system target decoder 13 , fetches TS packets
therefrom, and transmits the fetched TS packets to a PID filter
23. When transmitting the TS packets to the PID filter 23,
the source packetizer 21 adjusts input time to the decoder
according to ATS of each source packet. Specifically, when
the value of ATC generated by an ATC counter 22 coincides
with the value of ATC of the source packet, the source
packetizer 21 sends only the TS packet to the PID filter 23
in accordance with the recording rate of the ACVlip.
The PID filter 23 transfers, among the TS packets output
from the source packetizer 21, TS packets whose PID coincides
with PID required for the playback to, in accordance with
PID, a primary video decoder 24, a secondary video decoder
25, an IG decoder 26, a PG decoder 27, an audio decoder 28,
and a system packet decoder 29. For example, for a BD-ROM,
the PID filter 23 sends a TS packet to the primary video decoder
24 when PID included in the TS packet is 0x1011, to the secondary
video decoder 2 5 when PID is 0x1B00 to 0x1B1F, to the audio
decoder 28 when PID is 0x1100 to 0x111F, to the PG decoder
27 when PID is 0x1200 to 0x121F, to the IG decoder 26 when
PID is 0x1400 to 0x141F, and to the system packet decoder
29 when PID is 0x0000 indicating PAT or 0x0100 indicating
PMT.
The primary video decoder 24 includes TB
(TransportStreamBuffer) 30, MB (Multiplexing Buffer) 31, EB
(ElementaryStreamBuf fer) 32, a compressed video decoder 33,
RB (Re-order Buffer) 34, and a switch 35.
The TB 30 is a buffer temporarily storing TS packets
belonging to a video stream when the TS packets are output
from the PID filter 23.
The MB 31 is a buffer temporarily storing PES packets
when the TB 30 outputs the video stream to the EB 32.
[0097]
The EB 32 is a buffer storing encoded pictures
(I-pictures, B-pictures, and P-pictures).
The compressed video decoder 33 creates multiple frame
images by decoding each frame image in the video elementary
stream according to a predetermined decoding time (DTS).
Compression encoding methods used for video streams
multiplexed into an AV stream include MPEG2, MPEG4AVC, VC1,
and the like, and the compressed video decoder 33 is set
according to the attribute of the stream. The compressed video
decoder 33, when information on the entry maps has been
transmitted from the data analysis execution unit 17 to the
system target decoder 13 and the information instructs only
playback of I-pictures, notifies the data analysis execution
unit 17 upon completion of decoding of the I-pictures.
The RB 34 is a buffer for changing the order of the decoded
pictures from the order of encoding to the order of
presentation.
The switch 35 is a switch for changing the order of the
decoded pictures from the order of encoding to the order of
presentation. Changeover of the switch 3 5 causes the pictures
to be written into a plain memory 42 in accordance with the
presentation time (PTS).
The secondary video decoder 25 which has the same
structure as the primary video decoder 24 decodes input
secondary video streams and writes the pictures into a plain
memory 43 in accordance with the presentation time (PTS).
The IG decoder 26 extracts and decodes interactive
graphics streams from the TS packets input from the source
packetizer and writes uncompressed graphics data into a plain
memory 44 in accordance with the presentation time (PTS).
The PG decoder 2 7 extracts and decodes presentation
graphics streams from the TS packets input from the source
packetizer and writes uncompressed graphics data into a plain
memory 45 in accordance with their presentation time (PTS) .
The addition unit 4 6 instantaneously overlaps the data
written in the plain memories 42, 43, 44, and 45 and displays
the overlapped data on TV or the like.
The audio decoder 2 8 is composed of TB
(TransportStreamBuffer) 36, B (Buffer) 37, and a compressed
audio decoder 38.
The TB 36 stores the TS packets output from the PID filter
23 in a first-in first-out manner and transfers the stored
TS packets to the B 37 at a constant bitrate.
The B 37 stores the audio stream input from the TB 36
in a first-in first-out manner and provides the stored audio
stream to the compressed audio decoder 38 in units of PES
packets.
The compressed audio decoder 3 8 performs decoding
processing on the input PES packets, thereby obtaining audio
data in compressed LPCM, and outputs the obtained audio data
in accordance with the playback time (PTS). Compression
encoding methods for audio streams to be multiplexed into
an AV stream include AC3, DTS and the like. The compression
video decoder 33 is switched in accordance with the attribute
of the stream.
The system packet decoder 29 is composed of TB
(TransportStreamBuffer) 39, B (Buffer) 40, and a system packet
analysis unit 41.
The TB 39 stores the TS packets output from the PID filter
23 in a first-in first-out manner and transfers the stored
TS packets to the B 40 at a constant bitrate.
The B 40 transfers the data input from the TB 39 at a
constant transfer rate and data of PAT and PMT, to the system
packet analysis unit 41.
The system packet analysis unit 41 analyzes contents
of input transferred PAT and PMT. For example, the system
packet analysis unit 41 analyzes stream information described
in PMT and initializes the respective decoders. When PMT
includes a restoration descriptor at the beginning thereof,
the system packet analysis unit 41 extracts the restoration
descriptor and notifies the restoration entry generation unit
15 of SPN of the PMT packet.
Describedabove is the hardware structure of theplayback
apparatus of the present invention.
Next, detailed description is given on operations during
high-speed fast-forward/rewindplayback, which is the feature
of the playback apparatus of the present embodiment. The
operations during high-speed fast-forward/rewind playback
are controlled by the data analysis execution unit 17. FIG.
33 is a flowchart showing the processing by the data analysis
execution unit 17.
Upon receiving a fast-forward/rewind instruction by
user operation, the data analysis execution unit 17 first
sets a variable n allocated on a work memory to 0 (S101),
and determines a multiple-speed parameter A in accordance
with the specified playback speed (S102).
After that, the data analysis execution unit 17 selects
entry points of the primary video and secondary video for
playback by executing playback entry point selection
processing using the variable n and multiple-speed parameter
A (S103) and instructs the system target decoder 13 to play
back the I-pictures indicated by the selected entry points
(S104).
The data analysis execution unit 17 executes the
above-mentioned processing repeatedly (S103 to S105), and
upon receiving a stop instruction by the user or reaching
the end of the entry map (S105 : No) , ends the special playback.
Next, description is given on the playback entry point
selection processing. FIG. 34 is a flowchart showing
processing steps of the playback entry point selection
processing.
In the playback entry point selection processing, the
data analysis execution unit 17 first searches the entry map
of the primary video for the 4An-th entry point, and selects
the entry point as the playback target of the primary video
(S111).
Next, the data analysis execution unit 17 searches the
entry map of the secondary video for an entry point whose
PTS is closest to PTS of the entry point of the primary video
selected in S111 (S112). Here, when two entry points are
detected in the secondary video (S113: Yes), one of the two
which is posteriorly positioned to the other in terms of time
is selected as the playback target of the secondary video
(S114). When one entry point is detected in the secondary
video in S112 (S113 :No), the detected entry point is selected
as the playback target of the secondary video (S115). Lastly,
the data analysis execution unit 17 increments the variable
n by one (S116) and after that, performs the high-speed
fast-forward/rewind playback shown in FIG. 33.
Up to this point, the playback entry point selection
processing has been described in detail.
As described above, according to the present embodiment,
when an AV stream is read, for performing high-speed
fast-forward/rewindplayback thereof, from a recording medium
on which copyright protection at the TS packet level has been
realized by recording the AV stream which is partially
transformed, an increase in the processing load can be avoided
by selectively using the following TS packets: TS packets
which are ensured to be untransformed, that is, TS packets
constituting every fourth entry unit in the primary video
stream and TS packets constituting entry units in the secondary
video stream, each of which has a presentation time stamp
closest to any one of the every fourth entry unit in the primary
video stream.
[Third Embodiment]
In the third embodiment, an embodiment of the recording
apparatus and recording method of the present invention is
described. For the production and manufacturing of the BD-ROM
mentioned in the first embodiment, the recording apparatus
and the recording method of the present invention are used.
Here, the recording apparatus is so-called an authoring
apparatus which is installed at production studios for
distributing motion picture content and used by authoring
staff. A use form of the recording apparatus of the present
invention is as follows: the recording apparatus generates
digital streams which are compression encoded in accordance
with MPEG standard and scenarios which describe how to play
back motionpicture Titles, and generates, forBD-ROM, a volume
image including these. The object of the recording apparatus
of the present invention is to generate the recording medium
described in the first embodiment.
FIG. 35 shows the internal structure of the recording
apparatus of the present invention. As shown in the figure,
the recording apparatus of the present invention includes
a material production unit 201, a scenario generation unit
202, a multiplexing unit 203, a restoration entry generation
unit 204, a restoration byte code data generation unit 205,
a transformation processing unit 206, a format processing
unit 207, and a master production unit 208.
The material production 201 creates streams such as video
streams, audio streams, presentation graphics streams, and
interactive graphics streams. The material production unit
201 creates video streams by encoding video images such as
uncompressed bit map in accordance with a compression standard
such as MPEG4-AVC and MPEG2. Also, the material production
unit 201 creates audio streams by encoding uncompressed Linear
PCM audio and the like in accordance with a compression standard
such as AC3. The material production unit 201 creates
presentation graphics streams which are formats of subtitle
streams conforming to the BD-ROM standard, based on a subtitle
information file which includes subtitle images, presentation
timing, and subtitle effects such as fade-in/fade-out. The
material production unit 201 creates interactive graphics
streams which are formats of menu screens conforming to the
BD-ROM standard, based on bitmap images used for the menu
and a menu file describing transition of buttons on the menu
and presentation effects.
The scenario generation unit 202 creates scenarios in
a format conforming to the BD-ROM standard in accordance with
information on the streams created by the material production
unit 201 and operations by the authoring staff via GUI. Here,
the scenarios correspond to files such as the Index File,
Movie Object file, and PlayList file. The scenario generation
unit 202 further creates parameter files each describing which
streams compose which AV stream, to realize multiplexing
processing.
The multiplexing unit 203 multiplexes multiple streams
suchas video, audio, subtitles, buttons and the like described
in BD-ROM scenario data into an AV stream in MPEG2-TS format.
Here, a stream information file corresponding one-to-one with
the AV stream is created as well. Creation of the stream
information file by the multiplexing unit 2 03 is performed
as follows. The multiplexing unit 2 03 creates entry maps while
creating the AV stream. More specifically, the multiplexing
unit 2 03, in each of the streams generated by the material
production unit 2 01, detects where I-pictures exist if the
contained video stream is MPEG2, where I-pictures or IDR
pictures exist if the contained video stream is MPEG4-AVC,
and where I-pictures exist if the contained video stream is
VC-l. The multiplexing unit 203 then registers, in the entry
map, entry points each of which associates the presentation
time of the picture with a source packet, in the AV stream
in the MPEG2-TS format, in which the starting data of the
pictures exists. When there are two kinds of video streams.
that is, a primary video stream and a secondary video stream
in the AV stream, the multiplexing unit 2 03 creates entry
maps for these two simultaneously. The multiplexing unit 203
creates the stream information file in which the entry maps
created thereby correspond one-to-one with attribute
information indicating audio attribute, video attribute and
the like for each of the streams included in the AV stream.
Also, the multiplexing unit 203 creates, without causing
overflow to the buffer in the system target decoder 2409,
a large number such as 50 pieces, per second, of PMT packets.
In the BD-ROM, a restoration entry for transforming an AV
stream needs to be inserted as a restoration descriptor into
a PMT packet in the AV stream. Thus, a large number of PMT
packets are required to realize a large amount of data
transformation in the AV stream.
The restoration entry generation unit 204 analyzes
contents of the AV stream, selects pre-transformation data
to be transformed, and creates restoration entries. The
restoration entry generation unit 204 selects the
pre-transformation data effectively such that the image is
distorted and the AV stream cannot be played back properly
when an unauthorized playback apparatus plays back the AV
stream without restoration. Here, a large playback distortion
due to transforming pre-transformation data is defined as
"a large transformation effect". In order to select
pre-transformation data enabling a large transformation
effect when the AV stream contains a video stream, the following
priorities are taken into account. (1) Pre-transformation
data is selected in the following order of priority:
IDR-picture/I-picture -> P-picture -> B-picture. (Since a
compression method of a video stream uses compression based
on temporal correlation, transforming a picture which largely
affects correlation of pictures increases the transformation
effect.) (2) A slice header and a periphery around the
beginning of slice data in the picture are selected as
pre-transformation data. (A video stream can be decoded in
units of slices, and because slice headers and the beginning
of slice data are the most important data for the decoder,
transformation of these or a vicinity thereof increases the
transformation effect.) (3) When there are multiple slices
in the picture, the first slice is given higher priority when
selecting pre-transformation data. (The first slice header
includes such as a parameter common to slices in the picture,
and thus, transforming the first slice header increases the
transformation effect.) With respect to the
pre-transformation data selected as above, SPN of PMT
positioned anterior thereto is found out and the
transformation instruction flag, relative packet,
intra-packet position, and overwrite value are set, thereby
creating a restoration entry. Also, the restoration byte code
data generation unit 205 refers to the entry map in the stream
information file, and avoids selecting pre-transformation
data from the I-pictures, in the entry map of the primary
video, whose EP_ID is a multiple of four, for the primary
video stream. In addition, the restoration byte code data
generation unit 2 05 refers to the stream information file
in the entry map, and avoids selecting pre-transformation
data from an I-picture indicated by an entry point, in the
entry map of the secondary video, whose PTS is closest to
that of the entry point whose EP_ID is a multiple of four.
The restoration byte code data generation unit 205
calculates restoration segments based on the AV stream and
the stream information file, and creates restoration
parameters corresponding one-to-one with the restoration
segments. Also, the restoration byte code data generation
unit 205 generates restoration byte code data with respect
to the AV stream number and restoration segment ID so as to
be able to generate restoration parameter. When generating
the restoration byte code data, some efforts may be made.
These efforts are, for example, with use of a key on the BD-ROM
disc or in the playback apparatus, allowing only the playback
apparatus having the correct key to generate the restoration
parameter, thereby preventing an illegal playback apparatus
from performing playback, or obfuscating program codes to
prevent the program itself from being illegally analyzed.
Additionally, for the restoration byte code data, the
restoration byte code data generation unit 205 creates a mask
restoration entry obtained by performing XOR on the
restoration entry using the restoration parameter, and
creates a restoration entry packet in which a base SPN
indicating the pre-transformation data indicated by the
restoration entry is set, and includes these in the restoration
byte code data.
[0130]
The transformation processing unit 206 performs
transformation processing on the AV stream based on the
restoration entries created by the restoration entry
generation unit and the restoration parameters generated by
the restoration byte code data generation unit 205, thereby-
creating a transformed AV stream. The restoration byte code
data generation unit 205 creates a mask restoration entry
by performing XOR on the restoration entry using the
restoration parameter, converts the mask restoration entry
to the restoration descriptor, and inserts the converted
restoration descriptor into PMT positioned immediately before
the pre-transformation data indicated by the restoration
entry. Following that, the transformation processing unit
206 overwrites the position of the pre-transformation data
indicated by the restoration entry with a data string such
as a random value. When no pre-transformation data exists
between the PMT and the next PMT, the trans format ion processing
unit 206 creates a new restoration entry, sets the restoration
instruction flag to "transformation not required" , generates
a mask restoration entry by performing XOR on the restoration
entry with the restoration parameter, generates a restoration
descriptor, and inserts the generated restoration descriptor
into the PMT.
The format processing unit 207 arranges the following
into files and directories conforming to the BD-ROM standard,
thereby generating a disc image in the UDF format which is
a file system conforming to the BD-ROM standard: the BD-ROM
scenario data generated by the scenario generation unit 202,
the transformed AV stream generated by the transformation
processing unit 206, the stream information file generated
by the multiplexing unit 203, and the restoration byte code
data generated by the restoration byte code data generation
unit 205.
The master production unit 208 creates data for BD-ROM
pressing from the disc image generated by the format processing
unit 207 . A BD-ROM can be manufactured by performing pressing
processing on this data.
Described above is the structure of the recording
apparatus.
In the following, the BD-ROM recording method of the
recording apparatus is described with reference to FIG. 36.
In a step S201, the material production unit 201
generates the video streams, audio streams, IG streams, and
PG streams. In a step S202, the scenario generation unit 202
creates the BD-ROM scenario data describing playback scenario,
such as the IndexFile, Movie Object file, and PlayList file.
InastepS203, the multiplexingunit 203 creates the AV stream
and stream information file based on the BD-ROM scenario data.
Here, the restoration entry generation unit 204 executes
untransformable packet specification processing, thereby
specifying untransf ormable packets which are not allowed to
be transformed, among the TS packets in the primary video
and secondary video (S204). After that, the restoration entry
generation unit 204 selects pre-transformation data from
among TS packets which are other than the untransformable
packets specified in the step S204, and creates a restoration
entry (S205).
The restoration byte code data generation unit 205
generates restoration byte code data which outputs the
restoration parameter used to generate the restoration entry
in the step S205 (S206) , and the transformation processing
unit 206 creates a transformed AV stream based on the
restoration entry and the AV stream (S207).
Lastly, the format processing unit 207 rearranges the
BD-ROM scenario data, transformed AV stream, stream
information file, and restoration byte code data into a
file-directory structure conforming to the BD-ROM standard,
thereby creating a disc image conforming to the BD-ROM standard
(S208) , and the master generation unit 208 creates the data
for BD-ROM pressing (S209) . These are the processing steps
of the BD-ROM recording processing by the recording apparatus
of the present embodiment.
Next, the untransformable packet specification
processing is described in detail. FIG. 37 is a flowchart
showing processing steps of the untransformable packet
specification processing.
In the untransformable packet specif icationprocessing,
the restoration entry generation unit 204 first sets the
variable m allocated on the work memory to 0 (S211).
After that, the restoration entry generation unit 204
refers to the entry maps in the stream information file
generated by the multiplexing processing unit 203 in S203
in FIG. 36, and specif ies, among the TS packets constituting
the AV stream, TS packets constituting an I-picture indicated
by the entry point whose EP_ID is 4m in the entry map of the
primary video, as the untransformable packets (S212).
Furthermore, the restoration entry generation unit 2 04
specifies, as the untransformable packets, the TS packets
constituting an I-picture indicated by an entry point, in
the entry map of the secondary video, whose PTS is closest
to the entry point, in the entry map of the primary video,
whose EP_ID is 4m (S213).
Following that, restoration entry generation unit 2 04
increments the variable m by one (S214), repeats the processing
steps of S212 to S215, thereby adding specification of the
untransformable packets, until 4m exceeds the final EP_ID
of the entry map of the primary video, and when 4m exceeds
the final EP_ID of the entry map of the primary video (S215:
No), ends the untransformable packet specification
processing.
Above is the detail of the untransformable packet
specification processing.
As described above, according to the present embodiment,
even in a case where copyright protection at the TS packet
level has been realized by transforming part of an AV stream
and recording the AV stream, TS packets constituting every
fourth entry unit in the primary video stream and TS packets
constituting entry units in the secondary video stream each
having a presentation time stamp closest to any one of the
every fourth entry unit in the primary video stream are not
transformed. Consequently, as a result of selective use of
the I-pictures stored in these TS packets by the playback
apparatus, high-speed fast-forward/rewind playback can be
performed without restoration processing of TS packets.
(Other Modifications)
While the present invention has been described through
the embodiments above, it is not limited to these embodiments,
and, for example, includes the following modifications as
well.
(1) The present invention may be a playback/recording
method disclosed by the processing steps of the flowchart
explained in each embodiment. Also, the present invention
may be a computer program including program codes which operate
a computer using the processing steps, and may be a digital
signal of the computer program.
Also, the present invention may be a computer-readable
recording medium such as a flexible disk, a hard disk, a CD-ROM,
an MO, a DVD, a DVD-ROM, a DVD-RAM, a BD (Blu-ray Disc) or
a semiconductor memory, that stores the computer program or
the digital signal.
Furthermore, the present invention may be the computer
program or the digital signal transmitted on an electric
communication network, a wireless or wired communication
network, or a network of which the Internet is representative.
Furthermore, by transferring the program or the digital
signal to the recording medium, or by transferring the program
or the digital signal via a network or the like, the program
or the digital signal may be executed by another independent
computer system.
(2) The present invention can also be realized by a LSI
that controls the playback/recording apparatus described the
embodiments above. Such a LSI can be achieved by integrating
the functional blocks indicated in FIG. 31 of FIG. 35. These
functional blocks may be partially or entirely implemented
by one chip.
Though the LSI is described here, the circuit may be
called an IC, a system LSI, a super LSI, or an ultra LSI,
depending on the degree of integration.
Also, the integration is not limited to the LSI, and
may be performed using a dedicated circuit or a general
processor. A FPGA (Field Programmable Gate Array) that can
be programmed after LSI manufacturing or a reconfigurable
processor capable of reconfiguring connections and settings
of circuit cells in an LSI may be used.
Also, if an integrated circuit technique that replaces
a LSI emerges from advancement of semiconductor technology
or other derivative technology, such a technique can be used
for the integration of the functional blocks and components.
For instance, biotechnology may be adapted in this way.
(3) The first to third embodiments describe the structure
where the entry points, of the primary video, whose EP_ID
is a multiple of four are ensured to be untransformed at the
TS packet level. However, according to the present invention,
it is not limited to the entry points having EP_ID of a multiple
of four which are ensured to be untransformed at the TS packet
level. One TS packet in how many entry points is ensured to
be untransformed is set appropriately according to the format
characteristics.
(4) While in the first embodiment, as shown in FIG. 18,
the restoration entry is recorded on the recording medium
after being masked and inserted into PMT as a descriptor,
the restoration entry may be recorded on the recording medium
using another method.
For example, as shown in FIG. 38, the restoration entry
may be inserted into the restoration byte code data. In this
case, while having the same structures as those in FIG. 18,
the restoration entry and the mask restoration entry are
inserted into the restoration byte code data as a restoration
entry packet instead of as the restoration descriptor. The
restoration entry packet has a base SPNand the mask restoration
entry, and the base SPN stores a value obtained by subtracting
the relative packet count of the restoration entry from SPN
where the pre-transformation data exists. The restoration
entry packet is stored in the restoration byte code data and
is managed for each restoration segment ID.
(5) In the embodiments above, only part of the BD-ROM
standard which is related to the present invention is excerpted,
and description is given using only the representative
directories and files. However, obviously, the present
invention is able to record other files stipulated in the
BD-ROM standard on the BD-ROM.
[0157]
(6) While in the embodiments above, a BD-ROM conforming
to the BD-ROM standard are used as an example, the features
of the present invention do not depend on physical
characteristics of the BD-ROM, and the present invention can
be applied to other recording media.
(7) The present invention may be any combination of the
above-described embodiments and modifications.
[Industrial Applicability]
The information recording medium of the present
invention includes a copyright protection technique which
transforms part of an AV stream at the TS packet level and
restores the AV stream when playing it back, and at the same
time, enables efficient, fast-speed fast-forward/rewind
playback in which the primary video and secondary video are
synchronized. Accordingly, with use of the recording medium
of the present invention, attractive motion pictures can be
supplied to the market while also protecting the copyright
of the AV content, vitalizing the motion picture market,
consumer apparatus market and the like as a result. Thus,
the recording medium and the playback apparatus of the present
invention has high potential for use in the motion picture
industry, consumer apparatus industry and the like.
We claim:
1. A recording medium having recorded thereon an
AV stream and stream information, wherein
the AV stream includes (a) TS packets composing a primary-
video stream and (b) TS packets composing a secondary video
stream,
the stream information includes:
a first entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the primary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets; and
a second entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the secondary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets of the
secondary video stream,
each group of TS packets constituting an entry unit
stores an intra-frame encoded image therein,
among the TS packets composing the primary video stream,
one or more TS packets have been transformed and TS packets
which constitute every N-th entry unit, in an order of the
start position, are untransformed, N being an integer of 2
or more, and
each TS packet which constitutes one of the entry units
of the secondary video stream and whose presentation time
stamp is, among the presentation time stamps of the entry
units of the secondary video stream, temporally closest to
a presentation time stamp of any one of the every N-th entry-
unit of the primary video stream is untransformed.
2. A recording medium having recorded thereon an
AV stream and stream information, wherein
the AV stream includes (a) TS packets composing a primary
video stream and (b) TS packets composing a secondary video
stream,
the stream information includes:
a first entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the primary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets; and
a second entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the secondary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets of the
secondary video stream,
each group of TS packets constituting an entry unit
stores an intra-frame encoded image therein,
among the TS packets composing the primary video stream,
one or more TS packets have been transformed and TS packets
which constitute every N-th entry unit, in an order of the
start position, are untransformed, N being an integer of 2
or more, and
when the presentation time stamps with respect to two
of the entry units of the secondary video stream are, among
the presentation time stamps of the entry units of the secondary
video stream, temporally closest to a presentation time stamp
of a same one of the every N-th entry unit of the primary
video stream, TS packets constituting one of the two entry
units that is temporally posterior to the other entry unit
are untransformed.
3. The recording medium of any of Claims 1 and 2
further having recorded thereon a restoration program which
outputs a restoration parameter when executed, wherein
the AV stream includes a masked table multiplexed there in,
and
restoration processing for restoring the transformed
TS packets is executed by (a) performing calculation using
the masked table and the restoration parameter, and (b)
overwriting the transformed packets with a result of the
calculation.
4. A playback apparatus which reads an AV stream
and stream information from a recording medium and plays back
the read
AV stream, wherein
the AV stream includes (a) TS packets composing a primary
video stream and (b) TS packets composing a secondary video
stream,
the stream information includes:
a first entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the primary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets; and
a second entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the secondary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets of the
secondary video stream,
each group of TS packets constituting an entry unit
stores an intra-frame encoded image therein,
the playback apparatus comprises:
a read unit operable to read TS packets included
in the AV stream in accordance with the first entry map and
the second entry map;
a demultiplexing unit operable to demultiplex the
read TS packets into the TS packets composing the primary
video stream and the TS packets composing the secondary video
stream;
two video decoders operable to decode the TS
packets composing the primary video stream and the TS packets
composing the secondary video stream, respectively;
a read buffer operable to realize buffering of
TS packets between the read unit and the demultiplexing unit ;
and
a restoration unit operable to restore, among TS
packets in the read buffer, TS packets which have been
transformed,
among the TS packets composing the primary video stream,
one or more TS packets have been transformed and TS packets
which constitute every N-th entry unit, in an order of the
start position, are untransformed, N being an integer of 2
or more, and
each TS packet which constitutes one of the entry units
of the secondary video stream and whose presentation time
stamp is, among the presentation time stamps of the entry
units of the secondary video stream, temporally closest to
a presentation time stamp of any one of the every N-th entry
unit of the primary video stream, is untransformed.
5. A playback apparatus which reads an AV stream
and stream information from a recording medium and plays back
the read
AV stream, wherein
the AV stream includes (a) TS packets composing a primary
video stream and (b) TS packets composing a secondary video
stream,
the stream information includes:
a first entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the primary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets; and
a second entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the secondary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets of the
secondary video stream,
each group of TS packets constituting an entry unit
stores an intra-frame encoded image therein,
the playback apparatus comprises:
a read unit operable to read TS packets included
in the AV stream in accordance with the first entry map and
the second entry map,
a demultiplexing unit operable to demultiplex the
read TS packets into the TS packets composing the primary
video stream and the TS packets composing the secondary video
stream;
two video decoders operable to decode the TS
packets composing the primary video stream and the TS packets
composing the secondary video stream, respectively;
a read buffer operable to realize buffering of
TS packets between the read unit and the demultiplexing unit;
and
a restoration unit operable to restore, among TS
packets in the read buffer, TS packets which have been
transformed,
among the TS packets composing the primary video stream,
one or more TS packets have been transformed and TS packets
which constitute every N-th entry unit, in an order of the
start position, are untransformed, N being an integer of 2
or more, and
when the presentation time stamps with respect to two
of the entry units of the secondary video stream are, among
the presentation time stamps of the entry units of the secondary
video stream, temporally closest to a presentation time stamp
of a same one of the every N-th entry unit of the primary
video stream, TS packets constituting one of the two entry
units that is temporally posterior to the other entry unit
are untransformed.
6. The playback apparatus of any of Claims 7 and
8, wherein
the recording medium has further recorded a restoration
program which outputs a restoration parameter when executed,
the AV stream includes a masked table multiplexed
therein;
the multiplexing unit demultiplexes the masked table
from the AV stream,
the restoration unit includes:
an execution unit operable to obtain the
restoration parameter by executing the restoration program;
and
a calculation unit operable to obtain a plain table
by performing calculation using the masked table and the
restoration parameter, and
restoration processing to restore the transformed TS
packets is performed by overwriting the transformed TS packets
in the read buffer using the plain table.
7. The playback apparatus of Claim 10, wherein
the calculation is an XOR operation.
8. A recording apparatus comprising:
a multiplexing unit operable to obtain a multiplexed
stream by multiplexing TS packets composing a primary video
stream and TS packets composing a secondary video stream;
a first entry map generation unit operable to generate
a first entry map indicating a plurality of associations each
associating (a) a start position of, among the TS packets
composing the primary video stream, a group of TS packets
which constitute an entry unit storing therein an intra-frame
encoded image with (b) a presentation time stamp of the group
of TS packets;
a second entry map generation unit operable to generate
a second entry map indicating a plurality of associations
each associating (a) a start position of, among the TS packets
composing the secondary video stream, a group of TS packets
which constitute an entry unit storing therein an intra-frame
encoded image with (b) a presentation time stamp of the group
of TS packets of the secondary video stream;
a specification unit operable to specify as
untransformable packets, among the TS packets multiplexed
in the multiplexed stream,(a) TS packets which constitute
every N-th entry unit, in an order of the start position,
among the TS packets composing the primary video stream, N
being an integer of 2 or more, and (b)each TS packet which
constitutes one of the entry units of the secondary video
stream and whose presentation time stamp is closest to the
presentation time stamp of the every N-th entry unit;
a transformation unit operable to obtain an AV stream
by, with use of a restoration parameter, performing a
restorable transformation with respect to some of TS packets
among the TS packets in the multiplexed stream other than
the untransformable TS packets;
a program generation unit operable to generate a
restoration program which outputs the restoration parameter
when executed; and
a recording unit operable to record, onto a recording
medium, the AV stream, the first entry map, the second entry
map, and the restoration program.
9. A playback method which reads an AV stream and
stream information from a recording medium and plays back
the read AV stream, wherein
the AV stream includes (a) TS packets composing a primary
video stream and (b) TS packets composing a secondary video
stream,
the stream information includes:
a first entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the primary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets; and
a second entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the secondary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets of the
secondary video stream,
each group of TS packets constituting an entry unit
stores an intra-frame encoded image therein,
the playback method comprises:
a reading step of reading TS packets included in
the AV stream in accordance with the first entry map and the
second entry map, and buffering the read TS packets into a
read buffer;
a restoring step of restoring, among TS packets
in the read buffer, TS packets which have been transformed;
a demultiplexing step of demultiplexing, from the
read buffer, the TS packets composing the primary video stream
and the TS packets composing the secondary video stream; and
a decoding step of decoding the TS packets
composing the primary video stream and the TS packets composing
the secondary video stream, respectively,
among the TS packets composing the primary video stream,
one or more TS packets have been transformed and TS packets
which constitute every N-th entry unit, in an order of the
start position, are untransformed, N being an integer of 2
or more, and
each TS packet which constitutes one of the entry units
of the secondary video stream and whose presentation time
stamp is, among the presentation time stamps of the entry
units of the secondary video stream, temporally closest to
a presentation time stamp of any one of the every N-th entry
unit of the primary video stream is untransformed.
10. A recording method for a recording medium,
comprising:
a creating step of creating application data; and
a recording step of recording the created data onto a
recording medium, wherein
the application data includes an AV stream and stream
information,
the AV stream includes (a) TS packets composing a primary
video stream and (b) TS packets composing a secondary video
stream,
the stream information includes:
a first entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the primary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets; and
a second entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the secondary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets of the
secondary video stream,
each group of TS packets constituting an entry unit
stores an intra-frame encoded image therein,
among the TS packets composing the primary video stream,
one or more TS packets have been transformed and TS packets
which constitute every N-th entry unit, in an order of the
start position, are untransformed, N being an integer of 2
or more, and
each TS packet which constitutes one of the entry units
of the secondary video stream and whose presentation time
stamp is, among the presentation time stamps of the entry
units of the secondary video stream, temporally closest to
a presentation time stamp of any one of the every N-th entry-
unit of the primary video stream is untransformed.
11. An integrated circuit of a playback apparatus
which reads an AV stream and stream information from a recording
medium and plays back the read
AV stream, wherein
the AV stream includes (a) TS packets composing a primary
video stream and (b) TS packets composing a secondary video
stream,
the stream information includes:
a first entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the primary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets; and
a second entry map indicating a plurality of
associations each associating (a) a start position of, among
the TS packets composing the secondary video stream, a group
of TS packets which constitute an entry unit with (b) a
presentation time stamp of the group of TS packets of the
secondary video stream,
each group of TS packets constituting an entry unit
stores an intra-frame encoded image therein,
the integrated circuit comprises:
a read unit operable to read TS packets included
in the AV stream in accordance with the first entry map and
the second entry map;
a demultiplexing unit operable to demultiplex the
read TS packets into the TS packets composing the primary
video stream and the TS packets composing the secondary video
stream;
two video decoders operable to decode the TS
packets composing the primary video stream and the TS packets
composing the secondary video stream, respectively;
a read buffer operable to realize buffering of
TS packets between the read unit and the demultiplexing unit;
and
a restoration unit operable to restore, among TS
packets in the read buffer, TS packets which have been
transformed,
among the TS packets composing the primary video stream,
one or more TS packets have been transformed and TS packets
which constitute every N-th entry unit, in an order of the
start position, are untransformed, N being an integer of 2
or more, and
each TS packet which constitutes one of the entry units
of the secondary video stream and whose presentation time
stamp is, among the presentation time stamps of the entry
units of the secondary video stream, temporally closest to
a presentation time stamp of any one of the every N-th entry
unit of the primary video stream is untransformed.
12. An integrated circuit of a recording apparatus,
comprising:
a multiplexing unit operable to obtain a multiplexed
stream by multiplexing TS packets composing a primary video
stream and TS packets composing a secondary video stream;
a first entry map generation unit operable to generate
a first entry map indicating a plurality of associations each
associating (a) a start position of, among the TS packets
composing the primary video stream, a group of TS packets
which constitute an entry unit storing therein an intra-frame
encoded image with (b) a presentation time stamp of the group
of TS packets;
a second entry map generation unit operable to generate
a second entry map indicating a plurality of associations
each associating (a) a start position of, among the TS packets
composing the secondary video stream, a group of TS packets
which constitute an entry unit storing therein an intra-frame
encoded image with (b) a presentation time stamp of the group
of TS packets of the secondary video stream;
a specification unit, operable to specify as
untransformable packets, among the TS packets multiplexed
in the multiplexed stream,(a) TS packets which constitute
every N-th entry unit, in an order of the start position,
among the TS packets composing the primary video stream, N
being an integer of 2 or more, and (b)each TS packet which
constitutes one of the entry units of the secondary video
stream and whose presentation time stamp is closest to the
presentation time stamp of the every N-th entry unit;
a transformation unit operable to obtain an AV stream
by, with use of a restoration parameter, performing a
restorable transformation with respect to some of TS packets
among the TS packets in the multiplexed stream other than
the untransformable TS packets;
a program generation unit operable to generate a
restoration program which outputs the restoration parameter
when executed; and
a recording unit operable to record, onto a recording
medium, the AV stream, the first entry map, the second entry
map, and the restoration program.

Provided is a recording medium which enables special
playbackprocessing such as fast-forward/rewind although part
of the AV stream recorded therein is transformed. An AV stream,
a first EP map, and a second EP map are recorded on the recording
medium. In the AV stream, part of the multiplexed stream
including a first video stream and a second video stream is
transformed; the first EP map indicates one ore more entry
points of the first video stream; and the second EP map
indicates one or more entry points of the second video stream.
In the AV stream, TS packets constituting I-pictures, of the
first video stream, indicated by every 4N-th entry point in
the first EP map, and TS packets constituting I-pictures,
of the secondary video stream, indicated by the entry points
whose presentation time is closest to the presentation time
of any one of the every 4N-th entry point in the first EP
map.