Technical Field
[0001]
The present disclosure relates to a content supply
device, a content supply method, a program, a terminal
device and a content supply system, and more specifically,
relates to a content supply device, a content supply method,
a program, a terminal device and a content supply system
that enable rapid zapping of content for which HTTP is
performed.
Background Art
[0002]
MPEG-DASH (Moving Picture Experts Group-Dynamic
Adaptive Streaming over HTTP, hereinafter, referred to as
DASH) that uses the same HTTP as the HTTP for the browsing
of web sites and the like is known as a moving picture
distribution protocol that can be used in moving picture
distribution through the Internet and is standardized
internationally (for example, refer to NPL 1).
[0003]
An adaptive streaming technique is realized in DASH.
3
That is, a content supply side is made to prepare a
plurality of streams that have content with identical detail,
the image quality, the size of the angle of view and the
like of which have been altered depending on a communication
environment, and reception capacity and state of the
Internet that forms a distribution pass. Meanwhile, a
reception side can acquire and reproduce the most suitable
streams through selection depending on the communication
environment and self decoding capacity of the Internet from
among a plurality of streams that the content supply side
prepares.
[0004]
In this manner, in DASH, metafiles, which are referred
to as Media Presentation Descriptions (MPDs), are supplied
to the reception side from the supply source so that the
reception side can acquire streams through adaptive
selection.
[0005]
In MPDs, addresses (url information) of supply sources
of streaming data (media data of Audio/Video/Subtitles and
the like) of content that is chunked are defined. The
reception side requests streaming data by accessing a
predetermined server that will be the supply source of
content on the basis of the url information, and the
reception and reproduction of streaming data for which HTTP
4
distribution is performed depending on the request is
possible.
[0006]
Fig. 1 shows an example of a configuration of a content
supply system that performs streaming distribution of
content on the basis of DASH.
[0007]
The content supply system 10 is configured by multiple
DASH clients 30 on a side that receives content being
connected with a plurality of content supply devices 20 (20A,
20B and 20C in this case) on a side that supplies content,
using the Internet 11.
[0008]
The content supply device 20A distributes content with
identical detail as a Channel A using a plurality of streams.
The content supply device 20B distributes content with
identical detail that differs from the content of the
Channel A as a Channel B using a plurality of streams. The
same applies to the content supply device 20C. Hereinafter,
in cases in which it is not necessary to individually
discriminate between the content supply devices 20A, 20B and
20C, the content supply devices will simply be referred to
as the content supply devices 20.
[0009]
The content supply devices 20 include a content
5
management server 21, a DASH segment streamer 22, and a
DASH/MPD server 23.
[0010]
The content management server 21 manages content that
is supplied to the DASH client 30, generates a plurality of
items of streaming data with differing bit rates from
content with identical detail, and outputs the streaming
data to the DASH segment streamer 22. The DASH segment
streamer 22 divides each item of streaming data into
segments in a temporal manner, respectively saves the
segments through conversion into files, and notifies the
DASH/MPD server 23 of the addresses of the supply sources of
the files. Furthermore, the DASH segment streamer 22
performs the HTTP distribution of the files of the segmented
streaming data as an HTTP server depending on requests from
the DASH client 30 on the reception side.
[0011]
The DASH/MPD server 23 generates an MPD in which
addresses and the like that show the supply source of files
of (segments of) the plurality of items of streaming data
are defined, and performs the HTTP distribution of the MPD
depending on requests from the DASH client 30 of the
reception side.
[0012]
The DASH client 30 makes a request from the DASH/MPD
6
server 23, requests streaming data from the DASH segment
streamer 22 on the basis of the MPD for which HTTP
distribution is performed, and receives and reproduces files
for which HTTP distribution is performed depending on the
requests.
[0013]
Additionally, in place of the DASH/MPD server 23 or the
DASH segment streamer 22, a cache server (not shown in the
drawings) is also provided on the Internet 11 so that the
HTTP distribution of cached MPDs and segmented streaming
data is performed.
Citation List
Non Patent Literature
[0014]
NPL 1: "Realization of uninterrupted moving picture
distribution using existing Web servers", Mitsuhiro
Hirabayashi, NIKKEI ELECTRONICS 2012.3.19
Summary of Invention
Technical Problem
[0015]
As mentioned above, an adaptive streaming technique
that uses HTTP distribution is realized in DASH, and in the
configuration of Fig. 1, the simultaneous distribution to
the reception side of a plurality of items of content with
differing detail is made possible by preparing a plurality
7
of channels (content supply devices 20).
[0016]
In this manner, in a case in which it is possible to
simultaneously supply a plurality of items of content with
differing detail, it is assumed that so-called zapping (an
operation of retrieving content to be viewed by sequentially
switching channels in a short period of time) is performed
in the same manner as when a viewer is viewing a television
broadcast. Switching between channels in DASH is performed
in subsegment units in which segment units or segments have
been further subdivided. Additionally, in the following
continuous description, the switching between channels in
DASH refers to switching that is performed in segment units.
[0017]
Fig. 2 and Fig. 3 show the preparation of three streams
(Representations) with differing bit rates, which are
respectively content with identical detail in Channels A, B
and C of DASH, and show an aspect of switching when zapping
between channels.
[0018]
Additionally, since a segment length (a length of time)
in DASH is arbitrary, the segment lengths do not necessarily
coincide between channels. In addition, reproduction
initiation time points of the leading ends of segments of
content do not necessarily coincide between channels.
8
[0019]
Fig. 2 is an example of a case of the segment length
between channels not coinciding, and reproduction initiation
time points of the leading ends of segments of content
between channels not coinciding.
[0020]
In this case, even if a user of the DASH client 30
designates switching (zapping) to the Representation B2 of
the Channel B before the T1 of the DASH client temporal axis
while viewing the Representation A2 of the Channel A,
switching is delayed until the T2, which is a juncture of
the segments of the Representation B2. Furthermore, even if
switching to the Representation C2 of the Channel C is
designated before the T3 while viewing the Representation B2
of the Channel B, switching is delayed until the T4, which
is a juncture of the segments of the Representation C2.
[0021]
Fig. 3 is an example of a case of the segment length
between channels not coinciding, and reproduction initiation
time points of the leading ends of segments of content
between channels coinciding by synchronizing with the NTP
temporal axis.
[0022]
In this case, even if a user of the DASH client 30
designates switching to the Representation B2 of the Channel
9
B before the T1 of the NTP temporal axis while viewing the
Representation A2 of the Channel A, switching is delayed
until the T2, which is a juncture of the segments of the
Representation B2. Furthermore, even if switching to the
Representation C2 of the Channel C is designated before the
T3 while viewing the Representation B2 of the Channel B,
switching is delayed until the T4, which is a juncture of
the segments of the Representation C2.
[0023]
In the abovementioned manner, if the switching of
streams is performed between channels in DASH, surplus
delays are caused. Accordingly, in this case, it is not
possible to perform rapid zapping between channels.
[0024]
Additionally, if the segment length of the stream of
each channel is greatly reduced, it is possible to inhibit
the generation of the abovementioned delays. However, in
such a case, since the amount of data of the stream is
increased due to a deterioration coding efficiency, and
therefore, a wider communication band is necessary, there is
a concern that an excessive load will be applied to the
Internet 11 leading to a deterioration in service quality.
[0025]
Therefore, an object of the present disclosure is to
provide a content supply device in which it is possible to
10
realize rapid zapping between channels in DASH.
Solution to Problem
[0026]
A content supply device, which is a first aspect of the
present disclosure, supplies a plurality of items of
streaming data with differing attributes, which is content
with identical detail, to the same channel according to an
adaptive streaming technique, and includes a supply portion
that divides the streaming data into minimum units when the
reception of streaming data is switched according to a
timing that is made uniform with other channels, and
supplies the streaming data in the minimum units to a
reception side through a network, and a metafile generation
portion that generates metafiles for the reception side to
receive the streaming data that is supplied in the minimum
units, which show that the streaming data is for zapping.
[0027]
The supply portion may divide the streaming data into
the minimum units according to a timing that is made uniform
with other channels that belong to the same group.
[0028]
The supply portion may synchronize with an NTP temporal
axis, match leading ends of the minimum units with other
channels that belong to the same group, and divide the
streaming data into the minimum units using a length of time
11
that is made uniform with other channels that belong to the
same group.
[0029]
The supply portion may divide the streaming data for
zapping into the minimum units using a length of time that
is shorter than the minimum units of the streaming data for
viewing.
[0030]
The metafile generation portion may generate expanded
MPDs as the metafiles.
[0031]
The content supply device, which is a first aspect of
the present disclosure, may further include an accumulator
portion that accumulates the metadata for zapping, and
supplies the metadata for zapping to the reception side.
[0032]
The metafile generation portion may generate the MPDs
into which MPD/@NTPSynchronized attributes and
MPD/SegmentAlignedGroupID attributes have been introduced as
the metafiles, and the accumulator portion may accumulate
the metadata for zapping on the basis of the
MPD/@NTPSynchronized attributes and the
MPD/SegmentAlignedGroupID attributes.
[0033]
The metafile generation portion may generate the MPDs
12
into which MPD/@forZapping attributes have been introduced
as the metafiles, and the accumulator portion may accumulate
the metadata for zapping on the basis of the MPD/@forZapping
attributes.
[0034]
The metafile generation portion may define at least one
of a length of time of the minimum units or a maximum length
of time of the streaming data in the metadata as the
metafiles, and the accumulator portion may accumulate the
metadata for zapping on the basis of at least one of the
length of time of the minimum units or the maximum length of
time of the streaming data.
[0035]
A content supply method of a content supply device,
which is a first aspect of the present disclosure, and which
supplies a plurality of items of streaming data with
differing attributes, which is content with identical detail,
to the same channel according to an adaptive streaming
technique, includes a supply step of dividing the streaming
data into minimum units when the reception of streaming data
is switched according to a timing that is made uniform with
other channels, and supplying the streaming data in the
minimum units to a reception side through a network, and a
metafile generation step of generating metafiles for the
reception side to receive the streaming data that is
13
supplied in the minimum units, which show that the streaming
data is for zapping, which are executed by the content
supply device.
[0036]
A program, which is a first aspect of the present
disclosure, causes a computer that supplies a plurality of
items of streaming data with differing attributes, which is
content with identical detail, to the same channel according
to an adaptive streaming technique, to function as a supply
portion that divides the streaming data into minimum units
when the reception of streaming data is switched according
to a timing that is made uniform with other channels, and
supplies the streaming data in the minimum units to a
reception side through a network, and a metafile generation
portion that generates metafiles for the reception side to
receive the streaming data that is supplied in the minimum
units, which show that the streaming data is for zapping.
[0037]
In the first aspect of the present disclosure,
streaming data is divided into minimum units when the
reception of streaming data is switched according to a
timing that is made uniform with other channels, and the
minimum units are supplied to a reception side through a
network. In addition, metafiles for the reception side to
receive the streaming data that is supplied in the minimum
14
units, which show that the streaming data is for zapping,
are generated.
[0038]
A terminal device, which is a second aspect of the
present disclosure, that receives streaming data that is
supplied from a content supply device that supplies a
plurality of items of the streaming data with differing
attributes, which is content with identical detail, to the
same channel according to an adaptive streaming technique,
in which the content supply device includes a supply portion
that divides the streaming data into minimum units when the
reception of streaming data is switched according to a
timing that is made uniform with other channels, and
supplies the streaming data in the minimum units to a
reception side through a network and a metafile generation
portion that generates metafiles for the terminal device to
receive the streaming data that is supplied in the minimum
units, which show that the streaming data is for zapping,
and acquires the metafiles for zapping, and switches the
reception of the streaming data that is respectively
supplied from different channels on the basis of the
acquired metafiles for zapping.
[0039]
In the second aspect of the present disclosure,
metafiles for zapping are acquired, and the reception of the
15
streaming data that is respectively supplied from different
channels is switched on the basis of the acquired metafiles
for zapping.
[0040]
A content supply device, which is a third aspect of the
present disclosure, that is formed from a content supply
device that supplies a plurality of items of the streaming
data with differing attributes, which is content with
identical detail, to the same channel according to an
adaptive streaming technique, and a terminal device that
receives the streaming data, in which the content supply
device includes a supply portion that divides the streaming
data into minimum units when the reception of streaming data
is switched according to a timing that is made uniform with
other channels, and supplies the streaming data in the
minimum units to a reception side through a network, and a
metafile generation portion that generates metafiles for the
terminal device to receive the streaming data that is
supplied in the minimum units, which show that the streaming
data is for zapping. In addition, the terminal device
acquires the metafiles for zapping, and switches the
reception of the streaming data that is respectively
supplied from different channels on the basis of the
acquired metafiles for zapping.
[0041]
16
In the third aspect of the present disclosure, due to
the content supply device, streaming data is divided into
minimum units when the reception of streaming data is
switched according to a timing that is made uniform with
other channels, and the streaming data is supplied in the
minimum units to a reception side through a network. In
addition, metafiles for the reception side to receive the
streaming data that is supplied in the minimum units, which
show that the streaming data is for zapping, are generated.
In addition, due to the terminal device, the metafiles for
zapping are acquired, and the reception of the streaming
data that is respectively supplied from different channels
is switched on the basis of the acquired metafiles for
zapping.
Advantageous Effects of Invention
[0042]
According to aspects 1 to 3 of the present disclosure,
it is possible to realize rapid zapping between channels in
DASH.
Brief Description of Drawings
[0043]
[Fig. 1] Fig. 1 is a block diagram that shows an
example of a configuration of a content supply system of the
related art.
[Fig. 2] Fig. 2 is a view that describes a delay that
17
is caused by switching between channels.
[Fig. 3] Fig. 3 is a view that describes a delay that
is caused by switching between channels.
[Fig. 4] Fig. 4 is a view that describes the main parts
of the present disclosure.
[Fig. 5] Fig. 5 is a block diagram that shows a
configuration example of a content supply system in which
the present disclosure is applied.
[Fig. 6] Fig. 6 is a view that shows an example of MPDs
defined in XML format.
[Fig. 7] Fig. 7 is a view that shows an example of
expanded MPDs defined in XML format.
[Fig. 8] Fig. 8 is a flowchart that describes processes
prior to distribution.
[Fig. 9] Fig. 9 is a view that displays differences in
segment length for zapping and segment length for viewing.
[Fig. 10] Fig. 10 is a flowchart that describes a
series of processes of the content supply system.
[Fig. 11] Fig. 11 is a flowchart that describes a
modification example of the series of processes of the
content supply system.
[Fig. 12] Fig. 12 is a block diagram that shows a
configuration example of a computer.
Description of Embodiments
[0044]
18
Hereinafter, preferred aspects (hereinafter, referred
to as embodiments) for implementing the present disclosure
will be described, but prior to the description, a summary
of the present disclosure will be described with reference
to Fig. 4.
[0045]
Fig. 4 shows an aspect of switching when zapping
between multiple channels that are prepared by a content
supply system, which is the embodiment of the present
disclosure.
[0046]
The drawing also shows content that respectively
differs in Channels A, B and C, being distributed, and three
streams (Representations) with differing bit rates in each
channel, being prepared.
[0047]
In the content supply system in which the present
disclosure is applied, in addition to divisions of segments
of content being synchronized with an NTP temporal axis, a
segment length of each channel that belongs to a
predetermined group is made uniform with a common length of
time. Furthermore, starting points of media reproduction
time points (MPD/@availabilityStartTime+Period/@start) of
leading ends of segments are established so as to coincide
on the NTP temporal axis.
19
[0048]
As a result of establishing in this manner, as shown in
Fig. 4, if a viewer that is using the content supply system
designates switching to the Representation B2 of the Channel
B before the T1 of the DASH client temporal axis while
viewing the Representation A2 of the Channel A, switching is
performed in T1, which is a division of the segment of the
Representation A2, and is also a division of the segment of
the Representation B2. In addition, if switching to the
Representation C2 of the Channel C is designated before the
T2 while viewing the Representation B2 of the Channel B,
switching is performed in T2, which is a division of the
segment of the Representation B2, and is also a division of
the segment of the Representation C2. Furthermore, if
switching to the Representation A2 of the Channel A is
designated before the T3 while viewing the Representation C2
of the Channel C, switching is performed in T3, which is a
division of the segment of the Representation C2, and is
also a division of the segment of the Representation A2.
[0049]
Additionally, in the content supply system, which is an
embodiment of the present disclosure, it is configured so
that one or more streams for zapping and two or more streams
for viewing are prepared for content with identical detail
in each channel. In addition, in each channel that belongs
20
to the same group, it is configured so that the segment
length of each channel coincides with the streams for
zapping, and reproduction initiation time points of the
leading ends of segments of content in each channel coincide
by synchronizing with the NTP time point.
[0050]
As a result of this, it becomes it is possible to
perform zapping between channels that belong to the same
group rapidly without causing a surplus delay.
[0051]
[Configuration Example of Content Supply System]
Fig. 5 shows a configuration example of a content
supply system in which the present disclosure is applied.
[0052]
The content supply system 50 is configured by
connecting a plurality of content supply devices 60, an MPD
acquisition portal for zapping 70, and multiple terminal
devices 80 that correspond to each channel using the
Internet 11.
[0053]
Additionally, on the Internet 11, there is an NTP
server 12 that provides system time point information
according to the UTC time format. Each content supply
device 60 and each terminal device 80 respectively act in
synchronization with an NTP temporal axis according to
21
system time point information that is supplied from the NTP
server 12.
[0054]
A content supply device 60A that corresponds to the
Channel A includes a channel server 61 and a DASH server 62.
[0055]
The channel server 61 manages content source data that
is distributed as the channel A, generates a plurality of
items of streaming data (one or more item of streaming data
for zapping and two or more items of streaming data for
viewing) with identical detail, the bit rate of which differ,
from the source data, and supplies the streaming data to the
DASH server 62.
[0056]
The DASH server 62 includes a segment streamer for
zapping 63, an MPD server for zapping 64, a segment streamer
for viewing 65 and an MPD server for viewing 66.
[0057]
The segment streamer for zapping 63 divides the one or
more items of streaming data for zapping into periods in a
temporal manner, further separates the periods into segments
(segments), and respectively converts the segments into
files and saves the files. Additionally, a segment length
of the streaming data for zapping is shorter than a segment
length of the streaming data for viewing, and therefore,
22
coincides with other channels that belong to the same group
and a common length of time. In addition, since the segment
streamer for zapping 63 acts in synchronization with the NTP
temporal axis, the divisions of the segments also become in
synchronization with the NTP temporal axis.
[0058]
Furthermore, the segment streamer for zapping 63
notifies the MPD server for zapping 64 of addresses that
will be supply sources of files that are to be saved. In
addition, the segment streamer for zapping 63 performs HTTP
distribution of the files of the segmented streaming data
depending on requests from the terminal device 80 using the
Internet 11.
[0059]
The MPD server for zapping 64 generates expanded MPDs
for zapping (hereinafter, referred to as MPDs for zapping.
To be described in more detail later) that are necessary in
order for a terminal device 80 side to receive the streaming
data for zapping. Additionally, within a group that the
channel of the content supply device 60 belongs to, starting
points of media reproduction time points
(MPD/@availabilityStartTime+Period/@start) of leading ends
of segments coincide with the NTP temporal axis.
[0060]
In addition, the MPD server for zapping 64 supplies the
23
MPDs for zapping to the MPD acquisition portal for zapping
70 depending on crawl of the MPD acquisition portal for
zapping 70.
[0061]
The segment streamer for viewing 65 divides the
plurality of items of streaming data for viewing into
periods in a temporal manner, further separates the periods
into segments, and respectively converts the segments into
files and saves the files. Additionally, divisions of the
segments of the streaming data for viewing is configured to
coincide with divisions of the segments of the streaming
data for zapping. However, a segment length of the
streaming data for viewing can be set to be longer than a
segment length of the streaming data for zapping. As a
result of this, in addition to just being able to encode the
streaming data for zapping efficiently, it is possible to
perform switching between the streaming data for zapping and
the streaming data for viewing rapidly.
[0062]
Furthermore, the segment streamer for viewing 65
notifies the MPD server for viewing 66 of addresses that
will be supply sources of files that are to be saved. In
addition, the segment streamer for viewing 65 performs HTTP
distribution of the files of the segmented streaming data
depending on requests from the terminal device 80 using the
24
Internet 11.
[0063]
The MPD server for viewing 66 generates MPDs for
viewing that are necessary in order for the terminal device
80 side to receive the streaming data for viewing, and
performs HTTP distribution of the MPDs for zapping depending
on requests from the terminal device 80 using the Internet
11.
[0064]
Additionally, MPDs for zapping that are generated by
the MPD server for zapping 64, and MPDs for viewing that are
generated by the MPD server for viewing 66 correspond to
content with identical detail, and for example, the
association the MPDs is made clear by a URL or the like of
an acquisition point. More specifically, for example, in a
case in which a URL of an acquisition point of the MPDs for
zapping is set as http://a.com/channel_1.forZapping.mpd, a
URL of an acquisition point of the MPDs for viewing is set
as http://a.com/channel_1.mpd or the like.
[0065]
Since a content supply device 60B that corresponds to
the Channel B is configured in the same manner as the
content supply device 60A, the description thereof has been
omitted. Additionally, there may also be a plurality of
content supply devices 60X (not shown in the drawings) that
25
correspond to Channels X other than the Channels A and B.
[0066]
The MPD acquisition portal for zapping 70 accumulates
MPDs for zapping by crawling the content supply device 60 of
each channel depending on a query API that requests MPDs for
zapping from the terminal device 80, and transmits the MPDs
for zapping to the terminal device 80. Additionally, in a
case in which MPDs for zapping are not generated by the
content supply device 60 of each channel, the MPD
acquisition portal for zapping 70 accumulates MPDs for
viewing that satisfy predetermined conditions (to be
described later), and transmits the MPDs for viewing to the
terminal device 80.
[0067]
[Expansion of MPDs]
Next, MPDs in DASH, and the expansion thereof will be
described.
[0068]
In MPDs, information that is related to content (Media)
is divided into Periods. In each Period, a plurality of
Representations that are formed from information that is
related to streaming data that has identical detail, but in
which stream attributes such as the bit rate image quality
and size of the angle of view have been altered.
Information that is related to Segments, into which Periods
26
have been further separated in a temporal manner, is stored
in a Representation.
[0069]
Fig. 6 shows an example in which a structure of
Representations and below is defined in XML format.
[0070]
In the drawing, the "http://example.com/counter-
10mn_avc_dash.mp4" that is defined under the
MPD/Period/AdaptationSet/Representation/BaseURL shows an
address of a supply source of a file in which a plurality of
segments have been converted into a file together.
[0071]
In addition, the
MPD/Period/AdaptationSet/Representation/SegmentList/
SegmentURL/@mediaRange shows a byte range of segmented
streaming data in the file.
[0072]
For example,
MPD/Period/AdaptationSet/Representation/SegmentList/
SegmentURL/@mediaRange="795-83596" shows that a byte range
from byte number 795 to byte number 83596 in the file is a
first item of segmented streaming data.
[0073]
Therefore, when the terminal device 40 acquires the
first item of segmented streaming data, a HTTP request that
27
specifies a mediaRange of "795-83596" as a Range header in
addition to the url "http://example.com/counter-
10mn_avc_dash.mp4" of the file, may be performed. An HTTP
request in this instance is as follows.
GET /counter-10mn_avc_dash.mp4 HTTP/1.1
Host: example.com Range: bytes=795-83596
[0074]
Next, Fig. 7 shows an example in which a structure
directly below expanded MPDs is defined in XML format as the
MPDs for zapping.
[0075]
That is, in expanded MPDs, an MPD/@NTPSynchronized
(boolean type, value is true/false) attribute and an
MPD/@SegmentAlignedGroupID (group identifier) attribute are
newly introduced directly below MPD.
[0076]
In the MPD/@NTPSynchronized attribute, either true or
false that represent whether or not divisions of the
segments of streaming data of the MPD are synchronized with
the NTP temporal axis, is defined. In this case, since the
segment streamer for zapping 63 is acting in synchronization
with the NTP temporal axis, the value of the
MPD/@NTPSynchronized attribute becomes true.
[0077]
In the MPD/@SegmentAlignedGroupID attribute, an
28
identifier of a group that a channel, which coincides with
the division of the segment of streaming data, belongs to is
defined.
[0078]
Therefore, in the MPD acquisition portal for zapping 70,
MPDs (MPDs for zapping) for which the MPD/@NTPSynchronized
attribute is true, and the MPD/@SegmentAlignedGroupID
attribute is the same group identifier may be accumulated
depending on a query API such as that below
Http://MPDPortal.com/getMPDforZapping
that requests the MPDs for zapping from the terminal device
80. Since the divisions of segments are made uniform by
synchronizing with the NTP temporal axis, rapid zapping is
possible between channels that correspond to the accumulated
MPDs for zapping.
[0079]
In addition, display in the drawings has been omitted,
but in the MPDs for zapping, within a group that the channel
of the content supply device 60 belongs to, starting points
of media reproduction time points
(MPD/@availabilityStartTime+Period/@start) of leading ends
of segments coincide with the NTP temporal axis.
[0080]
Furthermore, in the MPDs for zapping and the MPDs for
viewing, the definition of at least one of a
29
segmentBase/@duration attribute that stores a value that
represents segment length, and an MPD/@maxSegmentDuration
attribute that stores a value that represents maximum
segment length is essential.
[0081]
If one of these two attributes is defined, it is
possible to accumulate MPDs for viewing that have not been
expanded, that is, MPDs for viewing into which the
MPD/@NTPSynchronized attribute and the
MPD/@SegmentAlignedGroupID attribute have not been
introduced, as the MPDs for zapping. More specifically, for
example, if the terminal device 80 requests MPDs from the
MPD acquisition portal for zapping 70 using a query API such
as that below, it is possible to cause accumulate MPDs for
viewing with a segment length (an expected segment length)
that satisfy a predetermined conditions to be accumulated.
Additionally, in the following example, a segment length of
two seconds or less is set as the expected segment length.
Http://MPDPortal.com/getMPD?expectedSegmentSizeLimit="P
T2S"
[0082]
Since the segment length is a comparatively short
period of time (two seconds in the abovementioned example)
rapid zapping between channels that correspond to
accumulated MPDs for viewing that correspond to the expected
30
segment length.
[0083]
Additionally, in place of introducing the
MPD/@NTPSynchronized attribute and the
MPD/@SegmentAlignedGroupID attribute, an MPD/forZapping
(boolean type, value is true/false) that shows whether or
not the MPDs are MPDs for zapping, may be introduced.
[0084]
[Action of Content Supply System 50]
Next an action of the content supply system 50 will be
described.
[0085]
Fig. 8 is a flowchart that describes processes that
each content supply device 60 performs in advance
(hereinafter, referred to as processes prior to
distribution) in order to distribute content.
[0086]
In Step S1, each content supply device 60 is caused to
synchronize the system time point thereof with the NTP
temporal axis according to system time point information
that is provided from the NTP server 12. As a result of
this, the segment streamer for zapping 63 or the like of the
content supply device 60 acts in synchronization with the
NTP temporal axis.
[0087]
31
In Step S2, the channel server 61 creates a plurality
of items of streaming data (one or more item of streaming
data for zapping and two or more items of streaming data for
viewing), the bit rate of which differ, from source data of
content that is distributed as the Channel A, and supplies
the streaming data to the DASH server 62.
[0088]
In Step S3, the segment streamer for zapping 63 divides
the one or more items of streaming data for zapping into
periods in a temporal manner, further separates the periods
into segments with a length of time (a segment length) that
coincides within a group that the content supply device 60
belongs to, and respectively converts the segments into
files and saves the files. In addition, the segment
streamer for zapping 63 notifies the MPD server for zapping
64 of addresses that will be supply sources of files that
are to be saved. In parallel with this, the segment
streamer for viewing 65 divides the plurality of items of
streaming data for viewing into periods in a temporal manner,
further separates the periods into segments, and
respectively converts the segments into files and saves the
files. In addition, the segment streamer for viewing 65
notifies the MPD server for viewing 66 of addresses that
will be supply sources of files that are to be saved.
[0089]
32
In Step S4, the MPD server for zapping 64 generates
MPDs for zapping that are necessary in order for the
terminal device 80 side to receive the streaming data for
zapping. In Step S5, the MPD server for viewing 66
generates MPDs for viewing that are necessary in order for
the terminal device 80 side to receive the streaming data
for viewing. This concludes the description of the
processes prior to distribution.
[0090]
Fig. 9 shows division of segments that are generated by
the processes prior to distribution that are described above.
As shown in the drawing, in the content supply device
60A that corresponds to the Channel A, one or more item of
streaming data for zapping (two items of streaming data in
Fig. 9) and two or more items of streaming data for viewing
(five items of streaming data in Fig. 9) are generated, and
the divisions of these segments are synchronized with the
NTP temporal axis.
[0091]
In addition, the divisions of segments of streaming
data for zapping coincide with the divisions of segments of
streaming data for zapping of other channels (not shown in
the drawings) that belong to the same group.
[0092]
Next, Fig. 10 is a flowchart that describes a series of
33
processes in which the terminal device 80 transitions into a
viewing phase after a content zapping phase (hereinafter,
referred to as a series of processes).
[0093]
Step S11, the terminal device 80 is caused to
synchronize the system time point thereof with the NTP
temporal axis according to system time point information
that is provided from the NTP server 12. In Step S12, the
terminal device 80 requests MPDs for zapping from the MPD
acquisition portal for zapping 70. That is, the terminal
device 80 transmits a query API in order to ask for a crawl
of the MPDs for zapping.
[0094]
In Step S21, depending on this query API, the MPD
acquisition portal for zapping 70 connects to the MPD server
for zapping 64 of each content supply device 60, and
requests MPDs for zapping (MPDs for which the
MPD/@NTPSynchronized attribute is true, and the
MPD/@SegmentAlignedGroupID attribute is the same group
identifier). Depending on this request, in Step S31, the
MPD server for zapping 64 of each content supply device 60
performs HTTP distribution of the MPDs for zapping to the
MPD acquisition portal for zapping 70. In Step S22, the MPD
acquisition portal for zapping 70 transmits the accumulated
MPDs for zapping to the terminal device 80 from which there
34
was a request.
[0095]
A terminal device 80 that receives MPDs for zapping
enters a zapping phase. In Step S13, the terminal device 80
requests segments of streaming data for zapping from the
segment streamer for zapping 63 of the content supply device
60 on the basis of the MPDs for zapping. Depending on this
request, in Step S32, the segment streamer for zapping 63
performs HTTP distribution of the requested segments. In
Step S15, the terminal device 80 receives the segments of
streaming data for zapping for which HTTP distribution was
performed, and reproduces the segments.
[0096]
During the zapping phase, by repeating the processes of
Step S13 and Step S15, it is possible for the terminal
device 80 to perform rapid zapping between channels that
belong to the same group.
[0097]
Additionally, the terminal device 80 is set so that the
MPDs for viewing are acquired during the zapping phase.
More specifically, in Step S14, the MPDs for viewing are
requested from the MPD server for viewing 66, and depending
on this request, the MPD server for viewing 66 receives the
MPDs for viewing for which HTTP distribution is to be
performed as Step S33.
35
[0098]
A terminal device 80 that receives MPDs for viewing
transitions from the zapping phase to the viewing phase. In
Step S16, the terminal device 80 requests segments of
streaming data for viewing from the segment streamer for
viewing 65 of the content supply device 60 on the basis of
the MPDs for viewing. Depending on this request, in Step
S34, the segment streamer for viewing 65 performs HTTP
distribution of the requested segments. In Step S17, the
terminal device 80 receives the segments of streaming data
for viewing for which HTTP distribution was performed, and
reproduces the segments.
[0099]
Additionally, after this, it is possible to return to
the zapping phase from the viewing phase, and then
transition to the viewing phase again. This concludes the
description of the series of processes. According to the
abovementioned series of processes, it becomes it is
possible to perform zapping between channels that belong to
the same group rapidly without causing a surplus delay.
[0100]
Next, Fig. 11 is a flowchart that describes a
modification example of the series of processes.
[0101]
The modification example of the drawing corresponds to
36
a case in which the segment streamer for zapping 63 and the
MPD server for zapping 64 are not provided in the content
supply device 60, and therefore, the MPDs for zapping and
the streaming data for zapping are not prepared. In this
case, on the basis of the MPDs for viewing, among the
streaming data for viewing, streaming data that is shorter
than a length of time that the segment length specifies
(streaming data of the expected segment length) is used for
zapping.
[0102]
Step S41, the terminal device 80 is caused to
synchronize the system time point thereof with the NTP
temporal axis according to system time point information
that is provided from the NTP server 12. In Step S42, the
terminal device 80 requests MPDs for viewing in order to
receive streaming data for viewing that can be used in
zapping from the MPD acquisition portal for zapping 70.
That is, the terminal device 80 transmits a query API in
order to ask for a crawl of the MPDs for viewing that
correspond to the expected segment length.
[0103]
In Step S51, depending on this query API, the MPD
acquisition portal for zapping 70 connects to the MPD server
for viewing 66 of each content supply device 60, and
requests MPDs for viewing that correspond to the expected
37
segment length (MPDs in which at least one of the
segmentBase/@duration attribute and the
MPD/@maxSegmentDuration attribute is less than or equal to
the expected segment length). Depending on this request, in
Step S61, the MPD server for viewing 66 of each content
supply device 60 performs HTTP distribution of the MPDs for
viewing that correspond to the expected segment length to
the MPD acquisition portal for zapping 70. In Step S52, the
MPD acquisition portal for zapping 70 transmits the
accumulated MPDs for viewing to the terminal device 80 from
which there was a request.
[0104]
A terminal device 80 that receives MPDs for viewing
that correspond to the expected segment length enters a
viewing phase in which rapid zapping is possible. In Step
S43, the terminal device 80 requests segments of streaming
data for viewing from the segment streamer for viewing 65 of
the content supply device 60 on the basis of the MPDs for
viewing. Depending on this request, in Step S62, the
segment streamer for viewing 65 performs HTTP distribution
of the requested segments. In Step S44, the terminal device
80 receives the segments of streaming data for viewing for
which HTTP distribution was performed, and reproduces the
segments. This concludes the description of the series of
processes.
38
[0105]
According to the abovementioned modification example of
the series of processes, it is possible to rapidly perform
zapping between streaming data for viewing in which the
segment length is comparatively short.
[0106]
Additionally, in the abovementioned description,
switching between channels in DASH was set to be performed
in segment units, but there are also circumstances in which
switching is performed in subsegment units in which segments
have been further subdivided. In such as case, in the MPDs
for zapping and the MPDs for viewing, the definition of an
MPD/@SubSegmentDuration attribute that stores a value that
represents a subsegment length is essential, and instances
of "segment" in the abovementioned description may be read
as "subsegment".
[0107]
Incidentally, in addition to respectively being
configured by hardware, it is possible to realize the
content supply device 60 and the terminal device 80 that
execute the abovementioned series of processes due to a
computer executing software. By using a computer in which
dedicated hardware is assembled, or installing various
programs on the computer, for example, general purpose
personal computers that are capable of executing various
39
functions can be included.
[0108]
Fig. 12 is a block diagram that shows a configuration
example of hardware of the abovementioned computer.
[0109]
In a computer 100, a Central Processing Unit (CPU) 101,
Read Only Memory (ROM) 102, and Random Access Memory (RAM)
103 are mutually connected by a bus 104.
[0110]
An input/output interface 105 is further connected to
the bus 104. An input unit 106, an output unit 107, a
storage unit 108, a communication unit 109 and a drive 110
are connected to the input/output interface 105.
[0111]
The input unit 106 is formed from a keyboard, a mouse,
a microphone or the like. The output unit 107 is formed
from a display, a speaker or the like. The storage unit 108
is formed from a hard disk, non-volatile memory or the like.
The communication unit 109 is formed from a network
interface or the like. The drive 110 drives removable media
111 such as a magnetic disc, an optical disc, a magnetooptical
disc, or semiconductor memory or the like.
[0112]
In the computer 100 that is configured in the
abovementioned manner, the CPU 101 performs the
40
abovementioned series of processes by loading and executing
programs that are stored in the storage unit 108 in the RAM
103 using the input/output interface 105 and the bus 104.
[0113]
The programs that the computer 100 (the CPU 101)
executes can for example, be provided and stored on the
removable media 111 as package media or the like. In
addition, the programs can be provided using a wired or
wireless transmission medium such as a local area network,
the Internet, or a digital satellite broadcast.
[0114]
In the computer 100, by mounting the removable media
111 in the drive 110, it is possible to install the programs
on the storage unit 108 using the input/output interface 105.
In addition, it is possible to install the programs on the
storage unit 108 by receiving the programs with the
communication unit 109 via a wired or wireless transmission
medium. In addition to these methods, it is possible to
install the programs on the ROM 102 or the storage unit 108
in advance.
[0115]
Additionally, the programs that the computer 100
executes may be programs in which the processes are
performed in chronological order in the sequence described
in the present specification, or may be programs in which
41
the processes are performed either in parallel, or at a
necessary timing such as when an alert is performed.
[0116]
The embodiments of the present disclosure are not
limited to the abovementioned embodiments, and various
alterations are possible within a range that does not depart
from the scope of the present disclosure.
[0117]
It is possible for the present disclosure to have the
following configurations.
(1)
A content supply device that supplies a plurality of
items of streaming data with differing attributes, which is
content with identical detail, to the same channel according
to an adaptive streaming technique including
a supply portion that divides the streaming data into
minimum units when the reception of streaming data is
switched according to a timing that is made uniform with
other channels, and supplies the streaming data in the
minimum units to a reception side through a network, and
a metafile generation portion that generates metafiles
for the reception side to receive the streaming data that is
supplied in the minimum units, which show that the streaming
data is for zapping.
(2)
42
The content supply device according to (1),
in which the supply portion divides the streaming data
into the minimum units according to a timing that is made
uniform with other channels that belong to the same group.
(3)
The content supply device according to (1) or (2),
in which the supply portion synchronizes with an NTP
temporal axis, matches leading ends of the minimum units
with other channels that belong to the same group, and
divides the streaming data into the minimum units using a
length of time that is made uniform with other channels that
belong to the same group.
(4)
The content supply device according to any one of (1)
to (3),
in which the supply portion divides the streaming data
for zapping into the minimum units using a length of time
that is shorter than the minimum units of the streaming data
for viewing.
(5)
The content supply device according to any one of (1)
to (4), in which the metafile generation portion generates
expanded MPDs as the metafiles.
(6)
The content supply device according to any one of (1)
43
to (5),
in which the content supply further includes an
accumulator portion that accumulates the metadata for
zapping, and supplies the metadata for zapping to the
reception side.
(7)
The content supply device according to (6),
in which the metafile generation portion generates the
MPDs into which MPD/@NTPSynchronized attributes and
MPD/SegmentAlignedGroupID attributes have been introduced as
the metafiles, and
the accumulator portion accumulates the metadata for
zapping on the basis of the MPD/@NTPSynchronized attributes
and the MPD/SegmentAlignedGroupID attributes.
(8)
The content supply device according to (6), in which
the metafile generation portion generates the MPDs into
which MPD/@forZapping attributes have been introduced as the
metafiles, and
the accumulator portion accumulates the metadata for
zapping on the basis of the MPD/@forZapping attributes.
(9)
The content supply device according to (6), in which
the metafile generation portion defines at least one of a
length of time of the minimum units or a maximum length of
44
time of the streaming data in the metadata as the metafiles,
and the accumulator portion accumulates the metadata for
zapping on the basis of at least one of the length of time
of the minimum units or the maximum length of time of the
streaming data.
Reference Signs List
[0118]
11 Internet
12 NTP server
50 content supply system
60 content supply device
61 channel server
62 DASH server
63 segment streamer for zapping
64 MPD server for zapping
65 segment streamer for viewing
66 MPD server for viewing
70 MPD acquisition server for zapping
80 terminal device
100 computer
101 CPU
45
CLAIMS
[Claim 1]
A content supply device that supplies a plurality of
items of streaming data with differing attributes, which is
content with identical detail, to the same channel according
to an adaptive streaming technique, comprising:
a supply portion that divides the streaming data into
minimum units when the reception of streaming data is
switched according to a timing that is made uniform with
other channels, and supplies the streaming data in the
minimum units to a reception side through a network; and
a metafile generation portion that generates metafiles
for the reception side to receive the streaming data that is
supplied in the minimum units, which show that the streaming
data is for zapping.
[Claim 2]
The content supply device according to Claim 1, wherein
the supply portion divides the streaming data into the
minimum units according to a timing that is made uniform
with other channels that belong to the same group.
[Claim 3]
The content supply device according to Claim 2, wherein
the supply portion synchronizes with an NTP temporal axis,
matches leading ends of the minimum units with other
channels that belong to the same group, and divides the
46
streaming data into the minimum units using a length of time
that is made uniform with other channels that belong to the
same group.
[Claim 4]
The content supply device according to Claim 2, wherein
the supply portion divides the streaming data for zapping
into the minimum units using a length of time that is
shorter than the minimum units of the streaming data for
viewing.
[Claim 5]
The content supply device according to Claim 2, wherein
the metafile generation portion generates expanded MPDs as
the metafiles.
[Claim 6]
The content supply device according to Claim 2, further
comprising:
an accumulator portion that accumulates the metadata
for zapping, and supplies the metadata for zapping to the
reception side.
[Claim 7]
The content supply device according to Claim 6, wherein
the metafile generation portion generates the MPDs into
which MPD/@NTPSynchronized attributes and
MPD/SegmentAlignedGroupID attributes have been introduced as
the metafiles, and
47
the accumulator portion accumulates the metadata for
zapping on the basis of the MPD/@NTPSynchronized attributes
and the MPD/SegmentAlignedGroupID attributes.
[Claim 8]
The content supply device according to Claim 6, wherein
the metafile generation portion generates the MPDs into
which MPD/@forZapping attributes have been introduced as the
metafiles, and
the accumulator portion accumulates the metadata for
zapping on the basis of the MPD/@forZapping attributes.
[Claim 9]
The content supply device according to Claim 6, wherein
the metafile generation portion defines at least one of a
length of time of the minimum units or a maximum length of
time of the streaming data in the metadata as the metafiles,
and
the accumulator portion accumulates the metadata for
zapping on the basis of at least one of the length of time
of the minimum units or the maximum length of time of the
streaming data.
[Claim 10]
A content supply method of a content supply device that
supplies a plurality of items of streaming data with
differing attributes, which is content with identical detail,
to the same channel according to an adaptive streaming
48
technique, the method comprising:
a supply step of dividing the streaming data into
minimum units when the reception of streaming data is
switched according to a timing that is made uniform with
other channels, and supplying the streaming data in the
minimum units to a reception side through a network; and
a metafile generation step of generating metafiles for
the reception side to receive the streaming data that is
supplied in the minimum units, which show that the streaming
data is for zapping,
which are executed by the content supply device.
[Claim 11]
A program that causes a computer that supplies a
plurality of items of streaming data with differing
attributes, which is content with identical detail, to the
same channel according to an adaptive streaming technique,
to function as:
a supply portion that divides the streaming data into
minimum units when the reception of streaming data is
switched according to a timing that is made uniform with
other channels, and supplies the streaming data in the
minimum units to a reception side through a network; and
a metafile generation portion that generates metafiles
for the reception side to receive the streaming data that is
supplied in the minimum units, which show that the streaming
49
data is for zapping.
[Claim 12]
A terminal device that receives streaming data that is
supplied from a content supply device that supplies a
plurality of items of the streaming data with differing
attributes, which is content with identical detail, to the
same channel according to an adaptive streaming technique,
wherein the content supply device includes:
a supply portion that divides the streaming data into
minimum units when the reception of streaming data is
switched according to a timing that is made uniform with
other channels, and supplies the streaming data in the
minimum units to a reception side through a network; and
a metafile generation portion that generates metafiles
for the terminal device to receive the streaming data that
is supplied in the minimum units, which show that the
streaming data is for zapping, and
acquires the metafiles for zapping, and switches the
reception of the streaming data that is respectively
supplied from different channels on the basis of the
acquired metafiles for zapping.
[Claim 13]
A content supply system that is formed from a content
supply device that supplies a plurality of items of the
streaming data with differing attributes, which is content
50
with identical detail, to the same channel according to an
adaptive streaming technique, and a terminal device that
receives the streaming data
wherein the content supply device includes:
a supply portion that divides the streaming data into
minimum units when the reception of streaming data is
switched according to a timing that is made uniform with
other channels, and supplies the streaming data in the
minimum units to a reception side through a network; and
a metafile generation portion that generates metafiles
for the terminal device to receive the streaming data that
is supplied in the minimum units, which show that the
streaming data is for zapping, and
wherein the terminal device acquires the metafiles for
zapping, and switches the reception of the streaming data
that is respectively supplied from different channels on the
basis of the acquired metafiles for zapping.