A Method and Device
BACKGROUND OF THE DISCLOSURE
Field of the Disclosure
5 The present disclosure relates to a method and device.
Description of the Prior Art
At present consumers have the opportunity to view televisual content over the Internet using a
so-called "video on demand" system. This type ofsystem enables a user to select video
content to view over the Internet. This video content may include televisual broadcasts
10 previously broadcast. One example ofthis is iPlayer provided by the British Broadcasting
Corporation (BBC).
However, in order to access this content, the televisual broadcast must be completed and
uploaded to the server by the video on demand service. This provides an inconvenience for
the viewer.
15
It is an aim ofembodiments of this disclosure to address this issue.
• 2
SUMMARY OF THE DISCLOSURE
Embodiments of the disclosure provide a software application linking broadcast content to
corresponding content available on a server. The corresponding content may be segmented
into portions. The corresponding content may be substantially time aligned to the broadcast
5 content, allowing for latency in the assembly ofthe content and/or delivery systems.
According to one aspect ofthe present disclosure, there is provided a method comprising:
receiving, via a broadcast channel, video data having an identifier that identifies a position
within the video and an address defining the location of a stored playlist; obtaining from a
10 server the playlist in response to a user input, the playlist containing location information
identifying the location of a stored transport stream; receiving the transport stream from the
location identified in the playlist over a network; and displaying the obtained transport stream.
This is advantageous because it allows the user to interact with broadcast content to provide
15 additional functionality to the content.
The stored transport stream may include at least one frame of said video data corresponding to
that received over the broadcast channel. This is advantageous because this allows the user to
effectively perform operations on the content such as pause, rewind, fast forward etc.
20
The method may further comprise storing the video data obtained over the broadcast channel
concurrently with displaying the transport stream obtained from the server; performing a
transition back to the received video data by increasing the speed ofplayback ofthe transport
stream; stopping display ofthe transport stream; and displaying the stored video data with an
25 increased playback speed. This is advantageous because the transition returning to the
broadcast content is smoother.
The method may further comprise storing the video data obtained over the broadcast channel;
stopping display of the transport stream and displaying the stored video data. This also
30 reduces the discontinuity between switching from server based content to broadcast content.
The transport stream may include a plurality of transport stream clips, each transport stream
clip being ofa predetermined clip duration; provide the location of each ofthe transport
• 3
stream clips and the duration of each ofthe transport stream clips in the playlist, and the
method may include selecting the transport stream clip to be retrieved in accordance with the
duration of each ofthe transport stream clips provided in the playlist and the identifier ofthe
position within the video; and retrieving the selected transport stream clip.
5
The identifier may be a video timestamp.
According to another aspect, there is provided a computer program containing computer
readable instructions which when loaded onto-a computer configuresthe computer to perform
lOamethod according to any embodiment.
A storage medium which is ~onfigured to store the computer program ofthe aspect therein or
thereon.
15 According to another aspect, there is provided a device comprising: a receiver configured in
use to receive, via a broadcast channel, video data having an identifier that identifies a
position within the video and an address defming the location of a stored playlist; a network
connector configured in use to obtain from a server the playlist in response to a user input, the
playlist containing location information identifying the location of a stored transport stream;
20 wherein the network connector is further configured in use to receive the transport stream
from the location identified in theplaylist over a network; and an output configured in use to
output the obtained transport stream for display.
The stored transport stream may include at least one frame of said video data corresponding to
25 that received over the broadcast channel.
The device may further comprise a memory configured in use to store the video data obtained
over the broadcast channel concurrently with displaying the transport stream obtained from
the server; and a controller configured in use to perform a transition back to the received
30 video data by increasing the speed of playback ofthe transport stream; stop display ofthe
transport stream; and to output the stored video data for display with an increased playback
speed.
• 4
The device may further comprise a memory configured in use to store the video data obtained
over the broadcast channel; and a controller configured in use to stop display of the transport
stream and to output the stored video data for display.
5 The transport stream may include a plurality oftransport stream clips, each transport stream
clip being of a predetermined clip duration and the playlist provides the location of each of
the transport stream clips and the duration of eachofthe transport stream clips in the playlist;
the device may further comprise a controller configured in use to select the transport stream
clip to be retrieved in accordance with the duration of each ofthe transport stream clips
10 provided in the playlist and the identifier of the position within the video; and the network
connector is configured in use to retrieve the selected transport stream clip.
The identifier may be avideo timestamp.
15 There is also provided a television comprising a display and a device according to anyone of
the embodiments.
There may also be provided a method of controlling video and/or audio stream playback,
comprising: detecting the presence of at least one point of contact on a touchscreen and
20 detecting the movement of the point of contact, wherein the stream of video and/or audio is
controlled in accordance with the detected presence of the at least one point and the
movement ofthe point of contact.
There may be also provided a computer program product containing computer readable
25 instructions which, when loaded onto a computer configure the computer to perform a method
comprising: detecting the presence of at least one point of contact on a touchscreen and
detecting the movement ofthe point of contact, wherein a stream ofvideo and/or audio is
controlled in accordance with the detected presence ofthe at least one point and the
movement of the point of contact.
30
A method of controlling video and/or audio stream playback, comprising: detecting the
presence of at least one point of contact on a touchscreen and detecting the movement of the
point of contact, wherein a first stream of video and/or audio is controlled to transition said
• 5
first stream of video and/or audio into a second stream of video and/or audio in accordance
with the detected presence ofthe at least one point and the movement of the point of
contact.
• 6
BRIEF DESCRIPTION OF THE DRAWINGS
The above objects, features and advantages of the disclosure will be apparent from the
following detailed description of illustrative embodiments which need to be read in
connection with the accompanying drawings, in which:
5
Figure 1 shows a system according to embodiments ofthe present disclosure;
Figure 2 shows a television according to embodiments of the present disclosure;
Figure 3 shows representative screenshots of embodiments ofthe present disclosure;
Figure 4 shows the structure of a look-up table stored in the server according to embodiments
10 of the present disclosure;
Figure 5 shows the structure of a playlist according to embodiments ofthe present disclosure;
Figure 6 shows a flow diagram explaining the encoding ofthe televisual content according to
embodiments;
Figure 7A shows a flow diagram explaining the viewing of live rewind according to
15 embodiments of the present disclosure when the live rewind is viewed on the television;
Figure 7B shows a flow diagram explaining the viewing of live rewind according to
embodiments of the present disclosure when the live rewind is viewed on a tablet;
Figure 8 shows a plan view of a tablet in use to control the video stream; and
Figure 9 shows different gestures to control the tablet.
20
• 7
DESCRIPTION OF TIlE PREFERRED EMBODIMENTS
Referring to Figure 1, a system 100 according to an embodiment ofthe present disclosure is
shown. In this system 100, a camera 105 captures video and/or audio content. The output of
5 the camera 105 is typically edited in an editing suite (not shown). The captured (and possibly
edited) content in encoded in an encoder 110.
In embodiments, the content is encoded using, for example, the Moving Pictures Expert
Group (MPEG) 2 format. However, the disclosure is not limited to such a format and any
10 other video and/or audio format is envisaged.
The encoded content is fed into a multiplexor 115. The multiplexor 115 multiplexes the
received encoded video and/or audio data with other data. In embodiments, the other data
includes an identifier that uniquely identifies the broadcast program and a Hybrid Broadcast
15 Broadband TV (HBBTV) URL. As the HBBTV programming language is known to the
skilled person, a detailed discussion ofthe HBBTV programming language will not be
provided. However, the HBBTV URL is an .htmllink which identifies the location of a
HBBTV application. However, the skilled person will appreciate that the HBBTV URL may
be an index.php, main.cgi, application.asp or the like. The identifier is, in embodiments, a
20 video timestamp, although any type of identifier that identifies the video is also envisaged.
The identifier may uniquely identify the frame of video for a very accurate playback or may
indicate the approximate location of a particular frame of video. For example, the location of
a particular frame may be approximately determined using the nearest video timestamp.
25 The other data, in embodiments, is inserted in the private field of the MPEG 2 transport
strearp adaptation field. In order to indicate that the private field ofthe MPEG 2 transport
stream adaptation field has data contained therein, the transport private data flag is set to 1 as
would be appreciated by the skilled person.
30 In addition, the other data may include metadata such as the Event Information Table (EIT)
that provides Electronic Program Guide (EPG) information. Additionally, closed caption
information may also be included with the metadata. The EIT and closed caption information
is known to the skilled person and are defmed by the various Digital Video Broadcast (DVB)
• 8
standards. Ofcourse, corresponding tables are also available in other transmission standards
which are equally applicable to embodiments ofthe present disclosure. Examples ofthese
standards include ATSC and ARIB.
5 Ofcourse, in embodiments, although the other data and the metadata is inserted into the
private field of the MPEG 2 transport stream adaptation field, the other data and metadata
may be inserted in any appropriate part ofthe transport stream.
The multiplexor 115 is connected to a database 145. In the database 145 is stored the video
10 timestamps which are used to identify the video in the transport stream and a triplet of
information including the original network identifier (ONID), transport stream identifier
(TSID) and the service identifier (SID) associated with the timestamp. The video timestamps
are retrieved by the multiplexor 115.
15 The multiplexed MPEG2 transport stream is fed to a broadcast station 150. The broadcast
station 150 is a terrestrial broadcast station. However, as would be appreciated, the broadcast
station 150 may be a satellite broadcast station, cable television broadcast station or indeed
any broadcast station such as a broadcast station broadcasting to handheld devices complying
with, for example, the Digital Video Broadcast - Handheld (DVB-H) format. Other broadcast
20 modes and/or standards may equally be used.
The broadcast station 150 broadcasts the multiplexed MPEG2 transport stream over the air
155. The broadcast signal is received by an antenna 160 within the user's home. The
received multiplexed transport stream is fed to television 140. Television 140 will be
25 described in more detail with reference to Figure 2.
Additionally, the multiplexor 115 multiplexes the encoded MPEG2 content to generate a
number ofMPEG2 transport stream files. In other words, the multiplexor 115 splits the
encoded MPEG2 transport streams into a plurality of segments and for each segment, the
30 multiplexor 115 generates a transport stream file. These transport stream files will be used to
enable a viewer to download video such that the user may "rewind" or perform other function
on the broadcast content. Although this will be explained later, it should be noted that the
generation ofMPEG2 transport stream files is to comply with the particular protocol used
• 9
(HTTP Live Streaming) used to deliver the content to the television. If a different protocol is
used, such as MPEG2 Dynamic Adaptive Streaming, then the generation ofthe transport
stream files may be un-necessary or may be different.
5 In embodiments, the multiplexor 115 segments the transport stream into a plurality of
transport stream files; each file containing 8 seconds ofencoded video. Additionally created
by the multiplexor 115 is a playlist file. The playlist file will be explained in more detail with
reference to Figure 5. However, in brief, the playlist file contains a pointer to each ofthe
created transport stream files and complies with the HTTP Live Streaming format. The
10 pointer stored within the playlist file may be a URL or a URI (Unique Resource Identifier).
The multiplexor 115 stores the created transport stream files and the playlist file in a server
120. The server 120 is accessible over the Internet or any kind of network 130. Such a
network mayor may not have quality of service guarantees. In Figure 1, it is immediately
15 apparent that the server 120 stores the playlist 126 (see Figure 5), a HBBTV look-up table 122
(see Figure 4) and the video transport stream files 124. As will be explained later, a router
135 which is also connected to the television 140 accesses the information stored within the
server 120 via the Internet 130.
20 The television 140 is controlled by a user operating a user control 205. The user control 205
may be a remote commander or the like. However, the user control 205 may be an
application running on a portable computing device such as a Tablet S produced by Sony ®.
Voice activated or gesture based commands may provide an alternative and in some
embodiments may obviate the need for a physical user control 205. The user control 205 ..
25 communicates with a control receiver 210 that decodes the control signals received from the
user control 205. The control receiver 210 is connected to the controller 215 which controls
the operation of the television 140. Also connected to the controller 215 is a decoder 240.
The decoder 240 is connected to the antenna 160 and decodes the broadcast signal received
from the broadcast station 150. The decoded signal is fed to the controller 215. In
30 embodiments, the decoder includes a tuner and demodulator.
In order to display the video, the controller 215 provides video and/or audio data received
from the decoder 240 to an audio and/or video (AIV) processor 220. The A/V processor 220
• 10
generates audio signals to be played over speakers (not shown) and video signals to be
reproduced on display 225. The display 225 may be a liquid crystal display type display such
as a Sony ® Bravia ® television.
5 Also connected to the controller 215 is memory 230. The memory 230 may be built in to the
television or may be provided externally. The memory 230 is, in embodiments, solid state
memory, but the disclosure is not limited and may be any kind ofmemory such as optically
readable or the like.
10 The memory 230 stores computer readable instructions which are in the form of a computer
program. The computer program stored within the memory 230 controls the controller 215 to
perform a method according to embodiments ofthe present disclosure. Additionally, and as
will be explained later, the memory 230 acts as a buffer to' store transport streams that the
television 140 retrieves from the server 120.
15
The controller 215 is also connected to an internet connector 235. In embodiments, the
internet connector 235 is an Ethernet connector. The internet connector 235 is connected to
the router 135. Ofcourse, embodiments ofthe present disclosure may be applied to any kind
of network connection. For example, the internet connector 235 may be wired, wireless,
20 Powerline or HomePlug® or a 3G/4G network.
Additionally a tablet 800 communicates with the television 140. The tablet 800 may be any
kind of tablet computer such as a Sony ® Tablet S or a Sony ® Xperia ® Tablet S which may
or may not also operate as the user control 205. The tablet 800 m'ay communicate using
25 Bluetooth or any kind ofwired or wireless connection. The operation ofthe tablet 800 will be
described in more detail with reference to Figures 7B and 8.
Figure 3 shows a sequence of screen shots illustrating the operation ofembodiments ofthe
present disclosure. A television signal is received at the antenna 160. The television 140
30 receives this signaland displays the associated video frame or sequence of video frames. A
first image 305 in an image sequence 300 is displayed to the user. The first image 305 shows
a frame oflive content. In other words, the first frame 305 is a frame of video currently being
broadcast by the broadcast station 150.
• 11
At this time, the viewer ofthe television 140 decides that he or she wants to rewind the
currently broadcast video. In order to interact with the currently broadcast content, the user
presses a button on the user control 205. This button may be the so-called "red button". The
5 live video stream continues and a Graphical User Interface (Gill) is shown on the display.
This is shown in the second frame 310. The Gill is generated using a HBBTV application
stored within the server 120. In order to obtain the HBBTV application, the television 140
retrieves the HBBTV URL which is located in the transport stream broadcast by the broadcast
station 150. The HBBTV URL provides the location ofthe HBBTV application which is
10 downloaded by the television 140 over the network 130. In other words, when the television
140 decodes the incoming transport stream broadcast by the broadcast station, the HBBTV
URL directs the television 140 to the location ofthe HBBTV application stored on the server
120. ·The television 140 then downloads the HBBTV application from the server 120 and
stores this locally in the storage memory 230.
15
The downloaded HBBTV application provides the code to display the Gill on the screen. It is
envisaged that the HBBTV application may be updated by the broadcast station 150 that
allows the Gill to be customised, such as advertising sponsors logos being included in the
GUr.
20
Once the HBBTV application has loaded, the user may control the video controls in the Gill
using the user control 205. In the example embodiment, the user wishes to rewind the
broadcast content. This is indicated by the dashed lines 316 surrounding the rewind symbol
in the GUI in the third frame 315.
25
As will be explained later, the URL stored in the look-up table 125 is used to access a playlist.
This URL is called the "Playlist URL" hereinafter. The playlist is then used to control the
content displayed on the television 140. In order for the playlist and the appropriate content
to be downloaded into the memory 230 ofthe television 140, the screen will be frozen for a
30 period oftime. This is because the broadcast content is segmented into 8 second segments
and then stored on server 120. Therefore, if the broadcast content is live content, the user
may have to wait upto 8 seconds until the segment of live video is completed and a further
small time, t to allow the segment to be saved, the playlist to be updated and the segment to be
• 12
downloaded by the television. Accordingly, given the length of time to wait, an egg-timer
321 is displayed in the comer ofthe frozen screen as shown in the fourth frame 320 to
indicate to the user that the application is being downloaded. Although an egg timer is
shown, any other kind ofmessage may be displayed. This may include a message asking the
5 viewer to please wait or even an advertisement. If an advertisement is provided the
broadcaster may transmit the advertisement at the start ofthe broadcast and the advertisement
may be stored in memory 230 ofthe television 140. The advertisement may be provided via
the network at that time or in advance. The broadcaster may therefore generate income by
selling the advertisement opportunity to a sponsor.
10
In the event that the broadcast content is pre-recorded, the delay described above with respect
to the live content does not occur. This is because the video timestamps, playlist and video
transport stream files have already been created and stored on the server 120. However, when
the recorded content is broadcast, the playlist will be modified in order to correspond to the
15 current broadcast content. In other words, the initial playlist for the recorded content (Le. the
playlist when the content was created) will have changed when the recorded content is
broadcast. The playlist stored on the server 120 will need to be updated accordingly.
After the user selects the rewind symbol using the user control 205, the television 140
20 retrieves the appropriate transport stream from the server 120 as will be explained later. After
the appropriate data is downloaded to the television 140 from the server 120, the egg-timer
will stop being shown and instead the television 140 will display the transport stream obtained
from the server 120. The transport stream obtained from the server 120 will be the transport
stream nearest in time to the transport stream ofthe frame currently being broadcast. During
25 the operation ofthe GUI, the video displayed to the user is the transport stream provided by
the server rather than the video broadcast by the broadcast station 150.
In order to indicate to the user that the video being displayed is that provided by the server
120 rather than the broadcast station 150, a message may be displayed to the user. This
30 message may include textual or graphical information indicating that the video is provided by
the server 120 rather than by the broadcast station 150. For example, if the indication to the
user is graphical, a time or clock showing the elapsed time between the content provided by
the server 120 and the content provided by the broadcast station 150 may be displayed. This
13
elapsed time may be derived from the video timestamps or some other mechanism. The user
may be able to toggle whether to show this information or not.
When the user wishes to start playback ofthe video obtained from the server 120, the user
5 highlights the playback button 326 shown in the fifth frame 325. The user then selects the
playback button 326 and the video content is played back. It is important to note that the
content during this period is the content downloaded from the server 120 rather than the
content being broadcast by the broadcast station 150.
10 When the user wishes to return to the live content (i.e. the content being broadcast by the
broadcast station 150), the user can press the red button again. However, it is useful for a
more seamless experience for the user to press a stop button on the Gill (not shown). As the
HBBTV applicafion must revert to displaying content broadcast by the broadcast station 150,
the egg timer is shown again in the sixth screen 330. The content displayed on the television
15 140 then returns to the live content being broadcast by the broadcast station 150 in the seventh
screen 335.
As noted in Figure 3, after the user starts the HBBTV application and selects to rewind the
broadcast content, a short delay occurs (see the fourth screen shot 320). During this delay, the
20 HBBTV application retrieves the video timestamp and a DVB triplet from the transport
stream. The HBBTV application also retrieves the playlist URL indicating the location ofthe
playlist from the server 120. The HBBTV application in the television 140 accesses the
server 120 over the Internet 130. The HBBTV application accesses the HBBTV lookup table
122 within the server 122. The HBBTV lookup table 122 is shown in Figure 4.
25
Referring to Figure 4, the DVB triplet which identifies a particular broadcast program is
stored in the HBBTV look-up table. Specifically, the DVB triplet is stored in a triplet column
125A ofthe look-up table. Additionally stored in a playlist URL column 125B is the playlist
URL. The playlist URL is stored in correspondence with the DVB triplet. The playlist URL
30 provides, in embodiments, an .htmllink to the location ofthe playlist for the program that is
associated with the DVB triplet (although other forms of pointer are envisaged). In
embodiments, the playlist is stored within the server 120.
• 14
Additionally, the playlist stored at the location associated with the playlist URL is retrieved.
Figure 5 shows a playlist according to embodiments of the present disclosure. The playlist
(.m3u8), in embodiments complies with the HTTP Live Streaming protocol, although the
5 disclosure is not so limited and any appropriate protocol is envisaged. Although this would
be appreciated by the skilled person, the "EXT-X-TARGETDURATION" value is set to 8.
This means that, in this case, each transport stream is 8 seconds long. However, the value of
"EXT-X-TARGETDURATION" can be varied to any value. The value ofthis determines the
length ofthe transport stream file. For example, ifthe value of"EXT-X-
10 TARGETDURATION" is 2, the transport stream file is 2 seconds long. This value can be
any suitable value such as 2 secoI}.ds or 10 seconds or the like.
Further, a transport stream file URL is provided in the playlist to each of the tra~sport
streams. Therefore, by following the transport stream file URL the appropriate 8 second
15 video segment may be downloaded.
It will be appreciated that the content being broadcast by the broadcast station 150 will be
stored in 8 second segments within the server 120. Each 8 second segment will have a
transport stream file unique URL. After the creation and storage ofthe 8 second segment, the
20 transport stream file URL will be stored within the playlist. This means that the playlist is
dynamically updated during the broadcast ofthe program.
The encoding ofthe content according to embodiments will be described with reference to the
flow chart 600 of Figure 6. Firstly, the content is captured 605. The captured content is
25 encoded to produce an MPEG2 transport stream in step 610. The encoded data is then fed to
the multiplexor 115 which produces a transport stream for broadcast and a separate transport
stream for storage on the server 120.
The transport stream for broadcast is produced in step 615. Specifically, the multiplexor 115
30 multiplexes the encoded captured content with the other data (the HBBTV URL and the video
timestamp). Additionally, the multiplexor 115 may include metadata such as the EIT and the
like in the transport stream. The multiplexed encoded data is then broadcast using the
broadcast station 150.
• 15
The multiplexor 115 also produces data for storage on the server 120. Specifically, the
multiplexor 115 generates the HBBTV look-up table 125 which stores the DVB triplet in
association with the playlist URL. Also, the multiplexor 115 generates the 8 second transport
5 stream clips and stores these on the server 120. The associated playlist is also updated to
include a link (the transport stream URL) to the newly created 8 second clip ofthe transport
stream by the multiplexor 115. The updated playlist file and the 8 second clips are uploaded
back onto the server 120. This is shown in steps 625, 630 and 635 of Figure 6.
10 The encoding steps end at step 640.
A flow diagram 700 explaining the operation ofthe system according to embodiments is
shown in Figure 7.-A us~r switches the television 140 on and chooses an appropriate channel
in step 705. The television 140 receives the multiplexed stream via the antenna 160. The
15 received stream is demultiplexed in step 710. The demultiplexed stream is decoded and
viewed on the television in step 715. Additionally, in step 717, the television 140 retrieves
the HBBTV URL from the transport stream and downloads the HBBTV application from the
server 120. The HBBTV application is stored in memory 230 within the television 140. The
television 140 also executes the HBBTV application at step 720. As the television 140
20 executes the HBBTV application prior to the user pressing the red button to activate the GUI,
the time taken for the television 140 to respond to the user input is significantly reduced.
The decision point at step 725 is then reached. Ifthe user does not wish to launch the
interactive Gill, the user does not press the red button and so the "no" path is followed. The
25 user continues to watch the broadcast transport stream. However if the user does press the red
button to launch the interactive GUI, the "yes" path is followed. At this point a second
decision point at 727 is reached. This decision point determines whether the tablet or the
television displays the video played back from the server.
30 If the television 140 plays back the video from the server, the HBBTV application shows the
GUIon the screen ofthe television 140. This is step 730. As previously mentioned, the
content displayed on the television 140 will be the broadcast content.
• 16
The user chooses to "rewind" the content in step 735. Therefore, the user selects the
appropriate icon on the Gill. After the selection of the appropriate icon is made, the frame is
frozen on the screen ofthe television 140 and the egg-timer or appropriate message is
displayed.
5
The HBBTV application retrieves the video timestamp and the DVB triplet from the frozen
video frame. This is step 740. Using the look-up table, the playlist URL corresponding to the
,
retrieved triplet is followed. This is step 745. The playlist stored at the retrieved playlist
URL is downloaded. This is step 750.
10
As the retrieved playlist contains links to many 8 second transport streams, the television must
determine which ofthe stored transport streams includes the frozen frame.
In order to do this, the television compares the retrieved video timestamp with the sum of the
15 8 second transport stream clips. In other words, if the video timestamp indicates that the
frozen frame is, say, 817 seconds from the start ofthe broadcast, then the appropriate frame
will be located within the 103rd transport stream within the playlist. In other words, for
transport stream clips 8 seconds long, the frame that is 817 seconds from the start of the
broadcast will be located approximately 1 second into the 103rd transport stream. This is step
20 755. The television 140 then retrieves, in this case, the 103rd transport stream identified in the
playlist. This is step 760. After downloading the 103rd transport stream, the television
identifies the approximate location ofthe frozen frame using the video timestamp. This
approximate location is determined as being the video timestamp in the stored transport
stream being closest to the video timestamp retrieved from the frozen image. This is step 765.
25 The television 140 then rewinds from the location. This is step 770. The process for
rewinding ends when the user presses the play button in the Gill. This is step 775.
The user then watches the content from the server 120. When the user wishes to return to
watching the broadcast content, the user presses the red button or the button on the Gill. The
30 HBBTV application may simply finish and return to displaying the broadcast content.
Howeve~ as the content is concurrently broadcast, the time taken to return to viewing the
broadcast content may result in a discontinuity in viewing ofthe content.
• 17
In order to reduce the effect ofthe discontinuity, a transition process is followed.
Specifically, the memory 230 within the television 140 is, in embodiments, used as a buffer to
store some ofthe video broadcast by the broadcast station 150. The memory 230 may be used
to store all the video broadcast by the broadcast station, or may be used to store only certain
5 frames ofthe video. For example, the memory 230 may be used to store only I-frames.
However, when using the memory 230 as a buffer, the video broadcast by the broadcast
station 150 will always be buffered by the memory 230 irrespective ofwhether the content
being displayed is actually being provided by the server 120.
10 The memory 230, in embodiments, stores, and buffers 8, seconds of video. In other words,
although the memory 230 could store any length of video, in embodiments, the amount of
video stored by the memory 230 is the same as the length as one ofthe transport stream files.
The video stored in memory 230 is tlien used to reduce the impact of the discontinuity.
15 In one mechanism of operation of the transition process, when the user wishes to return to
viewing broadcast content, the 8 second transport stream file retrieved from the server 120 is
played back at twice the normal speed. This means that the 8 second transport stream file is
played back in 4 seconds.
20 The next 8 seconds of broadcast content is then played back from the memory 230 at twice
the normal speed. In other words, the next 8 seconds of broadcast content are provided by the
memory 230 rather than the server 120 and is played back within 4 seconds. Thus, when
viewing oflive broadcast content resumes after this transition, the effect ofthe discontinuity
is reduced to zero time lag. In order to reduce the effect ofthe increased speed of playback
25 and in order to reduce the memory usage, it is possible to only play back I frames during this
speeded playback period.
In a second mechanism of operation, if the user has requested that the television 140 rewind
the live content, in embodiments, the television 140 will continuously store 8 seconds of
30 buffered content from the broadcast station 150. Therefore, when the user switches back to
watching live content, the content will be provided by the buffer in the memory 230 rather
than being provided by the antenna 160 directly. In other words, the user will watch video
content that is delayed by 8 seconds compared to the content received by the antenna 160.
• 18
This arrangement removes all discontinuities and requires no speeding up of displayed
content.
In other modes of operation, a so-called buffer flush may be employed upon detection of
5 selection signals from the user to allow a swift transition between the content stored in the
respective buffers. This operates by repositioning a pointer to the location in memory that
should be read.
In the case that the tablet 800 plays back the content, the flow diagram of Figure 7Bis
10 followed. Before the flow diagram ofFigure 7B is described, the interaction of the tablet 800
and the television 140 will be described.
In embodiments, the television 140 which receives both the broadcast channel and the
transport stream from the server itself acts as a server to the tablet 800. The television 140
15 may transmit either the video data from the broadcast channel, the transport stream identified
by the playlist or both. It is therefore possible for the broadcast channel to be displayed on
both the television 140 and the tablet 800.
So, after connection ofthe tablet 800 to the television 140, the television 140 receives the
20 broadcast channel. The television 140 then acts as a server from which the tablet 800 receives
content. The television 140 sends video data in a unicast fashion to the IP address to which
the tablet 800 is connected. Obviously, if more than one tablet is c~mp.ected to the television
140, video data can be transferred in a unicast or multicast fashion. This allows video data
from either the broadcast channel or the transport stream (or both) to be played back on the
25 tablet 800.
Returning to Figure 7B, when the tablet 800 is used to control the video played back from the
server, step 1730 is performed. The tablet may obtain the HbbTV application or be capable of
storing and executing a separate application for example defining the GUI. The Tablet mayan
30 appropriate application for example in HTML from the server. This may be achieved by
passing a URL from the HbbTV application in the television 140 to tablet 800. The tablet 800
shows the GUI on the screen as depicted in Figure 8. As is seen in Figure 8, the current video
1315 is shown on tablet 800. The GUI has a control bar 810 that appears and allows the user
• 19
810 to control the displayedvideo. In this case, the user 810 presses the rewind button 1316
displayed on the screen of the tablet 800. In other words, the user performs step 1735 of
Figure 7B. It should be noted here that although the aUI displays a control bar 810, in other
embodiments, other control mechanisms are envisaged. These are described with reference to
5 Figure 9 and will be described later.
The tablet 800 sends to the television 140 a control signal using Real Time Streaming
Protocol (RTSP). The control signal instructs the television 140 that the user wishes to
rewind from the frame displayed on the tablet 800. As the television 140 sends the video to
10 the tablet 800, the television 140 then returns to the flowchart ofFigure 7A from step 740 by
retrieving the ONIDrrSID/SID from the broadcast stream.
The television 140 retrieves the video from the shver and rather than playing back the video
transport stream on the television 140, the television transfers the retrieved video on the tablet
15 800 whilst the television either pauses the broadcast channel allowing the user to continue
watching the television 140 later, or continue to display the live broadcast channel
concurrently with the user viewing the retrieved video transport stream on the tablet 800.
In other embodiments the server may communicate directly over the IP network with the
20 tablet. The tablet may therefore be seen as a slave to the server rather than as a slave to the
television 140.
Figure 9 shows different examples of control mechanisms which do not require the control
bar 810. These control mechanisms mean that more screen space is provided to display the
25 video.
In drawing A of Figure 9, the mechanism for skipping to the next chapter of video is shown.
The user 810 places two fingers 810A and 81 OB on the touch sensitive screen ofthe tablet
800. The user 810 then swipes their fingers to the left whilst still touching the screen. The
30 tablet 800 detects both [mgers touching the screen and detects the movement to the left. The
tablet 800 then issues the command to move the video to the previous chapter. A similar
'-.
situation is given in drawing F except the user 810 swipes their fingers 810A and 81 OB to the
right to advance the video to the next chapter.
• 20.
In drawing B of Figure 9, the mechanism for rewinding the video is shown. The user 810
places one fmger 810A on the touch sensitive screen ofthe tablet 800. The user 810 then
swipes their finger to the left whilst still touching the screen. The tablet 800 detects that only
5 a single finger touches the screen and detects the movement to the left. The tablet 800 then
issues the command to rewind the video. In this case, the speed at which the user swipes their
fmger determines the speed of rewind. For example, if the user only wishes to rewind the
video at x2 speed, then the swipe should be slow. However, for a x30 rewind, the swipe
should be fast. A similar situation is given in drawing E except the user 810 swipes their
10 finger 81OA to the right to fast forward the video.
In drawing C ofFigure 9, the mechanism for pausing the video is shown. The user 810 places
two fingers 810A and 810B on the touch sensitive screen ofthe tablet 800. The user 810 then
holds their fingers on the screen for a period oftime such as 0.3seconds without movement.
15 The tablet 800 detects both fingers touching the screen and that there is no movement. The
tablet 800 then issues the command to pause the video.
In drawing D ofFigure 9, the mechanism for playback of the video is shown. The user 810
places one finger 810A on the touch sensitive screen ofthe tablet 800. The user 810 then
20 holds their finger on the screen for a period oftime such as O.3seconds without movement.
The tablet 800 detects that one finger touches the screen and that there is no movement. The
tablet 800 then issues the command to playback the video.
Although the foregoing describes controlling the video in relation to this disclosure, the touch
25 screen commands of Figure 9 could be used on any touch screen device to control playback of
any video on any video playback device. For example, the gestures given in Figure 9 could
be used to control a DVD player, a Blu-Ray player, a video streaming device or any kind of
device where video and/or audio playback needs to be controlled.
30 Although the foregoing embodiments, a broadcast channel has been described. However, in
some video distribution environments, video data or television signals can be distributed over
the internet or networks operating internet protocol technologies. These are sometimes
referred to as IPTV or OTT (Over the Top) services. In IPTV, a managed network with a
• 21
guaranteed quality of service may be used. With OTT, IPTV video data is carried over the
internet and is available through, for example, the xDSL (Digitial Subscriber Line)
subscription ofLong Term Evolution (LTE) subscription ofthe user.
5 In IP environments, video may be distributed in a unicast fashion. In this type ofsystem,
video is distributed in a point-to-point manner from a server to a target device. The video is
passed to the target device using a receiver such as a modem, router or home gateway device.
In other embodiments, video may be distributed using multicast protocols. Groups oftarget
10 devices may be predefined or actively defined by making requests to join multicast groups.
This may be in exchange for payment. Video data is then distributed using multicast
identifiers or addresses contained therein with header information or the like. The target
devices belonging to the multicast group then identifies and interpret the video data packets
received via the network. Other devices will ignore the packets. The skilled person will
15 appreciate that multicast transmission will save bandwidth when multiple devices are
receiving the same video content items. The disclosure is applicable to multicast channels in
a similar way to broadcast channels. Therefore, although broadcast channels are noted above,
the disclosure is relevant to multicast channels or any type of distribution channels. The
stored transport stream which the playlist identifies may be sent to the target devices using
20 unicast protocols.
Although the foregoing has been described with reference to a tablet 800, any kind of device
with a screen is envisaged. For example, a cell phone, laptop computer or the like could be
used instead of or as well as the tablet 800.
25
Although the foregoing has been explained with reference to the transport streams on the
server being produced from the captured content being broadcast, the disclosure is not so
limited. For example, the transport streams on the server may include the broadcast content
being captured from a different camera angle or level of zoom. Or, the transport stream on
30 the server may include content related to the broadcast content. For example, ifthe broadcast
content is a movie, the content on the server referenced by the playlist may be director's
commentary.
• 22
Although the foregoing has been explained with the playlist complying with the HTTP Live
Streaming Protocol, the disclosure is not so limited. Other suitable protocols include MPEG
DASH or Microsoft Smooth Streaming or the like.
5 Although the foregoing has been described with reference to the video timestamp being used
as the unique identifier, the disclosure is not so limited. Any unique identifier that enables the
location ofthe frame to be established within the playlist may be used. For example, if the
EIT is part ofthe broadcast transport stream, the elapsed time from the start time ofthe BIT
may be used. Indeed, if other metadata such as the unique time code (UTC) in the TDTrrOT
10 (Time and Data Tablerrime Offset Table) is provided in the other data, this may be used.
Although the foregoing has been explained with reference to the user rewinding the broadcast
content, the disclosure is not so limited. The user may pause the broadcast content, may fast
forward the content (by skipping frames), may play back the content in slow motion or indeed
15 perform any review ofthe content.
Although the foregoing has been explained with reference to the transport stream provided by
the server 120 being displayed instead ofthe transport stream provided by the broadcast
station 150, the disclosure is not so limited. The transport stream provided by the server may
20 be provided in addition to the broadcast transport stream. For example, the transport stream
provided by the server 120 may be displayed in a picture-in-picture arrangement with the
content provided by the broadcast station 150. This allows the user to view the obtained
transport stream concurrently with the broadcast transport stream.
25 Although the foregoing has been explained with HBBTV being used for the GUI, the
disclosure is not so limited and any kind of appropriate programming language such as Adobe
Flash or MHEG may be used instead.
Although the foregoing explains the use of a look-up table whereby the DVB triplet is stored
30 in association with the playlist URL, the disclosure is no way limited. Indeed, if the
broadcaster wishes to only associate one playlist with one channel, the playlist URL may be
included in the broadcast transport stream. In this case, no look~up table is required.
• 23
In some embodiments the HBBTV application may restrict fast-forwarding ofthe content.
This allows files to be uploaded to the server 120 in advance, but restricts fast-forwarding so
that a viewer cannot watch content from the server 120 that has yet to be broadcast.

• 24
CLAIMS
1. A method comprising:
receiving, via a distribution channel, video data having an identifier that identifies a
.pos~tion within the video and an address defining the location of a stored playlist;
5 obtaining from a server the playlist in response to a user input, the playlist containing
location information identifying the location of a stored transport stream;
receiving the transport stream from the location identified in the playlist over a network;
and
displaying the obtained transport stream.
10
2. A method according to claim 1, wherein the stored transport stream includes at least
one frame pf said video data corresponding to that received over the distribution
channel.
3. A method according to claim 1, comprising storing the video data obtained over the
15 distribution channel concurrently with displaying the transport stream obtained from
the server; performing a transition back to the received video data by increasing the
speed of playback ofthe transport stream; stopping display ofthe transport stream;
and displaying the stored video data with an increased playback speed.
4. A method according to claim 1, further comprising storing the video data obtained
20 over the distribution channel; stopping display of the transport stream and displaying
the stored video data.
5. A method according to claim 1, wherein the transport stream includes a plurality of
transport stream clips, each transport stream clip being of a predetermined clip
duration;
25 providing the location of each of the transport stream clips and the duration of each of
the transport stream clips in the playlist;
selecting the transport stream clip to be retrieved in accordance with the duration of
each of the transport stream clips provided in the playlist and the identifier of the
position within the video; and
30 retrieving the selected transport stream clip.
6. A method according to claim 1 wherein the identifier is a video timestamp.
7. A method according to claim 1 comprising: displaying on a second screen either the
stored transport stream or the distribution channel.
• 25
8. A computer program containing computer readable instructions which when loaded
onto a computer configures the computer to perform a method according to claim I.
9. A storage medium which is configured to store the computer program of claim 8
therein or thereon.
5 10. A device comprising:
a receiver configured in use to receive, via a distribution channel, video data having an
identifier that identifies a position within the video and an address defining the location of
a stored playlist;
a network connector configured in use to obtain from a server the playlist in response to a
10 user input, the playlist containing location information identifying the location of a stored
transport stream; wherein the network connector is further configured in use to receive the
transport stream from the location identified in the playlist over a network; and
an output configured in use to output the obtained transport stream for display. 15 11. A device according to claim 10, wherein the stored transport stream includes at least
one frame of said video data corresponding to that received over the distribution
channel.
12. A device according to claim 10, comprising a memory configured in use to store the
video data obtained over the distribution channel concurrently with displaying the
20 transport stream obtained from the server; and a controller configured in use to
perform a transition back to the received video data by increasing the speed of
playback of the transport stream; stop display ofthe transport stream; and to output the
stored video data for display with an increased playback speed.
13. A device according to claim 10, further comprising a memory configured in use to
25 store the video data obtained over the distribution channel; and a controller configured
in use to stop display of the transport stream and to output the stored video data for
display.
14. A device according to claim 10, wherein the transport stream includes a plurality of
transport stream clips, each transport stream clip being of a predetermined clip
30 duration and the playlist provides the location of each of the transport stream clips and
the duration of each of the transport stream clips in the playlist; the device further
comprising
a controller configured in use to select the transport stream clip to be retrieved in
, accordance with the duration of each of the transport stream clips provided in the
playlist and the identifier of the position within the video; and
the network connector is configured in use to retrieve the selected transport stream
5 clip.
15. A device according to claim 10 wherein the identifier is a video timestamp.
16. A device according to claim 10, wherein the controller is configured to communicate
with a second screen to display thereon either the stored transport stream or the
distribution channel.
17. A television comprising a display and a device according to claim 10.