EP2177032A1 - Procédé et système pour réduire la solution de continuité lors d'un changement de programme d'un environnement vidéo numérique - Google Patents

Procédé et système pour réduire la solution de continuité lors d'un changement de programme d'un environnement vidéo numérique

Info

Publication number
EP2177032A1
EP2177032A1 EP08706761A EP08706761A EP2177032A1 EP 2177032 A1 EP2177032 A1 EP 2177032A1 EP 08706761 A EP08706761 A EP 08706761A EP 08706761 A EP08706761 A EP 08706761A EP 2177032 A1 EP2177032 A1 EP 2177032A1
Authority
EP
European Patent Office
Prior art keywords
program
video data
video
data stream
receiving device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP08706761A
Other languages
German (de)
English (en)
Inventor
Alexander Stumpf
Heiko Dassow
Torsten Orth
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Deutsche Telekom AG
Original Assignee
Deutsche Telekom AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Deutsche Telekom AG filed Critical Deutsche Telekom AG
Publication of EP2177032A1 publication Critical patent/EP2177032A1/fr
Ceased legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
    • H04N21/44—Processing of video elementary streams, e.g. splicing a video clip retrieved from local storage with an incoming video stream or rendering scenes according to encoded video stream scene graphs
    • H04N21/44016—Processing of video elementary streams, e.g. splicing a video clip retrieved from local storage with an incoming video stream or rendering scenes according to encoded video stream scene graphs involving splicing one content stream with another content stream, e.g. for substituting a video clip
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
    • H04N21/234—Processing of video elementary streams, e.g. splicing of video streams or manipulating encoded video stream scene graphs
    • H04N21/23424—Processing of video elementary streams, e.g. splicing of video streams or manipulating encoded video stream scene graphs involving splicing one content stream with another content stream, e.g. for inserting or substituting an advertisement
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/25—Management operations performed by the server for facilitating the content distribution or administrating data related to end-users or client devices, e.g. end-user or client device authentication, learning user preferences for recommending movies
    • H04N21/262—Content or additional data distribution scheduling, e.g. sending additional data at off-peak times, updating software modules, calculating the carousel transmission frequency, delaying a video stream transmission, generating play-lists
    • H04N21/26275—Content or additional data distribution scheduling, e.g. sending additional data at off-peak times, updating software modules, calculating the carousel transmission frequency, delaying a video stream transmission, generating play-lists for distributing content or additional data in a staggered manner, e.g. repeating movies on different channels in a time-staggered manner in a near video on demand system
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/41—Structure of client; Structure of client peripherals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
    • H04N21/438—Interfacing the downstream path of the transmission network originating from a server, e.g. retrieving encoded video stream packets from an IP network
    • H04N21/4383—Accessing a communication channel
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
    • H04N21/438—Interfacing the downstream path of the transmission network originating from a server, e.g. retrieving encoded video stream packets from an IP network
    • H04N21/4383—Accessing a communication channel
    • H04N21/4384—Accessing a communication channel involving operations to reduce the access time, e.g. fast-tuning for reducing channel switching latency
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
    • H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
    • H04N21/442—Monitoring of processes or resources, e.g. detecting the failure of a recording device, monitoring the downstream bandwidth, the number of times a movie has been viewed, the storage space available from the internal hard disk
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client 
    • H04N21/63—Control signaling related to video distribution between client, server and network components; Network processes for video distribution between server and clients or between remote clients, e.g. transmitting basic layer and enhancement layers over different transmission paths, setting up a peer-to-peer communication via Internet between remote STB's; Communication protocols; Addressing
    • H04N21/643—Communication protocols
    • H04N21/64322—IP

Definitions

  • the invention generally relates to a video or multimedia network environment for distributing programs to a plurality of subscribers, and more particularly to a method and a data transfer system for reducing the switching gap when switching from a first program to a second program.
  • An essential aspect of such multimedia communication systems is to provide measures to enable a switchover from one program channel to another program channel.
  • the problem often arises that when switching between two program channels, a visible disturbance in the visualized content is perceived by the subscriber. Because when switching between channels at any time is not guaranteed that after switching a seamless transmission of the destination channel or an immediate playback of the destination channel at the subscriber is possible.
  • it when switching from a currently displayed program to a new program, it must be ensured that a full screen is sent at the beginning of the presentation of the new program, so that a continuous, seamless image structure after the
  • a known method for seamless switching between program channels in a digital video-based entertainment network is known, for example, from US 2004/0034864 A1. It discloses a system for transmitting digital video signals having a headend having, inter alia, an encoder, means for recognizing and evaluating handoff messages, and means for generating frames.
  • the headend is over a distribution network with a subscriber side Terminal connected.
  • a subscriber initiates a channel change by entering at his terminal a corresponding channel change command which is transmitted over the network to the headend.
  • the headend recognizer causes the encoder to generate an I frame, that is, a frame of the new destination channel.
  • the full screen of the new destination channel is then transmitted to the subscriber's terminal.
  • the actual switching between program channels takes place in the coder of the headend.
  • Data streams can not be switched from one program to another at any time. This has technical reasons. For example, when the program is switched to video data, it is necessary to wait for the next frame to start the presentation of the new program.
  • the MPEG encoding standard is the currently displayed on the TV program in the set-top box 120 arranged.
  • the video data stored in the memory 132 is transferred to a decoder 142, the video data stored in the buffer 131 is transferred to a decoder 141 and stored in the buffer 130
  • Video data is decoded in a decoder 142.
  • the decoders 140 through 142 are connected to a switching device 150 which, under the control of a microprocessor 155, can supply a selectable decoded video data stream to the television receiver 160.
  • the selection of the video data stream is under the condition that the switching gap is minimized when changing programs.
  • the microprocessor 155 takes control of the set-top box 120.
  • the microprocessor 155 also ensures that the set-top box 120 selects only certain video data streams at the multicast replication point 90, i. H. requests.
  • the set-top box 120 may also include a mixer 170 which, under the control of the microprocessor 155, may suitably mix decoded video data streams.
  • the composite signal is then output from mixer 170 via one of decoders 140, 141,
  • the set-top box shows
  • the coding device 31 encodes the video signal coming from the broadcasting station 21 into four parallel video data streams having the same bandwidth.
  • the four video streams (labeled streams 1, 2, 3 and 4) are shown in FIG. everybody coded
  • video data stream is encoded according to the MPEG standard and has regularly recurring frames, also called I frames, labeled I t in FIG. Furthermore, each video stream transmits so-called P-frames, each containing the image information different from the previous frame. Moreover, in each of the parallel video streams, one frame is simultaneously inserted when a scene change occurs within the program. This frame is indicated in Fig. 5 with I c . It should be noted at this point that the data structure shown in FIG. 5 has been selected only as an example. Encoder 31 ensures that the frames designated I t in the four video data streams are offset in time relative to each other. The times to which in each
  • Video data stream is a frame I t transmitted, the set-top box 120 must be known.
  • 120 • knows the set-top box the algorithm by which the encoder of the Encoder 31 insert frames I t in the respective video data stream.
  • the microprocessor 155 of the set-top box 120 can determine the video stream suitable for minimizing the switching gap.
  • Another possibility is to refer the times at which frames I t are inserted into the respective video data streams to a reference point which is communicated to the set-top box 120.
  • the reference point may be provided by a central clock or by synchronized clocks implemented in the encoders and the set-top box 120, respectively.
  • the relative times at which frames I t are inserted into the four video streams may then be within the video streams themselves or in a separate one
  • the differently coded video data streams of the program 2 make it possible to minimize the waiting time until the first displayable frame of the program 2 and thus the switching gap.
  • the video data streams encoded by the encoder 31, which represent the program 2 are transmitted via the IP distribution network 60 to the multicast replication point 90. Now suppose that the user has input to the set-top box 120 a toggle command to change from program 1 to program 2. Thereafter, the set-top box 120 causes the multicast replication point 90 to no longer transmit the video stream associated with the program 1. At this moment, a switching gap appears on the television receiver 160, which must be minimized.
  • the microprocessor 155 knows the timing of the frames I t within the four parallel ones Video data streams representing the program 2 and the switching time defined by the switching command. In response to this information, the microprocessor 155 at the multicast replication point 90 selects the video stream of the program 2 which next transmits a frame I t . In this example, the video stream Stream 1 is selected. As soon as at least the video data representing the first frame I t is stored in the buffer 132, the decoder 142 decodes the video data stored in the buffer 132 and passes it on to the television receiver 160 directly or via the switch 150. There, a corresponding full screen is then displayed. At this moment, the presentation of the second program begins with either a still image or immediately with a motion image. The different beginning of the representation of the second program will be explained in more detail in connection with FIG. In the described embodiment, it should be noted that each of the four encoded video data streams contains all the information to do so
  • the encoder 31 encodes the video signal reproducing the program 2 into two different video data streams shown as streams 1 and 2 in FIG.
  • the video stream "Stream 1" contains all the video data required to represent the program 2, which in the present example are I-frames and P-frames.
  • the second video stream "Stream 2" contains only Frames r t .
  • the frame rate of the second video data stream is greater than that of the first video data stream. This means that the time interval between successive frames in the second video data stream is shorter than the time interval between successive frames I t in the first video data stream.
  • Both video data streams are in turn transmitted from the encoder via the feed server 51 and the IP distribution network 60 to the multicast replication point 90.
  • the microprocessor 155 After entering a toggle command on the set-top box 120, the microprocessor 155 causes the transmission of the program 1 to be interrupted and, for example, only the two video streams of the program 2 to be transmitted via the VDSL line to the set-top box 120 , The video data of the first
  • video data stream is stored in the buffer 132 while the video data of the second video stream, which contains only frames, is stored in the buffer
  • the microprocessor 155 in turn knows the timing of the frames transmitted in the two video streams. In addition, the microprocessor 155 knows the contents of the two video data streams insofar as it knows when a difference image of the first video data stream can be replaced by a frame of the second video data stream containing only frames. In the present example, in response to the switching command and the position information, the microprocessor 155 recognizes that the video stream "stream 2" contains the next displayable frame I t . Thereafter, the microprocessor 155 transfers the memory
  • the output of the mixer 170 is supplied to the decoder 141, for example, which supplies the mixed output signal to the television receiver 160 via the switch 150, for example. Thanks to the use of both
  • Video data streams which transmit frames at different times, it is possible to minimize the switching gap occurring when changing the program 1 to the program 2.
  • the coding device 31 generates two video data streams for the program 2 provided by the broadcasting station 21.
  • the two video data streams are shown in FIG. 7 as stream 1 and stream 2.
  • each video data stream is suitable for displaying the program 2 on the television receiver 160, since each video data stream contains all the picture information (P and I frames).
  • the two video streams differ in that the first video stream "Stream 1" is a wideband video stream enabling high quality reproduction of the program 2, while the second video stream "Stream 2" is a narrow stream video stream representing a replay of the program 2 in poorer quality allows. Another difference is that the frame rate in the narrowband video data stream is higher than in the broadband
  • Video stream This means that the time interval between the frames inserted in the narrow-band video data stream is shorter than the time interval between the frames inserted into the broadband video data stream.
  • the time interval between the im For example, full-frame broadband video stream is four seconds, while the time interval between frames inserted in the narrow-band video stream may be 250 milliseconds.
  • the set-top box 120 is aware of where the frames are in the respective video streams.
  • the broadband video data stream is buffered in the buffer 42 while the narrowband video data stream is being stored in the buffer 43.
  • the buffer size of the buffer 42 is larger than that of the buffer 43.
  • the buffer size of the buffer 42 is, for example, dimensioned so that about 50 Mbit of the wideband video data stream can be stored while in the buffer 43 3 Mbit of the narrowband video data stream can be stored.
  • less data of the narrow-band video data stream is written into the buffer 43 than data of the wideband video data stream is written in the buffer 42 to represent the same program section.
  • the buffer 43 can also be read out faster than the buffer 42.
  • the narrowband video data stream must be delayed from the broadband video stream during transmission.
  • an unrepresented delay element with a predetermined delay time can be inserted into the transmission path of the narrowband video data stream.
  • the frames I t and I c generated in the video data streams and the Full screen also called I-frame or IDR frame.
  • the length of this interruption also called zapping gap, is determined by the time span between the confirmation of the
  • the present invention has for its object to provide a method and a data transmission system with which the zapping gap can be reduced.
  • a central idea of the invention is to distribute the video information to be transmitted to a plurality of parallel, preferably multicast streams, which are transmitted via an IP-based distribution network to at least one distribution point. If the receiving device set up at a user, in particular a set-top box, has the necessary knowledge as to when frames are included in the parallel multicast streams and how possibly several received multicast streams can be combined, the time of presentation of the first frame of the new one Optimized program on the terminal, so that the resulting switching gap can be minimized when changing programs.
  • the switching gap occurs at a terminal at a program change, ie when switching from a digital video data stream of a first program to a digital video data stream, a second program.
  • the video streams are distributed over an IP-based distribution network to multiple terminals.
  • video information of at least the second program is transmitted via several parallel video data streams to at least one distribution point of the distribution network.
  • the parallel video data streams are differently coded by inserting frames into each video data stream at predetermined times such that at least some of the frames in the parallel video data streams are differently distributed relative to each other.
  • Differently distributed relative to each other is meant that at least some frames of different video streams are inserted into the video streams at different times.
  • Any current program referred to herein as the first program, is displayed on the at least one terminal associated with the at least one distribution point.
  • a toggle command is input by at least one user at a receiving device associated with the terminal at which the current program is displayed.
  • the video stream of the second program which next contains a frame for display on the terminal, is automatically selected by the receiving device.
  • the second program is usually the one program to be changed to.
  • the second program is displayed on the terminal of the at least one user as soon as the first, in selected video data stream received full screen can be displayed. This means that at least the data representing the frame is stored in the receiving device.
  • the video information of the first program can be coded differently via several parallel
  • Video data streams are transmitted to the at least one distribution point of the distribution network, wherein in each video data stream at predetermined times frames are inserted such that at least some of the frames in the parallel video data streams are distributed differently relative to each other.
  • Video data streams of the at least one second program to the receiving device This information may be transmitted in the parallel video streams themselves or in a separate information channel.
  • the appropriate video stream of the second program is then selected by the receiving device in response to the switching command and the position information.
  • a suitable video data stream is to be understood as the video data stream which contains the first displayable frame after the switching command.
  • the parallel video data streams of at least the second program are coded with the same bandwidth according to an embodiment.
  • only the video stream of the second program is selected by the user's receiving device at the distribution point, i. H. requested, the next contains a full screen. In this way, the available bandwidth of the subscriber line connecting the distribution point to the receiving device can be efficiently utilized since only the video data stream is transmitted to the receiving device used in the terminal to display the second program.
  • the video information of at least the second program is transmitted via the distribution network via at least two parallel, differently coded video data streams.
  • the first video data stream of the second program transmits all the video information, while the second video data stream only transmits frames. Since only frames are transmitted in the second video data stream, the time interval between the frames transmitted in the second video stream may be shorter than the time interval between the frames transmitted in the first video stream.
  • the receiving device requests at least the first video data stream of the second program in response to the switching command.
  • the at least two video streams of the second program are only requested together and transmitted to the requesting receiver if the second video stream contains a frame that can be displayed earlier than the first frame in the first video stream.
  • the at least two video data streams of the second program in the receiving device if the second video stream contains a frame that can be displayed earlier than the first frame in the first video stream.
  • the mixing of the two video streams causes the frame transmitted in the second video stream to be the correct one
  • Position is inserted in the first video stream.
  • the difference image eg a P-frame in the case of the MPEG standard
  • the difference image of the first video data stream which carries the same sequence number as the first frame contained in the second video data stream, is replaced by the frame.
  • the video information of at least the second program is in each case via a broadband and a narrowband
  • the broadband video data stream can be reproduced as a high-resolution image on the terminal, while the narrow-band video data stream, the second program in poorer quality, but also in a moving form can be displayed.
  • the time interval between the frames transmitted in the narrow-band video data stream is shorter than the time interval between the frames transmitted in the wideband video data stream.
  • the video stream of the second program which next contains a frame for display on the user's terminal, is automatically selected by the receiving device. Since the frame rate in the narrow-band video data stream is higher than that in the wideband video data stream, the switching gap can be significantly reduced compared to the switching gap that occurs when transmitting broadband video data streams alone.
  • both video streams over the Subscriber line are transmitted to the receiving device.
  • the narrowband video data stream is first selected to represent the second program on the terminal, it will later switch to the wideband video data stream as soon as the wideband and narrowband video data stream receive the same frame for display on the terminal.
  • switching to the broadband video data stream only makes sense if the terminal is HDTV-capable.
  • both video data streams are transmitted to each delayed such that can be switched without interference from the narrowband video data stream to the broadband video data stream at the receiving device.
  • Receiving device terminated or interrupted after entering the switching command.
  • the narrowband video data stream of the at least one second program can be transmitted to the receiving device before entering the Umschaltbetation.
  • the transmission of the broadband video data stream of the second program can be done at a later time. If at a later time the broadband video data stream is received at the receiving device and the receiving device from the narrowband video data stream to the broadband
  • Switched video data stream of the second program the transmission of the narrowband video data stream from the distribution point to the receiving device can be stopped. This measure leads to a more efficient utilization of the bandwidth of the subscriber line.
  • the switching behavior of the user is preferably monitored on the receiving device.
  • at least the narrowband video data stream of the at least one second program may be transmitted to the receiving device prior to the input of the switching command. In this way it can be ensured that the first frame of the second program is already stored in the receiving device before or immediately after the input of the switching command and thus can be displayed immediately on the terminal.
  • Switching command for example when entering a multi-digit command, at least the narrowband Video data stream of the at least one second program is transmitted to the receiving device.
  • the currently available bandwidth of the subscriber line to which the receiving device is connected determined at predetermined times or continuously.
  • the transmission of the broadband video data stream and / or the narrowband video data stream of one or more programs to the receiving device is performed or interrupted.
  • the transmitted video data streams may preferably include recorded video programs or live video programs.
  • the receiving device can be arranged in the user's terminal or can be a set-top box.
  • the video data streams are expediently transmitted as multicast streams, that is to say the video data streams are intended for a selected group of subscribers.
  • the above technical problem is also solved by a data transmission system for reducing the switching gap.
  • the data transmission system comprises a first coding means for coding video information of the first program into a plurality of parallel video data streams, wherein frames are inserted into each video data stream at predetermined times such that at least some of the frames are distributed differently in parallel video data streams relative to each other.
  • the first encoder includes a plurality of encoders each generating one of the parallel video streams.
  • a second coding device for coding video information of the second program into a plurality of parallel video data streams. Again, frames are inserted into each video data stream at predetermined times such that at least some of the frames in the parallel video streams are differently distributed relative to each other.
  • An IP-based distribution network via which the parallel video data streams of the first and / or second program are transmitted to at least one distribution point of the distribution network.
  • at least one receiving device which is designed to receive at least one video data stream of at least one program, is connected.
  • the at least one receiving device is assigned a terminal for displaying a program.
  • the receiving device is arranged to automatically select, in response to a switching command, the video stream of the second program, which next includes a frame for presentation on the user's terminal, and to decode the selected video stream such that the first received frame of the second program can be displayed on the terminal.
  • the first and second coding means for inserting additional information are respectively formed in a separate information channel or in the parallel video data streams of the first and second programs.
  • the information contains information about the respective position of the frames in the parallel video data streams of the first and second programs, respectively.
  • the at least one receiving device selects, in response to the switching command and the additional information, the video data stream which next contains a displayable frame.
  • the first and second encoders encode the video information of the first and second programs, respectively, in parallel
  • Video data streams of the same bandwidth in response to the switching command, the receiving apparatus selects only the transmission of the video data stream of the second program at the distribution point, which includes a frame next.
  • the first and second encoders encode the video information of the first and second programs, respectively, into at least two parallel video data streams.
  • Video data stream of the first and second programs contains all the video information, that is, the information required to display motion pictures in the terminal.
  • the second video stream contains only frames.
  • the time interval between the frames transmitted in the respective second video data stream is shorter than the time interval between the frames transmitted in the respective first video data stream.
  • the receiving device selects, in response to the switching command, transmission of at least one of the two video streams of the second program at the distribution point.
  • the receiving device is designed to mix the at least two video data streams of the second program, provided that the second video stream contains a frame that can be displayed earlier than the first frame in the first video stream.
  • the first and second encoders encode the video information of the first and second programs respectively into a wideband and a narrowband video data stream.
  • the time interval between the encoded in the respective narrow-band video data stream frames is shorter than the time interval between encoded in the respective broadband video data stream frames.
  • the receiving apparatus is in this case configured to automatically select the video stream of the second program, which next contains a frame for display on the user's terminal.
  • the receiving device can also be designed for switching from the narrowband video data stream to the broadband video data stream of the second program, wherein the switching takes place when the same frame for presentation on the terminal is present in the receiving device for the broadband and the narrowband video data stream.
  • a delay element is inserted in the transmission path of the narrowband video data stream.
  • Delay time is to be selected such that the broadband and narrowband video data stream can be received synchronously in the receiving device, so that the receiving device can switch from the narrowband video data stream to the broadband video data stream without interference.
  • the receiving device may request at least the transmission of the narrowband video data stream of the second program and / or at least one other program prior to the input of the switching command at the distribution point.
  • the receiving device monitors the switching behavior of the user, evaluates the switching behavior and, responsive to the switching behavior, requests at least the transmission of the narrowband video data stream of the second program and / or at least one other program prior to the input of the switching command from the distribution point.
  • the receiving device may request at least the transmission of the narrowband video data stream of the second program and / or at least one other program at the distribution point.
  • At least one device for determining the current bandwidth is connected at least to the subscriber line to which the receiving device is connected.
  • the receiving device requests the transmission or interruption of the broadband video data stream and / or the narrowband video data stream of one or more programs as a function of the determined bandwidth
  • the above technical problem is also solved by a receiving device for use in a data transmission system.
  • the receiving device is preferably a set-top box that can be used in a data transmission system.
  • the receiving device has a plurality of input buffers for receiving a plurality of video data streams of at least one program transmitted in parallel. Multiple decoders are used to decode the received video data streams.
  • a controller automatically selects, in response to a switching command, the video stream of the program which next contains a frame for display on a terminal associated with the receiving device. The selected video data stream is decoded by the respective decoder so that the first received frame of the second program can be displayed on the terminal.
  • the receiving device may include means for mixing at least two video streams.
  • the mixer is primarily for selectively inserting a frame of one video stream into the other video stream so that the new program can be displayed at the terminal faster than would be the case for transmission of a single normal video stream.
  • Fig. 1 is a schematic block diagram of a
  • Fig. 2 is a schematic representation of the
  • Fig. 3 shows a switching under Consideration of the switching behavior of the
  • Fig. 4 shows a switching operation upon inputting a multi-digit switching command
  • Fig. 5 shows four parallel video data streams having the same bandwidth
  • Fig. 6 shows two parallel video data streams of the second
  • FIG. 7 shows a broadband video data stream and a narrowband video data stream of the program 2.
  • FIG. 10 An exemplary data transmission system 10, with which switching gaps which occur during program change at a terminal, is shown in FIG. The
  • Data transmission system 10 comprises an IP distribution network 60, via which, for example, television programs can be distributed to different end users.
  • the television programs are supplied by broadcasters, which are shown in FIG. 1 as broadcasters 20, 21 and 22.
  • the broadcaster 20 delivers the program 1, the broadcaster 21 the program 2 and the broadcaster 22 the program n.
  • the video information contained in the programs 1, 2 and n is supplied to a coding device 30, 31 and 32, respectively.
  • Each coding device is designed such that it can divide the video signals supplied by the broadcaster into a plurality of parallel video data streams which are coded differently.
  • the encoders may, but need not, generate the same number of parallel video streams.
  • each encoder 30, 31 and 32 has k encoders which are the simple representation because not shown. More specifically, the video signal coming from broadcaster 20 is supplied to encoder 30, the video signal from encoder 31 provided by broadcaster 21 and the video signal from encoder 32 provided by broadcaster 22. Each encoder generates a plurality of parallel differently coded video streams with the aim of to significantly reduce the switching gap when changing programs. The operation of the encoders 30, 31 and 32 will be explained in more detail below.
  • the video data streams coded by the coding device 30 are buffered in each case in a buffer. For the sake of simplicity, only the two buffers 40 and 41 are shown. Similarly, those of the
  • Encoder 31 generated video data streams each stored in a buffer, wherein only the two buffers 42 and 42 are shown.
  • the video data streams coded by the coding device 32 are likewise buffered in each case in a buffer, whereby only the two buffers 44 and 45 are shown symbolically.
  • the video data streams of the program 1 stored in the buffers 40 and 41 are supplied to the IP distribution network 60 via a feed-in server 50.
  • the video data streams of the program 2 stored in the buffers 42 and 43 are fed into the IP distribution network 60 via a feed-in server 51.
  • the video data streams of the program n stored in the buffers 44 and 45 are fed into the IP distribution network 60 via a feed server 52.
  • the video streams are then called
  • Multicast streams supplied to predetermined multicast replication points MRP.
  • MRP multicast replication points
  • the video signals supplied by broadcasters 20, 21 and 22 are transmitted as encoded video data streams to the multicast replication points 70 and 90.
  • the Video streams associated with programs 1, 2, and 3 are transferred to multicast replication point 90.
  • the programs 1, 2 and 3 are provided for example by the broadcasters 20, 21 and a third, not shown broadcaster.
  • the multicast replication point 90 may, upon request, distribute the received programs to a plurality of terminals. In the present example, only the two terminals 110 and 160, which may be conventional television receivers, are connected to the multicast replication point 90.
  • the television receiver 110 is associated with a video data stream receiving device 100, which is also referred to as a set-top box.
  • the set-top box 100 is connected in the present example via an ADSL line to the multicast replication point 90.
  • the ADSL line also called Asymmetry Digital Subscriber Line, for example, has a bandwidth of 6 Mbit / s.
  • the television receiver 160 is also connected to the multicast replication point 90 via a set-top box 120.
  • the set-top box 120 is connected to the multicast replication point 90 via a VDSL line.
  • the VDSL line has a bandwidth of 50 Mbps. It should be noted that in the television receiver 80, the functionality of the set-top box 120 is implemented.
  • the set-top box 120 includes three receive buffers 130, 131, and 132 for receiving three parallel video data streams of a new program to be switched to. It should be noted that the set-top box 120 shown in FIG. 1 does not reflect the complete structure. Of course, the set-top box may have additional buffers for storing the video data streams of other programs, for example, a picture-in-picture representation in the
  • a buffer and a decoder for receiving and decoding a P-frames have different sizes.
  • the encoder 31 ensures that the two buffers 42 and 43 do not overflow or idle.
  • the buffer 131 has a memory size of, for example, 3 megabits, while the buffer 132, for example, has a memory capacity of 50 megabits. For this reason, the narrow-band video data stream can be transmitted to the television receiver 160 faster than the wideband video data stream since video data can be read from the buffer 131 faster than from the buffer 132.
  • the multicast replication point 90 for example, to transmit both the narrowband and the broadband video data stream of the program 2 via the VDSL line to the set-top box 120.
  • the transmission of program 1 to the set-top box is interrupted.
  • the data of the wideband video data stream is stored in the buffer 132 while data of the narrow-band video data stream is stored in the buffer 131. Since the microprocessor 155 knows the temporal position of the frames in the narrowband and wideband video data stream as well as the exact switching timing, it can select the video data stream which will next contain a frame. In the Usually, this will be the narrowband video stream, as it will transmit more frames than the broadband video stream.
  • the microprocessor 155 recognizes that the narrowband video data stream next transmits a frame.
  • the microprocessor 155 causes data to be transferred to the decoder 141.
  • the decoded data is then displayed over the switch 150 on the television receiver 160.
  • the duration of the switching gap can thus be significantly reduced since the transmission of the second program can not be carried out first with the first frame in the broadband video data stream, which will be transmitted later, but earlier with the transmission of the first frame of the narrowband video data stream.
  • the microprocessor 155 is programmed to display the high-definition image on the television receiver 160 as soon as the buffer 132 and the buffer 131 each store a frame representing the same program section. At this moment, the video data of the buffer 132 is decoded in the decoder 142 and transferred to the television receiver 160 via the switch 150 instead of the narrow-band video data stream.
  • the microprocessor 155 may be programmed to interrupt transmission of the narrowband video data stream from the multicast replication point 90 to the set-top box 120 once the decoded wideband video data stream is presented to the television receiver 160.
  • the UmsehaltVorgang program 1 to program 2 and in particular the UmsehaltVorgang from the narrow-band video data stream on the broadband video data stream is shown graphically.
  • the broadband Video data stream is labeled 180, while the narrowband video data stream is labeled 181.
  • the program 1 is first displayed on the television receiver 160.
  • a switch command is issued to the set-top box
  • the microprocessor 155 requests the multicast replication point 90 to transmit both the broadband and narrowband video data streams of the program 2.
  • the video data of the P2 frame now partially enters the buffer 132, while the first data of the Il frame of the narrow-band video data stream 181 enters the buffer 131.
  • a frame namely the I-frame 12
  • This frame could already be displayed as a still picture of the program 2 on the television receiver 160.
  • further data must enter the buffer 131, which at least partially represents the next difference image P3. This is the case at time T3, since the following difference image P3 is present at least partially in the memory 131 at this time.
  • the data of the buffer 131 can be given to the decoder 141, so that the decoded narrow-band
  • Video data stream via the switch 150 as a motion picture on the television receiver 160 can be played.
  • the moving picture representation of the program 2 starts at time T3.
  • a still image reproduction of the program 2 could, as I said, already take place at time T2.
  • a full frame 16 of the wideband video data stream is completely stored in the buffer 132 for the first time.
  • the buffer memory 132 At the time T6 are in the buffer memory 132 all video data of the frame 16 and additional data at least the subsequent difference image P7. Also in the buffer 131 are all the data of the frame 16 and at least partially data of the difference image P7 of the narrowband video data stream. Now, a switch from the narrow-band video data stream to the broadband video data stream can be made without interference. For this purpose, the data stored in the buffer 132 is given to the decoder 142. The decoded video data of the broadband video data stream are transferred to the television receiver in the decoder 142 via the switch 150 and reproduced there.
  • the set-top box 120 is designed such that it transmits an expected program from the set-top prior to the actual input or activation of a switching command Box 120 requests from the multicast replication point 90.
  • the microprocessor 155 of the set-top box 120 may be implemented to handle the switching behavior of the
  • Program A is displayed on the television receiver 160.
  • the following switching behavior is shown graphically in FIG.
  • lower case letters indicate a narrow-band video data stream or low-quality picture reproduction.
  • Capital letters indicate a broadband video data stream or high-resolution image reproduction.
  • FIG. 3 shows two graphs, one showing the image content on the television receiver 160 and a graph representing the bandwidth on the VDSL line between the multicast replication point 90 and the set-top box 120.
  • the program A is broadcast, for example, by the broadcaster 20, while the program B is provided by the broadcaster 21.
  • the encoder 31 transmits the program B over a narrowband and a wideband video data stream, as previously described. Due to the learned switching behavior of the user or by entering the letter "B" on the set top box 120, the microprocessor 155 at one time requests the multicast replication point 90, in addition to the broadband video data stream of the program A, the narrowband one
  • Video stream "b" of the program B to transmit.
  • the simultaneous transmission of the narrow-band video data stream “b” of the program B and the wideband video data stream “A” of the program A is reproduced in the lower illustration of FIG.
  • the confirmation of the actual switching command which is marked OK in FIG. 3, follows.
  • the microprocessor 155 requests the multicast replication point 90, in addition to the narrowband video data stream "b" and the broadband video data stream
  • the transmission of the narrowband video data stream "b" to the set-top box 120 is terminated as soon as the broadband video data stream "B" is transmitted in decoded form via the switching device 150 to the television receiver 160.
  • Fig. 4 shows the UmsehaltVorgang and the transmission of the respective video data streams via the VDSL line to the set-top box 120.
  • the broadband video data stream of the program A is transmitted to the set-top box 120 (see bandwidth diagram) and the associated program A is displayed on the television receiver 160 (see image content diagram).
  • the user enters the first digit of the three-digit switching command, for example a 1 at the set-top box 120, which corresponds to the program B.
  • Microprocessor 155 interprets the entry of the first digit as a possible switching instruction to program B and then requests the transmission of the video B streamed video data stream "b" from the multicast replication point 90. As before, however, the program A is transmitted to the television receiver 160. Now the user gives the second digit of the three digit toggle command, e.g. As the number 2, a. The microprocessor 155 interprets the two-digit input value "12" as a possible switching instruction to the program C. Thereafter, the microprocessor 155 requests the multicast replication point 90 to transmit the narrowband video data stream of the program C and interrupt the transmission of the narrowband video data stream of the program B. As before, the program A is transmitted to the television receiver 160.
  • the user gives the last digit of the three digit toggle command, e.g. As the number 3, a.
  • the microprocessor 155 interprets the three-digit input value "123" as a switching command to the program D. Thereafter, the microprocessor 155 requests the multicast replication point 90 to transmit the narrowband video data stream of the program d and interrupt the transmission of the program C narrow-band video data stream. Still, however, the program A is displayed on the television receiver 160 (see image content diagram).
  • the set-top box 120 requests the transmission of the broadband video data stream of the program D and stops the transmission of the program A on the television receiver 160
  • Program D has already been stored in the set-top box 120 during the playback of the program A, there will be a high probability at the time of confirmation of the switching command or a short time thereafter a frame of the narrow-band video data stream in the set-top box 120, to be displayed on the television receiver 160. Switching from the narrowband video data stream to the wideband video data stream is done in the manner described with respect to the third embodiment.
  • An advantageous measure provides that after the confirmation of the switching command, the set-top box 120 in turn requests the transmission of the narrow-band video data stream of the program A (see bandwidth diagram in FIG. 4).
  • the microprocessor 155 knows the switching behavior of the user and expects the user to switch back to program A at a later time.
  • the set-top box 120 may be programmed to simultaneously request, in addition to the broadband video stream of program A, the narrowband video stream of a program B to which the user is expected to switch, for example, between o.o o and oo o'clock. It can be seen that within the scope of the invention there are any various switching operations that the set-top box 120 can automatically take into account. The only important thing is that in addition to the currently displayed program is already a narrowband
  • the traffic load is determined via this line.
  • a set up at the subscriber device such as a network access device, calculate the traffic load.
  • narrowband and / or broadband video data streams of one or more programs can then be requested or terminated.
  • two television receivers are connected to the VDSL line via two parallel-connected set-top boxes. If a current available bandwidth is determined, which allows the transmission of a broadband and narrowband video data stream over the VDSL line, so can be displayed on a television receiver, a high-resolution image, while the other television receiver only a picture with poorer quality can be displayed. Depending on the determined available bandwidth of the
  • VDSL line can be requested during operation new video streams from the multicast replication point 90 or the transmission of video streams are selectively interrupted.
  • the quality of a program currently displayed on the television receiver 160 may be temporarily displayed at low quality when higher priority services need to be transmitted over the VDSL line.
  • the transmission of a program via parallel video data streams can also be activated or deactivated by the content of the programs to be transmitted or in dependence on the broadcaster.
  • the encoders 30, 31 and 32 are then respectively driven by a central controller to either generate a plurality of parallel, differently encoded video streams or just a video stream carrying the video signals of the program.
  • the set-top box 120 requests transmission of video streams or interruption of transmission of video streams at the multicast replication point 90, this does not necessarily mean that all of them are for the set-top box 120 provided video data streams at the multicast replication point 90.
  • the IP distribution network 60 may have a hierarchical structure of multicast replication points, the requested video data streams may also be cached in higher-level multicast replication points. In this case, the multicast replication point 90 sends corresponding request commands to the parent multicast replication points.
  • Reference character list for FIG. 1

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Databases & Information Systems (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Business, Economics & Management (AREA)
  • Marketing (AREA)
  • Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)

Abstract

L'invention concerne un procédé et un système (10) de transmission de données qui permettent de réduire la solution de continuité qui survient sur un terminal (160) lors du passage d'un flux de données vidéo numériques d'un premier programme à un autre flux de données vidéo numériques d'un deuxième programme. L'objectif de la présente invention est de réduire à un mimium cette solution de continuité. A cet effet, les informations vidéo à transmettre d'un programme sont réparties dans un dispositif de codage (30, 31, 32) de préférence sur plusieurs flux parallèles de multidiffusion et sont transférées par au moins un réseau de répartition IP (60) à au moins un point de répartition (90). Si un dispositif de réception (120), en particulier un boîtier adaptateur, installé chez un utilisateur, dispose des informations nécessaires sur le moment où les flux parallèles de multidiffusion contiennent des images pleines et sur la façon dont plusieurs flux de multidiffusion reçus peuvent éventuellement être assemblés, l'instant de la présentation de la première image pleine du nouveau programme sur un terminal (160) associé au dispositif de réception (120) peut être optimisée de façon à réduire à un minimum la solution de continuité qui survient lors du changement de programme.
EP08706761A 2007-08-07 2008-01-16 Procédé et système pour réduire la solution de continuité lors d'un changement de programme d'un environnement vidéo numérique Ceased EP2177032A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102007037135 2007-08-07
PCT/DE2008/000064 WO2009018791A1 (fr) 2007-08-07 2008-01-16 Procédé et système pour réduire la solution de continuité lors d'un changement de programme d'un environnement vidéo numérique

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EP2177032A1 true EP2177032A1 (fr) 2010-04-21

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EP08706761A Ceased EP2177032A1 (fr) 2007-08-07 2008-01-16 Procédé et système pour réduire la solution de continuité lors d'un changement de programme d'un environnement vidéo numérique

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EP (1) EP2177032A1 (fr)
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KR100880893B1 (ko) * 2007-09-14 2009-01-30 한국전자통신연구원 복수의 멀티캐스트를 이용한 ｉｐｔｖ 고속 채널 전환을위한 장치 및 그 방법
US9894126B1 (en) * 2015-05-28 2018-02-13 Infocus Corporation Systems and methods of smoothly transitioning between compressed video streams

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EP1634458B1 (fr) 2003-06-16 2011-08-17 Thomson Licensing Procede et appareil de decodage permettant un changement rapide de canal de video comprimee
KR100678239B1 (ko) 2005-02-15 2007-02-02 삼성전자주식회사 인터넷 프로토콜 기반의 방송 서비스를 제공하기 위한 시스템
US8340098B2 (en) 2005-12-07 2012-12-25 General Instrument Corporation Method and apparatus for delivering compressed video to subscriber terminals

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