JP2009159625A - Method of storing stream for digital broadcast - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of storing a stream for digital broadcast mainly directed to facilitating connection to MPEG 2 decoder when a stream is stored in a receiver for digital broadcast and to perform retrieval of required information quickly when a trick play is performed. <P>SOLUTION: A trick-play control table, in which information required for performing a trick play such as the positions of TS packets, the number of the packets, a display time, etc. is written, is defined and distributed together with the stream. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a stream accumulation method intended to be accumulated in a BS or CS digital broadcast receiver using, for example, a satellite line.

In general, stream accumulation in MPEG2 is performed in the MPEG2-PS format as seen in DVD-Video and the like. On the other hand, stream distribution in the conventional digital broadcasting is performed in real time, and is performed in the MPEG2-TS format, which is used for reproducing a real time stream. For this reason, an MPEG2 decoder used in a digital broadcast receiver is generally of the MPEG2-TS format.
Also, in DVD-Video, encryption is not applied to a part of the stream in order to search for packets necessary for trick play such as fast forward and rewind.

JP 2001-24994 A Japanese Patent Application No. 2001-67450 (Japanese Patent Laid-Open No. 2001-24994) Japanese Patent Laid-Open No. 9-31818 International Publication No. 00/1777

A conventional MPEG2 decoder is assumed to reproduce an MPEG2-TS stream distributed from a digital broadcasting station or the like in real time, and cannot reproduce a stream stored in the MPEG2-PS format.
Also, it is necessary to analyze a part of the stream in order to perform trick play. Further, in the case of an encrypted stream, there is a drawback that a load for trick play processing increases because it is necessary to decrypt the stream once.

SUMMARY OF THE INVENTION In view of the above, the present invention provides a digital broadcasting method capable of efficiently executing trick play of packetized contents (TS packets) in a stream format, such as fast forward, rewind, digest reproduction, thumbnail display, and the like. To provide a receiver and the like.
In order to achieve such an object, trick play control information that enables trick play of stream-format packetized content (TS packet) is transmitted or received, and TS packet trick play can be performed with the trick play control information. .

  According to the present invention, trick play of a stream (TS packet) can be performed efficiently, for example, trick play can be performed easily and at high speed.

The stream delivery system block diagram. 1 is a configuration diagram of a receiver for digital broadcasting. Stream internal structure diagram. The trick play control table block diagram. Trick play control table position information file configuration diagram.

  A system to which the present invention is applied will be described. FIG. 1 shows a stream distribution system using a satellite line. First, the content provider 10 creates a stream 1. Stream 1 is encoded by a video format and an audio format standardized by MPEG2. The stream 1 is encrypted by the distribution center 2 using the scrambler 3. The content is encrypted and distributed in order to protect the rights of the copyright holder and the like, and the receiving side 6 can use only the user who has the right to use the content. Further, it is multiplexed with other contents by the multiplexing device 4 in a time division manner. The multiplexed stream is delivered to the receiving side 6 through the satellite line 5. On the receiving side 6, the content required by the user is extracted from the stream multiplexed in the digital broadcasting receiver 7 through the antenna, and is stored in an internal storage device. The user reproduces the stream with the digital broadcast receiver 7 as necessary and outputs it to the TV 8.

(Receiving terminal)
FIG. 2 shows an internal structure of the digital broadcast receiver 7 assuming stream accumulation. The stream distributed from the distribution center 2 is received by the receiving antenna 21. The tuner 22 extracts a digital signal from the input analog signal. This digital signal is in the format of an MPEG2 transport stream (TS), and information other than information required by the receiver for digital broadcasting (for example, in a multi-channel network, information other than the channel to be received) Since they are multiplexed, only necessary information is selected and extracted by the demultiplexer 23. The stream extracted by the demultiplexer 23 is accumulated in the storage device 24.

  When the stored content is reproduced, the descrambler 25 performs descrambling (decryption) processing of the content encrypted on the distribution side. The decrypted content is decoded by the MPEG2 decoder 26 and output to the TV 8. The decrypted content is output from the digital output I / F 27 to the external digital device 29 connected to the digital broadcast receiver 7.

(Stream accumulation method)
MPEG2 partial TS is obtained by multiplexing information such as video, audio, subtitles, and PSI / SI constituting one stream. As an accumulation format, it is assumed that time information is added to each TS packet constituting this, and these are stored in the storage device 24 of FIG. 2 as one file.

  FIG. 3 shows a stream accumulation method. The TS packet A41 and the TS packet B43 are packetized elementary streams such as video and audio. The time information A42 and B44 indicate times when the TS packets A41 and B43 should be output to the MPEG2 decoder 26. The digital broadcast receiver 7 compares the time information with the counter value counted in the digital broadcast receiver, and when the time indicated by the time information arrives, the TS packet is received from the MPEG2 decoder 26 and the digital output I / O. Output to F27.

(Stream accumulation procedure)
The following stream distribution forms exist according to the MPEG2 system. (1) PES distribution premised on real-time distribution.
(2) File distribution in section format such as DSM-CC data carousel.
The above (1) is a distribution form for distributing and using a stream of video, audio, etc. in real time, and (2) is not limited to a stream of video, audio, etc., considering the accumulation of data such as images and documents. It is a distribution form.
The procedure in which the receiver for digital broadcasting stores using the stream storing method according to the present invention will be described.

(1) In the case of real-time distribution A necessary TS packet is selected and extracted by the demultiplexer 23. When a necessary TS packet is taken out, the counter value held in the digital broadcast receiver is read, and the TS packet and the counter value are recorded in the recording device 24. This process makes it possible to configure the stream shown in FIG.
(2) In the case of file distribution A stream file having the format shown in FIG. This file is recorded as it is in the recording device 24 in the receiver for digital broadcasting by distributing the file with a DSM-CC data carousel or the like.
By doing in this way, it is possible to apply to the above stream distribution forms (1) and (2).

(Trick play control table)
When performing trick play in an MPEG2 stream, it is necessary to grasp the following positions.
(1) The position of the leading packet of the I frame having information that can restore one frame for the video stream.
(2) For the audio stream, the first packet position of the AAU, which is the minimum audio unit.
(3) Packet positions corresponding to video and audio for other streams.

  In general, these positions cannot be grasped unless the information part (payload) of the TS packet is analyzed. Therefore, if the stream is encrypted, it is necessary to decrypt it once, and it takes time and effort to specify the position. Take it. In order to simplify the processing, a trick play control table is devised as shown in FIG. As an example, assume that the stream contents are in the order of video A61, video B62, audio A63, video C64, subtitle A65, video D66, audio B67, and video E68. Here, it is assumed that the video A61 and the audio A63 are packets necessary for trick play reproduction. The control information A69 in the trick play control table describes the following control information for the video A61, and the control information B70 describes the following control information for the audio A63.

(1) Packet type 71
The type of packet indicated by the control information. Video, audio, subtitles, etc.
(2) Packet position 72
The first packet position in the stream file of the packet indicated by the control information.
(3) Number of packets 73
The number of packets that make up the packets required for trick play.
(4) Time information 74
Time when the MPEG2 decoder plays back the packet.
(5) Digest flag 75
It indicates that the packet indicated by the control information is a packet necessary for digest reproduction.
(6) Thumbnail flag 76
It indicates that the packet indicated by the control information is a packet necessary for performing thumbnail display.

  A necessary number of these pieces of control information are listed in the trick play control table. The distribution center creates a trick play control table at the same time as creating a stream, and delivers the stream and trick play control table as a set to the receiving side. When performing a trick play, the digital broadcast receiver can obtain a necessary packet position by referring to the trick play control table. Further, even if the stream itself is encrypted, the position can be specified without analyzing the packet payload.

(Digest and thumbnail display)
The trick play control table includes a digest flag 75 and a thumbnail flag 76. The digest flag 75 is used when digest playback is performed by combining a part of streams. It is possible to perform digest reproduction by searching the trick play control table and selecting a packet in which the digest flag 75 is set.
When the stream is divided into a plurality of chapters, the thumbnail flag 76 is used when displaying the contents of each chapter as a single image. It is possible to create a thumbnail image by searching only the packets for which the thumbnail flag 76 is set in the trick play control table and extracting the packets.

(Trick play control table distribution method)
As described above, the stream accumulation method of the present invention can perform accumulation in both real-time distribution and file distribution. A trick play control table delivery method according to these delivery modes will be described.
(1) In the case of real-time delivery A problem in storing a stream of real-time delivery is the description method of the packet position 72 in the trick play control table. Recording of a stream delivered in real time may start at any time, so there is no concept of the beginning of the stream. Therefore, a trick play control table is inserted in the stream as shown in FIG. 5, and the packet position 72 is described by a relative packet address from the inserted table.

  Since the trick play control table is inserted into the stream, the trick play control table must first be searched for trick play. In order to speed up the processing, the digital broadcast receiver generates a trick play control table position information file. The digital broadcast receiver accumulates the stream and simultaneously generates a trick play control table position information file. The trick play control table position information file records a set of trick play control table position 82 in the stream and time information 74 described in the trick play control table.

(2) In the case of file distribution When the stream is distributed in a file, the absolute position of the TS packet in the file can be specified, so the problem described in (1) does not occur. Therefore, in addition to the distribution method shown in (1), the trick play control table shown in FIG. 4 can be distributed as a separate file. The packet position 72 in the control information in the trick play control table describes the absolute packet address from the beginning of the stream file.

(Trick play operation with digital broadcasting receiver)
A procedure until trick play relating to video is performed using a stream in which a receiver for digital broadcasting is stored will be described separately for (1) real-time distribution and (2) file distribution.
(1) In the case of real-time distribution (a) The output timing of the accumulated stream file is controlled with reference to time information corresponding to the TS packet.
(B) The trick play control table position information file is opened and the currently required trick play control table position is grasped.
(C) When performing trick play, control information before and after the position (b) in the trick play control table is acquired, and then the TS packet position of the necessary I frame is acquired.
(D) The TS packets are output to the MPEG2 decoder by the number of packets specified by the trick play control table from the position of the acquired TS packets.

(2) In the case of file distribution (a) The output timing of the accumulated stream file is controlled with reference to the time information corresponding to the TS packet.
(B) The trick play control table is opened and the position of the currently required trick play control table is grasped.
(C) When performing trick play, control information before and after the position (b) in the trick play control table is acquired, and then the TS packet position of the necessary I frame is acquired.
(D) The TS packets are output to the MPEG2 decoder by the number of packets specified by the trick play control table from the position of the acquired TS packets.

DESCRIPTION OF SYMBOLS 1 ... Stream, 2 ... Distribution center, 3 ... Scrambler, 4 ... Multiplexer, 5 ... Satellite line, 6 ... Reception side, 7 ... Reception for digital broadcasting 8 ... TV, 10 ... Content provider, 21 ... Receiving antenna, 22 ... Tuner, 23 ... Demultiplexer, 24 ... Storage device, 25 ... Descrambler, 26 ... MPEG2 decoder, 27 ... Digital output I / F, 29 ... External digital device, 41 ... TS packet A, 42 ... Time information A, 43 ... TS packet B, 44 ..Time information B, 61 ... Video A, 62 ... Video B, 63 ... Audio A, 64 ... Video C, 65 ... Subtitle A, 66 ... Video D, 67 ..Voice B, 68 ... Video E, 69 ... Control information A, 70 Control information B, 71 ... Packet type, 72 ... Packet position, 73 ... Number of packets, 74 ... Time information, 75 ... Digest flag, 76 ... Thumbnail flag, 81 Trick play control table, 82 ... table position, 83 ... time information.

Claims (8)

In a method of packetizing content including video and audio information and digitally broadcasting the packetized content to a digital broadcast receiver in a stream format,
Transmitting the packetized content in a stream format;
Transmitting trick play control information enabling trick play of the streamed packetized content;
Consists of
The trick play control information includes control information for video and control information for audio.
A digital broadcasting method of content characterized by the above. The content digital broadcasting method according to claim 1, wherein the control information about the video or the control information about the audio of the trick play control information includes the type, position, number, and reproduction time information of the stream packet of the packetized content. . In a receiver for digital broadcasting that receives content including video and audio information distributed in a stream format from a digital broadcasting station,
A receiving unit that receives the packetized content in the stream format;
A receiver that receives trick play control information that enables trick play of the packetized content in the stream format;
An accumulator for accumulating packetized content and trick play control information in the received stream format;
A playback unit for playing back and decoding the packetized content of the storage unit;
The trick play control information includes control information about video and control information about audio,
A digital broadcast receiver for content, wherein the playback unit enables trick play of packetized content in the stream format with reference to the trick play control information. 4. The digital broadcast reception of content according to claim 3, wherein the control information for video or the control information for audio of the trick play control information includes the type, position, number, and playback time information of the stream packet of the packetized content. Machine. In a method for distributing content including video and audio to a digital broadcast receiver in the MPEG transport stream format,
Adding to each transport packet constituting the stream time information indicating the time to be output to a decoder that decodes the transport by a digital broadcast receiver, and delivering these as one file;
Delivering trick play control information enabling trick play of transport packets of the stream;
Consists of
The trick play control information includes control information about video and control information about audio,
A stream delivery method that enables trick play of the stream on the digital broadcast receiver side with the trick play control information when the transport is decoded by the decoder. The stream delivery method according to claim 5, wherein the control information for the video or the control information for the audio of the trick play control information includes information on the type, position, and number of the transport packets. In a receiver for digital broadcasting that receives content including digital video and audio information and time information for reproducing video, which is distributed from a digital broadcasting station in the MPEG transport stream format,
A receiving unit that receives the packetized content in the stream format;
A receiver that receives trick play control information that enables trick play of the packetized content in the stream format;
An accumulator for accumulating packetized content and trick play control information in the received stream format;
A reproducing unit for decoding and reproducing the packetized content of the storage unit;
The trick play control information includes control information about video and control information about audio,
A digital broadcast receiver for content, wherein the playback section enables trick play of video of packetized content in the stream format based on the trick play control information. The content digital broadcast receiver according to claim 7, wherein the control information for video or the control information for audio of the trick play control information includes information on a type, a position, and a number of the transport packets.

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