JP4242525B2 - Video / audio partial playback method and receiver in digital broadcasting - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a partial reproduction method for designating and reproducing a temporal portion (scene) of a program in a receiving apparatus that once accumulates and reproduces a program sent by broadcasting, and in particular, a designated time axis. The upper part can be reproduced accurately.
[0002]
[Prior art]
In the era of digital broadcasting, research and development of a receiving apparatus, that is, a home server, that accumulates programs transmitted by broadcasting and reproduces them as necessary has been advanced. The home server not only plays the stored program from the beginning to the end in order, but also selects and views the program scenes from the table of contents, and watches the video and audio according to a scenario that defines the playback order of multiple scenes. So-called non-linear viewing can be realized.
[0003]
By the way, in Japanese digital broadcasting, video and audio are once divided into PES (Packetized Elementary Stream) packets based on the international standard MPEG-2 Systems, and then multiplexed into TS (Transport Stream) packets. Is transmitted. This video and audio must be played back synchronously on the receiving side. Therefore, each PES packet of video and audio has a time STC (System Time Clock) (“synchronization reference” as a reference for decoding and playback processing). A time stamp indicating “time” is stored.
[0004]
The place where the time stamp is stored for the actual video / audio data is a field called PTS (Presentation Time Stamp) / DTS (Decode Time Stamp) in the PES header. FIG. 12 shows the location of the PTS / DTS in the PES header.
[0005]
The STC is a time axis of 27 MHz and 42 bits, and is not directly related to the time axis of the standard time in the hour, minute, and second format used for program management. The receiving device includes a counter that generates an STC. When the video and audio PTS values match the STC value, the receiving device is controlled to present the video and audio to the user. Thus, synchronization of video and audio is realized.
[0006]
Also, in order to synchronize STC, which is the synchronization reference time, between the receiving apparatus and the broadcasting station, information called PCR (Program Clock Reference) is stored in the header of the TS packet and transmitted. FIG. 10 shows the data structure of the TS packet, and FIG. 11 shows the data structure of the adaptation field including the PCR in the TS packet. This PCR conveys the current STC value, and is periodically transmitted from the broadcast station to the receiving apparatus at a frequency of about 10 times per second, for example.
[0007]
In the receiving apparatus, an STC is generated and output while the counter output is calibrated in real time by a PLL (Phase Locked Loop) circuit so as to match the PCR transmitted periodically.
[0008]
FIG. 9 is a block diagram of this PLL circuit.
[0009]
Now, non-linear viewing of programs stored in the receiving apparatus can be realized using a program index.
[0010]
The program index is broadcast metadata that provides information for assisting selection and search of a broadcast program defined in ARIB STD-B10 Version 1.2, which is a standard for digital broadcasting in Japan. This program index has a data structure of ERT (Event Relation Table) and LIT (Local Event Information Table), and is repeatedly broadcast as section format information (hereinafter referred to as section information) defined in MPEG-2 Systems.
[0011]
The program index can define a scene that is a temporal part of a program (LIT) and a relationship between scenes (ERT) for a program including video and audio transmitted by broadcasting. A scene is defined by the start time (start time) and duration (duration) of the scene in the program. As the time for program management, standard time in the form of hour, minute, second is used.
[0012]
However, since video / audio in digital broadcasting is transmitted in a compressed format such as MPEG-2 Video or MPEG-1 Audio, which are international standards, the transmission format of video / audio transmitted by broadcasting and the reproduction result An indefinite length of delay occurs between the video and audio. For this reason, it is not easy to determine the location of a scene with time accuracy of, for example, frame accuracy (accuracy of still image frame interval, approximately 1/30 second in Japan) on the transmission format of video and audio transmitted by broadcasting. Absent. Therefore, although the scene definition by the LIT of the program index can be described with millisecond accuracy, it can be assumed that accuracy of only about seconds can be assured when reproducing the scene of the receiving apparatus.
[0013]
Therefore, in the program index, section information called ITT (Index Transmision Table) is defined in order to perform scene reproduction with high time accuracy.
[0014]
The ITT includes information for associating the time axis based on the standard time and the time axis based on the STC. For example, the value of the STC corresponding to the start time of the program is transmitted by the ITT. Since the STC value increases by 1 every 27,000,000th of a second, any time included in the program can be converted between two time axes based on this ITT information. Is possible.
[0015]
FIG. 13 shows the data structure of ITT. The STC reference descriptor shown in FIG. 14 is stored as the descriptor (arrow) in the program index transmission information section of FIG. 13, and the correspondence (arrow) between the second and millisecond and the STC is described in this STC reference descriptor. The
[0016]
FIG. 15 illustrates an example of precisely reproducing a program scene using ITT information. In the program index, the beginning of the program is defined as 20: 00'00 "00 (exactly 8:00 pm) by standard time, and a certain scene is 17'15" 00-17 in relative time with respect to the beginning of the program. It is defined as '31 "00. When the STC value (STC ₀ ) corresponding to the top 20: 00'00" 00 of the program is given by ITT, the scene start time is set to Ts (= 17'15 “00), when the scene end time is Te (= 17'31” 00), the STC at the start of the scene (= STCs) is
STCs = STC ₀ + Ts × 27 × 10 ⁶
The STC at the end of the scene (= STCe) is
STCe = STC ₀ + Te × 27 × 10 ⁶
Can be obtained.
[0017]
As described above, the scene start / end times described in the standard time in the program index can be converted into STC time-axis values by using ITT information. The exact playback location can be specified.
[0018]
The receiving device compares the converted values STCs and STCe with the PTS of the PES packet, starts playback from the video / audio whose PTS matches STCs, and stops playback when the PTS matches STCe. Thus, by applying the precise time designation method using ITT, the receiving apparatus can reproduce the scene with, for example, frame accuracy. However, if PTS does not appear with sufficient frequency, PTS interpolation processing may be required separately.
[0019]
FIG. 7 shows a block diagram of a conventional receiving apparatus (home server). This apparatus includes a receiving unit 000 including an antenna, a demodulator 001 that demodulates a received signal, a TS processor 002 that extracts an AV stream, PCR, and section information from the received signal, and a PLL 003 that generates an STC based on the PCR. , Storage means 006 comprising a hard disk in which AV streams are stored, decoder 004 for decompressing and decoding compressed and encoded AV data, presentation means 005 for presenting (displaying and displaying) video and audio, and apparatus A CPU 007 for controlling the overall operation and a memory 008 for storing section information and the like are provided.
[0020]
In this receiving apparatus, the received signal demodulated by the demodulator 001 is input to a TS processor 002 made of LSI, and the TS processor 002 extracts an AV stream, PCR, and section information from the received signal. The section information includes a program index and ITT.
[0021]
The PLL 003 to which the PCR is input has the configuration shown in FIG. 9 and outputs the STC calibrated by the PCR. The AV stream separated by the TS processor 002 is accumulated in the accumulation means 006. In real-time viewing, the AV stream is input to the decoder 004. The decoder 004 decodes the video / audio data in which the PTS of the PES matches the STC, so that the video / audio is synchronized from the presentation unit 005. Is displayed. The program index and ITT information extracted by the TS processor 002 are stored in the storage unit 006.
[0022]
FIG. 8 shows an operation in the case of nonlinear viewing with this receiving apparatus. FIG. 8A shows an operation procedure during recording.
Step 1: When the user designates a program to be stored from the EPG (electronic program guide), under the control of the CPU 007,
Step 2: Wait for the program to start on air,
Step 3: The AV stream of the program is received, and storage in the storage means 006 is started.
Step 4: If there is a new ITT in the section information, obtain it and record it in the memory 008.
Step 5: Continue receiving the AV stream and storing it in the storage means 006,
Step 6: It is repeated until the program is on air.
[0023]
FIG. 8B shows an operation when a specific scene of a program is viewed on the receiving apparatus.
[0024]
Step 11: When the user specifies a scene to view from the scene list display based on the program index,
Step 12: The CPU 007 reads the ITT information from the memory 008, converts the start time of the designated scene into the STC time axis by the ITT,
Step 13: Also, the end time of the designated scene is converted to the STC time axis by ITT.
[0025]
Step 14: Search the location corresponding to the STC at the scene start time from the AV stream stored in the storage means 006,
Step 15: Instruct the decoder 004 to play the AV stream from the searched location,
Step 16: The decoder 004 performs AV data reproduction processing,
Step 17: Continue playback until the end time.
[0026]
As described above, by using ITT, a scene can be reproduced with high accuracy.
[0027]
[Problems to be solved by the invention]
However, the conventional scene reproduction method cannot reproduce the scene with high accuracy when there is no ITT information. As a situation where ITT does not exist, the following cases can be assumed.
・ When programs that do not send ITT are stored.
・ The program has started, but ITT has not yet been sent from the broadcasting station.
・ When ITT reception fails due to zapping viewing (watching frequently switching channels) or radio wave attenuation due to rain.
[0028]
In order to play a scene in the absence of ITT, the scene must be specified based on the standard time indicated in the program index. However, since there is a transmission delay, the scene is transmitted to the receiving device at the standard time. It is uncertain whether it has been received, and the time from reception to storage of the AV stream varies depending on the performance of the receiving apparatus. Therefore, it is impossible to specify a scene with high accuracy by simply using the standard time. As a result, the video and audio of the preceding and following scenes may be mixed at the beginning and end of the reproduced scene, or part of the video and audio of the specified scene may be lost, giving the viewer a sense of discomfort and discomfort. Become.
[0029]
The present invention solves such a conventional problem, and even in a situation where the ITT does not exist, a video / audio that can realize scene reproduction with a time accuracy relatively close to that when the ITT exists is provided. An object of the present invention is to provide a partial reproduction method and a receiving apparatus that implements the method.
[0030]
[Means for Solving the Problems]
The present invention relates to a video / audio partial playback method in a receiver for reproducing a specified portion of video / audio included in a TS transport stream received by digital broadcasting, and the real time clocked by the real-time clock of the receiver is used. A step of acquiring as standard time, a step of acquiring and generating STC, which is a reference time for decoding and reproducing processing, from PCR periodically sent by the TS transport stream, and the standard time and STC at the same moment acquiring, using the same set and moment the standard time and the STC obtained in step, and generating a pseudo ITT obtained by converting the standard time of program start to STC, which is designated the audiovisual And replaying the part based on STC .
[0031]
Also, in a receiving apparatus that reproduces a designated portion of video and audio included in a TS transport stream received by digital broadcasting, a real-time clock that measures standard time and the TS transport stream are periodically sent. It gets a PLL that generates the STC is a time serving as a reference of decoding and reproduction process while calibrated to match the STC represented by PCR, the standard time of the same moment as the said STC, said the same moment using a set of the standard time and the STC, the pseudo ITT generating means for generating a pseudo ITT obtained by converting the standard time of program start to STC, and reproducing means for reproducing based on a specified portion of the video and audio to STC,
It is characterized by providing.
[0032]
Therefore, a value corresponding to the information stored in the ITT is received by comparing the STC value output by the PLL or the STC value of the transmitted PCR with the value of the real-time clock that ticks the standard time. It can be generated in a pseudo manner in the apparatus, and by using this value instead of ITT information, it is possible to realize scene reproduction with high accuracy.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
As shown in FIG. 1, the receiving apparatus in the first embodiment includes a receiving unit 000 including an antenna, a demodulator 001 that converts a received signal into a digital signal, an AV stream, PCR, and section information from the received signal. TS processor 002 to be extracted, PLL 003 for generating STC based on PCR, storage means 006 for storing AV streams, decoder 004 for decompressing and decoding compressed and encoded AV data, and displaying video and audio Presenting means 005, a CPU 007 for controlling the operation of the entire apparatus, a memory 008 for storing section information, a real time clock 402 for measuring standard time, and a pseudo ITT generating means 401 for generating pseudo ITT. .
[0034]
The real-time clock 402 of this device can output with a resolution of seconds. The pseudo ITT generation unit 401 receives the STC value output from the PLL 003 and the standard time output from the real time clock 402. The pseudo ITT generation unit 401 inputs the standard time and STC input at the same moment. ITT data is artificially generated from a set of values.
[0035]
The generated pseudo ITT data is stored in the memory 008, and is used as an alternative to the received ITT when a scene is identified and reproduced from the AV stream.
[0036]
FIG. 2 (a) shows the operation when a program is stored in this apparatus.
[0037]
Step 1: When the user designates a program to be stored from the EPG (electronic program guide), under the control of the CPU 007,
Step 2: Wait for the program to start on air,
Step 3: The AV stream of the program is received, and storage in the storage means 006 is started.
Step 301: The pseudo ITT generating means 401 acquires a set of STC and standard time, generates ITT by simulation, and records the generated pseudo ITT in the memory 008.
[0038]
Step 5: Reception of the AV stream and storage in the storage means 006 are continued,
Step 6: Step 005 is repeated until the program ends on air.
[0039]
The pseudo ITT generation in step 301 is as shown in FIG.
Step 311: When the standard time measured by the real time clock 402 changes to the following value:
Step 312: The STC output from the PLL003 is acquired, and an ITT is pseudo-generated from the set of the standard time and the STC.
[0040]
FIG. 3 illustrates a specific example of generating ITT in a pseudo manner. The PLL 003 has the configuration shown in FIG. 9, and generates and outputs an STC that increases by 1 every 27,000,000 seconds while calibrating by PCR that is input at a frequency of about 10 times per second. To do. When the time of the real time clock 102 that measures the standard time in seconds changes from 20: 32'48 "to 20: 32'49", the STC value (STC_t1) output from the PLL003 at that time t1 is fetched. The ITT is pseudo-generated from the relationship between the standard time 20: 32'49 "and STC_t1.
[0041]
At this time, when the standard time (Tt1) fetched from the real-time clock 102 matches the program start time (T ₀ : the standard time of program start can be determined from the information in the electronic program guide). The fetched STC value (STC_t1) is recorded in the memory 008 as the STC value (STC ₀ ) corresponding to the program start time T ₀ .
[0042]
When the standard time (Tt1) taken from the real time clock 102 is different from the program start time T ₀ , STC ₀ is obtained by the following equation and recorded in the memory 008 as pseudo ITT information. However, Time time Tt1, T ₀ is the one described in seconds as a unit.
[0043]
STC ₀ = (STC_t1) − (Tt1−T ₀ ) × 27 × 10 ⁶
In this way, by generating and holding a pseudo ITT from a set of standard time and STC at the same instant, even if no ITT exists, it is possible to specify a portion to be reproduced in the video / audio stream by PTS. Thus, the scene can be identified and reproduced with an accuracy close to the frame accuracy.
[0044]
(Second Embodiment)
In the second embodiment, a case where pseudo ITT is generated by taking in PCR and standard time will be described.
[0045]
As shown in FIG. 4, this receiving apparatus is based on a real time clock 102 capable of output with a resolution of 1/100 second, a PCR output from the TS processor 002, and a standard time output from the real time clock 102. And pseudo ITT generating means 101 for generating pseudo ITT. Other configurations are the same as those of the first embodiment.
[0046]
In this apparatus, the operation for storing a program is not different from the procedure in FIG. However, the specific operation of step 301 for obtaining a set of STC and standard time and generating ITT in a pseudo manner is as shown in FIG.
[0047]
Step 321: Wait for a new PCR to be output from the TS processor 002, and when the PCR is output,
Step 322: The time in the real-time clock 102 at that time is acquired, and an ITT is pseudo-generated from the set of the standard time and the STC value represented by PCR.
[0048]
FIG. 6 shows a specific example of generating ITT in a pseudo manner. When the PCR # 5 is output from the TS processor 002, the time 20: 32'49 "72 of the real time clock 102 at the time t2 is fetched, and the STC value and the time 20: 32'49 represented by the PCR # 5 are fetched. Generate pseudo ITT from "72".
[0049]
At this time, if the standard time acquired from the real time clock 402 is Tt2, and the STC value represented by the acquired PCR is (STC_t2), the STC value (STC ₀ ) corresponding to the program start time T ₀ is
STC ₀ = (STC_t2) − (Tt2−T ₀ ) × 27 × 10 ⁶
It can ask for.
[0050]
As described above, even when there is no ITT, the pseudo ITT can be generated and held by measuring the standard time at the moment when the PCR arrives, and is reproduced in the video / audio stream as in the first embodiment. The part can be specified by PTS.
[0051]
【The invention's effect】
As is clear from the above description, according to the present invention, even when ITT, which is information for realizing scene reproduction with high time accuracy by the program index, does not exist in the receiving apparatus, it exists. It is possible to realize scene playback with relatively close accuracy.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a receiving device according to a first embodiment;
FIG. 2 is a flowchart showing an operation (a) at the time of video / audio accumulation and an operation (b) of pseudo ITT generation in the receiving apparatus according to the first embodiment;
FIG. 3 is a diagram showing a method for acquiring a set of real time and STC in the first embodiment;
FIG. 4 is a block diagram showing a configuration of a receiving device in the second embodiment;
FIG. 5 is a flowchart showing an operation of generating pseudo ITT in the second embodiment;
FIG. 6 is a diagram showing a method for acquiring a set of real time and STC in the second embodiment;
FIG. 7 is a block diagram showing a configuration of a conventional receiving device;
FIG. 8 is a flowchart showing a program storage operation (a) and a scene reproduction operation (b) by a conventional receiving device;
FIG. 9 is a block diagram of a PLL circuit;
FIG. 10 is a diagram showing a data structure of a TS packet;
FIG. 11 is a diagram showing a data structure of an adaptation field in which a PCR of a TS packet is stored;
FIG. 12 is a diagram showing a data structure of a PES header indicating a storage location of PTS / DTS;
FIG. 13 is a diagram showing a data structure of ITT;
FIG. 14 is a diagram showing a data structure of an STC reference descriptor;
FIG. 15 is a diagram showing an example of precise time designation by ITT.
[Explanation of symbols]
000 means of receiving
001 demodulator
002 TS processor
003 PLL
004 decoder
005 Presentation means
006 Accumulation means
007 CPU
008 memory
101, 401 Pseudo ITT generation means
102, 402 Real time clock

Claims (6)

In a video / audio partial playback method in a receiving apparatus for playing back a specified portion of video / audio included in a TS transport stream received by digital broadcasting,
Obtaining the real time measured by the real time clock of the receiving device as standard time;
Obtaining and generating an STC ( System Time Clock ) which is a reference time for decoding and reproducing processing from a PCR ( Program Clock Reference ) periodically sent by the TS transport stream ;
Obtaining the standard time and the STC at the same moment;
Generating a using the set of same instantaneous of the standard time and the STC obtained in step, the pseudo obtained by converting the standard time of program start the STC ITT (Index Transmission Table),
Replaying a designated portion of the video and audio based on STC ;
A method of partially reproducing video and audio, comprising: In order to generate a STC while calibrating to match the STC represented by the PCR using the PLL of the receiving device, and to obtain a set of the standard time and STC at the same moment, the standard time of the real time clock 2. The video / audio partial reproduction method according to claim 1 , wherein the standard time value at the moment when the value indicating the value changes and the STC value output from the PLL at the moment are obtained . In order to obtain a set of standard time and STC at the same moment, a value indicating the standard time of the real-time clock at the moment when PCR arrives and a value of STC represented by the PCR are obtained. The video / audio partial reproduction method according to claim 1 . In a receiving apparatus for playing back a designated portion of video and audio included in a TS transport stream received by digital broadcasting,
A real time clock that measures standard time,
A PLL that generates the STC, which is a reference time for decoding and reproduction processing while calibrating to match the STC represented by the PCR periodically sent by the TS transport stream;
Pseudo ITT generating means for acquiring the standard time and the STC at the same moment, and using the set of the standard time and the STC at the same moment, generating a pseudo ITT in which the standard time of the program start is converted into an STC;
Playback means for playing back a designated portion of the video and audio based on STC;
A receiving apparatus comprising: The pseudo ITT generation means obtains a set of the standard time and STC at the same moment, and outputs the standard time value at the moment when the value indicating the standard time of the real-time clock is changed, and is output from the PLL at the moment. 5. The receiving apparatus according to claim 4, wherein the STC value is obtained. The pseudo ITT generation means obtains a set of the standard time and STC at the same moment, a value indicating the standard time of the real time clock at the moment when the PCR arrives, and an STC value represented by the PCR, The receiving apparatus according to claim 4, wherein:

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