JP5352545B2 - Digital broadcast transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital broadcast transmission apparatus which constitutes one broadcast program by switching a plurality of streams of MPEG-2 TS format. <P>SOLUTION: A first correction is performed so that PCR may continue before and after switching. That is, a gap between the PCR and PTS after switching is made to slide as it was, and a correction is performed so that the PCR may continue before and after switching. However, in this correction, the PTS does not always continue. Then, a second correction which secures continuity of the PTS is performed. In addition, a stream after switching is need to be switched from an I frame which is not influenced by a previous frame at the time of carrying out decoding in terms of the property of MPEG-2 TS format stream. Therefore, the PTS of the I frame of the stream after switching is corrected so that the PTS may continue before and after switching. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a technique for configuring a broadcast program by switching a plurality of digitally encoded streams.

In order to easily realize a digital broadcast program structure, a digital broadcast transmission apparatus having means for switching various streams is disclosed.
The digital broadcast transmission apparatus encodes an input signal, performs multiplexing and remultiplexing, and transmits a broadcast TS (Transport Stream). For example, in Patent Document 1, by synchronizing an encoding unit with respect to a plurality of input signals, an arbitrary encoded signal can be obtained from a plurality of encoded signals without interrupting a reproduction signal. A technique for selecting and switching is disclosed. Patent Document 2 discloses a technique for seamlessly switching the system of a duplexed system by synchronizing signals input to an encoding unit.
Note that these switching technologies switch baseband signals such as NTSC (National Television System Committee).

Japanese Patent Laid-Open No. 2001-145022 JP 2000-269864 A

The material used for the composition of the broadcast program of the digital broadcast includes live material encoded in the MPEG (Moving Picture Experts Group) -2 TS format, and MPEG-2 TS format encoded in advance offline. There are accumulated materials. That is, these live materials and stored materials are already signals in the MPEG-2 TS format.
However, when using the disclosed technologies described in Patent Document 1 and Patent Document 2, it is necessary to decode the MPEG-2 TS format signal and return it to the baseband signal once. For this reason, if encoding and decoding are repeated many times, a deterioration in the quality of the baseband signal becomes a problem.

  Further, in order to configure a broadcast program by switching between live material and stored material at an arbitrary timing, it is necessary to synchronize the phases of the decoded baseband signals. Therefore, it is necessary to synchronize at least the decoding of the stored material, the encoding of the digital broadcast transmission apparatus, and the timing of the switcher, which causes a problem that the apparatus configuration becomes complicated.

  Therefore, an object of the present invention is to provide a digital broadcast transmission apparatus that configures one broadcast program by switching a plurality of MPEG-2 TS format streams.

  In order to solve the above-mentioned problems, the digital broadcast transmission apparatus encodes a baseband signal (for example, NTSC) and packetizes it into MPEG-2 TS, and inputs it via an ASI (Asynchronous Serial Interface) cable. MPEG-2 TS format ASI input, MPEG-2 TS format RTP input input via network using RTP (Real Time Protocol), MPEG-2 TS format file input read from stored file The switcher 60 which switches mutually is provided. The switcher 60 performs a first correction that synchronizes the input and the broadcast TS by continuing the PCR (Program Clock Reference) at the time of switching. Next, the switcher 60 executes the second correction for making the PTS (Presentation Time Stamp) at the time of switching continuous, and executes the switching process.

  ADVANTAGE OF THE INVENTION According to this invention, the digital broadcast transmission apparatus which switches the some stream of an MPEG-2 TS format and comprises one broadcast program can be provided.

It is a figure which shows the outline | summary of a switching process. It is a figure which shows the structural example of a digital broadcast transmission apparatus. It is a figure which shows the structural example of a switcher. It is a figure which shows the example of a correction flow of ASI input. It is a figure which shows the structural example of a pseudo PCR packet. It is a figure which shows the example of a correction | amendment flow of RTP input. It is a figure which shows the example of a correction flow of file input. It is a figure which shows the example of a flow switched to ASI / RTP / file input. It is a figure which shows the outline | summary of the process which determines switching PTS. It is a figure which shows the example of a flow switched to an encoding input.

  Next, modes for carrying out the invention (hereinafter referred to as “embodiments”) will be described in detail with reference to the drawings as appropriate.

(Overview)
An overview of switching processing performed on a plurality of MPEG-2 TS format streams (hereinafter also referred to as TS or TS packet) will be described with reference to FIG. However, FIG. 1 shows a case where the stream before switching is switched using the stream of stored material as the stream after switching. The stream before switching and the stream after switching are each independently encoded. Therefore, when the switching process is simply performed, a case may occur in which a stream after switching is not output to the receiving terminal. This is because, as shown in FIG. 1, PCR and PTS are not continuous before and after switching. Therefore, it is necessary to correct the PCR and PTS so that they are continuous between the stream before switching and the stream after switching.

First, before and after switching, the first correction is performed so that PCR continues. That is, as shown in FIG. 1, the interval between the PCR after the switching and the PTS is slid with the original interval, and correction is made so that the PCR continues before and after the switching. However, in this correction, PTS is not always continuous.
Next, a second correction for ensuring the continuity of PTS is performed. Even if the initial value of the interval between the PCR and the PTS in the stream before switching is the same as the initial value of the interval between the PCR and the PTS in the stream after switching, the PTS is not always continuous before and after switching after the PCR correction. Absent. This is because the amount of encoded data differs for each PTS. Further, due to the nature of the MPEG-2 TS format stream, the stream after switching needs to be switched from an I frame that is not affected by the previous frame at the time of decoding. Therefore, the PTS of the I frame of the stream after switching is corrected so that the PTS is continuous before and after switching. In the following description, the PTS at the time of switching will be referred to as switching PTS.

Also, the synchronization process for switching the input stream before switching to the input stream after switching differs depending on the input method of the stream after switching. As an input method, for example, a baseband signal (for example, NTSC) is encoded and packetized into MPEG-2 TS, an ASI input in MPEG-2 TS format input via an ASI cable, and RTP. MPEG-2 TS format RTP input that is input via a network, and MPEG-2 TS format file input that is read from a stored file. In the case of ASI input and RTP input, for example, a post-switching stream is synchronized by artificially adding a clock synchronized with a transmission stream such as PCR to the input stream. In the case of file input, synchronization is performed by correcting the PTS of the I frame that is the first frame of the stream after switching to the switching PTS. In the case of encoding input, the frame of the switching PTS is synchronized by encoding in the I frame format.
According to this, the digital broadcast transmission apparatus can switch a plurality of systems of input such as ASI input, RTP input, file input, and encoding input in the MPEG-2 TS format.

(Configuration of digital broadcast transmission device)
A configuration example of the digital broadcast transmission apparatus according to this embodiment will be described with reference to FIG. As shown in FIG. 2, the digital broadcast transmission apparatus 10 includes an encoding unit 20, a stored program file transmission unit 40, a scheduler 50, a switcher 60, a multiplexing unit 70, a remultiplexing unit 80, and a TS. The transmission unit 90 and the PCR generation unit 100 are configured. The digital broadcast transmission apparatus 10 constitutes a broadcast program using audio, video, and data as materials. Program information about the broadcast program is collectively recorded in PSI / SI (Program Specific Information / Service Information).

The encoding unit 20 captures and encodes the input NTSC signal and packetizes it into the MPEG-2 TS format. For example, the input sound is encoded into an AAC (Advanced Audio Coding) format, converted into a TS format, and output to the switcher 60. In addition, the input video is, for example, H.264. The data is encoded into the H.264 format, converted into the TS format, and output to the switcher 60.
The stored program file sending unit 40 holds an MPEG-2 TS format file in which stored material is encoded offline in advance. The MPEG-2 TS format signal can be freely read from the switcher 60.

The scheduler 50 manages the switching time of the input stream output as the broadcast TS, and notifies the switching time to the switcher 60 a predetermined time before the switching time.
The switcher 60 uses the PCR generated by the PCR generating unit 100 to receive from the encoding unit 20, the stored program distribution server 30 and the stored program file sending unit 40 described later at the switching time notified from the scheduler 50. The input stream in the MPEG-2 TS format is switched and output to the multiplexing unit 70. That is, the switcher 60 can use the MPEG-2 TS format encoding input, ASI input, RTP input, and file input as the material for program composition.

The multiplexing unit 70 multiplexes the input streams such as the audio TS, the video TS, and the DSMCC (Digital Storage Media Command and Control) section TS prepared for data broadcasting received from the switcher 60, and remultiplexes the multiplexed signals. To the conversion unit 80.
The remultiplexing unit 80 multiplexes the PSI / SI with the signal received from the multiplexing unit 70 to generate a broadcast TS format signal, and outputs the signal to the TS transmission unit 90.
The TS sending unit 90 sends the signal received from the remultiplexing unit 80 as a broadcast TS. The TS transmitted from the TS transmitter 90 is OFDM-modulated by an OFDM modulator (not shown) and output as a broadcast wave.
The PCR generation unit 100 generates a PCR to be added to the broadcast TS and outputs it to the switcher 60 and the remultiplexing unit 80.

The stored program distribution server 30 is communicably connected to the digital broadcast transmission device 10.
The stored program distribution server 30 outputs, for example, an MPEG-2 TS format signal held by itself to the switcher 60 in the ASI format. In addition, the stored program distribution server 30 sends the MPEG-2 TS format signal it holds to the switcher 60 via the Internet or a dedicated line in the RTP format used in the IP (Internet Protocol) network.

(Configuration of switcher)
Next, a configuration example of the switcher 60 will be described with reference to FIG.
As shown in FIG. 3, the switcher 60 includes a switching PTS determination unit 61, a GOP reading unit 65 (65a, 65b, 65c, 65d), a pseudo PCR addition unit 62 (62b, 62c), and a PCR correction unit 63 ( 63b, 63c), PTS correction units 64 (64b, 64c), 66 (66b, 66c, 66d), a frame reading unit 67d, and a TS selection unit 68. Each unit transmits and receives necessary information to each other.

The switching PTS determination unit 61 acquires a PCR from the PCR generation unit 100 and determines a switching PTS. The method for determining the switching PTS will be described later.
The GOP reading unit 65 acquires and temporarily stores an audio / video TS packet.
The pseudo PCR adding unit 62 generates a pseudo PCR based on the PCR acquired from the PCR generating unit 100, and adds the generated pseudo PCR to the received TS packet. The pseudo PCR is used to synchronize the received TS packet with the broadcast TS.
The PCR correction unit 63 corrects the PCR described in the received PCR TS packet with the stream correction value. However, the stream correction value is the difference between the PCR described in the TS packet for PCR and the pseudo PCR.

The PTS correction unit 64 corrects the PTS described in the audio-video TS packet with the stream correction value.
The PTS correction unit 66 corrects the PTS of the TS packet after switching stored in the GOP reading unit 65 with the second stream correction value. However, the second stream correction value is a difference between the switching PTS acquired from the switching PTS determination unit 61 and the PTS of the I frame that is the first frame after switching.

The frame reading unit 67d reads out an audio / video packet for each frame (one image) from the file held in the stored program file transmission unit 40, and outputs it to the GOP reading unit 65d. It is assumed that the AU (Access Unit) value is 1 at the time of encoding.
At the time of the switching PTS, the TS selection unit 68 selects the TS packet after switching from the TS packets before switching corrected by the PTS correction units 66b, 66c, and 66d, or the TS packets held in the GOP reading unit 65a. Switching is performed to select a packet, and the selected TS packet is output to the multiplexing unit 70.

(Switcher processing)
Next, the processing flow of the switcher 60 will be described. Processing in the switcher 60 is performed in two stages. The first correction process is for synchronizing the MPEG-2 TS with the broadcast TS as a preparation stage for switching. Specifically, correction for continuing PCR is performed. Next, the second correction process is for ensuring the continuity of PTS. Then, after the second correction process, a switching process is executed. As a premise of processing in the switcher 60, information is stored so that the head of each video frame is the head of the TS packet. That is, the AU (Access Unit) value is 1.

(First correction processing for ASI input)
A first correction processing flow for ASI input will be described with reference to FIG. 4 (see FIGS. 2 and 3 as appropriate).
In step S401, the pseudo PCR adding unit 62b determines whether or not an MPEG-2 TS format TS packet (input stream) is received from the stored program distribution server 30 by ASI input.

  When it is determined that a TS packet has been received (Yes in step S401), in step S402, the pseudo PCR adding unit 62b generates a pseudo PCR based on the PCR acquired from the PCR generating unit 100. Specifically, the pseudo PCR is generated as follows. (1) An approximate time (hereinafter referred to as buffer time) until a TS packet is input to the multiplexing unit 70 and transmitted from the TS transmission unit 90 is acquired. The buffer time is a value unique to the system, and is constant unless the specifications of the multiplexing unit 70, the remultiplexing unit 80, and the TS transmission unit 90 are changed. (2) A value obtained by adding the buffer time to the PCR acquired from the PCR generation unit 100 is referred to as pseudo-PCR. That is, the pseudo PCR is set so that the TS packet received by the pseudo PCR adding unit 62b is the PCR when it is sent from the TS sending unit 90.

In step S403, the pseudo PCR adding unit 62b adds the pseudo PCR generated in step S402 to the TS packet received in step S401.
Here, FIG. 5 shows an example of the TS packet 502 to which the pseudo PCR 501 is added. The pseudo PCR 501 is represented by 33 bits similarly to the PCR. When the pseudo PCR 501 exceeds 33 bits, it loops so as to start again from 0, similarly to PCR. By doing so, the pseudo-PCR 501 can be handled in the same way as PCR.

Returning to FIG. 4, in step S404, the PCR correction unit 63b determines whether the TS packet is for PCR based on the PID (Packet Identification) of the TS packet.
When it is determined that the TS packet is for PCR (Yes in step S404), in step S405, the PCR correction unit 63b determines whether or not the stream correction value is not calculated. The stream correction value is a difference between the PCR described in the received TS packet and the pseudo PCR.
If it is determined that the stream correction value has not been calculated (Yes in step S405), in step S406, the PCR correction unit 63b calculates the difference between the PCR described in the received TS packet and the pseudo PCR, and performs stream correction. Set (hold) as a value.

In step S407, the PCR correction unit 63b corrects the PCR described in the received TS packet with the stream correction value.
In step S408, the PTS correction unit 64b determines whether the TS packet is for audio / video based on the received PID of the TS packet.
When it is determined that the TS packet is for audio / video (Yes in step S408), in step S409, the PTS correction unit 64b corrects the PTS of the received TS packet with the stream correction value.

If it is determined in step S401 that a TS packet has not been received (No in step S401), the process ends.
If it is determined in step S404 that the TS packet is not for PCR (No in step S404), the process proceeds to step S408.
If it is determined in step S405 that the stream correction value is not yet calculated (No in step S405), the process proceeds to step S407.
If it is determined in step S408 that the TS packet is not for audio / video (No in step S408), the process ends.
With the above processing, it is possible to synchronize MPEG-2 TS with ASI input with broadcast TS.

(First correction processing for RTP input)
The processing flow of the first correction for the RTP input will be described with reference to FIG. 6 (see FIGS. 2 and 3 as appropriate).
In the case of RTP input, the timing at which the TS packet output from the stored program distribution server 30 arrives at the switcher 60 may fluctuate due to router congestion or the like when it is transmitted over the network. Therefore, the first correction processing for the RTP input is different from the case of the ASI input in that a jitter which is a fluctuation in the arrival time of the TS packet is taken into consideration.

In step S601, the pseudo PCR adding unit 62c determines whether or not an MPEG-2 TS format TS packet (input stream) is received from the stored program distribution server 30 by RTP input.
When it is determined that the TS packet has been received (Yes in step S601), in step S602, the pseudo PCR adding unit 62c generates a pseudo PCR based on the PCR acquired from the PCR generating unit 100. Specifically, the generation of the pseudo PCR is the same as in the case of the ASI input shown in step S402 of FIG.

In step S603, the pseudo PCR adding unit 62c adds the pseudo PCR generated in step S602 to the TS packet received in step S601. The addition method is the same as in the case of the ASI method shown in step S403 in FIG. 4 (see FIG. 5).
In step S604, the PCR correction unit 63c determines whether the TS packet is for PCR based on the PID of the TS packet.
When it is determined that the TS packet is for PCR (Yes in step S604), in step S605, the PCR correction unit 63c determines whether or not the stream correction value is not calculated. The stream correction value is a difference between the PCR described in the received TS packet and the pseudo PCR.

If it is determined that the stream correction value has not been calculated (Yes in step S605), in step S606, the PCR correction unit 63c calculates the difference between the PCR described in the received TS packet and the pseudo PCR, and performs stream correction. Set (hold) as a value.
In step S607, the PCR correcting unit 63c holds, as a jitter reference value, a difference between an STC (System Time Clock) value that is an output time from the program distribution server 30 described in the TS packet and the pseudo PCR.
In step S608, the PCR correction unit 63c determines whether or not the jitter reference value calculated in step S607 is out of the already held jitter reference value. Specifically, it is determined whether or not the jitter reference value calculated in step S607 is larger (out of) the already held jitter reference value.

If it is determined that it is out of the jitter reference value (Yes in step S608), in step S609, the PCR correction unit 63c recalculates and holds (updates) the stream correction value and the jitter reference value.
In step S610, the PCR correction unit 63c corrects the PCR described in the received TS packet with the held stream correction value.
In step S611, the PTS correction unit 64c determines whether the TS packet is for audio / video based on the received PID of the TS packet.
If it is determined that the received TS packet is for audio-video (Yes in step S611), in step S612, the PTS correction unit 64c uses the stream correction value stored in the PTS described in the received TS packet. to correct. Then, the process ends.

If it is determined in step S601 that a TS packet has not been received (No in step S601), the process ends.
If it is determined in step S604 that the TS packet is not for PCR (No in step S604), the process proceeds to step S611.
If it is determined in step S605 that the stream correction value has not been calculated (No in step S605), the process proceeds to step S608.
If it is determined in step S608 that the jitter reference value is not deviated (No in step S608), the process proceeds to step S610.
If it is determined in step S611 that the received TS packet is not for audio / video (No in step S611), the process ends.
Through the above processing, the MPEG-2 TS with RTP input can be synchronized with the broadcast TS while resynchronizing even when jitter is large.

(First correction processing for file input)
In the case of file input, PTS is used instead of PCR when synchronizing MPEG-2 TS with broadcast TS. This is because the file size can be measured in advance for the stored material, so adjusting the bit rate in GOP (Group of Pictures) units reduces (averages) the fluctuations in the bit rate that occurred when creating the stored material, It becomes possible to synchronize with the broadcast TS.
Therefore, a processing flow for file input using MPEG-2 TS read from a file held in the stored program file transmission unit 40 as an input stream will be described with reference to FIG. 7 (see FIGS. 2 and 3 as appropriate). ).

In step S701, the frame reading unit 67d reads out the audio / video packet for each frame from the file held in the stored program file sending unit 40, and outputs it to the GOP reading unit 65d.
In step S702, the GOP reading unit 65d determines whether or not reading up to the next I frame, that is, one frame of GOP has been completed.
If it is determined that reading has been completed up to the next I frame (Yes in step S702), in step S703, the GOP reading unit 65d obtains the playback time for one GOP from the PTS difference between the I frames.

In step S704, the GOP reading unit 65d acquires the data size for one GOP.
In step S705, the GOP reading unit 65d divides the data size by the reproduction time, and calculates a bit rate for sending out the audio / video packet for one read GOP. When the GOP reading unit 65d finishes sending out the read audio video packet for one GOP at the calculated bit rate, the GOP reading unit 65d acquires the next one GOP audio video packet from the frame reading unit 67d.
In step S706, the GOP reading unit 65d determines whether reading has been completed up to the last frame of the file.

If it is determined that the reading has been completed up to the last frame of the file (Yes in step S706), in step S707, the GOP reading unit 65d reads the audio video read from the difference between the PTS of the I frame and the last frame. Get packet playback time.
In step S708, the GOP reading unit 65d acquires the data size of the read audio-video packet.
In step S709, the GOP reading unit 65d divides the data size by the reproduction time, and calculates a bit rate for transmitting the read audio / video packet. When the GOP reading unit 65d finishes sending the read audio / video packet at the calculated bit rate, the GOP reading unit 65d finishes reading the file from the stored program file sending unit 40.

If it is determined in step S702 that reading has not been completed until the next I frame (No in step S702), the process proceeds to step S706.
If it is determined in step S706 that reading has not been completed up to the last frame of the file (No in step S706), the process ends.
Through the above processing, the MPEG-2 TS of file input can be synchronized with the broadcast TS by averaging the fluctuations in the bit rate generated at the time of creating the storage material in units of GOP.

(First correction processing for encoded input)
Regarding the encoding input, the encoding unit 20 originally generates a TS synchronized with the broadcast TS, so the first correction process is not necessary.

(Second correction processing and switching processing for ASI input, RTP input, and file input)
Next, the second correction for ensuring the continuity of PTS and the switching process executed when the input is switched to the ASI input, the RTP input, or the file input will be described with reference to FIG. FIG. 3).
In the following description, when switching the input, each unit that performs processing on the TS before switching is referred to as “before switching unit (for example, GOP reading unit before switching)”, and processing is performed on the TS after switching. Each unit that performs the process is referred to as a “after switching unit” (for example, a GOP reading unit after switching).

In step S <b> 801, the switching PTS determination unit 61 determines whether or not the time T (predetermined time) before the switching time set in the scheduler 50 has come.
When it is determined that the time T has elapsed before the switching time (Yes in step S801), in step S802, the switching PTS determination unit 61 acquires the PCR from the PCR generation unit 100, and the acquired PCR has a time until the switching time. The switching PTS is determined by adding T and the PTS start value. Here, the time T is set to a value slightly larger than the buffer time used when the pseudo PCR is generated in step S402. The PTS start value is the difference between the PCR and the PTS attached to the first frame of the TS after switching (that is, the difference between the initial values). Details of the process for determining the switching PTS will be described later.

In step S803, the GOP reading unit 65 after switching holds the TS after switching. Note that the TS after switching is held from a frame having a PTS slightly before the switching PTS in order to set the I frame at the head at the time of switching.
In step S804, the post-switching GOP reading unit 65 obtains the PTS of the first I frame from the TS after switching, and discards the TS having the PTS before the I frame.
In step S805, the post-switching PTS correction unit 66 calculates the difference between the switching PTS acquired from the switching PTS determination unit 61 and the PTS of the first I frame, and this is the second stream correction of the TS after switching. Determine as value.
In step S806, the post-switching PTS correction unit 66 corrects the PTS of the switched TS held in the post-switching GOP reading unit 65 with the second stream correction value.

In step S807, the pre-switching PTS correction unit 66 corrects the PTS of the TS held in the pre-switching GOP reading unit 65 with the already calculated second stream correction value of the TS before switching. However, when the TS before switching is an encoded input, the PTS of the TS held in the GOP reading unit 65a before switching is not updated.
In step S808, the TS selection unit 68 selects a TS before switching, which is corrected by the pre-switching PTS correction unit 66, or a TS of a PTS smaller than the switching PTS among TSs held in the pre-switching GOP reading unit 65a, The data is output to the multiplexing unit 70.
In step S809, the TS selection unit 68 selects the TS corrected by the post-switching PTS correction unit 66 and outputs the selected TS to the multiplexing unit 70.
In step S810, the TS selection unit 68 updates the current stream to the TS after switching (in a switched state), and ends the switching process.

If it is determined in step S801 that the time T has not been reached before the switching time (No in step S801), that is, if the switching process is not being performed, in step S811, the PTS correction unit 66 determines that the current stream Then, the PTS of the current stream is corrected with the already calculated second stream correction value. However, when the current stream is an encoded input, the PTS of the current stream is not updated.
In step S812, the TS selection unit 68 selects the current stream and outputs it to the multiplexing unit 70.
Through the above processing, the PTS of the stream before and after switching takes a continuous value, and the start of the stream after switching starts from the I frame. This makes it possible to seamlessly switch and reproduce the stream when viewed on the receiving terminal.

  Here, an outline of the process for determining the switching PTS will be described with reference to FIG. 9 (see FIG. 3 as appropriate). Before the switching time T, the switching time 902, and the switching PTS 903, in step S802, the switching PTS determination unit 61 acquires the PCR, and adds the time T until the switching time 902 and the PTS start value to the PCR. The relationship of the elements used when determining the switching PTS is shown. Here, if the time T until the switching time is set to a value slightly larger than the buffer time used in step S402, the output timing of the TS to which the pseudo PCR is added 901 before the switching time T is the position of the pseudo PCR 904. . That is, the TS packet to which the pseudo PCR 904 is added at the time 901 before the switching time T becomes a TS packet just before the switching, and the switching process is in time.

  As described above, by determining the switching PTS 903, the timing for switching to the MPEG-2 TS output from the stored program distribution server 30 is set to the first I input to the switcher 60 at 901 before the switching time T. It becomes possible to make a frame. Further, every time switching is performed, the PTS of the TS output from the switching PTS 903 becomes a value obtained by adding the PTS start value to the PCR value, so that the interval between the PTS and the PCR is properly maintained even when the switching process is repeated.

(Second correction processing and switching processing for encoded input)
The second correction and switching process in the case where the encoding input is the TS after switching will be described with reference to FIG. 10 (see FIG. 3 as appropriate). In the case of encoding input, the MPEG-2 TS switching timing is determined by the elapsed time from the start of capture. Therefore, since the TS after switching starts with the I frame, the PTS cannot be replaced. Therefore, the encoding unit 20 is controlled to encode the switching timing frame with the I frame, thereby synchronizing the MPEG-2 TS of the encoded input with the broadcast TS.

In step S1001, the switching PTS determination unit 61 determines whether or not the time T before the switching time has come.
When it is determined that the time T has elapsed before the switching time (Yes in step S1001), in step S1002, the switching PTS determination unit 61 acquires the PCR from the PCR generation unit 100, and the acquired PCR has a time until the switching time. The switch PTS is determined by adding T and the PTS start value.
In step S1003, the switching PTS determination unit 61 notifies the encoding unit 20 of information related to the switching PTS.

In step S1004, the encoding unit 20 encodes a frame having a switching PTS with an I frame.
In step S1005, the switched GOP read unit 65a holds the switched TS from the encoded I frame.
In step S1006, the post-switching GOP reading unit 65a discards the TS having the PTS before the switching PTS from the GOP reading unit 65a.
In step S1007, the pre-switching PTS correction unit 66 (66b, 66c, 66d) uses the TS PTS held in the pre-switching GOP reading unit 65 (65b, 65c, 65d) as the second TS of the pre-switching TS that has already been calculated. Correct with the stream correction value.

In step S1008, the TS selection unit 68 selects a TS with a PTS smaller than the switching PTS from the TSs corrected by the pre-switching PTS correction unit 66 (66b, 66c, 66d), and outputs the selected TS to the multiplexing unit 70.
In step S1009, the TS selection unit 68 selects a TS held in the post-switching GOP reading unit 65a and outputs the TS to the multiplexing unit 70.
In step S1010, the TS selection unit 68 updates the current stream to the TS after switching (in a switched state), and ends the switching process.

In step S1001, if the time T has not been reached before the switching time (No in step S1001), that is, if the switching process is not being performed, in step S1011, the PTS correction unit 66 (66b, 66c, 66d) The PTS of the current stream is corrected with the second stream correction value that has already been calculated for the stream.
In step S1012, the TS selection unit 68 selects a current stream and outputs the current stream to the multiplexing unit 70.
With the above processing, the TS PTS before and after switching takes a continuous value, and the start of the TS after switching starts from the I frame. Thereby, each input can be switched seamlessly.

  As described above, the digital broadcast transmission apparatus according to the present embodiment encodes a baseband signal (for example, an NTSC signal) and packetizes it into MPEG-2 TS, or MPEG-2 TS input via an ASI cable. A switcher 60 that switches between an ASI input in a format, an RTP input in an MPEG-2 TS format input via a network using RTP, and an MPEG-2 TS format file input input from a stored file is provided. The switcher 60 executes a first correction that causes the PCR at the time of switching to continue. Next, the switcher 60 performs the second correction for making the PTSs at the time of switching continuous, and performs the switching.

  In the first correction, in the case of ASI input, a pseudo PCR is generated based on the PCR acquired from the PCR generation unit 100, and the difference between the PCR and the pseudo PCR described in the TS packet is set as a stream correction value, and the PCR and PTS are calculated. Correct with the stream correction value. In addition, in the case of RTP input, considering the jitter, the difference between the STC value described in the TS packet and the pseudo PCR is held as a jitter reference value, and if it is determined that it is out of the jitter reference value, stream correction is performed. After recalculating the value and the jitter reference value, the PCR and the PTS are corrected with the stream correction value as in the case of the ASI input. In the case of file input, a bit rate is calculated for each GOP, and an audio / video packet is transmitted based on the calculated bit rate. In the case of coding input, the first correction is not necessary.

  Next, in the second correction, when switching to ASI input / RTP input / file input, the time T and the PTS start value are added to the PCR acquired from the TS packet before the time T at the switching time, and the switching PTS is changed. decide. The PTS of the first I frame is acquired from the TS packet after the switching, and the difference between the switching PTS and the PTS of the first I frame is calculated and used as the second stream correction value. The TS after switching is corrected with the second stream correction value, and switching processing is performed at the switching time. When switching to the coding input, the coding unit 20 is controlled so that the frame at the switching timing is coded with the I frame.

DESCRIPTION OF SYMBOLS 10 Digital broadcast transmission apparatus 20 Encoding part 30 Stored program delivery server 40 Stored program file transmission part 50 Scheduler 60 Switcher (switching part)
61 switching PTS determining unit 62 pseudo-PCR adding unit 63, 63b, 63c PCR correcting unit 64, 64b, 64c PTS correcting unit 65, 65a, 65b, 65c, 65d GOP reading unit 66, 66b, 66c, 66d PTS correcting unit 67d frame Reading unit 68 TS selection unit 70 Multiplexing unit 80 Remultiplexing unit 90 TS sending unit 100 PCR generation unit 501 Pseudo PCR
903 switching PTS

Claims (6)

A multiplexing unit for multiplexing an input stream in MPEG-2 TS (Moving Picture Experts Group-2 Transport Stream) format;
A remultiplexing unit for generating a broadcast TS in which PSI / SI (Program Specific Information / Service Information) is multiplexed on the output signal of the multiplexing unit;
Two or more MPEG-2 TS format input streams are received, the received input stream and the broadcast TS are synchronized, and the received input stream is switched to the other received input stream and the multiplexed A switching unit that outputs to the unit,
A PCR generator for generating a PCR (Program Clock Reference) to be added to the broadcast TS;
A TS transmission unit for modulating the broadcast TS and outputting it as a broadcast wave ;
With
When the input stream received by the switching unit is an ASI input input in an ASI (Asynchronous Serial Interface) format,
The switching unit is
A buffer time indicating a time required for the output signal of the switching unit to be processed in the multiplexing unit, the remultiplexing unit, and the TS transmission unit is added to the PCR acquired from the PCR generation unit. Calculate pseudo-PCR,
Calculating a stream correction value indicating a difference between the PCR described in the input stream and the pseudo-PCR,
Corrects the PCR of the stream after the switching in the stream correction value, wherein the to Lud digital broadcast sending device to synchronize with the input stream and the broadcast TS. A multiplexing unit for multiplexing an input stream in the MPEG-2 TS format;
A remultiplexing unit for generating a broadcast TS obtained by multiplexing PSI / SI on the output signal of the multiplexing unit;
Two or more MPEG-2 TS format input streams are received, the received input stream and the broadcast TS are synchronized, and the received input stream is switched to the other received input stream and the multiplexed A switching unit that outputs to the unit,
A PCR generator for generating a PCR to be added to the broadcast TS;
A TS transmission unit for modulating the broadcast TS and outputting it as a broadcast wave ;
With
When the input stream received by the switching unit is an RTP input input via a network using RTP (Real Time Protocol),
The switching unit is
A buffer time indicating a time required for the output signal of the switching unit to be processed in the multiplexing unit, the remultiplexing unit, and the TS transmission unit is added to the PCR acquired from the PCR generation unit. Calculate pseudo-PCR,
Calculating a stream correction value indicating a difference between the PCR described in the input stream and the pseudo-PCR,
A difference between an STC (System Time Clock) value indicating an emission time of the RTP packet described in the RTP packet and the pseudo PCR is held as a jitter reference value,
When it is determined that the difference is larger than the jitter reference value already held,
Calculating a stream correction value indicating the difference between the PCR described in the input stream and the pseudo-PCR and the jitter reference value, and updating the held jitter reference value with the calculated jitter reference value;
The PCR of the stream after the switching is corrected with the stream correction value, and the input stream and the broadcast TS are synchronized.
It features a call and be Lud digital broadcast delivery device. A multiplexing unit for multiplexing an input stream in the MPEG-2 TS format;
A remultiplexing unit for generating a broadcast TS obtained by multiplexing PSI / SI on the output signal of the multiplexing unit;
Two or more MPEG-2 TS format input streams are received, the received input stream and the broadcast TS are synchronized, and the received input stream is switched to the other received input stream and the multiplexed Switching unit that outputs to the
With
When the input stream received by the switching unit is a file input read from a file encoded with MPEG-2 TS,
The switching unit is
The GOP (Group of Pictures) unit obtains the data size and the playback time, divides the data size by the playback time, calculates the bit rate, and averages the fluctuation of the bit rate. by controlling the output of the GOP, features and to Lud digital broadcast sending device that synchronizes the input stream to the broadcast TS. The switching unit is
A predetermined time before the switching time of the input stream,
The difference between the PCR and the PTS (Presentation Time Stamp) attached to the first frame of the input stream after the predetermined time and switching is added to the PCR acquired from the PCR generation unit, and the added value is used as the switching PTS. Set,
First frame of the input stream after switching, selected to be I frames, and corrects the PTS of the frame to the switching PTS, claims 1 and switches to the input stream digital broadcasting transmission apparatus according to any one of 3. A multiplexing unit for multiplexing an input stream in the MPEG-2 TS format;
A remultiplexing unit for generating a broadcast TS obtained by multiplexing PSI / SI on the output signal of the multiplexing unit;
Two or more MPEG-2 TS format input streams are received, the received input stream and the broadcast TS are synchronized, and the received input stream is switched to the other received input stream and the multiplexed A switching unit that outputs to the unit,
A PCR generator for generating a PCR to be added to the broadcast TS;
An encoding unit that encodes the video signal for broadcasting to generate an input stream of the MPEG-2 TS format for output to the switching unit,
With
The switching unit is
A predetermined time before the switching time of the input stream,
Add the difference between the PCR and the PTS attached to the first frame of the input stream after switching to the PCR acquired from the PCR generation unit, and set the added value as the switching PTS,
Sending information on the switching PTS to the encoding unit;
From the encoding unit, an input stream in which the first frame of the input stream after switching is encoded to be an I frame and the switching PTS is added to the frame is received, and the input stream is received. features and to Lud digital broadcast sending device to switch. It said input stream, AU (Access Unit) value of a digital broadcast transmitting apparatus according to any one of claims 1 to 5, characterized in that it is encoded as 1.

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