JPH09186942A - Digital signal processor and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain quick decoding of video data and audio data at a change in programs reproduced continuously by a digital VTR and received from a digital interface. SOLUTION: An MPEG video decoder 4 and an MPEG audio decoder respectively decode MPEG video data and MPEG audio data demultiplexed by a demultiplexer 2. A digital interface 11 is used to make transmission reception of the MPEG video data, the MPEG audio data and additional information between the demultiplexer 2 and an external device. When the digital interface 11 detects a flag representing discontinuity of programs, a microcomputer 9 controls initialization of buffer memories 4a, 5a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for receiving and decoding digital broadcasting, and more particularly, when inputting undecoded video data and audio data output from an external recording / reproducing device. Is related to the processing of.

[0002]

2. Description of the Related Art In recent years, in the United States and European countries, MPE
G (Moving Picture Image Cod)
A system in which a video signal and an audio signal are encoded by applying a high efficiency encoding technique such as ing Experts Group), transmitted through a communication satellite or the like, and demodulated at the receiving side is becoming popular. .

These systems require a dedicated receiving / demodulating device on the receiving side. In this receiving / demodulating device, a portion for selecting a transport stream of a desired channel from a transport stream in which data of a plurality of channels are multiplexed, and video data and audio of a desired program from the transport stream of the desired channel. It has a part for separating the data and a part for decoding the separated video data and audio data.

Further, in this system, in order to enable the receiving / demodulating device to receive the transport stream of the desired channel and to separate the video data and the audio data of the desired program,
In the multiplexed transport stream, PSI (P
program Specific Information
on: Program specification information) and EPG (Electro)
ic Program Guide: Electronic Program Guide) or SI (Service Information)
(n: service information) is added.

[0005]

A video tape recorder (hereinafter referred to as DVCR) for encoding / recording / reproducing a video signal and an audio signal has been proposed. Then, it is considered to record / reproduce the video data and audio data of the above-mentioned digital broadcast on such a DVCR without decoding them (Kubota Yukio ed., "Illustrated Digital Video Reader", pp.140-152,
Ohmsha Co., Ltd., August 25, 1995).

According to the present invention, when the DVCR as described above continuously reproduces a plurality of digital broadcasting programs and inputs them to the receiving / demodulating device, the video data and the video data in the receiving / demodulating device are changed when the programs change. An object of the present invention is to enable a decoding operation of audio data to be performed quickly.

[0007]

In order to solve the above-mentioned problems, a digital signal processing apparatus according to the present invention selects an arbitrary one-channel transport stream from multiplexed multiple-channel transport streams. 1 means, 2nd means for separating video data and audio data of an arbitrary program from this transport stream by referring to additional information in the selected transport stream, and decoding the separated video data and audio data Fourth means for transmitting video data, audio data, and additional information sent from the outside to the second means and detecting information indicating a discontinuity of the program; The third means initializes the third means when the means detects the information indicating the discontinuity of the program. It is characterized in further comprising a means.

Further, in the digital signal processing method according to the present invention, the first means for selecting an arbitrary one-channel transport stream from the multiplexed multiple-channel transport streams and the first means are selected. A second means for separating video data and audio data of an arbitrary program from this transport stream by referring to additional information in the transport stream;
Third means for decoding the separated video data and audio data, and video data sent from the outside,
Send the audio data and additional information to the second means,
And a fourth means for detecting information indicating a discontinuity of the program, the digital signal processing device comprising: when the fourth means detects the information indicating the discontinuity of the program, the third means is initialized It is characterized by performing conversion.

According to the present invention, when the fourth means detects the information indicating the discontinuity of the program sent from the outside, the third means is initialized.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a digital signal processing device to which the present invention is applied. This digital signal processor is an IRD (Integral)
This is called a "Rated Receiver Decoder".

This digital signal processing device receives an RF signal sent from a down converter (not shown) and selects a transport stream of a desired channel, and a front end 1 and a transformer selected by the front end 1. M of desired program from port stream
A demultiplexer 2 for separating PEG video data, MPEG audio data, and additional information, and a buffer memory 3 for temporarily storing data input / output through the demultiplexer 2 are provided.

Further, this digital signal processing device is an M which decodes the video data separated by the demultiplexer 2.
A PEG video decoder 4, an MPEG audio decoder 5 for decoding the audio data separated by the demultiplexer 2, and an NT for converting the video signal decoded by the MPEG video decoder 4 into an NTSC video signal.
The SC encoder 6, the D / A converter 7 that analogizes the output of the NTSC encoder 6, and the D / A converter 8 that analogizes the output of the MPEG audio decoder 5 are provided. The MPEG video decoder 4 is provided with a buffer memory 4a for temporarily storing video data, and the MPEG audio decoder 5 is provided with a buffer memory 5a for temporarily storing audio data.

Further, this digital signal processing apparatus has a microcomputer (hereinafter referred to as a microcomputer) 9 for controlling the operation of the entire apparatus, a front panel 10 and MPEG video data separated by a demultiplexer 2 and MPEG.
It has a digital interface 11 for transmitting audio data and additional information to the outside and for sending MPEG video data, MPEG audio data and additional information received from the outside to the demultiplexer 2.

The front end 1 is a tuner and QPSK
It is composed of a demodulator and an error correction circuit, and selects a transport stream of a desired channel designated by the user on the front panel 10 from the multiplexed transport streams of a plurality of channels to select QP.
SK demodulation is performed, and further error detection / correction is performed.

FIG. 2 shows an example of a transport stream for one channel. As shown in this figure, a plurality of programs (here, program numbers 1 to 3 are shown) are multiplexed in the transport stream of one channel. Here, the program is a virtual broadcasting channel, and in the case of current broadcasting in Japan, for example, a broadcasting service such as NHK satellite No. 1 and NHK satellite No. 2 etc.

The data of each program has a predetermined length (18
It is packetized with 8 bytes) and has a header at the beginning. Then, in the header, a PID (Packet Identifier) for identifying the data
on: packet ID) is assigned.

The transport stream of the desired channel selected by the front end 1 is temporarily written in the buffer memory 3 through the demultiplexer 2. Then, the MPEG video data and the MPEG audio data of a desired program are read from here and separated, and the video data is sent to the MPEG video decoder 4 and the audio data is sent to the MPEG audio decoder 5. In FIG. 2, the video data and audio data of program 2 are separated.

At the time of this separation, the PID (packet ID) given to the packet is checked. If it is a PID for identifying video data and audio data of a desired program, it is sent to the MPEG video decoder 4 and the MPEG audio decoder 5, respectively. FIG.
In, the PID given to the video data of the program 2 is “xx”, and the PID given to the audio data is “yy”. A method of knowing the correspondence between the program number and the PID in the digital signal processing device will be described later.

The video data sent to the MPEG video decoder 4 is stored in the buffer memory 4a, appropriately read and decoded. Decoded video data is N
The video signal is converted into an NTSC video signal by the TSC encoder 6, converted into an analog video signal by the D / A converter 7, and then supplied to an external monitor device (not shown). Further, the audio data sent to the MPEG audio decoder 5 is stored in the buffer memory 5a, read out as appropriate, and decoded. The decoded audio data is converted into an analog audio signal by the D / A converter 8 and then supplied to a speaker (not shown) such as a monitor device.

As described above, the video signal and audio signal of the digital broadcast can be received, decoded and displayed on the monitor device.

Next, the additional information will be described. As described above, PSI may be included in the multiplexed bitstream.
(Program use information), EPG (electronic program guide) or SI (service information) is added. Here, PSI defined by MPEG and DVB (Digital Video Br), which is a digital broadcast in Europe, are used.
SI prescribed by the Oadcasting system
Will be described.

: PAT (Programmable Ass)
(Occurrence Table) This table is defined by MPEG, and PID (packet ID) is 0. The main contents are the description of the PID of the NIT and the PID of the PMT described later.

: PMT (Program Map
Table) This table is also defined by MPEG, and the PID is determined by the PAT described above. The main contents are a description of the correspondence between the program number and the PID, and a description of the PID of the ECM (scramble data accompanying the program).

： CAT (Conditional A
access table) This table is also defined by MPEG, and the PID is 1.
It is. The main content is a description of EMM (scramble information for customers).

[0025]: NIT (Network Info)
mation table) PID is 0010. The main contents are a description of the network name (satellite name, terrestrial transmission station, etc.) and a description of the modulation method and frequency for each transport stream (physical channel).

The following table is specified by DVB. : BAT (Bouquet Association)
Table) PID is 0011. The main contents are the description of the bouquet (Bouquet: program supplier) and the destination country, and the transport stream (physical channel).
Content of services and CASS (Condition)
nal Access Service System
m) A description of the method.

[0027]: SDT (Service Descr)
Iption Table) PID is 0011. The main content of the transport stream (physical channel) is a description of the service ID and the name of the bouquet included in the service stream. Here, the service ID is NHK satellite 1st, NH
It is a broadcasting channel such as the second satellite of K satellite. That is, it is the same as the program number specified by MPEG.

[0028]: EIT (Event Information)
Tion Table) PID is 0012. The main content is a description of the event ID, its start time, broadcast time, program content, and the like. Then, a transport stream ID and a service ID are described for each event ID. Here, the event is, for example, “7 o'clock news (December 1
It is a program such as "broadcast for daily broadcast".

: TDT (Time and Data)
Table) PID is 0010. And the main content is the description of the information of the world standard time. Using this TDT, the time of a clock (not shown) in the apparatus can be adjusted.

RST (Running Status)
s Table) PID is 0013. The main content is a description of the execution status of the event. That is, the description such as before the start of a certain event, during the execution, and the end is described.

Next, how the microcomputer 9 in the digital signal processing device processes the PSI and SI described above will be described.

First, in the digital signal processing device,
Set the constants etc. according to the method of each network. Since this information is described in NIT, the modulation method, frequency, bit rate, error correction method, etc. can be obtained for each transport stream. After setting, these pieces of information are stored in the EEPROM (not shown) of the microcomputer 9.

Next, an event is searched using the EIT. A unique event ID is given to each broadcast event, the name and contents of the broadcast program are described in the EIT together with the start time, and the transport stream I for each event is recorded.
D and the service ID are described. Therefore, the transport stream ID is determined from the EIT, the digital signal processing device is set using the constant of the transport stream obtained by NIT, and the transport stream of the desired channel is selected.

The processing for selecting the transport stream of the desired channel in the front end 1 has been described above. Next, the output of the demultiplexer 2 is MPEG
The processing of the microcomputer 9 when sending to the video decoder 4 and the MPEG audio decoder 5 will be described.

FIG. 3 shows an example of the transport stream input to the demultiplexer 2 and PAT and P therein.
The contents of MT are shown. Further, FIG. 4 shows an example of the internal configuration of the buffer memory 3. FIG. 5 is a diagram showing the flow of this processing. Here, it is assumed that the program number 1 broadcast is selected.

First, as shown in step S1 of FIG. 5, the output of the front end 1 is written into the buffer memory 3 through the demultiplexer 2. The buffer memory 3 is shown in FIG.
Since the storage areas 3A to 3C are defined for each data as shown in, the data is written in each area.

Next, as shown in step S2, the PAT is searched from the additional information written in the additional information area 3C of the buffer memory 3. This processing may be performed by searching for a packet whose PID is 0. As shown in FIG. 3B, the PAT has a PID of the PMT for each program (here, PID of the PMT1).
(ID is "cc", PMT2 PID is "dd")
Is described.

Then, a packet with a PID of "cc" is searched for next. As a result, the PMT corresponding to program number 1
1 can be detected. As shown in FIG. 3 (3),
In the PMT 1, MPEG video data, MPEG audio data of program number 1, and PID of ECM are described.

Therefore, when watching the program number 1, the packet with PID "aa" is read from the MPEG video data area 3A of the buffer memory 3 and sent to the MPEG video decoder 4 through the demultiplexer 2 to receive the MPEG audio data. A packet having a PID of "ab" is read from the area 3B and sent to the MPEG audio decoder 5 through the demultiplexer 2.
As shown in FIG. 2, at this time, only the data excluding the header is sent. Also, the scramble is decoded using the ECM information described in the packet with the PID of "xx".

If the program number 2 is to be viewed, the packet with PID "dd" is searched for in the same manner. In this packet, as shown in FIG. 3 (4), video data, audio data, and ECM of program number 2
PID is described. Therefore, the packet with the PID "ba" is read from the MPEG video data area 3A and sent to the MPEG video decoder 4, and the packet with the PID "bb" is read from the MPEG audio data area 3B and sent to the MPEG audio decoder 5.
In addition, E described in the packet whose PID is "zz"
Decode the scramble using the CM information.

The normal processing for decoding the transport stream input from the front end 1 has been described above. The digital signal processing device of FIG. 1 further includes MPEG video data M and M separated by the demultiplexer 2.
The PEG audio data and the additional information are transmitted via the digital interface 11 to an external recording / reproducing device such as D
It can be output to a VCR. In addition, the MPEG video data, the MPEG audio data, and the additional information output from the external recording / reproducing apparatus are transferred to the digital interface 1.
It can be received via 1 and sent to the demultiplexer 2. Next, these processes will be described.

First, the microcomputer 9 for sending the output of the demultiplexer 2 from the digital interface 11 to the outside
Will be described. Since most of this processing is the same as the normal processing described above, only different points will be described.

The MPEG video data and MPEG audio data are sent to the digital interface 11 with the packet header attached. That is, when the microcomputer 9 reads from the buffer memory 3, the header is read and the digital interface 11 is read through the demultiplexer 2.
Send to

The PSI and SI are also sent to the digital interface 11 with the header attached. However, the PAT leaves only the PID designating the PMT of the selected program number and removes the others. For example, when the program number 1 is selected, only the PID of PMT 1 (“cc” in the case of FIG. 3) is left and the others are removed.

In this way, the digital interface 1
The data sent to 1 is sent out from here. The digital interface 11 is, for example, IEEE-139.
4 is compliant. In this case, the data is IEEE
-Output in a 1394 isochronous packet. The isochronous packet output from the digital interface 11 is sent to the external DVCR. Then, here, data is extracted from the isochronous packet, added with an error correction code in the recording system, subjected to channel coding processing, and then recorded.

Next, the case where the data recorded in the DVCR as described above is reproduced and input to the digital signal processing device will be described. The external DVCR puts the reproduced data in an isochronous packet and outputs it. This isochronous packet is input to the digital interface 11, where the original MPEG video data, MPE
The G video data and the additional information are taken out and written in the buffer memory 3 through the demultiplexer 2.

MPEG written in the buffer memory 3
The processing of video data and MPEG audio data is
This is the same as the processing of these data in the transport stream input from the front end 1 described above. On the other hand, the microcomputer 9 processes the PSI and SI written in the buffer memory 3 as follows.

The PAT and PMT are used as they are. As described above, the digital signal processor is connected to the external DVCR.
When outputting data to the PAT, only the PID designating the PMT of the program number selected from the PAT is left and the others are removed. Therefore, the PAT in the data input from the external DVCR is being input to the PAT. Only the PID designating the PMT of the program number is described. Therefore, P
It is possible to look for the PMT by looking at the AT, and read the PMT to read the MPEG video data and the MPEG audio data of the program being input. Read MPEG
The video data and the MPEG audio data pass through the demultiplexer 2 and the MPEG video decoder 4 and M
The data is sent to the PEG audio decoder 5 and thereafter processed in the same manner as these data from the front end 1.

Regarding EIT, only the information of the actual and present of the program described in PAT is decoded,
Ignore the others. Here, “actual” means a transport stream of the selected channel, and “present” means that the selected program is currently being broadcast.

Regarding RST, only those relating to the program described in PAT are decoded, and the others are ignored. Regarding SDT, only the actual one of the program described in PAT is decoded, and the others are ignored.

The NIT is necessary for the setting in the front end 1, but is not necessary in the demultiplexer 2 and is ignored. Similarly, BAT is ignored.

Regarding the TDT, when the reproduction signal of the external DVCR is input, the TDT in the reproduction signal indicates the time at the time of recording, and does not indicate the current time. Therefore, this TDT is ignore. As a result, it is possible to avoid a situation where the internal clock is set to the wrong time when the time is set.

Further, a case where a plurality of programs are continuously input from an external DVCR will be described. As described above, the microcomputer 9 looks at the PAT to find the PMT, looks at the PMT, and reads the MPEG video data and MPEG audio data of the program being input from the external DVCR. However, when the external DVCR continuously outputs a plurality of programs, the microcomputer 9
When the program is switched, the new PAT is searched to find the PMT, and the MPEG of the switched program
Video data and MPEG audio data cannot be read. Further, since the MPEG video decoder 4 and the MPEG audio decoder 5 use the past data for the decoding process, when the program is switched, the data of the program before the switching remaining in the buffer memories 4a and 5a is used. If it is not cleared, correct decryption cannot be done.

Similarly, regarding the SI, when the program is switched to a different transport stream, it is necessary to rewrite the SI in the buffer memory 3.

Therefore, in the present embodiment, when the program reproduced by the DVCR changes, a flag for identifying it is provided in the header of the isochronous packet. FIG. 6 is a diagram showing the format of an isochronous packet. 2 bits of the tag field are 0
When 1 ₂ is set, a 2-quadlet common isochronous packet header (hereinafter referred to as CI
P header). The value of tag is 01 ₂ for the purpose of handling real-time data of a digital audio / video signal of a digital video device or a digital audio device.

[0056] CI if 7 takes a value tag = 01 ₂
Indicates the P header. FIG. 8 shows an example of FMT (format type) allocation in the CIP header.
As shown in FIG. 6, DMT with FMT = 000000 ₂ .
In R, 100001 ₂ specifies the format of the MPEG signal transmission. In this embodiment, the FDF
A discontinuity flag is provided in bit b0 of (format dependent field).

This discontinuity flag is set to the "H (high)" level for a predetermined time (for example, 1 second) when the transport stream becomes discontinuous in the DVCR reproduction signal. Specifically, when recording video data in the DVCR, the recording start position (REC S
Since the video auxiliary data (VAUX data) indicating the TART) and the end position (REC END) is recorded, the discontinuity flag is set to the “H (high)” level when these auxiliary data are detected during reproduction.

Further, in the present embodiment, even when the DVCR mode is changed from stop (STOP) to reproduction (PB), the above-mentioned discontinuity flag is set to the "H (high)" level. This makes it possible to clear the data in the buffer memories 4a and 5a and rewrite the SI in the buffer memory 3 even when the program is reproduced from the middle.

Further, in this embodiment, the variable speed reproduction flag is provided in the bit b1 of the FDF. This is DVC
This flag is set to "H (high)" level when the operation mode of R is slow and cue / review. During such variable speed reproduction, only the MPEG I picture is valid data, so the buffer memory 4a underflows, and as a result, the output of the MPEG video decoder 4 is interrupted until the next I picture is decoded. Will end up. Therefore, in the digital signal processing device, when this flag is detected, the last decoded I picture is output from the MPEG video decoder 4 until the next I picture is input.

FIG. 9 is a flow chart showing the processing of the microcomputer 9 at the time of external input. First, the microcomputer 9 determines whether it is an external input (step S11). Whether it is an external input or not is determined by the output of the front panel 10.

Next, it is judged whether or not the discontinuity flag is detected (step S12). This judgment is made based on whether or not the digital interface 11 detects the discontinuity flag shown in FIG. If the discontinuity flag is detected, the MPEG video decoder 4 is instructed to rewrite PAT, PMT, and SI in the buffer memory 3 and clear the data in the buffer memories 4a and 5a.
And to the MPEG audio decoder 5 (step S13).

Next, it is judged whether or not the variable speed reproduction flag is detected (step S14). This determination is made based on whether or not the digital interface 11 detects the variable speed reproduction flag shown in FIG. 7, as in step S12.
If the variable speed reproduction flag is detected, the MPEG video decoder 4 is instructed to continue outputting the last decoded I picture.

[0063]

As described in detail above, according to the present invention, it is possible to quickly decode video data and audio data when a program input from the outside changes.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a digital signal processing device to which the present invention has been applied.

[Fig. 2] Fig. 2 is a diagram illustrating an example of a transport stream for one channel.

FIG. 3 is a diagram showing an example of a transport stream input to a demultiplexer and the contents of PAT and PMT therein.

FIG. 4 is a diagram showing an internal configuration example of a buffer memory 3 in FIG.

FIG. 5 is a diagram showing a processing flow of a microcomputer when sending an output of a demultiplexer to an MPEG video decoder and an MPEG audio decoder.

FIG. 6 is a diagram showing a format of an isochronous packet.

7 is a diagram showing a CIP header when taking tag = 01 ₂ values.

FIG. 8 is a diagram showing an example of FMT (format type) allocation in a CIP header.

FIG. 9 is a flowchart showing processing of a microcomputer at the time of external input.

[Explanation of symbols]

1 ... Front end, 2 ... Demultiplexer, 4 ... MP
EG video decoder, 5 ... MPEG audio decoder, 9 ... Microcomputer, 11 ... Digital interface

Claims (3)

[Claims] 1. A first means for selecting a transport stream of any one channel from a multiplexed transport stream of a plurality of channels, and the transport with reference to additional information in the selected transport stream. A second for separating video and audio data of an arbitrary program from the stream
Means, a third means for decoding the separated video data and audio data, a video data, audio data, and additional information sent from the outside to the second means, and a program A fourth means for detecting information indicating continuity; and a fifth means for initializing the third means when the fourth means detects information indicating discontinuity of the program. A digital signal processing device characterized by the above. 2. The digital signal processing according to claim 1, wherein the fifth means further updates the additional information in the second means when the fourth means detects the information indicating the discontinuity of the program. apparatus. 3. A first means for selecting a transport stream of any one channel from a multiplexed transport stream of a plurality of channels, and the transport with reference to additional information in the selected transport stream. Second means for separating video data and audio data of an arbitrary program from the stream, third means for decoding the separated video data and audio data, and video data sent from the outside,
A fourth step of sending audio data and additional information to the second means, and detecting information indicating a discontinuity of the program
In the digital signal processing device, the third signal means is initialized when the fourth means detects information indicating the discontinuity of the program. Method.