JP2004088797A - Digital signal processing apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a decoding operation of video data and audio data to be performed quickly, when a plurality of programs are reproduced in series on a digital VTR and the programs input from a digital interface are changed. <P>SOLUTION: A MPEG video decoder 4 and a MPEG audio decoder 5 decode MPEG video data and MPEG audio data which are separated by a demultiplexer 2, respectively. A digital interface 11 performs the transmission and reception of the MPEG video data, the MPEG audio data, and additional information, between the demultiplexer 2 and the outside. When the digital interface 11 detects a flag which indicates the discontinuity of programs from an input signal, a microcomputer 9 is controlled to initialize buffer memories 4a and 5a. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a digital signal processing apparatus and method for receiving and decoding a digital broadcast, and more particularly, to processing for inputting undecoded video data and audio data from an external recording / reproducing apparatus. It is.

In recent years, in the United States and European countries, video and audio signals have been encoded by applying high-efficiency encoding technologies such as MPEG (Moving Picture Image Coding Experts Group), transmitted via communication satellites, etc. Systems for demodulating this are becoming widespread.

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

Further, in this system, the multiplexed transport stream is received by the receiving / demodulating device so that the transport stream of the desired channel can be received and the video data and audio data of the desired program can be separated. PSI (Program Spesific Information: program specification information), EPG (Electronic Program Guide: electronic program guide) or SI (Service Information: service information) is added to the inside.

By the way, a video tape recorder (hereinafter referred to as DVTR) for encoding and recording / reproducing a video signal and an audio signal has been proposed. Non-Patent Literature 1 considers recording / reproducing such digital broadcast video data and audio data on such a DVTR without decoding them.

Edited by Yukio Kubota, "Illustration Digital Video Reader", pp.140-152, Ohmsha, August 25, 1995

According to the present invention, when the DVTR reproduces a plurality of digital broadcast programs continuously and inputs the digital broadcast programs to the above-described receiving / demodulating apparatus, even when the program changes or is discontinuous, the video in the receiving / demodulating apparatus is controlled. It is an object of the present invention to provide an electronic device and a signal processing method that can quickly perform a decoding operation of data and audio data and do not interrupt decoding output.

In order to solve the above-mentioned problems, a digital signal processing apparatus according to the present invention comprises: a first unit for selecting an arbitrary one-channel transport stream from a multiplexed multi-channel transport stream; A second means for separating video data and audio data of an arbitrary program from the transport stream with reference to the additional information in the stream, a third means for decoding the separated video data and audio data, Means for sending video data, audio data, and additional information sent from the second means to the second means, and detecting information indicating program discontinuity, and the fourth means indicating program discontinuity. And a fifth means for initializing the third means when detecting information. It is intended to.

Further, the digital signal processing method according to the present invention includes a first means for selecting an arbitrary one-channel transport stream from the multiplexed transport streams of a plurality of channels, and a transport stream selected by the first means. A second means for separating video data and audio data of an arbitrary program from the transport stream with reference to the additional information therein, a third means for decoding the separated video data and audio data, A fourth means for sending the video data, audio data and additional information to be sent to the second means, and detecting the information indicating the discontinuity of the program. Initializes the third means when detecting information indicating discontinuity of the program. It is characterized in.

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

According to the present invention, it is possible to quickly decode video data and audio data when a program inputted from the outside is changed, and the decoded output is not interrupted.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a digital signal processing device to which the present invention is applied. This digital signal processing device is called an IRD (Integrated Receiver Decoder).

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

The digital signal processing apparatus includes an MPEG video decoder 4 for decoding video data separated by the demultiplexer 2, an MPEG audio decoder 5 for decoding audio data separated by the demultiplexer 2, and an MPEG video decoder 4. An NTSC encoder 6 for converting the decoded video signal into an NTSC video signal, a D / A converter 7 for converting the output of the NTSC encoder 6 into an analog signal, and a D / A converter 8 for converting the output of the MPEG audio decoder 5 into an analog signal. And 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 device includes a microcomputer (hereinafter, referred to as a microcomputer) 9 for controlling the operation of the entire device, a front panel 10, and MPEG video data and MPEG audio data separated by the demultiplexer 2 and external information. And a digital interface 11 for transmitting MPEG video data, MPEG audio data, and additional information received from outside to the demultiplexer 2.

The front end 1 includes a tuner, a QPSK demodulator, and an error correction circuit. The front end 1 converts a multiplexed transport stream of a plurality of channels into a transport stream of a desired channel specified by the user on the front panel 10. Select and perform QPSK demodulation, and further detect and correct errors.

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 multiplexed) are multiplexed in a transport stream of one channel. Here, the program is a virtual broadcasting channel, which is, for example, a broadcasting service of the NHK satellite No. 1 and the NHK satellite No. 2 in the current broadcasting in Japan.

The data of each program is packetized with a predetermined length (188 bytes), and has a header at the beginning. The header is provided with a PID (Packet Identification) for identifying data.

(4) The transport stream of the desired channel selected by the front end 1 is temporarily written to the buffer memory 3 through the demultiplexer 2. Then, the MPEG video data and the MPEG audio data of the desired program are read and separated therefrom, 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, video data and audio data of the program 2 are separated.

に 際 し て At the time of this separation, look at the PID (packet ID) assigned to the packet. If it is a PID for identifying video data and audio data of a desired program, the PID is sent to the MPEG video decoder 4 and the MPEG audio decoder 5, respectively. In FIG. 2, the PID assigned to the video data of the program 2 is “xx”, and the PID assigned 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, and is read and decoded as appropriate. The decoded video data is converted into an NTSC video signal by an NTSC encoder 6, converted to an analog video signal by a D / A converter 7, and supplied to an external monitor device (not shown). The audio data sent to the MPEG audio decoder 5 is stored in the buffer memory 5a, and is read and decoded as appropriate. 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 the audio signal of the digital broadcast can be received, decoded, and displayed on the monitor device.

Next, additional information will be described. As described above, PSI (program use information), EPG (electronic program guide) or SI (service information) is added to the multiplexed bit stream. Here, a description will be given of PSI specified by MPEG and SI specified by DVB (Digital Video Broadcasting) system which is a digital broadcast in Europe.

(1): PAT (Programme Association Table)
This table is defined by MPEG, and the 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.

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

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

(4): NIT (Network Information Table)
The PID is 0010. The main contents are a description of a network name (satellite name, terrestrial transmission station, etc.) and a description of a modulation method and a frequency for each transport stream (physical channel).

The following table is specified in DVB.
(5): BAT (Bouquet Association Table)
The PID is 0011. The main contents are the name of a bouquet (program supplier) and a description of a destination country, the contents of a service related to a transport stream (physical channel), and a description of a CASS (Conditional Access Service System) system.

(6): SDT (Service Description Table)
The PID is 0011. The main content is a description of a transport stream (physical channel) such as a service ID included therein and a name of a bouquet thereof. Here, the service ID is a broadcast channel such as NHK Satellite 1 and NHK Satellite 2. That is, it is the same as the program number defined in MPEG.

(7): EIT (Event Information Table)
The PID is 0012. The main contents are the description of the event ID and its start time, broadcast time, program contents, and the like. Then, a transport stream ID and a service ID are described for each event ID. Here, the event is, for example, a program such as "7:00 News (broadcast on December 1)".

(8): TDT (Time and Data Table)
The PID is 0010. The main content is the description of information in Coordinated Universal Time. Using the TDT, the time of a clock (not shown) in the apparatus can be adjusted.

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

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

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

Next, search for events using EIT. Each broadcast event is given a unique event ID, the name and contents of the broadcast program are described in the EIT together with the start time, and the transport stream ID and service ID are described for each event. Therefore, the transport stream ID is determined from the EIT, the digital signal processing device is set using the transport stream constant obtained in the NIT, and the transport stream of the desired channel is selected.

The processing for selecting a transport stream of a desired channel in the front end 1 has been described above. Next, the processing of the microcomputer 9 when sending the output of the demultiplexer 2 to the MPEG 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 the contents of the PAT and PMT therein. 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, description will be made assuming that the broadcast of program number 1 is selected.

First, as shown in step S1 of FIG. 5, the output of the front end 1 is written to the buffer memory 3 through the demultiplexer 2. In the buffer memory 3, as shown in FIG. 4, storage areas 3A to 3C are defined for each data, so that data is written in each area.

Next, as shown in step S2, a PAT is searched for from the additional information written in the additional information area 3C of the buffer memory 3. In this process, a packet having a PID of 0 may be searched for. As shown in FIG. 3 (2), the PAT describes the PID of the PMT for each program (here, the PID of the PMT1 is “cc” and the PID of the PMT2 is “dd”).

(4) Then, a packet with a PID of “cc” is searched next. Thereby, PMT1 corresponding to program number 1 can be detected. As shown in FIG. 3 (3), PMT1 describes MPEG video data of program number 1, MPEG audio data, and PID of ECM.

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

見 る If the broadcast of program number 2 is to be watched, a packet having a PID of “dd” is similarly searched. As shown in FIG. 3 (4), the PID of the video data, the audio data, and the ECM of the program number 2 are described in this packet. Therefore, a packet whose PID is "ba" is read from the MPEG video data area 3A and sent to the MPEG video decoder 4, and a packet whose PID is "bb" is read from the MPEG audio data area 3B and sent to the MPEG audio decoder 5. Also, the scramble is decoded using the ECM information described in the packet with the PID “zz”.

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 can further output the MPEG video data, MPEG audio data, and additional information separated by the demultiplexer 2 to an external recording / reproducing device, for example, a DVTR via the digital interface 11. In addition, MPEG video data, MPEG audio data, and additional information output from an external recording / reproducing device can be received via the digital interface 11 and sent to the demultiplexer 2. Next, these processes will be described.

First, the processing of the microcomputer 9 when transmitting 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 above-described normal processing, only different points will be described.

(4) 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 out the data from the buffer memory 3, it reads out the entire header and sends it to the digital interface 11 through the demultiplexer 2.

$ 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 program number 1 is selected, only the PID of PMT1 ("cc" in the case of FIG. 3) is left, and the others are removed.

(4) The data sent to the digital interface 11 in this way is sent from the outside to the outside. The digital interface 11 is based on, for example, IEEE-1394. In this case, the data is output in an IEEE-1394 isochronous packet. The isochronous packet output from the digital interface 11 is sent to an external DVTR. Then, data is extracted from the isochronous packet, an error correction code in a recording system is added thereto, and the data is recorded after being subjected to a channel coding process.

Next, a case where data recorded on the DVTR as described above is reproduced and input to the digital signal processing device will be described. The external DVTR outputs the reproduced data in an isochronous packet. The isochronous packet is input to the digital interface 11, where the original MPEG video data, MPEG video data, and additional information are extracted and written into the buffer memory 3 through the demultiplexer 2.

The processing of the MPEG video data and MPEG audio data written in the buffer memory 3 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.

Use PAT and PMT as they are. As described above, when outputting data from the digital signal processor to the external DVTR, only the PID designating the PMT of the program number selected from the PAT is left, and the others are removed. Only the PID designating the PMT of the program number being input is described in the PAT in the data input from. Therefore, the PMT is searched by looking at the PAT, and the MPEG video data and the MPEG audio data of the program being input can be read by looking at the PMT. The read MPEG video data and MPEG audio data are sent to the MPEG video decoder 4 and the MPEG audio decoder 5 through the demultiplexer 2, and thereafter processed in the same manner as these data from the front end 1.

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

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

NIT is required for setting in the front end 1 but is not required in the demultiplexer 2 and is ignored. BAT is similarly ignored.

Regarding TDT, when a reproduction signal of an external DVTR is input, the TDT in the reproduction signal indicates the time at the time of recording and does not indicate the current time, so this TDT is ignored. As a result, it is possible to avoid a situation where the internal clock is set to an incorrect time when setting the time.

(4) Further, a case where a plurality of programs are continuously input from an external DVTR will be described. As described above, the microcomputer 9 searches the PAT for the PMT, and reads the MPEG video data and the MPEG audio data of the program being input from the external DVTR by looking at the PMT. However, when the external DVTR is continuously outputting a plurality of programs and the program is switched, the microcomputer 9 searches the PAT for a new PAT, searches for the PMT, and stores the MPEG video data and the MPEG video data of the switched program. MPEG audio data cannot be read. Further, in the MPEG video decoder 4 and the MPEG audio decoder 5, since the past data is used 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 replaced. If it is not cleared, correct decoding cannot be performed.

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

Therefore, in the present embodiment, when the program being reproduced by the DVTR changes, a flag for identifying the change is provided in the header of the isochronous packet. FIG. 6 is a diagram showing a format of an isochronous packet. When the tag (tag) 2-bit field is _012, it inserts a 2 Kuadoretto common isochronous packet header (hereinafter referred to as CIP header) at the beginning of the data field. For the purpose of dealing with real time data in a digital audio video signal, such as digital video equipment and digital audio equipment, the value of the tag 01 _2.

Figure 7 shows a CIP header when taking the value of the tag = 01 _2. FIG. 8 shows an example of allocation of FMT (format type) in the CIP header. As shown in FIG. 6, which specifies the format of the MPEG signal transmission FMT = 0000000 ₂ in DVTR, 100001 _2. In the present embodiment, a discontinuity flag is provided for bit b0 of the FDF (format dependent field).

This discontinuity flag is set to the “H (high)” level for a predetermined time (for example, one second) when the transport stream becomes discontinuous in the DVTR reproduction signal. More specifically, since the DVTR records video auxiliary data (VAUX data) indicating a recording start position (REC START) and an end position (REC END) together with the video data at the time of recording the video data, these data are recorded at the time of reproduction. When the auxiliary data is detected, the discontinuity flag is set to “H (high)” level.

Also, in the present embodiment, the discontinuity flag is set to the “H (high)” level even when the mode of the DVTR changes from stop (STOP) to reproduction (PB). Thus, even when the program is reproduced from the middle of the program, the data in the buffer memories 4a and 5a can be cleared and the SI in the buffer memory 3 can be rewritten.

In addition, in the present embodiment, a variable speed reproduction flag is provided in the bit b1 of the FDF. This is a flag that is set to “H (high)” level when the operation mode of the DVTR is slow and cue / review. At the time of such variable speed reproduction, only the MPEG I picture becomes valid data, so that 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. Would. Therefore, the digital signal processing device is configured so that, 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 flowchart showing the processing of the microcomputer 9 at the time of external input. First, the microcomputer 9 determines whether the input is an external input (step S11). Whether the input is an external input is determined based on the output of the front panel 10.

Next, it is determined whether or not a discontinuity flag has been detected (step S12). This determination is made based on whether the digital interface 11 has detected the discontinuity flag shown in FIG. If the discontinuity flag is detected, a command to rewrite the PAT, PMT, and SI in the buffer memory 3 and clear the data in the buffer memories 4a and 5a is sent to the MPEG video decoder 4 and the MPEG audio decoder 5. Is given (step S13). That is, when the discontinuity flag is detected, PAT, PMT, and SI, which are additional information in the transport stream, are fetched and the buffer memory 3 is rewritten.

Next, it is determined whether or not the variable speed regeneration flag has been detected (step S14). This determination is made based on whether or not the digital interface 11 has detected the variable speed reproduction flag shown in FIG. 7, as in step S12. Then, if the variable speed reproduction flag is detected, an instruction is given to the MPEG video decoder 4 to keep outputting the last decoded I picture.

According to the embodiment of the present invention described in detail above, it is possible to quickly decode video data and audio data when a program input from the outside is changed, and to interrupt the decoding output. There is no.

1 is a block diagram illustrating a configuration of a digital signal processing device to which the present invention has been applied. FIG. 3 is a diagram illustrating an example of a transport stream for one channel. FIG. 3 is a diagram illustrating an example of a transport stream input to a demultiplexer and the contents of a PAT and a PMT therein. FIG. 2 is a diagram illustrating an example of an internal configuration of a buffer memory 3 in FIG. 1. FIG. 4 is a diagram illustrating a processing flow of a microcomputer when sending an output of a demultiplexer to an MPEG video decoder and an MPEG audio decoder. It is a figure showing the format of an isochronous packet. It is a diagram showing a CIP header when taking the value of the tag = 01 _2. FIG. 4 is a diagram illustrating an example of allocation of FMT (format type) in a CIP header. 6 is a flowchart illustrating a process of the microcomputer at the time of external input.

Explanation of reference numerals

{1} front end, {2} demultiplexer, {4} MPEG video decoder, {5} MPEG audio decoder, {9} microcomputer, {11} digital interface

Claims (3)

First means for selecting a transport stream of an arbitrary channel from multiplexed transport streams of a plurality of channels; and referring to additional information in the selected transport stream to select an arbitrary program from the transport stream. A second means for separating the video data and the audio data, a third means for decoding the separated video data and the audio data, and the video data, the audio data, and the additional information sent from the outside. A fourth means for sending to the second means and detecting information indicating the discontinuity of the program; and a fourth means for detecting the information indicating the discontinuity of the program when the fourth means detects the information indicating the discontinuity of the program. And a fifth means for performing initialization. The digital signal processing apparatus according to claim 1, wherein the fifth means further updates the additional information in the second means when the fourth means detects information indicating discontinuity of the program. First means for selecting a transport stream of an arbitrary channel from multiplexed transport streams of a plurality of channels; and referring to additional information in the selected transport stream to select an arbitrary program from the transport stream. A second means for separating the video data and the audio data, a third means for decoding the separated video data and the audio data, and the video data, the audio data, and the additional information sent from the outside. A fourth means for sending to the second means and detecting information indicating the discontinuity of the program, wherein the fourth means detects the information indicating the discontinuity of the program And a step of initializing the third means.

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