JP3520595B2 - Encoded image and audio data receiving device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressed image / sound data receiving apparatus for receiving coded data obtained by compressing and coding image data and sound data by a high efficiency coding means and decoding the coded data.

[0002]

2. Description of the Related Art Due to the large amount of image data, it is possible to reduce the transmission / recording cost by transmitting or recording the encoded data after compression and encoding by a high-efficiency encoding means for removing redundancy. Reduction is achieved. As an example of the high-efficiency encoding means, the MPEG method standardized by ISO / SC29 / WG11 is well known. In the MPEG system, images,
In addition to the audio encoding method, the encoding method of these encoded data is standardized as an MPEG / system.
For details of the MPEG system, see ISO / IEC 13818-1 Draft.
Although it is described in International Standard, its outline is also described in “International Standard of MPEG / Multimedia Coding”, edited by Hiroshi Yasuda, pages 159 to 166, published by Maruzen.

FIG. 8 is a diagram showing a structure of a transport packet (hereinafter referred to as a TS packet) adopted in a transport system which is one multiplexing method of the MPEG / system.

A 1TS packet is a fixed length packet of 188 bytes, and is composed of a 4-byte header and a 184-byte data section. The 4-byte header is composed of sync byte, error flag, unit start flag, scramble control flag, priority flag, PID data, adaptation field control flag, and cyclic counter, and the data part in the TS packet depends on the PID data value. Identify the content category of.

The data section includes an adaptation field (hereinafter referred to as AF) whose existence is indicated by the adaptation field control flag, and a payload such as coded data of images and voices and multiplexed information data. AF
Consists of AF length data, discontinuity flag, random access flag, priority flag, PCR flag indicating presence / absence of AF option data, OPCR flag, splice point flag, private data flag, and option data whose existence is indicated by these flags. . Among these optional data, PCR data is information for clock synchronization between the transmitting side and the receiving side, and the receiving side generates a reference clock defined at 27 MHz by using a phase locked loop.

FIG. 9 is a diagram showing a method for accessing coded data of images and audio belonging to a specific channel from a bit stream (hereinafter referred to as TS stream) in which a plurality of programs (hereinafter referred to as channels) are multiplexed. Is.

The program association table (hereinafter referred to as PAT) is always transmitted in TS packets with PID = "0". The PAT is used as multiplexing information for a plurality of channels, and a program map table for each channel (hereinafter referred to as PMT). Which PID value is transmitted in a TS packet having a PID value.

The example of FIG. 9 is an example in which three channels are multiplexed, but when the jth channel is selected, a TS packet with PID = Mj is captured in order to obtain the PMT corresponding to the jth channel. To do. The PMT describes that image data is transmitted in TS packets of PID = Vj and audio data is transmitted in TS packets of PID = Aj. It is possible to receive voice encoded data by capturing TS packets of PID = Aj for the encoded data.

However, the above-described MPEG / system only defines the syntax of the TS stream and the like, and does not define the actual configuration of the receiving device. Also, multiplexing of value-added services such as program guide is not specifically defined, but can be arbitrarily defined by a broadcasting company or a program delivery company.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a compressed image / audio data receiving apparatus which receives a bit stream in which a plurality of channels are multiplexed and restores image data and audio data. There is also a flexible way to receive value-added services.

[0011]

In order to achieve the above object, the present invention provides a data selecting means for selecting a coded stream for one channel, multiplexed information data, and additional information data from a multiplexed stream. Bus access means for supplying the selected encoded stream or the like to the bus,
And a microprocessor connected to the bus, a random access memory, a program memory, a processing unit for the additional information data, a decoding unit for image data, and a decoding unit for audio data.

Further, means for generating a clock signal based on the glock information associated with the encoded stream, packet synchronization supply means for supplying a packet synchronization signal of the encoded stream to the microcomputer, and an error indicating a transmission error correction omission. A means for adding a flag to the encoded stream and a recording media interface means are provided.

[0013]

The data selecting means selects a coded stream or the like for one channel from the multiplexed stream and stores it in the random access memory via the bus access means. The microprocessor reads the data from the random access memory and divides the contents of the read data. Image data is decoded to image data, audio data is decoded to audio data, and multiplexing information is selected as PID data. The additional information data is sent to the means as it is or after being processed, it is sent to the means for processing the additional information data via the bus.

The image data decoding means decompresses / decodes the image coded data, and the audio data decoding means decompresses / decodes the audio coded data to receive the image and the audio. Further, the additional information data processing means enables the overlay display on the image data obtained by decoding the program guide or the like.

The means for generating a clock signal supplies the image data decoding means, the audio data decoding means, the clock signal of the microprocessor to facilitate the data transfer of encoded data and the like, and the packet synchronization supply means. Is
Facilitates recognition of packet synchronization within the microprocessor.

Further, the means for adding an error flag makes it possible for the image data decoding means and the like to recognize the presence of an error without using a special signal line, and the recording media interface means recognizes from the received multiplexed stream. One channel's worth is supplied to the recording medium to enable recording / playback of image / audio data at a low bit rate.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing an example of a receiving apparatus for compressed image / audio data according to the present invention.

In the figure, 1 is an error correction decoder, 2 is a channel demultiplexer, 3 is a random access memory (hereinafter referred to as RAM), 4 is a microcomputer, 5 is a program memory, and 6 is an on-screen display. A processor (hereinafter referred to as an OSD processor), 7 is an image decoder, and 8 is an audio decoder. Further, in the figure, the tuner section of the receiving device for compressed image / audio data and the like are not directly related to the present invention, and therefore the description thereof is omitted.

FIG. 2 is a diagram showing a configuration of the channel demultiplexer 2, 10 is a PSI-PID filter, and 11 is a PSI-PID filter.
Is SI-PID filter, 12 is image / sound PID filter, 13 is P
CR extraction circuit, 14 synchronization signal delay circuit, 15 error flag delay circuit, 16 mixing circuit, 17 error flag addition circuit, 18 direct memory access buffer (hereinafter referred to as DMA buffer), 19 PID data interface , 20 are clock generation circuits.

Further, FIGS. 3 and 4 are diagrams for explaining the operation of the embodiment shown in FIGS. 1 and 2, and FIG.
FIG. 3 is a diagram showing a job (hereinafter referred to as a task) assigned to the microcomputer 4.

In FIG. 1, the coded stream a input to the error correction decoder 1 is a TS corresponding to the coded data of each channel shown by CH1, CH2, and CH3 in (a) of FIGS. 3 and 4. In addition to packets, TS packet of PSI (program specification information) and S
TS packet of I (additional service information) is multiplexed. Also, parity data is added to each TS packet for correction and detection of transmission errors. Error correction decoder
In 1, error correction is performed using the above parity data,
The encoded stream after error correction (b in FIG. 1), the synchronization signal c of the TS packet corresponding to the header of the TS packet (see FIGS. 3 and 4).
(b)), and further, when there are remaining transmission errors that could not be corrected within the range of the parity data, an error flag d ((d) in FIG. 4) indicating the existence of the error is set in the channel demultiplexer 2. Send out.

The channel demultiplexer 2 shown in FIG.
Then, the encoded data b after the error correction is converted into the PSI-PI of FIG.
It is distributed to the D filter 10, the SI-PID filter 11, the image / sound PID filter 12, and the PCR extraction circuit 13. In the PSI-PID filter 10, TS packets of multiplexing information such as the PAT and PMT (hereinafter referred to as PSI
(Indicated as a packet), and SI-PID filter 11 uses additional service information such as program guide and conditional access information.
The image / sound PID filter 12 extracts TS packets (hereinafter referred to as SI packets) from the TS packets (hereinafter referred to as image packets and sound packets) corresponding to encoded data of images and sounds of a specific channel. Further, the PCR extraction circuit 13 captures the TS packet having the PCR data and extracts the PCR data. Further, the PSI packet, the SI packet, the image packet, and the voice packet are re-multiplexed by the mixing circuit 16 and sent to the error flag addition circuit as a coded stream after channel selection. The coded stream after the channel selection is shown in (c) of FIGS. 3 and 4. The figure shows an example of the coded stream when the CH2 channel is selected, but as shown in the figure, the coded stream includes PSI packets, SI packets, and CH2 TS packets (in the figure, the distinction between image and audio is particularly shown. No)) only.

To the error flag adding circuit 17, the coded stream after channel selection and the error flag d which has been subjected to appropriate timing adjustment by the error flag delay circuit 15 are also inputted, and as shown in FIG. 4 (c). Then, mark the presence of an error in the encoded stream. It is preferable to select sequence_error_code in the MPEG system, for example, so that the mark signal has a unique pattern in the encoded stream. Then the encoded stream is DMA buffer 18
It is connected to the bus via, and performs DMA transfer with the microcomputer 4, and stores the encoded stream in the RAM 3.

The MPEG system sequence_error_code is a 4-byte code. In this way, when using the error flag code of a plurality of bytes, in the error flag adding circuit 17, when the position to add the error flag is between the last byte of the TS packet (final -3) bytes,
To prevent the error flag code from straddling two packets, add the error flag code from the (final-4) byte position.

Further, a PID interface 19 is also connected to the bus, receives PID information from the microcomputer 4 described later, and receives the PSI-PID filter 10, SI-PID filter 11,
Image / audio PID filter 12, PCR extraction circuit 13 should capture
The PID information of TS packets is distributed to each.

The microcomputer 4, as shown in FIG.
In addition to transfer, the encoded stream is read from RAM3, the header of the TS packet is analyzed, and the data classification of each TS packet, that is, image data, audio data, PSI data, SI Identify whether it is data. After that, processing is performed according to the content of the data.

In the case of image data, it is sent to the image decoder 7 connected to the bus and the image data is decoded. Similarly, in the case of audio data, the audio data is sent to the audio decoder 8 and the audio data is decoded.

In the case of PSI data, the content is analyzed, and further, based on the selected channel information instructed by the user using a remote control device (not shown), the PSI-PID filter 10 in the channel demultiplexer 2 is analyzed. , SI-PID
Filter 11, image / sound PID filter 12, PCR extraction circuit 13
There determined whether PID information of the TS packet to be captured is what what is sent to the PID data interface 19 of the channel demultiplexer 2 the PID information via the bus.

Further, in the case of SI data, the content is analyzed, and for example, in the case of program guide information, data for on-screen display (referred to as OSD) is generated from the information, and the OSD It is sent to the processor 6. O
In the SD processor 6, the OSD data f is transferred to the image decoder 7 in synchronization with the synchronization g of the image data decoded by the image decoder 7.
The program guide and the like are displayed by overlaying the decoded image data.

The program memory 5 stores a program describing the operation of the microcomputer 4. A read only memory (ROM) may be used as the program memory 5, but various types of SI information can be flexibly dealt with by using a rewritable nonvolatile memory, an IC card, or the like.

Furthermore, between the channel demultiplexer 2 and the microcomputer 4, clock signals clk and T
The S packet sync signal e is connected. The information captured by the PCR extraction circuit 13 causes a clock generation circuit 20 to generate a reference clock signal synchronized with an image, a sound, or both. 27 MHz is selected in the MPEG system. The clock signal is commonly used as a clock signal for the microcomputer 4 and also as a clock signal for the image decoder 7 and the audio decoder 8.

The synchronizing signal is timing-adjusted by the synchronizing delay circuit 14 so as to be synchronized with the TS packet transmitted via the bus, and supplied from e as an interrupt signal of the microcomputer 4. After giving the interrupt signal, the microcomputer 4 transfers data for one TS packet.

As a result, in this embodiment, a bit stream in which a plurality of channels are multiplexed is received, and image data,
It is possible to distinguish the audio data and send the data to a decoder suitable for each. Moreover, the same microcomputer 4 is used for the processing of additional information such as SI, and the processing of additional information such as SI can be performed flexibly by replacing the program.

Further, since the common clock signal is used in the microcomputer 4, the image decoder 7 and the audio decoder 8, the encoded data can be transferred efficiently. Furthermore, the synchronization signal of the TS packet is used as the interrupt signal of the microcomputer 4, and the synchronization detection of the TS packet only needs to be performed once by the error correction circuit 1, and the device can be realized simply.

FIG. 6 shows the channel demultiplexer 2
2 is a second configuration example of. In the figure, the same components as those in the first configuration example shown in FIG. 2 are denoted by the same reference numerals. In this configuration example, in addition to the first configuration example, the selection circuit 21 and the recording media interface 22 are added. Is equipped with.

The coded data after the channel selection, which has been subjected to the error flag processing by the error flag adding circuit 17, is sent to the selection circuit 21 and the recording media interface 22. From the recording medium interface 22, the encoded data after the channel selection is sent out as a recording signal p to a recording medium such as a VTR or a hard disk. In addition, the playback signal q of the recording medium is the recording medium interface
2 is input to the selection circuit 21.

The selection circuit 21 selects whether to decode the coded data directly received by a control signal (not shown) or the reproduction signal signal from the recording medium,
The selected encoded data is sent to the DMA buffer.

In this example, recording / reproducing of image / sound data can be performed digitally without providing an image / sound encoding / decoding device in the recording medium device, and a channel-selected signal is transmitted to the recording medium. It is a recording signal, and its data rate can be suppressed to the necessary minimum.

FIG. 7 shows the channel demultiplexer 2
3 is a third configuration example of. In the figure, the same components as those of the second configuration example shown in FIG. 6 are denoted by the same reference numerals, and in this configuration example, in addition to the second configuration example, the PSI-PID filter 23, the image
The audio PID filter 24, the mixing circuit 25, and the error flag adding circuit 26 are duplicated.

The recording signal to the recording medium is generated by using the doubled PSI-PID filter 23, the image / sound PID filter 24, the mixing circuit 25, and the error flag adding circuit 26.

As a result, in this example, it is possible to set the channels to be recorded on the recording medium independently of the channels to be decoded by the image decoder 7 and the audio decoder 8.

[0043]

As described above, according to the present invention, a bit stream in which a plurality of channels are multiplexed is received,
A compressed image / audio data receiving device for restoring image data and audio data can be simply realized, and a value-added service can be received flexibly.

[Brief description of drawings]

FIG. 1 is a receiver for compressed image / audio data according to the present invention.

FIG. 2 is a first configuration example of a channel demultiplexer.

FIG. 3 is a diagram showing an operation of a compressed image / audio data receiving device (1)

FIG. 4 is a diagram showing the operation of a compressed image / audio data receiving device (2)

[Figure 5] Diagram showing the tasks of the microcomputer

FIG. 6 is a second configuration example of the channel demultiplexer.

FIG. 7: Third example of configuration of channel demultiplexer

FIG. 8 is an explanatory diagram of an encoded stream.

FIG. 9 is a diagram showing the principle of channel selection.

[Explanation of symbols]

1 ... Error correction decoder, 2 ... Channel demultiplexer,
3 ... Random access memory, 4 ... Microcomputer, 5 ... Program memory, 6 ... OSD processor, 7 ... Image decoder, 8 ...
Audio decoder, 10 ... PSI-PID filter, 11 ... SI-PID filter, 12 ... Image / audio PID filter, 13 ... PCR extraction circuit,
18 ... DMA buffer, 19 ... PID data interface, 20 ...
Clock generation circuit, 22 ... Recording media interface

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-275151 (JP, A) JP-A-7-303118 (JP, A) JP-A-7-297855 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H04N ^7/ 00-7/088 H04N 7/12 H04N ^7/ 24-7/68

Claims (7)

(57) [Claims] 1. Multiplexing in which a plurality of sets of a set of encoded streams consisting of compressed and encoded image data and audio data, multiplexed information data having upper and lower layers, and additional information data are multiplexed. Stream to microp
A set of encoded streams instructed by the processor,
All upper layer multiplexed information data and the microprocessor
Some lower layer multiplexed information data specified by the server
And some additional information specified by the microprocessor.
Data selection means for selecting information data , the selected encoded stream and multiplexed information data, bus access means for supplying additional information data to the bus, microprocessor, random access memory, program memory, processing of the additional information data Means, decoding of image data
Means , audio data decoding means, and stores the set of encoded streams selected by the data selecting means, multiplexed information data, and additional information data in a random access memory via the bus access means and the bus, and The data read from the random access memory is analyzed by the microprocessor, and based on the upper layer multiplexed information data, the data selecting means
Instructing the selection of lower layer multiplexed information data,
The lower layer multiplexed information data is identified, and a code is added to the data selection means based on the lower layer multiplexed information data.
Instructing the selection of the encoded stream and the additional information data,
The selected image data, audio data, and additional information data are identified, and the image data is processed by the image data decoding unit, the audio data is processed by the audio data decoding unit, and the additional information data is processed by the additional information data . A device for receiving encoded image / audio data, which is supplied to the means via the bus. 2. A receiving apparatus for encoding image and audio data according to claim 1, generates a clock signal based on the extraction unit and the clock information of the clock information corresponding to the set of encoded streams Means for converting the clock signal into the microprocessor, image data decoding means,
An encoded image / sound data receiving device, which is supplied to a sound data decoding means . 3. The encoded image / audio data receiving apparatus according to claim 1, wherein the multiplexed stream is a packet format stream, and the selected set of encoded streams and multiplexed information data. and additional information packet synchronization signal multiplexed stream obtained by multiplexing the data receiving apparatus of the encoded image and audio data, characterized in that it has a packet sync supply means for supplying to the microprocessor. 4. The coded image / audio data receiving apparatus according to claim 3, wherein the packet synchronization signal is input as an interrupt signal of the microprocessor, and one packet of the packet is succeeded by the interrupt signal. A receiving device for encoded image / audio data, characterized in that the data is stored in a random access memory. 5. The encoded image / audio data receiving apparatus according to claim 1, wherein the multiplexed stream is a packet format stream, and further includes error correction parity data, and the error correction parity data. A transmission error correction means for detecting and correcting a transmission error by using an error flag, and a means for adding an error flag in the coded stream. A device for receiving coded image / sound data, wherein an error flag is set in one packet when a flag is added. 6. The receiver of the encoded image and audio data according to claim 1, wherein the recording medium interface unit, the recording medium interface means, a set of coding selected in the data selection means A coding for sending a multiplexed stream obtained by multiplexing a stream, multiplexed information data, and additional information data to a recording medium, and supplying a reproduction stream from the recording medium to the bus access means. Image and audio data receiving device. 7. The encoded image / audio data receiving apparatus according to claim 1, further comprising a second data selecting means different from the data selecting means and a recording media interface means, the recording media interface means. Sends to the recording medium a multiplexed stream obtained by multiplexing the set of encoded streams selected by the second data selecting means with multiplexed information data and additional information data, and reproduces the reproduced stream from the recording medium. A device for receiving coded image / audio data, which is supplied to the bus access means.