JPH11205383A - Decode circuit, conversion method for packet data and storage medium recording decode program and read by machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of the circuit by simplifying the configuration so as to make the circuit small in size. SOLUTION: A new header generating section 12 generates a new header based on a time stamp extracted from packet data by a header decode section 11 and on auxiliary data relating to decoding. A new real data generating section 13 inserts a new header as a frame header of real data obtained by eliminating the header part from the packet data at the header decode section 11 in order to generate new real data and the data are stored once in a buffer section 14. A new real data decode section 15 reads the new real data from the buffer section 14 and decodes the fame real data in succession to the header so as to obtain expanded data based on the time obtained by collating the time stamp in the frame header of the new real data with a time information of a time stamp management section 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decoding circuit for decoding and expanding compressed data having a packet structure transmitted and received over a communication network, a packet data conversion method, and a machine-readable recording medium on which a decoding program is recorded. .

[0002]

2. Description of the Related Art Conventionally, since data such as MPEG received by a personal computer or the like from the Internet is compressed, these data are decompressed by a decoding circuit, returned to the original data, and then displayed or displayed as audio data. Output has been done.

The above-described conventional decoding circuit decodes and decompresses data having a packet structure. Hereinafter, a decoding process of data having the packet structure (hereinafter, simply referred to as packet data) will be described.

First, the decoding circuit must first decode a header section 501 (data containing information necessary for decoding) 501 in packet data having a configuration as shown in FIG. Here, this processing is referred to as preprocessing,
The decoding process of the real data portion 502 other than the header portion in the packet is post-process.

[0005] The header 501 of the packet data as shown in FIG. 6A includes a time stamp indicating the time when the post-processing starts, as shown in FIG. 6B. Since this time stamp is obtained by performing the pre-processing, the time indicated by the time stamp must necessarily be later than the decoding time of the pre-processing.

As a result, there is a time difference between the pre-processing and post-processing times, and the decoding circuit needs to absorb the time difference. Further, since the actual data section 502 is composed of several continuous frame data in a time series, it is necessary to define to which frame data in the actual data 502 a time stamp is to be allocated by some method.

Accordingly, when the decoding circuit performs post-processing,
A process of allocating a time stamp to the frame data in accordance with the above-described rules is performed, and the start time of decoding of the actual data 502 is managed. FIG. 6C is a detailed diagram of the frame j header data shown in FIG.

FIG. 5 is a block diagram showing a configuration example of a conventional decoding circuit. The packet data is input to the header decoding unit 1. The header decoding unit 1 decodes the header 501 of the packet data to extract a time stamp, passes the extracted time stamp to the time stamp and real data address storage unit 2, and removes the header 501 from the packet data. The obtained actual data (hereinafter referred to as frame data) is temporarily stored in the buffer unit 3 so as to absorb the time difference described above. The time stamp and frame data address storage unit 2 stores the passed time stamp and stores the storage location (address) in the buffer unit 3 of the frame data to which the time stamp is assigned.

On the other hand, the time stamp allocation and actual data decoding section 4 reads the time stamp from the time stamp and frame data address storage section 2 and the address of the frame data to which the time stamp is allocated, and reads the frame of the address from the buffer section 3. After reading the data and assigning the time stamp, the read frame data is decoded at the start time specified by the assigned time stamp, and the obtained decompressed data is output.

FIG. 7 is a block diagram showing a detailed example of the conventional decoding circuit shown in FIG. A buffer memory 31 for temporarily storing an input stream and output data and a memory control unit 32 of the buffer memory 31 correspond to the buffer unit 3 shown in FIG. 5, and a memory control unit 32, an MPEG video recorder 41, an MPEG
The audio recorder 42 and the time stamp management unit 5 correspond to the time stamp allocation and actual data decoding unit 4.

The time stamp extracted by the header decoding unit 1 is directly stored in the time stamp and actual data address storage unit 2. The frame data (actual data) obtained by decoding the header data from the packet data by removing the header from the packet data is stored in the buffer memory 31 by the memory control unit 32. At this time, the memory control unit 32 stores the storage destination address of the frame data in the time stamp and actual data address storage unit 2.

The memory control unit 32 reads the time stamp from the time stamp and real data address storage unit 2, reads the frame data to which the time stamp is assigned from the address of the buffer memory 31, and stores the time stamp in the frame data. Allocate MPEG video recorder 41 and MPEG
Output to the audio decoder 42.

The MPEG video decoder 41 compares the time stamp assigned to the input frame data with the time information supplied from the time stamp management unit 5 so that the start time indicated by the time stamp and the frame data To obtain the decompressed data.

The decompressed data thus obtained is temporarily stored in the buffer memory 31 by the memory control unit 32.
And then output to the outside as video data. The MPEG audio decoder 42 also decodes the input frame data from the start time indicated by the time stamp in the same manner as described above. The decompressed data thus obtained is temporarily stored in the buffer memory 31 and then output to the outside as audio data. At this time, since the decoding start time of the frame data is managed by the time stamp, the video of the video data and the audio of the audio data are output without deviation.

[0015]

In the conventional decoding circuit as described above, an address indicating a storage location on the buffer memory 31 for storing frame data and a time stamp are stored in the time stamp and actual data address storage unit 2. By reading the dedicated hardware having the function and the time stamp from the real data address storage unit 2 and the address of the frame data to which the time stamp is assigned, the frame data read from the address of the buffer memory 31 is read. Since dedicated hardware having a function for assigning a time stamp is required, the circuit scale of the decoding circuit becomes large, which not only reduces the reliability of the circuit and also negates the miniaturization of the circuit, but also reduces the size of the circuit. There was a problem of making it expensive.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to simplify a circuit, reduce the size of the circuit, and improve the reliability of the circuit. An object of the present invention is to provide a decoding circuit capable of being read, a machine-readable recording medium on which a decoding program is recorded, and a method of converting packet data necessary for simplifying the circuit.

[0017]

According to a first aspect of the present invention, there is provided a decoding circuit which starts decoding actual data of packet data from a time indicated by a time stamp extracted from a header portion of the packet data. A data creating means for creating new actual data by inserting the time stamp as a frame header of the actual data to which the time stamp is assigned at a data input stage; and a new actual data created by the data creating means. Decoding means for decoding the actual frame data in the data from the time indicated by the time stamp extracted from the frame header of the new actual data.

According to the first aspect, since the input packet data has a configuration suitable for transmission, it is converted into new real data having a configuration suitable for decoding at the input stage. Decode new real data. The new actual data has a time stamp in the frame header, and the actual frame data to which the time stamp is assigned follows the header. Therefore, each actual frame data is extracted from the frame header of the actual frame data. Decoding may be started in order from the time indicated by the time stamp, and actual data can be decoded with an extremely simple circuit configuration.

The data generating means according to the second aspect of the present invention includes: header decoding means for decoding a header part of the packet data to extract a time stamp and removing the header part to separate actual data; New frame header creating means for creating a new frame header including the time stamp obtained by the decoding means, and the header decoding to which the time stamp in the new frame header created by the new frame header creating means is assigned Means for creating new actual data by inserting the new header as a header of actual frame data in the actual data obtained by the means.

According to the second aspect, a plurality of time stamps are stored in the header portion of the packet data. Each time stamp is inserted into the frame header of each real data to which each is assigned. , New real data is created. Accordingly, a new frame header having a time stamp and a plurality of sets of frame real data to which the time stamp is allocated following the header are connected in a dependent manner as new real data.

A feature of the third invention is that the frame header in the new actual data includes information on decoding extracted from the header of the packet data.

According to the third aspect, the information relating to decoding includes, for example, random access point instruction information. This random access point instruction information is information indicating that a proper image can be reproduced even if the indicated position is in the middle of the actual data, if the reproduction is performed from the real data (image data) portion indicated by the information. is there.

According to a fourth aspect of the present invention, there is provided a method for converting packet data having a header section including a time stamp and actual data having a frame structure, wherein an extracting step of extracting a time stamp from the header section of the packet data; A separating step of separating the actual data by removing the header portion from the packet data; and a data creating step of creating new actual data by inserting the extracted time stamp as a frame header in the separated actual data. And

According to the fourth aspect, the packet data suitable for transmission is converted to new real data suitable for decoding in which a time stamp and the frame real data to which the time stamp is allocated are paired. Therefore, this new real data can be decoded very easily in terms of hardware and software under the management of the time stamp.

A feature of the fifth invention is that the time stamp is inserted as a frame header in the actual data to which the time stamp is assigned at the input stage of the packet data composed of the header part and the actual data. The computer to perform the process of creating the actual data and the process of decoding the frame actual data in the new actual data created by this process from the time indicated by the time stamp extracted from the frame header in the new actual data. The program to be recorded is recorded.

According to the fifth aspect, the computer reads the program from the recording medium and executes the program, whereby the time stamp stored in the header portion of the input packet data is assigned to the packet data. The new real data is created by inserting the time stamp as a frame header of the real data, and the frame real data in the new real data is decoded from the time indicated by the time stamp extracted from the header of the new real data. The recording medium includes various types such as a magnetic tape type recording medium, a disk type recording medium, a card type memory, and a semiconductor memory.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a decoding circuit according to one embodiment of the present invention.
The header decoding unit 11 decodes a header portion of the input packet data, extracts auxiliary data and a time stamp relating to the decoding, removes the header portion from the packet data and separates the actual data, and creates the new actual data. Hand over to section 13. The new frame header creating unit 12 creates a new header from the auxiliary data and the time stamp related to the decoding, and passes the created new header to the new packet data creating unit 13.

The new packet data creation unit 13 creates new packet data from the passed new header and actual data, and stores this in the buffer unit 14. The new real data decoding unit 15 compares the time stamp of the new real data read from the buffer unit 14 with the time information generated by the time stamp management unit 16 so that the new real data is decoded at the time specified by the time stamp. , And outputs the obtained decompressed data.

FIG. 2 is a block diagram showing a detailed example of the decoding circuit shown in FIG. The header decoding unit 111 corresponds to the header decoding unit 11 in FIG. 1, the new frame header creation unit 121 corresponds to the new frame header creation unit 12 in FIG. 1, and the new real data creation unit 131 is the new real data creation unit 131 in FIG. 1, the memory control unit 141 and the buffer memory 142 correspond to the buffer unit 14 in FIG. 1, and the MPEG video decoder 151 and the MPEG audio decoder 152 correspond to the new real data decoding unit 15 in FIG. The management unit 161 corresponds to the time stamp management unit 16 in FIG.

Next, the operation of this embodiment will be described with reference to FIG. The packet data (see FIG. 6) is input to the header decoding unit 111, where the header part of the packet data is decoded to extract time stamps and auxiliary data related to decoding.
The real data is separated by removing the header part from the packet data, and this real data is used as the new real data creation unit 131.
Pass to. The new frame header creation unit 121 creates a new header incorporating the time stamp extracted by the header decode unit 111 and auxiliary data related to decoding, and passes the created new header to the new real data creation unit 131.

The new real data creation unit 131 inserts the new header 301 shown in FIG. 3B passed from the new header creation unit 121 as a frame header portion of the real data passed from the header decode unit 111. Then, new real data as shown in FIG. 3A is created, and the obtained new real data is passed to the memory control unit 141.

The memory control unit 141 temporarily stores the transferred new real data in the buffer memory 142. After that, the memory control unit 141 reads the new real data from the buffer memory 142 in the oldest order and inputs the new real data to the MPEG video decoder 151 and the MPEG audio decoder 152.

If the new real data is video data, the MPEG video decoder 151 decodes the input new real data. At this time, a time stamp is extracted from the frame header of the new real data, and the time stamp is extracted. At the time obtained by comparing with the time information generated by the time stamp management unit 161 to obtain the decompressed data of the video data.
If the new real data is audio data, the MPE
The G audio decoder 151 decodes the input new real data. At this time, a time stamp is extracted from the header of the new real data, and the time stamp is compared with the time information generated by the time stamp management unit 161. At the time obtained, decoding of the frame data following the header is started to obtain expanded data of the audio data.

The decompressed data thus obtained is temporarily stored in the buffer memory 142 by the memory control unit 141, and then the video data is output as video data, and the audio data is output as audio data. .

By the way, the decoding circuit shown in FIG. 1 can be constructed by software except for the buffer memory 142, and FIG. 4 is a flowchart showing a processing procedure at that time.

In step 401, the decoding circuit decodes the header of the packet data to obtain a time stamp, auxiliary data, and actual data. Then step 40
In step 2, a new frame header is created using the time stamp and the auxiliary data. In step 403, new packet data is created by inserting the new header as the header of the actual data.

After that, in step 404, the created new real data is temporarily stored in the buffer memory 142, and then read out from the buffer memory 142 in step 405. In step 406, the frame data of the read new real data is It is determined whether the data is video data or audio data. If the data is video data, the process proceeds to step 407;
Proceed to 8.

In step 407, the decoding circuit decodes the read new real data, extracts a time stamp of the header, and starts decoding frame data following the header at the time indicated by the time stamp. Thus, the decompressed data of the video data is obtained, and the process ends. On the other hand, in step 408, the decoding circuit decodes the read new real data, extracts a time stamp of the header, and starts decoding frame data following the header at the time indicated by the time stamp. The process ends after obtaining the decompressed data of the audio data.

According to the present embodiment, a timestamp designating the decoding start time of the actual frame data is inserted as the frame header of the actual frame data in the actual data of the packet data suitable for transmission.
Create new real data (also called packet data conversion)
Since the frame actual data is decoded while adjusting the decoding start time of each frame actual data according to the time stamp of the new actual data, the address on the buffer memory 142 for storing the actual data and the time A dedicated hardware having a function of storing a stamp in the real data address storage unit 2, a time stamp from the real data address storage unit 2, and an address of frame data to which the time stamp is assigned, Dedicated hardware having a function of assigning the time stamp to the frame data read from the address of the memory 142 can be omitted;
The decoding circuit can be simplified as compared with the related art.
Thereby, the circuit scale of the decoding circuit can be reduced, and the reliability of the circuit can be improved.
In addition, the circuit can be manufactured inexpensively.

In this example, hardware for creating a new frame header and new real data is required as compared with the prior art. However, since the scale of these hardware is small,
As described above, the circuit scale can be reduced as a whole as compared with the related art.

Also, when the decoding circuit is constructed by software, a program portion corresponding to the function of the dedicated hardware, which has been conventionally required, can be omitted, and the scale of software can be reduced. The circuit can be constructed at low cost.

Further, as the software is reduced, a decoding circuit can be configured even with a CPU having a small processing capability, and a system including the decoding circuit can be made inexpensive.

In the post-processing of the new real data, the positional relationship between the time stamp and the allocated frame data is clear, so that the time management of the start of decoding the frame data can be easily performed.

The new header created by the new header creation unit 121 can be composed of only a time stamp. In this case, the auxiliary data related to decoding is not necessarily required. The auxiliary data relating to decoding includes, for example, random access point instruction information. If the random access point instruction information is reproduced from the actual data (image data) portion indicated by the information, the random access point instruction information is, for example, the instruction data. This is information that allows a proper image to be reproduced even when the position is in the middle of the actual data.

[0045]

As described above in detail, according to the present invention, a circuit is realized by converting input packet data into new real data and decoding the new real data with a simple hardware configuration. Can be reduced in size, and the reliability of the circuit can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a decoding circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a detailed example of a decoding circuit illustrated in FIG. 1;

FIG. 3 is a diagram showing a configuration example of new real data used in the decoding circuits of FIGS. 1 and 2;

FIG. 4 is a flowchart showing a processing procedure when the decoding circuit shown in FIG. 1 is constructed by software.

FIG. 5 is a block diagram showing a configuration example of a conventional decoding circuit.

FIG. 6 is a diagram showing a configuration example of conventional packet data.

FIG. 7 is a block diagram showing a detailed example of a decoding circuit shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Header decoding part 12 New frame header creation part 13 New real data creation part 14 Buffer part 15 New real data decoding part 16 Time stamp management part 111 Header decoder unit 121 New frame header creation unit 131 New real data creation unit 141 Memory control unit 142 buffer memory 151 MPEG video decoder 152 MPEG audio decoder 161 time stamp management unit

Claims (5)

[Claims] 1. A decoding circuit which starts decoding actual data of a packet data from a time indicated by a time stamp extracted from a header portion of the packet data. Data creating means for creating new actual data by inserting the time stamp into a frame header in the actual data of the real data of the real data. Decoding means for decoding from the time indicated by the time stamp extracted from the frame header. 2. A packet header decoding means for decoding a header portion of the packet data to extract a time stamp and removing the header portion to separate actual data, and a packet header decoding device for obtaining the data. New frame header creating means for creating a new frame header including the obtained time stamp, and the header decoding means to which the time stamp in the new frame header created by the new frame header creating means is assigned. 2. The decoding circuit according to claim 1, further comprising: creating means for creating new actual data by inserting the new header as a header of frame actual data in the actual data. 3. The decoding circuit according to claim 1, wherein the frame header of the new actual data includes information on decoding extracted from a header part of the packet data. 4. A method for converting packet data having a header part including a time stamp and actual data having a frame structure, comprising: an extracting step of extracting a time stamp from a header part of the packet data; And a data creating step of creating new actual data by inserting the extracted time stamp as a frame header in the separated actual data. Characteristic packet data conversion method. 5. At the input stage of packet data consisting of a header part and real data, new real data is created by inserting the time stamp as a frame header in the real data to which the time stamp is assigned. And a step of decoding the new real data created by this process from the time indicated by the time stamp extracted from the frame header of the new real data; and a machine-readable recording medium storing a program for causing a computer to execute .