JPH0851623A - Multiplexer for mpeg coding device - Google Patents

Abstract

PURPOSE:To reduce the loads of a multiplexing processing by a software and to perform a coding processing at a high coding rate at a high speed. CONSTITUTION:This multiplexer 5 is constituted of a header detection part 3 for detecting header information in video data outputted from a video coding device 1, a header flag preparation part 4 for preparing a corresponding header flag based on the header information detected in the header detection part 3 and a multiplexing part 8 for integrating the video data, audio data and the other data signals. By analyzing the header flag prepared in the header flag preparation part 4 only when the header information is detected in the header detection part 3, the time required for a pattern comparison processing is substantially shortened compared with the case of performing the comparison processing of header patterns to all the video data as before.

Description

Detailed Description of the Invention

[0001]

The present invention relates to MPEG (Moving Pic)
ture coding Expert Group: Video compression coding standard)
Using I, II video and audio data compression technology,
The present invention relates to a multiplexing device of an MPEG encoding device capable of simultaneously transmitting video data and audio data or recording them on a recording medium by multiplexing these data.

[0002]

2. Description of the Related Art Conventionally, detection of header information in video data in multiplex processing has been performed by software. In this method, all video data input to the multiplex device is compared with a header pattern to detect pattern matching.

[0003]

As described above, conventionally, all the video data input to the multiplex device is compared with the header pattern, and the header information is detected by detecting the pattern match. Was there.

By the way, the amount of data for one screen of video is
It increases as the coding rate increases. An increase in the amount of data leads to an increase in the amount of data targeted for header pattern comparison, which means that the processing time spent for header detection increases. On the other hand, in the multiplexing process after the header information is detected, it is necessary to process more data within a certain fixed time as the coding rate increases.

As described above, at the time of high coding rate, both the header detection processing time and the multiplex processing time by software increase. Therefore, in order to realize the operation at the high coding rate, there is a problem that a DSP (Digital Signal Processor) having a higher processing capability, a microprocessor, or the like must be used.

The present invention has been made to solve such a problem, and can reduce the load of the multiplexing process by software and can perform the encoding process at a high encoding rate at high speed. The purpose is to do so.

[0007]

A multiplex device of an MPEG encoding device according to the present invention is a multiplex device of an MPEG encoding device which integrates video data, audio data and other data, and the video data and the video data in advance. A header detection unit that detects header information by comparing it with a given header pattern, and a header flag creation unit that creates a corresponding header flag based on the header information detected by the header detection unit. There is.

Another feature of the present invention is that the header flag created by the header flag creating section indicates that the first bit is header information, and
It is characterized in that the type of header information is indicated by a combination of subsequent bits, and a combination of bits for reducing the determination process is assigned to the header information having a high detection frequency.

Still another feature of the present invention is that the header flag is analyzed only when the header information is detected by the header detector.

[0010]

The concept of comparing the header detecting process according to the present invention with the header detecting process according to the conventional method is shown in FIG.

The detection of each header information in the video data is performed by
This is done by comparing the header information pattern given in advance with the read video data. In the conventional method, the comparison between the header information pattern and the video data is performed by software using a DSP or the like, and the data reading process and the pattern comparison process are repeatedly performed as shown in FIG. 2B.

Video data is read in 1-byte units, and a picture header "00000" as shown in FIG.
In the conventional method, the video data is read byte by byte, and the read data is compared with the pattern “00h” every time the video data is read. Then, the pattern “00h” is detected.
If "h" is detected, then the pattern "0" is similarly obtained.
It is confirmed whether or not 0h ”,“ 01h ”, and“ 00h ”are continuously input. Thus, in the conventional method, one header pattern comparison process is performed for one data read process. Was needed.

On the other hand, in the present invention, since the header pattern is detected by the header detecting section 3 shown in FIG.
As shown in (c), the data reading process is continuously performed. If the header information in the video data is detected,
A header flag indicating the position of the header information and the type of header information is valid. Then, only when this header flag becomes valid, pattern comparison processing (analysis of header flag information) is performed by software such as DSP. That is, the pattern comparison process is not performed on the data other than the header information.

The amount of video data generated per screen is not constant, but is about several tens of kilobytes. According to the present invention, the header can be detected without performing the pattern comparison processing on all of the data of several tens of kilobytes, so that the processing time is significantly shortened.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A detailed embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the MPEG encoding apparatus according to the present embodiment is a multiplex including a video encoding apparatus 1, an audio encoding apparatus 2, a header detecting unit 3, a header flag creating unit 4 and a multiplexing unit 8. It is constituted by the device 5.

In FIG. 1, a video signal input to the video encoding device 1 and an audio signal input to the audio encoding device 2 are compressed according to the MPEG recommendation. The compressed video data, audio data, and a data signal provided through an interface circuit (not shown) such as RS232C are input to the multiplexing device 5. Then, the multiplexing unit 8 integrates the respective data to generate one data string.

The multiplex processing in the multiplex device is performed on the basis of video data. Therefore, it is necessary to recognize the following information about the video data. 1) Break of data for one screen of video data 2) Operation mode related to video encoding (when the mode is changed during operation)

By the way, such information can be recognized by grasping the position of the header information in the video data and analyzing the data that follows it. The position of the header information in the video data and the type of the header information are detected by the header detection unit 3 and the header flag creation unit 4.

The header detector 3 compares the video data output from the video encoder 1 with a header pattern given in advance, and if a match is detected, a detection signal 6 corresponding to the type of the header information is detected. Is output. The types of the detection signal 6 include, for example, a picture header and a GOP.
There are detection signals for the (Group of Picture) header and the sequence header. Further, the header flag creation unit 4 creates a header flag 7 corresponding to the type of header based on the detection signal 6 output from the header detection unit 3.

An example of creating the header flag 7 is shown in FIG. The header flag 7 assigns 1 bit of "0" to data other than header information, and assigns a 4-bit flag composed of "0" and "1" to header information.

The flag of this header information part has the following meaning. 1) The flag “1” of the first bit indicates header information (indicates the header information position). 2) The flag of the 2nd bit and the flag of the 3rd bit expresses the kind of header information by the combination. That is, "0
If it is 0, it is a picture header, if it is 10, it is a sequence header, and if it is 11, it is a GOP header.

The combination of the flag of the second bit and the flag of the third bit in the above item 2) will be described in more detail.
FIG. 4 shows the position of the header information in the video data. As is clear from FIG. 4, a plurality of GOP headers are included in the section of one sequence header from one sequence header to the next sequence header, and
A section of one GOP header includes a plurality of picture headers. Therefore, as for the header information in the video data, the picture header is the largest, so that the picture header is detected most frequently.

In order to shorten the header information detection processing time, it is effective to perform a high frequency detection processing with a smaller number of determinations. That is, for the picture header, it is effective to select a combination that can be determined only by the flags up to the second bit.

In the example of FIG. 3, if the first bit is "1" and the second bit is "0", it can be recognized as a picture header. That is, the picture header can be recognized only by the first 2 bits. On the other hand, regarding the sequence header and the GOP header, it is necessary to determine the flag up to the third bit.

The multiplexing device 5 starts the analysis of the subsequent header flag 7 when the header flag 7 becomes "1" during the reading of the video data. Here, if the header flag 7 is "0" when the header flag 7 is "1" at the time of the next data reading, it can be immediately recognized that it is a picture header. If the header flag 7 of the second bit is "1", the header flag 7 of the next data is further analyzed. If it is "0", it is a sequence header, and if it is "1", it is a GOP header. You can recognize that there is.

According to the above-described embodiment, the header information detection processing by software is performed only when the header flag 7 of the first bit is "1", so that the header detection time is greatly reduced. can do.

That is, the processing time ratio of the data read processing by the software such as DSP and the header pattern comparison processing is about 1: 3, and the data for one video screen is several tens of kilobytes. The time required for header detection by the conventional method is the sum of both processing times because the data reading process and the pattern comparison process are always performed for all video data.

On the other hand, the time required for the header detection according to the present embodiment is performed only when the flag information of the first bit is "1", and the video data has a large amount of data other than the header information. Considering this, it is considered to be almost equal to the data read processing time. Therefore,
The ratio of the header detection time of the conventional method and the header detection time of this embodiment is about 4: 1. Therefore, according to the present embodiment, the header information detection processing can be speeded up by about 75% as compared with the conventional case.

[0029]

As described above, according to the present invention,
The header flag is detected by detecting the header information position by comparing the video data input to the multiplex device with a header pattern given in advance, and creating a header flag signal indicating the type of the detected header information. Since the header information can be analyzed only when is enabled, pattern comparison processing for data other than header information can be omitted, and the header detection processing time by software can be reduced compared to the conventional method. Can be significantly shortened.

Further, according to another feature of the present invention, a header flag is created by assigning a combination for reducing the number of determination processes to the header information having a high detection frequency. The recognition can be performed faster.

[Brief description of drawings]

FIG. 1 is an MP including a multiplex device according to the present invention.
It is a block diagram which shows the structure of one Example of an EG encoding device.

FIG. 2 is a conceptual diagram comparing a header detection process according to the present invention with a header detection process according to a conventional method.

FIG. 3 is a diagram showing an example of creating a header flag.

FIG. 4 is an explanatory diagram showing a position of header information in video data.

[Explanation of symbols]

 1 Video Encoding Device 2 Audio Encoding Device 3 Header Detection Unit 4 Header Flag Creation Unit 5 Multiplex Device 6 Detection Signal 7 Header Flag 8 Multiplex Unit

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Claims (3)

[Claims] 1. A multiplex device of an MPEG encoding device which integrates video data, audio data and other data, and detects header information by comparing the video data with a header pattern given in advance. A multiplex device of an MPEG encoding device, comprising: a header detection unit; and a header flag creation unit that creates a corresponding header flag based on the header information detected by the header detection unit. 2. The header flag created by the header flag creation unit indicates that the first bit of the header flag is header information, indicates the type of header information by a combination of the following bits, and detects the detection frequency. 2. The multiplexing device of the MPEG encoding device according to claim 1, wherein a combination of bits for reducing the number of determination processes is assigned to the high header information. 3. The multiplexing device of the MPEG encoding device according to claim 1, wherein the header flag is analyzed only when header information is detected by the header detection unit.