JP2001136074A - Information encoding device and method, information encoding system, and computer-readable recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information encoding device and method by which a fluctuation in a time delay of image compression data (variable length coded data) in a data buffer can be suppressed in the case that an encoding bit rate or an encoding parameter is revised. SOLUTION: An MPEG2 encoder 101 changes a quantization step to control a generated amount of ES data (variable length coding data) so that number of slice headers in existence in a data buffer 102 is a prescribed value on the basis of a buffer occupied amount SHN detected and supplied by a header counter 105 in order to avoid occurrence of overflow or underflow in the data buffer 102.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an information encoding apparatus, and more particularly, to an information encoding apparatus and method for generating variable-length encoded data, an information encoding system, and a computer-readable recording medium.

[0002]

2. Description of the Related Art In recent years, MPEs that have been put into practical use as compression encoding systems for digitally compressing video and audio have been developed.
There is a G2 system (IS01818, hereinafter referred to as MPEG2). MPEG2 compressed video (image) data is composed of a variable-length code string. When transmitting compressed video data via a general transmission medium such as wireless or optical fiber, the compressed video data is received. It is necessary to keep the data transmission rate constant for the reason that data can be easily received (without performing special control) by a device on the side, for example, an image decoding device. For this reason, conventionally, when transmitting the compressed video data as a burst (discontinuous) signal, the data transmission rate is fixed by using a buffer having a predetermined capacity, and then the radio or optical fiber is transmitted. The compressed video data is output to a transmission medium such as the above.

FIG. 2 is a block diagram showing an example of such a conventional information encoding device. As shown in FIG.
A conventional information encoding device is an MPEG2 encoder 201,
It comprises a data buffer 202 and a counter 203. In the following description, as variable-length encoded data,
A description will be given using compressed video (image) data as an example.

The MPEG2 encoder 201 digitally compresses video and audio signals based on the compression coding standard of MPEG2 (IS01818). The data buffer 202 is temporary storage means for storing variable-length coded data, which is digital compressed data output from the MPEG2 encoder 201, and for reading out (keeping a fixed rate) the variable-length coded data at a fixed rate. is there. The counter 203 counts the amount of variable-length coded data stored in the data buffer 202, and
The amount of variable-length encoded data output from the second encoder 201 is controlled so that the amount of variable-length encoded data accumulated in the data buffer 202 becomes a predetermined value.

Next, the operation of the conventional information coding apparatus will be described. In FIG. 2, an MPEG2 encoder 201 generates variable-length coded data conforming to the MPEG2 standard, and supplies it to a data buffer 202 as an elementary stream (hereinafter, also simply referred to as ES). As described above, ES is a burst (discontinuous) signal.

The MPEG2 encoder 201 also supplies a write signal WS to the data buffer 202 when the variable-length coded data is valid, that is, when the variable-length coded data is being output. The data buffer 202 sequentially writes ES (variable-length coded data) in the buffer based on the write signal WS.

[0007] Further, data reading from the data buffer 202 is performed by a read signal RS of a constant rate supplied from outside (not shown). Data buffer 2
02 is, for example,
The data is supplied to an unillustrated device (such as an image (information) decoding device) capable of processing the variable-length encoded data conforming to the MPEG2 standard via a not-shown I / F circuit or the like or a transmission medium.

On the other hand, the data counter 203
When the write signal WS supplied from the second encoder 201 becomes active (for example, high level), the counter value is incremented. That is, the data buffer 20
2 each time data is written to the data counter 203
Is counted up. Similarly, the data counter 203 decrements the counter value when the read signal RS is supplied. That is, each time data is read from the data buffer 202, the counter value in the data counter 203 is counted down. From the above, the number of data existing in the data buffer 202, that is, the buffer occupancy BS is detected from the counter value in the data counter 203.

The buffer occupancy BS detected by the data counter 203 is supplied to an MPEG2 encoder 201. In the MPEG2 encoder 201, the supplied buffer occupation amount B is set so that the data buffer 202 does not overflow or underflow.
Based on S, the generation amount of the variable-length encoded data is controlled so that the buffer occupation amount becomes a predetermined value. The control of the data generation amount is performed, for example, by changing the quantization step in the quantization.

As described above, according to the conventional information coding apparatus, the burst-like ES data supplied to the data buffer 202 is transmitted from the data buffer 202 to the data transmission rate by the data buffer 202. Is output as the fixed ES data.

By the way, according to the above prior art, MPE
The G2 encoder 201 controls the generation amount of the variable-length encoded data so that the data occupation amount of the data buffer 202 becomes a predetermined value.
Even when the encoding parameters such as (Group of pictures) structure are changed, the buffer occupancy becomes the predetermined value regardless of this.

However, the amount of coded image data generated in one frame or field of an image varies greatly depending on the coding bit rate and the coding parameters. Are very different from each other. That is, even if the amount of data stored in the data buffer is constant, the number of frames of the stored image will be different. Therefore, when the encoding bit rate or the encoding parameter is changed, the data buffer 202
, For example, the time required for each image of one frame to be read from the data buffer 202 greatly varies.

[0013]

As described above, in the conventional information encoding apparatus, the MPEG2 encoder controls the amount of generated variable-length encoded data so that the data occupancy of the data buffer becomes a predetermined value. However, since the coding bit rate and coding parameters are changed, the amount of image coding data generated in one frame or field (one screen) of the image fluctuates greatly, and is stored in the data buffer. Even if the data amount is constant, the number of frames or fields of the stored image differs. For this reason, when the encoding bit rate or the encoding parameter is changed, there is a problem that the readout time delay amount of the encoded image data for one frame (one screen) in the data buffer greatly changes.

The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above-described problems, and has been made in consideration of the problems described above. It is an object to provide an apparatus and a method, an information encoding system, and a computer-readable recording medium.

[0015]

According to a first aspect of the present invention, there is provided an information encoding apparatus comprising:
Encoding means for compressing and encoding information data in a predetermined data unit; storage means for storing the information data encoded by the encoding means; and detecting the number of data in the predetermined data unit stored in the storage means And a control unit that controls an encoding parameter for controlling a compression ratio in the encoding unit according to a detection result of the detection unit.

According to a second aspect of the present invention, in the information encoding apparatus, the information data is image data, and the image data stored in the storage means is a predetermined image data for each screen. It is characterized in that it is read out from the storage means in time.

Further, the information encoding apparatus according to claim 3 is characterized in that the encoding means performs encoding in accordance with the MPEG2 standard.

Further, the information coding apparatus according to claim 4 is characterized in that the predetermined data unit is one slice.

The information encoding apparatus according to claim 5, wherein the encoding means outputs header information indicating the start of one slice, and the detecting means detects the number of the header information. Having.

According to another aspect of the present invention, there is provided an information encoding apparatus for digitally compressing data information to generate variable length encoded data, and a variable length code generated by the information compression means. Detecting means for detecting a predetermined data block and its header information in encoded data, and buffer means for storing the header information detected by the header detecting means and the variable-length coded data generated by the information compressing means And detecting the number of header information stored in the buffer means, and controlling the amount of variable length encoded data generated by the information compression means based on the detected number of header information. It is characterized in that it is provided with a header counting means.

According to a seventh aspect of the present invention, in the information encoding apparatus, the information compressing means converts the data information into an MPEG format.
It is characterized in that digital compression is performed based on the compression coding standard of No. 2.

An information coding apparatus according to the present invention is characterized in that the data information is an image and / or an audio signal.

An information coding apparatus according to a ninth aspect is characterized in that the header detecting means detects a slice header in the variable length coded data.

Further, in the information encoding apparatus according to the present invention, the header counting means may have a predetermined number of slice headers based on the number of slice headers stored in the buffer means. As described above, the present invention is characterized in that the amount of generation of variable-length encoded data in the information compression means is controlled.

According to the information encoding method of the present invention, there is provided an encoding procedure for compressing and encoding information data in a predetermined data unit, and storing the information data encoded by the encoding procedure in a storage means. A storage procedure for storing, a detection procedure for detecting the number of data of the predetermined data unit stored in the storage means, and an encoding parameter for controlling a compression ratio in the encoding procedure according to a detection result of the detection procedure. And a control procedure for controlling.

According to a twelfth aspect of the present invention, in the information encoding method, the information data is image data, and the image data stored in the storage means is a predetermined image data for each screen. It is characterized in that it is read out from the storage means in time.

An information coding method according to a thirteenth aspect is characterized in that the coding means performs coding in accordance with the MPEG2 standard.

Further, the information encoding method according to the present invention is characterized in that the predetermined data unit is one slice.

The information encoding method according to claim 15, wherein the encoding step outputs header information indicating the start of one slice, and the detecting step detects the number of the header information. Having.

An information encoding method according to claim 16, further comprising: an information compression procedure for digitally compressing data information to generate variable length encoded data; and a variable length code generated by the information compression procedure. A header detection procedure for detecting a predetermined data block in the encoded data and its header information, header information detected by the header detection procedure, and variable-length encoded data generated by the information compression procedure are stored in buffer means. And detecting the number of header information stored in the buffer means,
A header count procedure for controlling the amount of variable-length encoded data generated by the information compression procedure based on the number of the detected header information.

Further, in the information encoding method according to the present invention, the information compression step may include the step of converting the data information into an MPEG format.
It is characterized in that digital compression is performed based on the compression coding standard of No. 2.

An information encoding method according to claim 18 is characterized in that the data information is an image and / or an audio signal.

An information encoding method according to claim 19 is characterized in that the header detection step detects a slice header in variable-length encoded data.

Further, in the information encoding method according to the present invention, in the header counting procedure, the number of the slice headers becomes a predetermined value based on the number of the slice headers stored in the buffer means. As described above, the present invention is characterized in that the generation amount of variable-length encoded data in the information compression procedure is controlled.

According to a twenty-first aspect of the present invention, there is provided an information encoding system, comprising: the information encoding device according to any one of the first to tenth aspects; and a variable length code supplied from the information encoding device. It is characterized by comprising an information decoding device for decoding encoded data, and communication means for connecting the information encoding device and the information decoding device.

According to a second aspect of the present invention, there is provided a computer-readable recording medium for causing a computer to function as each unit included in the information encoding apparatus according to any one of the first to tenth aspects. The feature is that the program is stored.

According to a twenty-third aspect of the present invention, a computer-readable recording medium for causing a computer to execute each procedure included in the information encoding method according to any one of the eleventh to twentieth aspects. The feature is that the program is stored.

[0038]

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

FIG. 1 is a block diagram showing the configuration of an information encoding device according to the present invention. As shown in FIG. 1, an information encoding apparatus according to the present invention includes an MPEG2 encoder 101,
It comprises a data buffer 102, a header detector 104, and a header counter 105. In the following description,
As in the case of the conventional example, video (image) compressed data will be described as an example of variable-length encoded data.

The MPEG2 encoder 101 converts video (image) and / or audio signals into MPEG2 (IS013)
Digital compression is performed based on the compression coding standard of 818). The data buffer 102 is an MPEG2 encoder 1
01, variable-length encoded data (hereinafter also simply referred to as ES), which is digital compressed data, and a slice header (including a synchronization code at the beginning of a slice layer) included in variable-length encoded data (ES) ) And temporary storage means for keeping the variable-length encoded data (ES) at a fixed rate. The header detector 104 detects a slice header in the variable length coded data (ES). The header counter 105 counts the number of slice flags stored in the data buffer 102, controls the amount of variable-length encoded data (ES) output from the MPEG2 encoder 101, and Is controlled so that the number of slice headers stored in the.

Next, the operation of the information encoding apparatus of the present invention will be described. In MPEG2, in order to compress information of one color screen, the screen is divided into slices, which are one unit of encoding according to the MPEG2 standard. A slice is composed of an arbitrary number of macroblocks, and the first and last macroblocks of the slice are divided and arranged so that they are located in the same horizontal row of macroblocks, that is, one slice does not extend between rows. . In the present embodiment, description will be made on the assumption that encoding is performed so that all slices are composed of substantially the same number of macroblocks. Note that the encoding unit is not limited to slices.

In FIG. 1, an MPEG2 encoder 10
1 generates an ES conforming to the MPEG2 standard and supplies the ES to the data buffer 102 and the header detector 104.
As described above, since the ES is a burst (discontinuous) signal, the MPEG2 encoder 101
When the variable length coded data (ES) output from the encoder 101 is valid, that is, when the variable length coded data is being output, the write signal WS is supplied to the data buffer 102.

The data buffer 102 supplied with the write signal WS sequentially writes ES (variable length coded data) in the buffer in slice units based on the write signal WS.

On the other hand, the header detector 104
The slice header in the ES output from the encoder 101 is detected, and a header flag WF is output to the header counter 105. The header flag WF is a 1-bit signal that becomes active (eg, high level) when a header is detected.

Reading of the ES (variable length coded data) and the header flag WF from the data buffer 102 is performed by a read signal RS of a constant rate supplied from an external device (not shown). The ES (variable-length coded data) read from the data buffer 102 is transmitted, for example, via a not-shown I / F circuit or the like at the subsequent stage or a transmission medium.
The data is supplied to a device (not shown) (such as an image decoding device) capable of processing variable-length encoded data conforming to the MPEG2 standard. The header flag RF read out together with the ES (variable length encoded data) is supplied to the header counter 105.

In the header counter 105, when the header flag WF becomes active (for example, high level),
Increment the counter value. That is, the slice detector is detected by the header detector 104, and ES (variable length coded data) is stored in the data buffer 102 in slice units.
Is written, the counter value in the header counter 105 is counted up. Similarly, when the header flag RF becomes active (eg, high level), the header counter 105 decrements the counter value.
That is, every time the header flag is read from the data buffer 102, the counter value in the header counter 105 is counted down. As described above, based on the counter value in the header counter 105, the data buffer 10
2, the number of slice headers, that is, the buffer occupancy SHN, is detected.

The buffer occupancy SHN detected by the header counter 105 is supplied to the MPEG2 encoder 101. In the MPEG2 encoder 101, the number of slice headers existing in the data buffer 102 becomes a predetermined value based on the supplied buffer occupancy SHN so that the data buffer 102 does not overflow or underflow. In this way, the amount of generated variable-length encoded data is controlled. The control of the data generation amount is performed, for example, by changing the quantization step in the quantization.

As described above, according to the information encoding apparatus of the present invention, the burst ES data supplied to the data buffer 102 is transmitted through the data buffer 102,
The number of slices output as ES data having a fixed data transmission rate and existing in the data buffer 102 can be kept constant.

Further, the buffer occupancy of the data buffer 102 is determined based on the number of slice headers, that is, based on the image area. Even when the encoding bit rate or the encoding mode is changed, the buffer occupancy is present in the data buffer 102. Since the number of slices is kept constant, the delay amount at the image level in the data buffer 102 is kept constant (for example, one frame or one field (one screen)).
Can be kept constant).

The present invention described above may be applied to a system including a plurality of devices or to an apparatus including a single device. Further, a software program for realizing the functions of the above-described embodiments is provided to an apparatus connected to the various devices or a computer in the system so as to operate various devices for realizing the functions of the above-described embodiments. The present invention also includes a case in which the above-described various devices are supplied and operated according to a program stored in a computer (CPU or MPU) of the system or the apparatus.

In this case, the software program code itself implements the functions of the above-described embodiment, and the program code itself and means for supplying the program code to the computer are provided.
For example, a recording medium storing such a program code constitutes the present invention. As a recording medium for storing such a program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM,
A magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the supplied program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) or other operating system running on the computer. Needless to say, even when the functions of the above-described embodiments are realized in cooperation with application software and the like, such program codes are included in the embodiments of the present invention.

Further, after the supplied program code is stored in the memory provided on the function expansion board of the computer or the function expansion unit connected to the computer, the function expansion board or the function expansion unit is specified based on the instruction of the program code. It is needless to say that the present invention also includes a case where the CPU or the like provided in the first embodiment performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

It should be noted that the shapes and structures of the respective parts shown in the above embodiment are merely examples of the embodiment for carrying out the present invention, and the technical scope of the present invention is limited thereby. It must not be interpreted in a way. That is, the present invention can be embodied in various forms without departing from its spirit or its main features. For example, instead of the MPEG2 encoder, H.264 is used as information compression means. For example, a H.261 encoder or an MPEG1 encoder may be used.

[0055]

As described above, according to the present invention,
Since the occupation amount of the data buffer is determined based on the number of slice headers, that is, the image area basis, the time delay amount in the data buffer can be kept constant even if the encoding bit rate or the encoding parameter is changed. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an information encoding device according to the present invention.

FIG. 2 is a block diagram illustrating an example of a conventional information encoding device.

[Explanation of symbols]

 101 MPEG2 encoder (information compression means) 102 data buffer (buffer means) 104 header detector (header detection means) 105 header counter (header counter means) ES elementary stream WF header flag (for count up) RF header flag (for count down) ) WS write signal RS read signal SHN buffer occupancy

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C059 KK21 KK35 MC31 SS20 TA16 TA60 TB04 TC18 TC20 TD11 UA02 UA32 5C078 BA21 CA00 CA02 CA35 DA01 DA07 DB07 5J064 AA00 BA09 BB10 BB12 BC02 BC05 BC24 BD03 BD04 9A001 EE27H15

Claims (23)

[Claims] An encoding unit configured to compress and encode information data in a predetermined data unit; a storage unit configured to store the information data encoded by the encoding unit; and the predetermined data unit stored in the storage unit. An information encoding apparatus, comprising: a detection unit that detects the number of data items; and a control unit that controls an encoding parameter that controls a compression ratio in the encoding unit in accordance with a detection result of the detection unit. 2. The information data is image data, and the image data stored in the storage means is such that image data for each screen is read from the storage means at a predetermined time. The information encoding device according to claim 1, wherein: 3. The encoding device according to claim 1, wherein the encoding unit performs encoding in accordance with the MPEG2 standard.
An information encoding device according to claim 1. 4. The information encoding apparatus according to claim 3, wherein the predetermined data unit is one slice. 5. The information encoding apparatus according to claim 4, wherein said encoding means outputs header information indicating the start of one slice, and said detecting means detects the number of said header information. . 6. An information compression means for digitally compressing data information to generate variable-length coded data, a predetermined data block in the variable-length coded data generated by said information compression means, and header information thereof. Header detecting means for detecting the header information, buffer means for storing the header information detected by the header detecting means, and the variable length coded data generated by the information compressing means, and header information stored in the buffer means. A number is detected, and based on the number of the detected header information,
An information encoding device, comprising: header counting means for controlling an amount of variable-length encoded data generated by the information compression means. 7. The information encoding apparatus according to claim 6, wherein said information compression means digitally compresses said data information based on a compression encoding standard of MPEG2. 8. The information encoding apparatus according to claim 7, wherein the data information is an image and / or an audio signal. 9. The information encoding apparatus according to claim 7, wherein said header detecting means detects a slice header in the variable length encoded data. 10. The header counting unit according to claim 1, wherein the number of slice headers is a predetermined value based on the number of slice headers stored in the buffer unit.
10. The information encoding apparatus according to claim 9, wherein an amount of generation of variable length encoded data in said information compression means is controlled. 11. An encoding procedure for compressing and encoding information data in a predetermined data unit; a storage procedure for storing information data encoded by the encoding procedure in a storage unit; An information code, comprising: a detection procedure for detecting the number of data in a predetermined data unit; and a control procedure for controlling an encoding parameter for controlling a compression ratio in the encoding procedure according to a detection result of the detection procedure. Method. 12. The information data is image data,
12. The information encoding apparatus according to claim 11, wherein the image data stored in the storage unit is obtained by reading out image data for each screen from the storage unit at a predetermined time. Method. 13. The information encoding method according to claim 11, wherein the encoding unit performs encoding in accordance with the MPEG2 standard. 14. The information encoding method according to claim 13, wherein the predetermined data unit is one slice. 15. The information encoding method according to claim 14, wherein said encoding step outputs header information indicating the start of one slice, and said detecting step detects the number of said header information. . 16. An information compression procedure for digitally compressing data information to generate variable length encoded data, a predetermined data block in the variable length encoded data generated by the information compression procedure, and header information thereof. A header detection procedure for detecting the header information, a header information detected by the header detection procedure, and a variable length coded data generated by the information compression procedure are stored in a buffer means; and a header stored in the buffer means. While detecting the number of information, based on the number of the detected header information,
A header count procedure for controlling the amount of variable-length encoded data generated by the information compression procedure. 17. The information encoding method according to claim 16, wherein in the information compression procedure, the data information is digitally compressed based on an MPEG2 compression encoding standard. 18. The information encoding method according to claim 17, wherein the data information is an image and / or an audio signal. 19. The information encoding method according to claim 17, wherein said header detection step detects a slice header in variable-length encoded data. 20. The header counting procedure, wherein the number of slice headers becomes a predetermined value based on the number of slice headers stored in the buffer means.
20. The information encoding method according to claim 19, wherein an amount of generation of variable-length encoded data in the information compression procedure is controlled. 21. The information encoding device according to claim 1, an information decoding device decoding variable length encoded data supplied from the information encoding device, and the information code. An information encoding system comprising: an encoding device; and communication means for connecting the information decoding device. 22. A computer according to claim 1, wherein
A computer-readable recording medium storing a program for causing the information encoding apparatus to function as each unit included in the information encoding device according to any one of the above. 23. The computer according to claim 11, wherein
0. A computer-readable recording medium storing a program for executing each procedure included in the information encoding method according to any one of 0.