JP3263582B2 - Encoding / decoding 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 method for transmitting data between a transmitting side and a receiving side when a variety of encoding / decoding tools exist in an algorithm, such as a next-generation image encoding method (MPEG4, etc.). The present invention relates to an encoding / decoding technique for performing communication between encoding / decoding apparatuses having different capacities, and particularly to an encoding / decoding that enables simultaneous transmission of tool information and encoded information in a hierarchical encoding / decoding tool. The present invention relates to a gasifier.

[0002]

2. Description of the Related Art In recent years, ISDN (Integrated Services Di
As a new communication service, an image communication service has been realized with the spread of a gital network (service digital network). Examples are a videophone and a video conference system. Also, with the development of wireless transmission networks represented by PHS and FPLMTS, demands for further advancement, diversification, and portability of services are rapidly increasing. In general, when transmitting image information as in a videophone or a video conference system, the amount of image information is enormous, whereas the amount of information of the image to be transmitted is reduced in view of the line speed and cost of the line used for transmission. It is necessary to perform compression encoding and transmission with a reduced amount of information.

As a coding method for compressing image information, JPEG (Joint Photographic) is used as a still image coding method.
Coding Experts Group). 261, MPEG1 as a moving picture coding method for storage
(Moving Picture Coding Expert Group 1), MPE
G2 has already been internationally standardized. Further 64 kbp
MPE as an encoding method at an extremely low bit rate
G4 standardization activities are underway. In MPEG4,
In order to be able to flexibly cope with a wide variety of applications and to perform encoding in an optimal manner for each application, existing JPEG, H.264, and JPEG formats are used. 261, MPEG1, MP
Rather than a method of performing encoding according to an algorithm like the EG2 encoding method, a number of encoder tools (transformers, quantizers, inverse transformers, inverse quantizers, etc.) are prepared, and their appropriate It is necessary that the encoding be performed by a combination. In recent years, the above-mentioned JPEG and MPEG1 tools have been downloaded via personal computer communication, etc.
Since it is possible to receive and decode an image, it is easily presumed that in the future video communication, communication will be performed by downloading each of the decoding and encoding tools.

[0004] FIG. FIG. 4B shows a data string of encoded output information encoded by an encoding method with a flexible algorithm. In the case of FIG. 4B, since the combination of each tool of the encoder can be freely selected, it is necessary to transmit information on which tool is used to perform the encoding together with the encoded output information. is there. In this figure, a motion compensation tool A101, an inverse transformation tool B103, a motion compensation tool C105, and an inverse transformation tool D1
07, the quantization tool E 109 is tool information followed by motion vector information 102, transform coefficient 104, motion vector information 106, transform coefficient 108, quantization step 110
Is the processed data. Considering the configuration for implementing these encoding algorithms, a method that implements by implementing dedicated hardware and software,
A method that can be realized by executing appropriate software on a general-purpose arithmetic unit is considered.

FIG. 26 is a block diagram of an encoder according to H.261, where 111 is an encoding control unit that performs encoding control;
Reference numeral 112 denotes a conversion unit that performs DCT conversion, and 113 denotes a conversion unit 11.
2, a quantization unit that quantizes the coefficient transformed in 2, an inverse quantization unit that performs inverse quantization of the coefficient quantized by the quantization unit 113, and an inverse transformation unit that performs inverse DCT transform. . Reference numeral 116 denotes a memory having a variable delay function for motion compensation used for motion compensation inter-frame prediction.
Is an in-loop filter that can be turned on / off for each macroblock. When this algorithm is implemented by dedicated hardware and software, the encoding control unit 111, the conversion unit 112, the quantization unit 113, the inverse quantization unit 114, the inverse transformation unit 115, and the motion compensation delay function, which are tools, are used. The memory 116 and the loop filter 117 are provided by dedicated hardware and software, respectively.

[0006] H. H.261 is included in the encoder, and FIG. 2 shows a H.261 decoder. The decoder includes an inverse quantization unit 114, an inverse transformation unit 115, a memory 116 (having a variable delay function for motion compensation), and an in-loop filter 117. The encoded data is supplied to the inverse quantization unit 114
Are inversely quantized, and are inversely DCT transformed and decoded by the inverse transform unit 115. (Memory 116 and in-loop filter 1
Reference numeral 17 is used when decoding motion compensation prediction encoded data. ) JPEG, H .; In order to process several types of algorithms by a method of performing encoding using a fixed algorithm such as H.261, MPEG1, and MPEG2, hardware and software for realizing each algorithm are required. With one terminal, for example, 261, the moving image
When a still image is encoded by PEG, the configuration is as shown in FIG. In FIG. 261 encoder, 121 is J
PEG encoder.

Similarly, when the flexible encoding algorithm shown in FIG. 4B is realized by dedicated hardware and software, 261, a transform unit, a quantization unit,
There are several types of tools for the inverse quantization unit and the inverse transformation unit, and the portion 118 in FIG. 5 has the configuration shown in FIG. As for the configuration of the decoder, the portion 119 in FIG. 6 has the configuration 122 in FIG. The operation includes a motion compensation tool A101, an inverse transformation tool B103, and a motion compensation tool C shown in FIG.
105, inverse transformation tool D107, quantization tool E109
Are transmitted to the control unit 120, and the subsequent data, that is, the motion vector information 102, the transform coefficient 104, the motion vector information 106, and the transform coefficient 108 are transmitted to the respective tools. The control unit 123 controls selection of which tool to use from each tool information,
Each data is processed and decoded by the tool selected by the control unit 123.

Next, the case of decoding FIG. 4B by a general-purpose operation processing unit and a compiler will be described with reference to FIG. FIG.
The motion compensation tool A101 and the inverse conversion tool B shown in FIG.
103, motion compensation tool C105, conversion tool D10
7. The tool information such as the quantization tool E109 is transmitted to the compiler 125, and the subsequent data, ie, the motion vector information 102, the conversion coefficient 104, the motion vector information 106, the conversion coefficient 108, and the quantization It is transmitted to the unit processing unit 124. Compiler 125
Generates a processing program for the general-purpose operation processing unit 124, and transmits the next transmitted data to the general-purpose operation processing unit 12.
4 and the data is decoded.

[0009]

The coding / decoding device of the above-mentioned conventional system can communicate only with a limited coding / decoding algorithm. However, in a case where a variety of applications can be flexibly supported and encoding is performed in an optimal method for each application, as in a next-generation image encoding method (MPEG4 or the like), J
PEG, H.P. In order to perform processing of several types of algorithms in a method of performing encoding using a fixed algorithm such as H.261, MPEG1, or MPEG2, hardware / software for realizing each algorithm is required. In this way, it is thought that it is sufficient to have all the various algorithms on both the transmitting side and the receiving side.However, if tools for all the algorithms are available, a huge amount of hardware and software will be required, resulting in cost reduction. It is thought that the device must be large. Then, it is more likely that a device that does not have the same capability will be unable to communicate if the cost is reduced or the device is reduced in size.

[0010] In addition, encoding / decoding systems that do not have the above-mentioned capabilities are also required.
It is conceivable that the decoding device downloads a tool that configures an algorithm on the receiving side and enables decoding by flexibly corresponding to various applications, but the tool that configures this algorithm is downloaded and used last time. In an encoding / decoding device capable of storing the encoded tool, if the saved tool is not the requested tool at the next communication, the tool must be downloaded again prior to transmitting the encoded information. Therefore, the transmission start delay before decoding the encoded information becomes large.

[0011] In the encoding / decoding device capable of storing the previously used tool, a higher quality tool is used as a lower layer tool, and a tool having a minimum quality that cannot be compensated by another tool. Is used as an upper layer, and encoding / decoding tools for providing upper compatibility are hierarchized, even between encoding / decoding apparatuses having different capabilities.
Decoding with the minimum number of tools is possible, and transmission start delay due to download of tool information is eliminated, but decoding with the required quality cannot be performed. Even in this case, when trying to decode with a tool of the required quality, it is necessary to download the tool with the required quality in advance, and as in the case where the tool is not hierarchized, the transmission until the encoded information is decoded is performed. The start delay is large and the layered features of the tool are lost. The present invention has been made in view of the above-described problems, and provides an encoding / decoding device that solves these problems.

[0012]

According to the present invention, in order to solve the above-mentioned problems, according to the first aspect of the present invention, before transmitting encoded information from an encoding apparatus to a decoding apparatus, the information is transmitted. Transmit a tool that constitutes an algorithm that is a means for decoding, reconfigure the tool as an algorithm on the decoding device side, decode the received encoded information using it, and then save the tool, When coded information received by the same tool is received again, decoding is performed using the tool that has already been stored, and it is at least possible to use a higher-level tool instead of a tool in a certain layer. In the encoding / decoding device in which the tools are defined hierarchically so that the maximum quality can be guaranteed, there is a decoding tool required by the transmission side for the reception side decoding device in the transmission side encoding device. If there is for transmitting decryption tool information and the encoded information simultaneously. Further, in the invention according to claim 2, when the decoding device on the transmitting side does not have the decoding tool requested by the transmitting side in the encoding device on the transmitting side, the encoding tool corresponding to the decoding tool existing on the receiving side Then, the encoding is temporarily changed to perform encoding. Further, in the invention according to claim 3, when there is no decoding tool required by the encoding device on the transmitting side in the decoding device on the receiving side, the quality temporarily decreases, but the decoding is performed by an upper-level tool capable of decoding. Instead, while decoding the encoded information, the decoding tool information sent from the transmitting side is downloaded at the same time to construct a request decoding tool. Further, in the invention according to claim 4, after the construction of the request decoding tool is completed, the decoding by the request decoding tool is started.

In the encoding / decoding device, the transmitting side or the receiving side uses a tool whose quality is lower than the request but which can be substituted, even if the receiving side does not have a tool of the required quality at the time of the first communication. To start encoding or decoding, and the transmitting side transmits the requested tool to the receiving side simultaneously with the encoded information. The receiving side downloads the request tool and prepares it while decoding the encoded information using a tool whose quality is lower than that of the request but can substitute it. Start high-quality image communication.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. For explanation, an inter-frame prediction encoding / decoding method which is a specific hierarchical encoding / decoding tool is taken as an example, and a 1-pixel sampling method, a 1 / 2-pixel sampling method, A description will be given as a 4-pixel unit sampling method. FIG. 1 shows an example of a system configuration according to an embodiment of the present invention.
Is an encoding / decoding device, and 3 is a communication network. The encoding / decoding device 1 includes a video input unit 11, a switch 12, a conversion unit 13, a quantization unit 14, an inter-frame prediction encoding unit 15, a transmission unit 16, a tool information transmission / reception unit 17, a tool information and download control unit. Encoding / decoding device 2
Is a video output unit 21, a switch 22, an inverse transformation unit 23, an inverse quantization unit 24, an inter-frame prediction decoding unit 25, and a reception unit 2.
6, a tool information transmitting / receiving unit 27, a tool information and download control unit 28.

Hereinafter, a case will be described where an input video is transmitted from the encoding / decoding device 1, received by the encoding / decoding device 2 via the communication network 3, and then output. A flowchart of the encoding / decoding device 1 at this time is shown in FIG. 2, and a flowchart of the encoding / decoding device 2 is shown in FIG. In the encoding / decoding device 1, the video input unit 1
When a video is input to 1, an encoding is performed by a conversion unit 13, a quantization unit 14, and an inter-frame prediction encoding unit 15 equipped with several tools. Each tool is previously hierarchized, and a tool that can be substituted by another tool is defined as a lower layer tool, and a minimum tool that cannot be supplemented by another tool is defined as an upper layer. In the present invention, as shown in FIG.
For convenience, the tool A, tool B, and tool C are arranged from the upper side to the lower side. In this example, as shown in FIG. 1, attention is paid to the inter-frame prediction coding, and from the upper side to the lower side, the inter-frame prediction coding by sampling of one pixel unit (tool A), the half-pixel unit , And inter-frame prediction coding (tool C) by sampling in quarter-pixel units. For this reason, according to the quality of the encoded video data transmitted by the encoding / decoding device 1, each tool of the conversion unit 13, the quantization unit 14, and the inter-frame prediction encoding unit 15
Determined through switch 12. In the case of this example, the higher quality is inter-frame predictive coding by sampling in 1/4 pixel units, and the lower quality is inter-frame predictive coding by sampling in 1 pixel units.

According to the present embodiment, the input video is selected by the switch 12 to select each tool C, which is a high-quality tool. In particular, in the inter-frame coding system, the input video is coded by sampling in quarter-pixel units. , To the communication network 3. Then, the encoded information is transmitted to the communication network 3 by the encoding / decoding device 2.
More to receive. At this time, the encoding / decoding device 1 knows the state of the encoding / decoding device 2 by the tool information transmitting / receiving unit 17 on the transmitting side and the tool information transmitting / receiving unit 27 on the receiving side.
Necessary tool information is constructed by the tool information and download control unit 18, and encoded information is simultaneously transmitted from the tool information transmitting / receiving unit 17 and the transmitting unit 16. At this point, it is conceivable that the encoding / decoding device 1 can temporarily change its own tool and transmit the encoded information until the preparation of the tool of the encoding / decoding device 2 is completed.
As a result, the processing on the transmission side is lighter than the processing using a high-quality tool requested, and the processing on the reception side is deliberately processing high-quality encoded information. Then, since there is no need to obtain low-quality encoded information, the load on both devices is reduced. In this example, encoding is temporarily performed by a sampling tool for each pixel in inter-frame prediction encoding.

In this example, the inverse transform unit 23 and the inverse quantizer 24 of the encoding / decoding device 2 on the receiving side in FIG.
There is a required decryption tool, Tool C,
The inter-frame prediction decoding unit 25 has a required tool
There is no 1/4 pixel sampling. For this reason,
As shown in the flowchart of FIG.
The decoding device 1 transmits the tool information at the same time as either the coded information whose quality has been reduced by changing the tool to be coded or the coded information of the same quality. Also, as shown in FIG. 3, the encoding / decoding device 2 on the receiving side
Although the quality of the request is lower than that of the request because there is no tool of the request, the tool information is decoded by the upper tool, and the tool information of the request is received by the tool information transmitting / receiving unit 27 at the same time. Build tools. In this way, as soon as the requested tool is ready, the higher level tool can be switched to the requested tool by the switch 22 to decode the coded information of the requested quality.
1 outputs an image. In the case of this example, the coded information coded by the inter-frame predictive coding by sampling in 1/4 pixel units is temporarily decoded by the inter-frame predictive decoding by sampling in 1 pixel units, and 1 / A tool for inter-frame prediction decoding by sampling in units of four pixels is downloaded, and as soon as the tool is completed, decoding is performed by inter-frame prediction decoding by sampling in units of quarter pixels.

As described above, the present invention is (1) means for decoding coded information when transmitting the coded information, if the receiving side confirms a decodable tool at the receiving side, but the quality is degraded. This is a tool for simultaneously transmitting a request tool constituting an algorithm and encoded information. (2) On the transmitting side, the above-mentioned encoded information, which is degraded in quality but adapted to a decodable tool, is temporarily transmitted simultaneously with the tool information. Further, (3) the receiving side downloads the necessary tools at the same time while decoding with a degradable tool while the quality is degraded, and (4) the receiving side prepares the requested tool, It decodes the encoded information of the required quality.

[0019]

[Effect of the Invention] Next-generation image coding method (MPEG4 etc.)
When there is a wide variety of encoding / decoding tools in the algorithm as in the above, the encoding / decoding tool which is reduced in quality but is substituted by another tool is a higher quality lower layer tool, and another The minimum tools that cannot be complemented by the tools are defined hierarchically so as to have upward compatibility with the upper layer, and this tool information is downloaded. According to the present invention, such encoding In the case where the decoding device requested by the transmitting side does not exist in the decoding device on the receiving side in the decoding device, the decoding tool information and the encoded information are transmitted simultaneously from the encoding device on the transmitting side. When only the tool information is sent and downloaded, and only the tool information is downloaded compared to the one that is decrypted based on the downloaded decryption tool after downloading it It can be omitted, thus, it is possible to increase the transmission start time of the encoded information.

If the decoding device on the receiving side does not have a decoding tool requested by the transmitting side in the decoding device on the receiving side, the coding method is temporarily changed on the transmitting side by an encoding tool corresponding to the decoding tool present on the receiving side. Therefore, although the quality temporarily decreases, the delay of the decoding start time can be reduced.

If the decoding device on the receiving side does not have a decoding tool required by the encoding device on the transmitting side, the quality temporarily deteriorates, but the higher-order decoding-capable tool is used instead. While decoding the information, the decoding tool information sent from the transmitting side is downloaded at the same time and the decoding tool for the request is constructed, so that the tools in the upper layer can be used early, and the quality temporarily decreases. But,
The delay of the decoding start time can be reduced.

Further, after the construction of the request decryption tool is completed, the decryption by the request decryption tool is started, so that the quality is guaranteed after the construction of the request decryption tool is completed.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing an embodiment of an encoding / decoding device according to the present invention.

FIG. 2 is a flowchart on the transmission side showing an embodiment of the encoding / decoding device according to the present invention.

FIG. 3 is a flowchart on the receiving side showing one embodiment of the encoding / decoding device according to the present invention.

FIG. 4 is a configuration diagram showing a data string of conventional encoded output information.

FIG. 261 is a block diagram of the 261 encoder. FIG.

FIG. FIG. 26 is a block diagram of a H.261 decoder.

FIG. 7 is a configuration diagram of an encoder having a plurality of algorithms.

FIG. 8 is a configuration diagram in a case where a decoding device that decodes encoded output information by a flexible encoding algorithm is realized using dedicated hardware and software.

FIG. 9 is a configuration diagram of a case where a decoding device that decodes encoded output information by a flexible encoding algorithm is realized using a general-purpose operation processing unit and a compiler.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 encoding / decoding device 11 video input unit 12 switch 13 conversion unit 14 quantization unit 15 inter-frame prediction encoding unit 16 transmission unit 17 tool information transmission / reception unit 18 tool information and download control unit 2 encoding / decoding device 21 Video output unit 22 Switch 23 Inverse change unit 24 Inverse quantization unit 25 Interframe predictive decoding unit 26 Receiving unit 27 Tool information transmitting / receiving unit 28 Tool information and download control unit 3 Communication network

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H03M 7/48

Claims (4)

(57) [Claims] Before transmitting encoded information from an encoding device to a decoding device, a tool that constitutes an algorithm as a means for decoding the information is transmitted, and the decoding device uses the tool as an algorithm. Reconstruct, use it to decode the received coded information, then save the tool, and if you receive coded information encoded with the same tool again, use the saved tool In an encoding / decoding device in which tools are defined in a hierarchical manner, a tool is hierarchically defined so that a minimum level of quality can be guaranteed even if a higher-level tool is used instead of a certain level of tool. In the encoding device on the transmitting side, if the decoding device on the receiving side does not have a decoding tool requested by the transmitting side, encoding is characterized by simultaneously transmitting decoding tool information and encoded information. Decoder. 2. In a coding apparatus on the transmitting side, when a decoding tool requested by the transmitting side does not exist in the decoding apparatus on the receiving side, a coding tool corresponding to the decoding tool present on the receiving side temporarily stores the decoding tool. 2. The encoding / decoding device according to claim 1, wherein encoding is performed by changing an encoding method. 3. If the decoding device on the receiving side does not have a decoding tool required by the encoding device on the transmitting side, the quality temporarily drops, but the code is replaced by a higher-order decoding-capable tool. 2. The encoding / decoding apparatus according to claim 1, wherein the decoding tool information sent from the transmitting side is downloaded at the same time as the decoding information is decoded, and the decoding tool requested is constructed. 4. The encoding / decoding apparatus according to claim 3, wherein after the construction of the request decoding tool is completed, decoding by the request decoding tool is started.