JP3258217B2 - Encoding / decoding method and apparatus therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method and apparatus for encoding (compressing) / decoding (expanding) image data and the like, and more particularly, to processing between an encoding tool and a decoding tool. The present invention relates to an encoding / decoding method and apparatus capable of communicating even if the capabilities do not match.

[0002]

2. Description of the Related Art In recent years, ISDN (Integrated Services)
With the spread of Digital Network (Service Integrated Digital Network), image communication services have been realized as new communication services. 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,
In the case of transmitting image information, such as a videophone or video conference system, the amount of image information is enormous, but in terms of the line speed and cost of the line used for transmission,
It is necessary to compress and encode the information amount of an image to be transmitted and to reduce the amount of information for transmission.

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), MPEG2
Has already been internationally standardized. Further, MPEG4 is used as an encoding method at an extremely low bit rate of 64 kbps or less.
Standardization activities are underway. According to 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. FIG. FIG. 2 is a conceptual diagram illustrating the structure of a data string of encoded information obtained by encoding (compressing) image data in accordance with H.261. Each piece of coded information data (unsigned) such as motion vector information, DCT coefficients, and quantization steps shown in FIG. 3A is an image coded (compressed) based on a coding algorithm fixed in the coder. Information data, the decoder comprises a fixed decoding algorithm corresponding to this encoding algorithm,
The received encoded information data is decoded.

FIG. 6B is a conceptual diagram showing the structure of a data string of coded information obtained by coding (compressing) image data using a flexible coding method using an algorithm such as MPEG4. The data sequence of the coded information shown in FIG. 3B includes the coded (compressed) image information data such as the motion vector information 2, the variable coefficient 4, the motion vector information 6, the transform coefficient 8, the quantization step 10, and the like. , And tool information such as a motion compensation tool 1, an inverse transformation tool 3, a motion compensation tool 5, an inverse transformation tool 7, and a quantization tool 9 for decoding each of the image information data. In this case, each piece of tool information such as the motion compensation tool 1 can be selected from a plurality of types of tool information, and a combination of each piece of tool information can be freely selected. For this reason, the encoder transmits tool information used for encoding together with the image information data to the decoder, and the decoder decodes the tool information transmitted from the encoder when decoding the received image information data. It decodes the image information data encoded using the information.

As a method of implementing these encoding / decoding processes, a method of implementing dedicated hardware and software, and a method of executing appropriate software using a general-purpose arithmetic unit and a compiler. There is a way. First, a method of implementing the encoding process by mounting dedicated hardware and software will be described. FIG. FIG. 7 is a block diagram illustrating a configuration of an encoder that generates encoded information data illustrated in FIG. 7, an encoder includes an encoding control unit 11 for performing encoding control, a transforming unit 12 for performing DCT transform, and a quantizing unit 1 for quantizing coefficients transformed by the transforming unit 12.
3. It includes an inverse quantization unit 14 for performing inverse quantization of the coefficient quantized by the quantization unit 13, an inverse transformation unit 15 for performing inverse DCT transform, a memory 16, and a filter 17 in a loop.
Note that the memory 16 is a memory having a variable delay function for motion compensation used in motion-compensated inter-frame prediction, and the filter 17 is a filter in a loop that can be turned on / off for each macroblock.

When the encoding algorithm for generating the encoded information data shown in FIG. 6A is realized by dedicated hardware and software, the function of each tool constituting the algorithm is based on the encoding control shown in FIG. Unit 11, transformation unit 12, quantization unit 13, inverse quantization unit 14, inverse transformation unit 1
5. This is realized by dedicated hardware and software for the memory 16 having the motion compensation delay function and the loop filter 17, respectively. FIG. 261 is a block diagram illustrating a configuration of a decoder that decodes encoded information data encoded according to H.261. This decoder is configured so as to share the components constituting the encoder shown in FIG. 7, and the same components as those constituting the encoder shown in FIG. . That is, in FIG.
4 is an inverse quantization unit, 15 is an inverse transformation unit, 16 is a memory having a variable delay function for motion compensation, and 17 is a filter in a loop. The encoded information data encoded by the encoder shown in FIG. 7 is inversely quantized by the inverse quantization unit 14,
In step 5, it is inverse DCT transformed and decoded. The memory 16
The in-loop filter 17 is used when decoding motion-compensated prediction encoded data.

As described above, H. In the case where several types of algorithms are processed using a method of performing encoding using a fixed algorithm such as H.261, hardware and software for realizing each algorithm are individually required. FIG. FIG. 1 is a block diagram illustrating a structure of an encoder that encodes a still image according to JPEG according to H.261. For example, with one terminal, a moving image is stored in H.264. In the case of encoding according to H.261 and encoding a still image according to JPEG, the encoder has a configuration as shown in FIG. Thus, both the H.261 encoder 20 and the JPEG encoder 21 are provided independently. In FIG.
H. The H.261 encoder 20 and the JPEG encoder 21 receive moving image data and still image data, respectively, and output encoded information data that is compressed data.

When the algorithm for generating the encoded information data shown in FIG. 6B is realized by dedicated hardware and software, the encoder for realizing this algorithm is a circuit block of the encoder shown in FIG. 18 is realized by the configuration shown in FIG. That is, in this case, the encoder includes the conversion unit 12 and the quantization unit 1
3, each of the inverse quantization unit 14 and the inverse transformation unit 15 has a plurality of tools.
0, converter tools AX, quantizer tools AX,
The necessary tools are selected from the inverse quantizer tools A to X and the inverse transformer tools A to X) to perform the encoding process.

A decoder for decoding the encoded information data shown in FIG. 6B is realized by replacing the circuit block 19 constituting the decoder shown in FIG. 8 with the structure of a circuit block 22 shown in FIG. Is done. That is, in this case, the decoder has a plurality of types of tools of the inverse quantization unit 14 and the inverse transform unit 15, respectively, and each of the tools (the inverse quantizer tools A to X shown in FIG. A necessary tool is selected from the tools AX to perform the decoding process. In this decoding process, each tool information of the motion compensation tool 1, the inverse transform tool 3, the motion compensation tool 5, the inverse transform tool 7, and the quantization tool 9 shown in FIG. 6B is transmitted to the control unit 23. The image information data of the motion vector information 2, the conversion coefficient 4, the motion vector information 6, and the conversion coefficient 8 following the respective tool information are transmitted to the respective tools for processing the respective image information data.
At this time, the control unit 23 selects which tool (the inverse quantizer tools A to X and the inverse transformer tools A to X shown in FIG. 10) to use from the respective tool information, and Is processed and decoded by the tool selected by the control unit 23.

Next, a description will be given of a method of implementing a decoding process by executing appropriate software using a general-purpose arithmetic unit and a compiler. Hereinafter, the case of decoding the encoded information data having the structure shown in FIG. 6B will be described with reference to FIG. FIG. 11 is a block diagram illustrating a structure of a decoder including the general-purpose operation processing unit 24 and the compiler 25. The tool information of the motion compensation tool 1, the inverse transformation tool 3, the motion compensation tool 5, the transformation tool 7, the quantization tool 9 and the like shown in FIG.
5, the compiler 25 includes a general-purpose arithmetic processing unit 24
Generates a processing program for controlling the operation of. Also, motion vector information 2 following these tool information,
The image information data of the transform coefficient 4, the motion vector information 6, the transform coefficient 8, and the quantization step 10 are stored in the general-purpose arithmetic processing unit 2
4 given. Then, in accordance with the processing program generated by the compiler 25, the general-purpose operation processing unit 24
Processes the encoded image information data following the tool information, decodes the image information data, and generates decoded data.

[0011]

By the way, when encoding a video signal or the like, an encoding tool having an appropriate encoding processing capability is selected according to the quality of a reproduced image required on the decoding side. Encoding is performed. When decoding the encoded data obtained by this, it is necessary to use a decoding tool having a decoding processing capability corresponding to the encoding processing capability of the encoding tool used for encoding on the decoding side. . For this reason, when the processing capabilities of these tools are not compatible, there is a problem that encoded data cannot be decoded and communication becomes impossible.

In the following, the effect on communication when the respective processing capabilities of the inter-frame prediction coding tool and the inter-frame prediction decoding tool do not correspond will be described in detail by taking the inter-frame prediction coding algorithm as an example. I do. Inter-frame predictive encoding, for the purpose of improving the image display quality on the decoding side, based on pixel data directly obtained by sampling the video signal on the encoding side,
This is an image data processing technique for predicting and interpolating each pixel data of a display pixel on the decoding side which is divided more finely than a sampling pixel on the encoding side.

FIGS. 12A to 12C are conceptual diagrams for explaining the principle of inter-frame predictive coding. 1A, 1B, and 1C show a pixel unit and a half, respectively, based on image data A to D directly obtained by encoding a video signal input from a visual sensor such as a camera. Pixel data (a _{1 to} d ₁ ,...) Obtained using an inter-frame predictive encoding tool of pixel unit, quarter pixel unit sampling
It represents the sequence of _{a 2 ~i 2, a 4 ~y} 4). This pixel data is transmitted from the encoding side to the decoding side as encoded data obtained by performing inter-frame prediction encoding. In each of the inter-frame prediction coding tools, the calculation of each pixel data is performed based on the calculation formula shown in Table 1.

[0014]

[Table 1]

In FIG. 12A, pixel data a _{1 to} d ₁ of pixels indicated by “+” are inter-frame predictive coding tools for sampling on a pixel-by-pixel basis. N-th inter-frame prediction coding tool
Pixel data (corresponding to the (n + 1) -th coding tool when the coding tool is used as the coding tool) (pixel data obtained by an inter-frame predictive coding tool of half-pixel sampling described later is referred to as an n-th coding tool). (Corresponding to the (n + 1) th encoded data when the encoded data is used). In this case, the pixel data a _{1 to} d ₁ obtained by the inter-frame prediction coding have the same value as the image data A to D directly obtained by coding the video signal.

In FIG. 2B, "+" and "〇"
The pixel data a _{2 to} i ₂ of the pixels represented by the marks are inter-frame predictive encoding tools for half-pixel sampling (the n-th inter-frame predictive encoding tool for quarter-pixel sampling is described below). The (n + 1) th coding tool
Pixel data (corresponding to the encoding tool of (1), (n + 1) -th code when the pixel data obtained by the inter-frame prediction encoding tool of quarter-pixel sampling described later is the n-th encoded data) Data). Among them, the pixel data of the pixel represented by the “+” mark is the same value as the pixel data obtained by the inter-frame prediction coding tool of sampling of one pixel unit.
The pixel data indicated by “〇” is pixel data that has been predicted and interpolated based on the image data A to D.

In FIG. 3C, "+",
Pixel data a ₄ to pixel data of pixels represented by “〇” and “△”
y ₄ is pixel data generated by an inter-frame prediction encoding tool of quarter-pixel sampling.
Among these, the pixel data of the pixels represented by the “+” and “〇” marks have the same value as the pixel data obtained by the inter-frame predictive encoding of the sampling on a half-pixel basis. Further, the pixel data of the pixel indicated by “+” is the same value as the pixel data obtained by the inter-frame predictive coding of the sampling of one pixel unit, and the image of the pixel indicated by “〇” and “△” The data is pixel data predicted and interpolated based on the image data A to D.

As can be understood from FIGS. 12 (a) to 12 (c), pixel data a _{2 to} i ₂ obtained by inter-frame predictive coding with half-pixel sampling are used to obtain one-pixel sampling frames. It contains pixel data a _{1 to} d ₁ (image data A to D) obtained by inter prediction coding, and has a pixel density four times as high as the density of sampling pixels of a video signal. The pixel data a _{4 to} y ₄ obtained by the inter-frame predictive coding process of quarter-pixel unit sampling is performed for one-pixel unit sampling and half.
It contains pixel data obtained by the inter-frame prediction encoding process of pixel unit sampling, and has a pixel density 16 times as high as the density of the sampling pixels of the video signal.

As described above, the pixel data obtained by the inter-frame predictive coding tool for generating the pixel data of the high-density display pixels is the same as that of the inter-frame prediction for generating the pixel data of the lower-density display pixels. It hierarchically includes pixel data obtained by the predictive coding tool. For example, pixel data a _{4 to} y ₄ obtained by using the inter-frame predictive encoding tool of quarter-pixel sampling described above is obtained by hierarchically converting pixel data a _{2 to} i ₂ and pixel data a _{1 to} d ₁ . Included.

FIGS. 13A to 13C are diagrams for explaining an image display effect by inter-frame prediction coding.
Each represents a display image of the graphic TA obtained by decoding coded data obtained by inter-frame prediction coding of 1-pixel sampling, 1 / 2-pixel sampling, and 1 / 4-pixel sampling. In FIGS. 7A to 7C, “〇” and “●” indicate a figure TA as a subject.
By decoding the coded data obtained by performing the inter-frame predictive coding on the video signal, the pixels whose display states are determined to be “bright” and “dark”, respectively. In FIGS. 7A to 7C, the graphic TA as the subject moves in a lower right direction, and is used as a reference for understanding the correspondence between the graphic TA and the pixels. This is superimposed on the display image.

In FIG. 13, according to the inter-frame predictive coding in units of one pixel, the number of pixels representing the graphic TA is three before the movement of the graphic TA and one after the movement of the graphic TA. According to the inter-frame predictive coding in units of one pixel, the value is 6 before the movement of the graphic TA and 3 after the movement of the graphic TA. In addition, according to the inter-frame prediction coding in quarter-pixel units, the value becomes 15 before the movement of the graphic TA, and becomes 10 after the movement. As described above, as the number of pixel divisions in the inter-frame predictive coding is increased and the density of display pixels on the decoding side is increased, it is possible to reproduce a high-quality and high-precision image.

However, if the number of pixel divisions in the inter-frame predictive coding is different (that is, if the inter-frame predictive coding tool is different), the data structure of the coded data becomes completely different, and Incompatibility is lost. For this reason, according to the conventional encoding / decoding method and apparatus, the decoding side needs to perform decoding using a decoding tool suitable for the structure of the encoded data. Decoding has to be performed using a decoding tool having a decoding processing capability corresponding to the encoding processing capability on a one-to-one basis. Therefore, when the processing capability of the decoding tool does not correspond to the processing capability of the encoding tool, there is a problem that the received encoded data cannot be decoded at all.

In the case where data encoded using an algorithm having various tools represented by MPEG4 is to be decoded by a device such as MPEG1 having only a single algorithm, the data is decoded. On the side, the algorithm used for encoding (encoding tool)
It is necessary to add hardware / software for realizing the above, which causes a problem that the size of the apparatus is increased and the cost is increased.

The present invention has been made in view of such a problem, and is intended for a case where the encoding processing capability of the encoding tool of the encoding side does not correspond to the decoding processing capability of the decoding tool of the decoding side. It is an object of the present invention to provide an encoding / decoding method and an apparatus capable of decoding encoded data and realizing a small and inexpensive apparatus on the decoding side.

[0025]

Means for Solving the Problems The present invention has the following arrangement to achieve the above object. The encoding / decoding method according to the first aspect of the present invention is an n-th code generated using an n-th (positive integer) encoding tool and decoded using the n-th decoding tool. Data is n +
1 that includes the (n + 1) th encoded data generated using the first encoding tool and decoded using the (n + 1) th decoding tool, wherein the nth encoding tool is The encoding side includes: (a) generating the n-th encoded data using the n-th encoding tool; and (b) the N-th encoded data included in the n-th encoded data (N ≧ The Nth identification unit is added to the (nth positive integer satisfying n) encoded data except for the (N + 1) th encoded data included in the Nth encoded data, and the mth (m> n) is satisfied. The decoding side provided with a decoding tool of (positive integer) performs (c) the N-th encoding from the n-th encoded data to which the N-th identification unit satisfying N ≧ m is added.
(D) using the m-th decoding tool to reconstruct the m-th encoded data,
Is decoded.

The encoding / decoding device according to the second aspect of the present invention is an encoding / decoding device which is generated using an n-th (positive integer) encoding tool and decoded using an n-th decoding tool. Is generated using an (n + 1) th encoding tool and is decoded using an (n + 1) th decoding tool.
+1 encoded data, and the encoding side provided with the n-th encoded tool uses the n-th encoded tool to execute the n-th encoded data. And N + 1 (n + 1) -th encoded data included in the n-th encoded data in the N-th encoded data included in the n-th encoded data. A decoding unit provided with an identification unit adding an N-th identification unit except for encoded data, and a decoding side including an m-th (a positive integer satisfying m> n) decoding tool, N ≧
data reconstruction means for extracting the N-th encoded data provided with the N-th identification unit satisfying m and reconstructing the m-th encoded data; decoding means for decoding m encoded data.

According to a third aspect of the present invention, in the encoding / decoding method according to the first aspect, the encoding tool is an inter-frame predictive encoding tool. Is an inter-frame prediction decoding tool. An encoding / decoding device according to a fourth aspect of the present invention is the encoding / decoding device according to the second aspect, wherein the encoding tool is an inter-frame prediction encoding tool, and the decoding tool is an inter-frame prediction encoding tool. It is configured to be a predictive decoding tool.

According to the encoding / decoding method according to the first aspect of the present invention, the n-th encoding tool is generated by using the n-th encoding tool and is decoded by using the n-th decoding tool. The encoded data has a hierarchical structure including the (n + 1) th encoded data generated using the (n + 1) th encoding tool and decoded using the (n + 1) th decoding tool, and is an arbitrary positive integer. N has this inclusion relation. The encoding side including the n-th encoding tool generates: (a) the n-th encoded data using the n-th encoding tool. (B) Then, an N-th identification unit is added to the N-th encoded data included in the n-th encoded data. However, the N-th encoded data included in the N-th encoded data
Excluding +1 encoded data. In this case, N is a positive integer equal to or greater than n, and the upper limit is determined by the depth of the layer of the encoded data. As a result, for example, when n = 1, the first encoded data includes the second encoded data included in the first encoded data.
The first identification unit is attached except for the encoded data of. Further, the second identification data is included in the second encoded data included in the first encoded data, except for the third encoded data included in the second encoded data. Hereinafter, similarly, the fourth and fifth identification units are assigned according to the depth of the hierarchy of the encoded data included in the first encoded data.

Next, the m-th (positive integer that satisfies m> n) decoding side is: (c) the n-th encoded data is included and N is m
A set of N-th encoded data to which the above-described N-th identification unit has been added is extracted. Thereby, for example, n = 1, m = 2
In the case of (2), the second coded data included in the first coded data (a set of coded data to which the second, third,... Identification units are added) is extracted. Also, n = 1, m
= 3, the third encoded data included in the first encoded data
(A set of encoded data to which the third, fourth,... Identification units are added) is extracted. The m-th encoded data is reconstructed from the set of the N-th encoded data to which the extracted N-th identification unit is added. (D) Then, the m-th encoded data is decoded using the m-th decoding tool.

According to the encoding / decoding device according to the second aspect of the present invention, the n-th code generated using the n-th encoding tool and decoded using the n-th decoding tool The encoded data has a hierarchical structure including the (n + 1) -th encoded data generated using the (n + 1) -th encoding tool and decoded using the (n + 1) -th decoding tool. n has this inclusion relation. On the encoding side including the n-th encoding tool, encoding means generates the n-th encoded data using the n-th encoding tool. Then, the identification unit adding means adds the N-th encoded data included in the n-th encoded data to the N-th encoded data.
Is attached. However, the (N + 1) th encoded data included in the Nth encoded data is excluded. In this case, N
Is a positive integer equal to or greater than n, and the upper limit is determined by the depth of the layer of the encoded data. As a result, for example, when n = 1, the first coded data is provided with the first identification unit except for the second coded data included in the first coded data. Further, the second identification data is included in the second encoded data included in the first encoded data, except for the third encoded data included in the second encoded data. Less than,
Similarly, the fourth and fifth identification units are assigned according to the depth of the hierarchy of the encoded data included in the first encoded data.

Next, on the m-th (positive integer satisfying m> n) decoding side, the data reconstructing means includes an N-th identification code which is included in the n-th encoded data and N is not less than m. The set of the N-th encoded data to which the part is added is extracted. This allows
For example, when n = 1 and m = 2, the second encoded data (second, third,...) Included in the first encoded data
The set of coded data to which the identification unit of (.) Is added is extracted. When n = 1 and m = 3, the third coded data included in the first coded data (the coded data added with the third, fourth,. Set of
Is extracted. The m-th encoded data is reconstructed from the set of the N-th encoded data to which the extracted N-th identification unit is added. Then, decoding means decodes the m-th encoded data using the m-th decoding tool.

According to the encoding / decoding method according to the third aspect of the present invention, in the encoding / decoding method according to the first aspect, the encoding tool is an inter-frame predictive encoding tool, and decoding is performed. Encoding / decoding is performed using the coding tool as an inter-frame prediction decoding tool. According to the encoding / decoding device according to the fourth aspect of the present invention, in the encoding / decoding device according to the second aspect, the encoding tool is an inter-frame prediction encoding tool, and the decoding tool is a frame encoding device. Encoding / decoding is performed as an inter prediction decoding tool.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, a video signal is subjected to inter-frame prediction encoding of quarter-pixel sampling, transmitted as encoded data, and received and decoded. An encryption / decryption method and its apparatus will be described below with reference to the drawings. FIG. 1 is a system block diagram showing an entire configuration of a transmission / reception system to which an encoding / decoding method and apparatus according to the present invention are applied. A transmission system 1 shown in FIG. 1 converts a video information input from a visual sensor (not shown) into a video signal, and encodes the video signal input from the video input unit 101 to generate encoded data. Encoding device 1
02, and a transmission unit 103 that outputs the encoded data generated by the encoding device 102 to the communication network 300.

Here, the encoding device 102 receives a video signal and performs a DCT (Discrete Cosine Transform) transform, and a quantization unit that quantizes a DCT coefficient obtained by performing a DCT transform by the transform unit 121. And an inter-frame prediction encoding unit 123 that inputs image data obtained by quantization by the quantization unit 122 and executes an inter-frame prediction encoding process. In addition, the inter-frame prediction encoding unit 123 includes an inter-frame prediction encoding tool EC ₁ for sampling one pixel, an inter-frame prediction encoding tool EC ₂ for sampling one-half pixel, and a quarter.
Inter-frame prediction coding tool E for pixel sampling
And a C _4, according to the display quality of the image required by the decoding side, one of inter-frame predictive coding tool is selected. For transmission system 1 shown in FIG. 1, the inter-frame prediction coding unit 123, between the one pixel unit sampling a quarter-frame predictive coding tool EC ₄ has been selected, to obtain a highest quality display image Is selected.

On the other hand, the receiving system 2
A receiving unit 201 as an input interface for taking in the encoded data of the image transmitted from the communication network 300 from the communication network 300,
It comprises a decoding device 202 that inputs coded data from the receiving unit 201 and decodes it into a video signal, and a video output unit 203 that receives a video signal from the decoding device 202 and displays video information on a monitor (not shown). Have been. Here, the decoding device 202 is an inter-frame predictive decoding unit 2 that generates inter-frame predictive decoding of the encoded data to generate image data.
21, an inverse quantization unit 222 that inversely quantizes image data obtained by decoding by the inter-frame predictive decoding unit 221 and converts the image data into DCT coefficients, and converts the DCT coefficients generated by the inverse quantization unit 222 into video signals. And an inverse conversion unit 223 that converts the data into Also, in the case of the receiving system 2 shown in FIG. 1, the inter-frame prediction decoding unit 221 includes an inter-frame prediction decoding tool DC _{2 for} sampling in half pixel units.
It has only one.

Through the description of the operation of the transmission system 1 and the reception system 2 configured as described above,
02 and the operation of the decoding apparatus 202 will be described in order. Also not a, a description will be given of the operation of the transmission system 1. The video input unit 101 converts video information input from a visual sensor such as a camera into a video signal and provides the video signal to the encoding device 102. The video signal input to the encoding device 102 is converted into image data via the conversion unit 121 and the quantization unit 122. The inter-frame prediction encoding unit 123 receives the image data, performs inter-frame prediction encoding, generates encoded data, and supplies the encoded data to the transmission unit 103. Transmission unit 103
Outputs the encoded data to the communication network 300.

Here, the inter-frame prediction encoding unit 123
Is to generate encoded data in a hierarchical manner in accordance with the encoding processing capability of an inter-frame predictive encoding tool used for encoding. Before describing the operation of the inter-frame predictive coding unit 123 in detail, hierarchization of coded data will be described. When hierarchizing the encoded data, first, a hierarchy of an inter-frame predictive encoding tool used to generate the encoded data is defined. That is, when the encoded data obtained by the inter-frame prediction coding tool of a certain layer includes the encoded data obtained by another inter-frame prediction coding tool of a certain layer, the inter-frame prediction of a certain layer is performed. The coding tool hierarchy is defined as being lower than the hierarchy of the inter-frame predictive coding tool of another certain hierarchy. According to this definition, each layer of the inter-frame predictive encoding tool of 1-pixel sampling, 1 / 2-pixel sampling, and 1 / 4-pixel sampling has higher ranks from the inclusion relation of the encoded data described above. , Middle and lower.

FIG. 2 is a conceptual diagram for explaining a hierarchical structure of coded data obtained by using an inter-frame predictive coding tool of quarter-pixel sampling.
The encoded data _Dr1 , _Dr2 , _Dr4 of the middle and lower layers are:
It represents coded data generated by using the above-described upper, middle, and lower layer inter-frame predictive coding tools. Figure 12 pixel data a ₁ are shown in _{(c) ~d 1, a 2} ~
i _2, a ₄ ~y _4, respectively upper, middle, corresponding to the encoding of the lower layer data _{D r1, D r2, D r4} . As understood from FIG. 2 and FIGS. 12A to 12C, the encoded data of the lower layer has a data structure that hierarchically includes the encoded data of the middle and upper layers. The encoded data of the middle layer has a data structure that hierarchically includes the encoded data of the upper layer.

The layering of the encoded data obtained by the inter-frame predictive encoding is performed by paying attention to the hierarchical structure of the encoded data as described above.
02, a header for identifying the data hierarchy (identification section), by selectively added to each pixel data a ₄ ~y ₄ constituting the coded data D _r4 of lower hierarchy, between frames It generates encoded data in which a hierarchy is defined in association with the encoding processing capability of the predictive encoding tool.

Hereinafter, the operation of the inter-frame prediction encoding unit 123 will be described in detail with reference to the operation flowchart shown in FIG. First, the inter-frame prediction encoding unit 1
23 inputs image data from the quantization unit 122 (step S01). Next, an inter-frame prediction coding tool is selected according to the quality of the display image on the decoding side (step S02). As described above, the inter-frame predictive encoding unit 123 performs sampling of the quarter unit pixel capable of displaying a high-quality image.
₄ since it is assumed that (a lower layer frame predictive coding tool) is selected, the image data is inter-frame predictive coding using inter-frame prediction coding tool EC ₄ (step S03) . The coded data a ₄ ~y ₄ thereby obtained, are given the header HD ₁ ~HD ₄ in accordance with the hierarchy of inter-frame predictive coding tool (step S04), the encoded data D of a lower hierarchy generate _r4 ,
The coded data _Dr4 is output to the transmitting section 103, and the operation ends. Also, in step S02 described above, if high quality is not required as the quality of the display image, 2
Inter-frame predictive encoding is performed using a sampling pixel-per-pixel or inter-frame predictive encoding tool in units of one pixel (step S05 or S07). Then, a header is similarly attached to the encoded data obtained thereby (step S06 or S08).

The headers HD _{1 to} HD ₄ will be described below. Figure 4 (a) and (b) is a diagram showing the data structure of the lower encoded data D _r4 generated are denoted by the header HD ₁ ~HD ₄ in accordance with the hierarchy of inter-frame predictive coding tool, among the pixel data a ₄ ~y ₄ shown FIG. 12 (c), the representative of the data structure designated by the header HD ₁ ~HD ₄ to each pixel data a ₄ to j ₄ arranged in 1-2 rows. FIG.
(A), the header HD ₁ is pixel data corresponding to the data generated by inter-frame predictive coding in units of one pixel sampling (in FIG. 12 (c), the pixel data of the pixel represented by "+") Attached to Also, header H
D ₂ is pixel data corresponding to data generated by performing inter-frame predictive encoding in 1-pixel sampling, among pixel data corresponding to data generated by performing inter-frame predictive encoding in half-pixel sampling. Are added to the pixel data (pixel data of the pixel represented by “〇” in FIG. 12C). Furthermore, header HD
₄ excludes pixel data corresponding to data generated by inter-frame predictive encoding with half-pixel sampling, out of pixel data generated by inter-frame predictive coding with quarter-pixel sampling. 12 (c in FIG. 12 (c)).

[0042] Thus, for each pixel data constituting the coded data D _r4, when subjected a header corresponding to the hierarchy of inter-frame predictive coding tool, a set of pixel data header HD ₁ is added is The set of data that is the same as the content of the coded data obtained by using the inter-frame prediction coding tool EC ₁ of the upper layer and to which the header HD ₁ or HD ₂ is added is the inter-frame prediction of the middle layer. the same as the content of the coded data obtained using the coding tool EC _2. Therefore, in the decoding side, by identifying the type of header attached to the pixel data a ₄ ~y ₄ constituting the coded data D _r4, inter-frame predictive coding for each hierarchy from the coded data D _r4 Pixel data a _{1 to} d ₁ , a _{2 to} i ₂ , and a _{4 to} y ₄ corresponding to the tool can be identified. Also, by recognizing the type of header,
It is possible to specify the encoding tool used to generate the encoded data _Dr4 . In this way, the encoded data _Dr4 of the lower hierarchy composed of the pixel data string to which the header is added is transmitted to the communication network 300 via the transmission unit 103. In the case where the same header is added to continuous pixel data as shown in FIG. 4B, a header may be added only to the first pixel data. By doing so, an increase in the data amount due to the addition of the header can be suppressed.

Next, the operation of the receiving system 2 will be described.
I do. Receiving as an input interface of the receiving system 2
The communication unit 201 transmits the encoded data D_r4Take
And gives it to the decoding device 202. Decryption device 202
Encoded data D input to _r4Is the inter-frame predictive decoding
The image data is decoded by the conversion unit 221 and converted into image data. This
The image data obtained by the conversion of
The signal is converted to a video signal via the inverse conversion unit 223. Video
The output unit 203 converts the video signal into video information on a monitor.
Visualize. Note that the inter-frame prediction decoding unit 221
Inter-frame prediction coding tool EC_TwoEncoding processing capacity
1/2 pixel unit sun with corresponding decoding capacity
Pulling inter-frame prediction decoding tool DC_TwoOnly have
The inter-frame prediction decoding tool D
C_TwoIs defined as the middle hierarchy.

The operation of the inter-frame predictive decoding unit 221 will be described with reference to the operation flowchart shown in FIG.
This will be described in detail below. Inter-frame prediction decoding unit 221
Receives the encoded data _Dr4 from the receiving unit 201 (step S11), and sets the hierarchy (encoding processing capability) of the encoding tool of the inter-frame prediction encoding tool used for encoding to the inter-frame prediction decoding unit. 221 interframe predictive decoding tool DC ₂ hierarchies (decoding ability) and hierarchy determines same or not provided (step S12). This judgment is
Header HD ₁ ~HD ₄ which is added to the encoded data performed by identifying the header HD _4. Since coded data D _r4 input is encoded data of the lower layer, the decoding tool DC ₂ provided in the inter-frame prediction decoding unit 221
(Step S12, No).

Next, the hierarchy (lower) of the encoding tool EC ₄ used for generating the encoded data _Dr4 is higher than the hierarchy (middle) of the decoding tool DC ₂ provided in the inter-frame predictive decoder 221. It is determined whether it is on the lower side (step S1).
5). In this determination, if it is determined that the lower side (step S15, Yes), compatible with decoding capability of the inter-frame predictive decoding tool DC ₂ medium hierarchy header H
D ₁ and HD ₂ is to extract only encoded pixel data from the encoded data D _r4 to reconstruct the encoded data (step S16).

That is, the pixel data a obtained by the inter-frame predictive coding of the sampling of a quarter pixel unit.
From ₄ ~y _4, by extracting pixel data corresponding to the obtained encoded data by predictive coding between the sampling of one pixel unit of a half frame to reconstruct the encoded data (step S16). The extraction of the data was carried out recognizes header attached to each pixel data, header HD ₁ or HD ₂ pixel data a ₄ ~y ₄ additional pixel data are extracted. Remove the header from this extracted data,
The coded data D _r4 reconstituted into encoded data D _r2, execute inter-frame predictive decoding using tools DC ₂ medium hierarchy on the encoded data D _r2 that this reconfiguration (step S17 ).

[0047] Assuming that a and a inter-frame prediction decoding unit 221 quarter-pixel frame predictive decoding tool DC ₄ sampling unit (not shown), determined in step S12, decoding the decoding side comprises tool hierarchy is determined to be the same as the hierarchical coding tool (step S12, Yes), from the encoded data D _r4 to remove a header HD ₁ ~HD _4, the coded data D _r4 without the header Is reconstructed (step S13). And
By using inter-frame predictive decoding tool DC _4, performs inter-frame predictive decoding process on the reconstructed encoded data D _r4, and outputs image data obtained by this process to the inverse quantization unit 222 (Step S14), the decoding is terminated.

It is also assumed that the inter-frame predictive encoding tool EC is a sampling inter-frame predictive encoding tool EC of one pixel unit.
_In the case of using ₁ , the encoded data to be received is the upper encoded data _Dr1 , so in the above-described determination in step S15, it is determined that the hierarchy of the encoding tool is not the lower hierarchy. (Step S15, No). In this case, it is impossible to reconstruct the matching coded data D _r2 inter-frame predictive decoding tool DC ₂ from the encoded data D _r1 received comprises the decoding side, ends without executing the decoding process .

[0049]

As is clear from the above description, according to the encoding / decoding method and apparatus of the present invention, the encoding / decoding tools are defined by hierarchies, and the hierarchized tools are defined. By adding a header for identifying the processing capability of the tool to the data that conforms to the processing capability of the tool to form encoded data, the decoding side reconstructs the data into a data structure that conforms to the processing capability. Since decoding can be performed, encoded data can be decoded even when the processing capability of the encoding / decoding tool is not compatible.

In order to cope with data encoded by an algorithm having various encoding / decoding tools, such as the next-generation encoding standard represented by MPEG4, the decoding side requires a variety of encoding tools. Since it is not always necessary to equip all the tools, the cost of the apparatus can be reduced. Further, since the hardware configuration of the decoding device can be relaxed, it is possible to decode data encoded according to the next-generation coding standard by a simple and inexpensive device. Become.

[Brief description of the drawings]

FIG. 1 is a system block diagram showing an overall configuration of a transmission / reception system to which an encoding / decoding method and apparatus according to the present invention are applied.

FIG. 2 is a conceptual diagram illustrating a hierarchical structure of encoded data obtained by using an inter-frame predictive encoding tool for sampling in quarter pixel units.

FIG. 3 is an operation flowchart for explaining the operation of an inter-frame prediction encoding unit.

FIGS. 4A and 4B are diagrams illustrating a data structure of lower-order encoded data generated by attaching a header corresponding to a layer of an inter-frame predictive encoding tool.

FIG. 5 is an operation flowchart for explaining the operation of the inter-frame prediction decoding unit.

FIG. FIG. 2 is a conceptual diagram illustrating the structure of a data string of encoded information obtained by encoding (compressing) image data in accordance with H.261. FIG. 2B is a conceptual diagram illustrating a structure of a data string of encoded information obtained by encoding (compressing) image data using a flexible encoding method such as an MPEG4 algorithm.

FIG. 261 is a block diagram illustrating a configuration of an encoder that generates encoded information data according to H.261.

FIG. 261 is a block diagram illustrating a configuration of a decoder that decodes encoded information data encoded according to H.261.

FIG. 261 conforming to still image
It is a block diagram showing the structure of the encoder which codes based on EG.

FIG. 10 is a circuit block diagram of a circuit that constitutes a part of a decoder that decodes encoded information data obtained by encoding (compressing) image data by using a flexible encoding method using an algorithm such as MPEG4.

FIG. 11 is a block diagram illustrating a structure of a decoder including a general-purpose operation processing unit and a compiler.

FIGS. 12A to 12C are conceptual diagrams for explaining the principle of inter-frame predictive coding.

FIGS. 13A to 13C are diagrams for explaining an image display effect by inter-frame predictive coding.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transmission system 2 reception system 101 video input unit 102 encoding device 103 transmission unit 121 conversion unit 122 quantization unit 123 inter-frame prediction encoding unit 201 reception unit 202 decoding device 203 video output unit 221 inter-frame pre-decoding unit 222 Inverse quantization unit 223 Inverse transformation unit

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H03M 7/30 H03M 7/38

Claims (4)

(57) [Claims] An n-th encoded data generated using an n-th (positive integer) encoding tool and decoded using an n-th decoding tool uses an (n + 1) -th encoding tool. The hierarchical data including the (n + 1) -th encoded data generated and decoded using the (n + 1) -th decoding tool, wherein the encoding side including the n-th encoding tool includes: (A) generating the n-th encoded data using the n-th encoding tool, and (b) N-th (positive integer satisfying N ≧ n) included in the n-th encoded data To the N-th identification unit except for the (N + 1) -th encoded data included in the N-th encoded data, and decode the m-th (positive integer satisfying m> n) The decoding side equipped with the tool: (c) converts the n-th encoded data into N
Extracting the N-th encoded data to which the N-th identification unit satisfying ≧ m is added to reconstruct the m-th encoded data, and (d) using the m-th decoding tool, An encoding / decoding method, which comprises decoding m encoded data. 2. The n-th encoded data generated using the n-th (positive integer) encoding tool and decoded using the n-th decoding tool uses the (n + 1) -th encoding tool. The hierarchical data including the (n + 1) -th encoded data generated and decoded using the (n + 1) -th decoding tool, wherein the encoding side including the n-th encoding tool includes: The n-th
Encoding means for generating the n-th encoded data by using the encoding tool of (1), and N-th (positive integer satisfying N ≧ n) encoded data included in the n-th encoded data. Identification unit adding means for attaching an N-th identification unit except for the (N + 1) -th encoded data included in the N-th encoded data, and decoding the m-th (positive integer satisfying m> n) decoding The decoding side equipped with the tool extracts the N-th encoded data provided with the N-th identification unit satisfying N ≧ m from the n-th encoded data and reconstructs the m-th encoded data. An encoding / decoding device comprising: a data reconstructing unit that performs decoding; and a decoding unit that decodes the m-th encoded data using the m-th decoding tool. 3. The encoding / decoding apparatus according to claim 1, wherein the encoding tool is an inter-frame prediction encoding tool, and the decoding tool is an inter-frame prediction decoding tool.
The method of decryption. 4. The encoding / decoding apparatus according to claim 2, wherein the encoding tool is an inter-frame predictive encoding tool, and the decoding tool is an inter-frame predictive decoding tool.
Decryption device.