JP2008193308A - Coding system conversion method and device, and coding system conversion program and its storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coding system conversion device for estimating a coding mode of H. 264 on the basis of code information on an MPEG-2 and converting the coding system at high speed while suppressing deterioration of picture quality to the minimum. <P>SOLUTION: An estimation part 12 includes: an intra estimation part 122 for estimating whether or not an intra mode is valid in the H. 264 with respect to an intra MB of the MPEG-2; an inter estimation parts 123, 124 and 125 for estimating whether or not an inter mode is valid in the H. 264 with respect to an inter MB of the MPEG-2; an inter coding condition determination part 126 for determining the coding condition in the H. 264 of the inter MB where the inter mode is estimated to be valid in H. 264; an intra coding condition determination part 127 for determining the coding condition in the H. 264 of the intra MB where the intra mode is estimated to be valid in the H. 264; and an all search part 128 for performing all search in the MB where an identical coding mode is estimated to be invalid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an encoding method conversion method and apparatus, an encoding method conversion program, and a storage medium thereof, and more particularly, to an encoding method conversion method and apparatus suitable for conversion from an MPEG-2 stream to an H.264 stream, and an encoding method. The present invention relates to a conversion method conversion program and its storage medium.

  While various image compression schemes have been established as international standards, MPEG is widely used from broadcasting to consumers. In particular, MPEG-2 is used not only for satellite / terrestrial digital broadcasting but also for DVD encoding. However, when the MPEG-2 content is used for streaming distribution for the Internet, the transmission band is greatly limited, and the bit rate must be significantly reduced.

  On the other hand, H.264 / MPEG-4 AVC (hereinafter, H.264) is becoming popular as a new image encoding method. H.264 defines various prediction modes (prediction directions). From the viewpoint of compression efficiency, it has the performance of halving the bit rate with the same image quality as MPEG-2, but the coding cost is It has increased significantly.

  In order to realize one-source multi-use that distributes the same content to networks of various bands such as wireless terminals, ADSL, or optical fiber, there is a great demand for converting MPEG-2 as master content to H.264. However, the process of completely decoding MPEG-2 and then re-encoding it to H.264 is too costly, so it is difficult to realize it within a practical time.

  Patent Document 1 discloses a method for speeding up the encoding of H.264. In the technique of Patent Document 1, in encoding with many prediction modes such as H.264, the generated code amount can be estimated with high accuracy prior to encoding, and it is optimal for image quality, compression rate and rate. Encoding control is possible.

Patent Document 2 reports a method for speeding up the format conversion from MPEG-2 to MPEG-4. In the technique of Patent Document 2, when a specific type of picture (I, P picture) is extracted from an MPEG-2 stream and a partial image signal is generated, the encoded image signal is converted into a different encoding method. The time required for conversion can be shortened.
JP 2005-203905 A JP 2005-64569 A

  Since the technique disclosed in Patent Document 1 deals only with H.264 encoding, it must be combined with MPEG-2 decoding to be applied to encoding method conversion. In addition, since Patent Document 1 does not have a means for reusing MPEG-2 code information, it cannot be expected to significantly reduce the time spent for encoding method conversion.

  Since Patent Document 2 deals only with conversion to MPEG-4, which has fewer prediction modes than H.264, the prediction mode is limited in application to H.264, resulting in significant image quality degradation. In particular, H.264 defines an intra prediction mode in order to improve compression efficiency. However, the intra prediction mode is a prediction mode that does not exist in MPEG-2, and the encoding characteristics of MPEG-2 and H.264 are greatly different, so the MPEG-2 encoding mode is simply inherited to H.264. If you do so, you will not be able to fully demonstrate the performance of H.264.

  The object of the present invention is to solve the above-mentioned problems of the prior art and estimate the H.264 encoding mode at high speed by directly using the MPEG-2 code information, while minimizing the degradation of image quality. It is an object to provide an encoding method conversion method and apparatus, an encoding method conversion program, and a storage medium thereof for converting an encoding method at high speed.

  In order to achieve the above-described object, the present invention provides a first moving image encoded by the first encoding method, wherein the first and second encoding methods include an inter mode and an intra mode as encoding modes. In the moving picture coding method conversion apparatus for converting the video into the second moving picture encoded by the second coding method, the first moving picture decoding means, and the control blocks of the decoded first moving picture The estimation means for estimating the encoding mode in the second encoding scheme, and the means for encoding each control block of the first moving image in the second encoding scheme based on the estimation result, The same encoding mode is effective for the second encoding scheme for the inter block as the estimation unit determines whether each control block of the first moving image is an inter block or an intra block. Whether or not Means for estimating whether or not the same coding mode is valid even in the second coding scheme for the intra block, and the control block in which the inter mode is estimated to be valid is designated as the second code. Means for determining an encoding condition for encoding in the inter mode of the encoding method, and an encoding condition for encoding the control block estimated to be effective in the intra mode in the intra mode of the second encoding method. And a means for performing a full search for an estimated control block for which the same coding mode is not valid and searching for the coding mode and coding conditions.

According to the present invention, in the moving image coding method conversion for converting the first moving image encoded by the first encoding method into the second moving image encoded by the second encoding method, Such an effect is achieved.
(1) It is determined whether or not the encoding mode employed in the first encoding method is also effective in the second encoding method. If it is effective, the code in the second encoding method is determined. Since the search range of the encoding condition is limited to the encoding mode employed in the first encoding method, high-speed conversion is possible.
(2) It is determined whether or not the coding mode employed in the first coding method is also effective in the second coding method, and the second coding method is different from the first coding method. If it is determined that there is a possibility that the encoding mode is effective, the encoding mode and the encoding condition of the second encoding method are searched, so that conversion with less quality degradation is possible.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a main part of a coding system conversion system according to the present invention. Here, a case where an MPEG-2 stream is converted into an H.264 stream will be described as an example.

  The extraction unit 10 extracts code information from the input MPEG-2 stream V1. The extracted code information is provided to the decoding unit 11 and the estimation unit 12. The decoding unit 11 decodes the code information into pixel information and provides it to the estimation unit 12. The estimation unit 12 estimates the optimal prediction mode in H.264 for each control block from the code information and the pixel information, and provides this estimation result to the encoding unit 13. In this embodiment, an optimal prediction mode is estimated for each macroblock (MB) of MPEG-2. The encoding unit 13 encodes the pixel information with the H.264 encoding method based on the provided prediction mode estimation result, and outputs an H.264 stream V2.

  The estimation unit 12 reads the code information in MB units, and determines whether the current MB of interest is an intra block encoded in the intra mode or an inter block encoded in the inter mode. 121 and a correlation determination unit as an intra estimation means for estimating whether or not encoding in intra mode is effective in H.264 with respect to intra MB encoded in intra mode in MPEG-2 122 and MV reliability determination as an inter estimation means for estimating whether inter-mode coding is effective in H.264 as well as inter-MB coded in inter-mode in MPEG-2 Unit 123, edge determination unit 124, and residual component determination unit 125.

  The estimation unit 12 further includes an inter encoding condition determination unit 126 that determines the encoding condition in H.264 of inter MB, in which the inter mode is estimated to be effective in the same way as MPEG-2 in H.264, and H.264 However, as with MPEG-2, it was estimated that the intra coding condition determination unit 127 that determines the coding conditions in the H.264 of the intra MB where the intra mode is estimated to be effective, and the same encoding mode is not effective. And a full search unit 128 that executes a full search for the MB and determines an encoding mode and an encoding condition in H.264.

  The correlation determination unit 122 determines the spatial correlation of the intra MB. The MV reliability determination unit 123 determines the reliability of inter MB motion information (MV). The edge determination unit 124 determines whether or not only an edge in a predetermined direction is included in the inter MB. The residual component determination unit 125 determines whether or not the residual component of the inter MB orthogonal transform coefficient is below a predetermined threshold.

  The inter coding condition determination unit 126 determines a coding condition including a block size and a prediction mode with respect to the inter MB by limiting the coding mode to the inter mode. The intra encoding condition determination unit 127 determines an encoding condition including block size and motion information by limiting the encoding mode to the intra mode for the intra MB.

  FIG. 2 is a flowchart showing a procedure of encoding mode estimation processing in the estimation unit 12. In this embodiment, for each MB of 16 × 16 pixel unit of MPEG-2, each DCT coefficient of four luminance blocks of 8 × 8 pixel unit and two color difference blocks of 8 × 8 pixel unit, and further motion information if inter MB Based on this, an optimal encoding mode is estimated when the MB is predictively encoded by the H.264 encoding method, and the encoding condition is set.

  In step S1, the encoding mode determination unit 121 determines whether the current MB of interest is an intra MB encoded in the intra mode or an inter MB encoded in the inter mode. If it is inter MB, the process proceeds to step S2, and the reliability of the motion information (motion vector MV) is determined in the MV reliability determination unit 123.

The MV reliability determination unit 123 determines the reliability of the input motion information based on the following equation (1). In the present embodiment, attention is paid to the fact that neighboring MBs show similar characteristics among the MBs in the vicinity, and regarding the motion vectors of a plurality of MBs located within a predetermined range from the target MB, the dispersion in the horizontal direction σ ² MV _X and vertical variance σ ² MV _Y are compared to a predetermined MV threshold TH _MV .

If the following equation (1) holds, that is, if either σ ² MV _X or σ ² MV _Y exceeds the MV threshold TH _MV , it is determined that the reliability of the motion information is low, and the edge of step S3 Proceed to the determination process. On the other hand, if the following equation (1) is not satisfied, that is, if both σ ² MV _X and σ ² MV _Y are below the MV threshold TH _MV , it is determined that the reliability of the motion information is high. , The process proceeds to step S5 in order to succeed the inter mode in H.264.

  In step S3, the edge determination unit 124 determines whether the current MB of interest includes an edge for which the intra mode is valid. FIG. 3 is a flowchart showing details of the edge determination process in step S3. In this embodiment, as shown in FIG. 4, whether or not each of the four luminance blocks of the target MB includes an edge. If it is included, it is further determined whether or not intra prediction is effective for the MB of interest based on the edge direction of each luminance block.

  In FIG. 3, in step S31, an initial value “0” is set in a variable i for specifying the positions of the four luminance blocks, and the upper left luminance block is designated. In step S32, whether or not an edge is included in the luminance block at position i is determined based on the following equation (2).

In the above formula (2), Sum _AC is the sum of absolute values of DCT coefficients (only AC component) of the luminance block, and the DC component (second term) of the sum of the DCT coefficients of the luminance block (middle side first term). ) Is required. In the present embodiment, the Sum _AC is compared with the no edge determination threshold TH _{No_Edge} . This _edgeless determination threshold TH _{No_Edge} is a function of the quantization parameter QP.

  If the above equation (2) holds, it is determined that no edge exists in the luminance block at position i, and the process proceeds to step S34. If the above equation (2) is not established, it is determined that an edge exists in the luminance block at the position i, and the process further proceeds to step S33, where the edge direction is determined based on the following equations (3) and (4).

In the above equation (3), the ratio of the sum of absolute values of the AC component F _Yi (0, v) of the zero-row each column of the DCT coefficient of the luminance block with respect to the Sum _AC is compared with the vertical edge determination threshold TH _{V_Edge,} and If the ratio exceeds the vertical edge determination threshold TH _{V_Edge} , the edge is determined to be a vertical edge. In the above equation (4), the ratio of the sum of absolute values of the AC components F _Yi (u, 0) of each row zero column of the DCT coefficient of the luminance block with respect to the Sum _AC is compared with the horizontal edge determination threshold TH _{H_Edge,} and the ratio If the value exceeds the horizontal edge determination threshold TH _{H_Edge} , the edge is determined to be a horizontal edge. The vertical edge determination threshold TH _{V_Edge} and the horizontal edge determination threshold TH _{H_Edge} are also functions of the quantization parameter QP.

  In step S34, it is determined whether or not the edge determination described above has been completed for the luminance blocks at all positions. If not completed, the variable i is updated in step S35, and each process described above is repeated while changing the target luminance block.

  When the above-described determination processing is completed for all four luminance blocks, the process proceeds to step S36 to determine whether the edge patterns of the four luminance blocks correspond to any of the first to fourth patterns shown in FIG. Is done.

  The first pattern suggests that the luminance block at each position of i = 0,1 includes a horizontal edge, and the luminance block at each position of i = 2,3 does not include a vertical edge. The second pattern suggests that the luminance block at each position of i = 2, 3 includes a horizontal edge, and the luminance block at each position of i = 0, 1 does not include a vertical edge. The third pattern suggests that the luminance block at each position of i = 0, 2 includes a vertical edge, and the luminance block at each position of i = 1, 3 does not include a horizontal edge. The fourth pattern suggests that the luminance block at each position of i = 1, 3 includes a vertical edge, and the luminance block at each position of i = 0, 2 does not include a horizontal edge.

  Therefore, for example, if the luminance block at each position of i = 0, 1 includes a horizontal edge and the luminance block at each position of i = 2, 3 does not include an edge, or includes only a horizontal edge. It is determined that it corresponds to the first pattern. However, even if each luminance block at each position of i = 0, 1 includes a horizontal edge, if at least one of the luminance blocks at each position of i = 2, 3 includes a vertical edge, the first pattern is included. Therefore, it is determined that none of the patterns is applicable.

  As described above, if it is determined that the edge included in the current MB of interest corresponds to one of the edge patterns, even if it is inter MB in MPEG-2, it is suitable for encoding in intra mode in H.264 Therefore, the process proceeds to a full search in step S6. On the other hand, if it does not correspond to any edge pattern, the process further proceeds to DC determination processing in step S4.

  In step S4, the residual component determination unit 125 performs the residual of the DCT coefficients of four luminance blocks of 8x8 pixel units and the DCT coefficients of two color difference blocks of 8x8 pixel units for the current MB of interest of 16x16 pixel units. Based on the component, it is determined whether encoding in the inter mode is valid.

In this embodiment, as shown in the following equation (5), the sum of absolute values of the DC components F _Yi (0,0) of the DCT coefficients of the four luminance blocks is compared with a predetermined luminance DC component threshold TH _DC1. Further, as shown in the following equation (6), the DC components F _Cb (0,0) and F _Cr (0,0) of the DCT coefficients of the two color difference blocks are compared with the color difference DC component threshold TH _DC2 .

  Here, if the above equations (5) and (6) are both established, it is determined that the residual component of the DCT coefficient is large, and the process proceeds to step S6 in order to search all the coding modes. On the other hand, if at least one of the above equations (5) and (6) is not established, the residual component is sufficiently small, and there is no significant difference in coding efficiency in any coding mode. Proceed to step S5 to inherit the inter mode from the viewpoint.

  On the other hand, if it is determined in step S1 that the current MB of interest is an intra MB, the process proceeds to step S7. In step S7, the correlation determination unit 122 evaluates the spatial correlation based on the DCT coefficient of the luminance block of the MB of interest.

In the present embodiment, as shown in the following equation (7), the DC component variance σ ² _DC of the DCT coefficients of the four luminance blocks in the unit of 8 × 8 pixels is the luminance DC component threshold for the current MB of interest in the unit of 16 × 16 pixels. Compared with TH _DC3 . If σ ² _DC ≦ TH _DC3 , the spatial correlation of DCT coefficients is large, and intra prediction functions effectively, so the process proceeds to step S8 and the intra mode is inherited.

On the other hand, if σ ² _DC > TH _DC3 , the spatial correlation is small, and inter prediction may function effectively, so that each encoding mode of intra prediction and inter prediction can be set with each encoding cost. In order to evaluate based on the above, the process proceeds to a full search in step S6.

  In step S5, the inter-encoding condition determining unit 126 determines the encoding conditions such as the optimum block size and motion information by limiting the encoding mode to the inter mode. The prediction mode can be determined by any method.For example, the optimal prediction mode is determined using a cost function that linearly combines the degree of image quality degradation (D) and the amount of generated code (R) (RD-Optimization: RDO), or motion information in MPEG-2 may be used to estimate H.264 motion information at high speed.

  In step S8, the intra coding condition determination unit 127 limits the coding mode to the intra mode, and determines the coding conditions such as the optimum block size and intra prediction mode. The prediction mode can be determined by any method.For example, the optimal prediction mode is determined using a cost function that linearly combines the degree of image quality degradation (D) and the amount of generated code (R) (RD-Optimization: RDO), or may be estimated at high speed in the intra mode from the combination of the ratio of the partial absolute value sum of the transform coefficients in MPEG-2 and the positive / negative sign.

  In step S6, the full search unit 128 determines the optimal encoding mode by full search without limiting the encoding mode. The coding mode can be determined by any method.For example, the optimal prediction mode is determined using a cost function that linearly combines the degree of image quality degradation (D) and the amount of generated code (R) (RD-Optimization : RDO), or H.264 estimated by using the intra mode estimated from the combination of the partial absolute value sum ratio and the sign of the sign in MPEG-2 and motion information in MPEG-2 May be selected from the viewpoint of coding cost or the like.

  FIG. 6 is a diagram showing a configuration of a main part of an encoding system conversion system according to the second embodiment of the present invention, and the same reference numerals as those described above represent the same or equivalent parts.

  In the present embodiment, instead of the correlation determination unit 122 as intra estimation means for estimating whether or not the encoding in the intra mode is effective in the H.264 as well as the intra MB in MPEG-2. A proximity determination unit 120 is provided. Furthermore, as an inter estimation means for estimating whether or not encoding in the inter mode is effective in the H.264 as well as in the inter MB in MPEG-2, instead of the residual component determination unit 125, the neighborhood A determination unit 129 is provided.

  FIG. 7 is a flowchart showing the operation of the second embodiment of the present invention. In the processing given the same step number as in FIG. 2, the same or equivalent processing is executed.

  The neighborhood determination unit 129 targets the MB of interest (inter MB), for which it is determined that intra prediction is not valid in step S3, in step S10, other MBs in the vicinity, and encoding in H.264 Reference is made to the estimation results of encoding modes of neighboring MBs whose modes are already estimated, for example, the left, upper, and upper right of the target MB. If most of the encoding modes of each neighboring MB (for example, two or more neighboring MBs out of three neighboring MBs) are the same inter mode as the encoding mode in MPEG-2 of the target MB, this inter mode The process proceeds to step S5 so as to inherit. On the other hand, if many of the encoding modes of the neighboring MBs are different from the encoding mode of MPEG-2 of the target MB, the process proceeds to full search in step S6.

  Similarly, in step S9, the neighborhood determination unit 120 estimates other MBs in the vicinity of the target MB (intra MB) and the coding modes of neighboring MBs whose coding modes in H.264 have already been estimated. With reference to the result, many of the encoding modes of each neighboring MB (for example, two or more neighboring MBs out of three neighboring MBs) are the same intra mode as the encoding mode in MPEG-2 of the target MB. The process proceeds to step S7 to inherit this intra mode. On the other hand, if many of the encoding modes of the neighboring MBs are different from the encoding mode of MPEG-2 of the target MB, the process proceeds to full search in step S6.

It is a block diagram of the encoding system conversion system which concerns on 1st Embodiment of this invention. It is the flowchart which showed the encoding mode estimation procedure in 1st Embodiment. It is the flowchart which showed the procedure of the edge determination process. It is the figure which showed the relationship between MB and a luminance block. It is the figure which showed the method of determining the direction of the edge contained in MB. It is a block diagram of the encoding system conversion system which concerns on 2nd Embodiment of this invention. It is the flowchart which showed the encoding mode estimation procedure in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Extraction part, 11 ... Decoding part, 12 ... Estimation part, 13 ... Encoding part, 120 ... Neighborhood determination part, 121 ... Coding mode determination part, 122 ... Correlation determination part, 123 ... MV reliability determination part, 124 ... edge determination unit, 125 ... residual component determination unit, 126 ... inter coding condition determination unit, 127 ... intra coding condition determination unit, 128 ... full search unit, 129 ... neighborhood determination unit

Claims (21)

The first and second encoding methods include an inter mode and an intra mode as encoding modes, and the first moving image encoded by the first encoding method is encoded by the second encoding method. In a moving image coding system conversion device for converting into two moving images,
Decoding means for decoding the first moving image;
Estimating means for estimating a coding mode in a second coding scheme for each control block of the decoded first moving image;
Encoding means for encoding each control block of the first moving image by the second encoding method based on the estimation result;
The estimating means is
Encoding mode determination means for determining whether each control block of the first moving image is an inter block encoded in the inter mode or an intra block encoded in the intra mode;
Inter estimation means for estimating whether or not the same encoding mode is effective in the second encoding scheme for the inter block;
Intra estimation means for estimating whether or not the same coding mode is valid in the second coding scheme for the intra block;
Inter coding condition determining means for determining a coding condition when the control block estimated to be effective in the inter mode is encoded in the inter mode of the second coding scheme;
Intra coding condition determining means for determining a coding condition for coding the control block in which the intra mode is estimated to be valid in the intra mode of the second coding method;
Coding method conversion characterized by including a full search means for performing a full search for an estimated control block in which the same coding mode is not valid and searching for the coding mode and coding conditions apparatus.   The code according to claim 1, wherein the inter coding condition determining means searches for coding conditions including block size and motion information for an inter block by limiting the coding mode to the inter mode. Conversion method converter.   2. The code according to claim 1, wherein the intra coding condition determining unit searches for an intra block with respect to a coding condition including a block size and a prediction mode by limiting the coding mode to the intra mode. Conversion method converter. The intra estimation means comprises correlation determination means for determining a spatial correlation of intra blocks,
The encoding method conversion apparatus according to claim 1, wherein the correlation determination unit estimates an encoding mode of the intra block having a high spatial correlation as an intra mode. The intra estimation means comprises proximity determination means for determining an estimation result relating to coding modes of a plurality of other control blocks near the intra block;
The said neighborhood determination means estimates the encoding mode of the intra block whose ratio that the estimation result of the said control block of the neighborhood is an intra mode is higher than a predetermined threshold value as an intra mode. Encoding method converter. The inter designation means comprises a reliability judgment means for judging the reliability of the motion information of the inter block,
The encoding method conversion apparatus according to claim 1, wherein the reliability determination unit estimates an encoding mode of a highly reliable inter block as an inter mode. The inter estimation means comprises an edge determination means for determining whether or not an edge in a predetermined direction is included in the inter block,
The encoding method conversion apparatus according to claim 1, wherein the edge determination unit estimates an encoding mode of an inter block that does not include an edge in the predetermined direction as an inter mode. The inter estimation means comprises residual component determination means for determining whether or not the residual component of the orthogonal transform coefficient of the inter block is below a predetermined threshold;
The encoding method conversion apparatus according to claim 1, wherein the residual component determination unit estimates an encoding mode of an inter block whose residual component is lower than a predetermined threshold as an inter mode. The inter estimation unit further includes a proximity determination unit that determines an estimation result related to encoding modes of a plurality of other control blocks in the vicinity of the inter block,
The neighborhood determination unit estimates an inter-block coding mode in which a ratio that the estimation result of the neighboring control block is an inter mode is higher than a predetermined threshold as an inter-mode. Encoding method converter. The inter estimation means is
A reliability determination means for determining the reliability of the motion information of the inter block;
Edge determining means for determining whether or not an edge in a predetermined direction is included in the inter block determined to have low reliability;
A residual component determining unit that determines whether or not a residual component of an orthogonal transformation coefficient of an inter block determined to include no edge in the predetermined direction is below a predetermined threshold;
The encoding system conversion apparatus according to claim 1, wherein an encoding mode of an inter block in which the residual component is below a predetermined threshold is estimated as an inter mode. The inter determination means further includes
In place of the residual component determination means, comprising: proximity determination means for determining an estimation result of a plurality of other control blocks in the vicinity of the inter block determined to include no edge in the predetermined direction;
11. The encoding scheme conversion according to claim 10, wherein an encoding mode of an inter block whose ratio of the estimation results of the other plurality of control blocks being an inter mode is higher than a predetermined threshold is estimated as an inter mode. apparatus.   5. The encoding method conversion apparatus according to claim 4, wherein the correlation determination unit determines that the spatial correlation is high when the variance of the orthogonal transform coefficients of the intra block is lower than a predetermined threshold.   The code according to claim 6, wherein the reliability determination unit determines that the reliability is high when the variance of motion information of other inter blocks in the vicinity of the inter block is lower than a predetermined threshold. Conversion method converter.   The encoding method conversion apparatus according to claim 7, wherein the edge determination unit estimates an encoding mode of an inter block that does not include an edge in a vertical direction or a horizontal direction as an inter mode. The first and second encoding methods include an inter mode and an intra mode as encoding modes, and the first moving image encoded by the first encoding method is encoded by the second encoding method. In a moving image coding method conversion method for converting into two moving images,
A procedure for decoding the first moving image;
A procedure for estimating a coding mode in a second coding scheme for each control block of the decoded first moving image;
An encoding procedure for encoding each control block of the first moving image with the second encoding method based on the estimation result;
The estimation procedure comprises:
A procedure for determining whether each control block of the first moving image is an inter block encoded in the inter mode or an intra block encoded in the intra mode;
An inter estimation procedure for estimating whether or not the same encoding mode is valid in the second encoding scheme for the inter block;
An intra estimation procedure for estimating whether the same coding mode is valid in the second coding scheme for the intra block;
A procedure for determining a coding condition when coding the control block estimated to be effective in the inter mode in the inter mode of the second coding scheme;
A procedure for determining an encoding condition when encoding the control block in which the intra mode is estimated to be effective in the intra mode of the second encoding method;
A coding method conversion method comprising: a procedure unit that performs a full search for an estimated control block in which the same coding mode is not valid, and searches for the coding mode and coding conditions. . The intra estimation procedure comprises determining a spatial correlation of intra blocks;
The encoding method conversion method according to claim 15, wherein an encoding mode of the intra block having a high spatial correlation is estimated as an intra mode. The intra estimation procedure further comprises a step of determining an estimation result regarding coding modes of other control blocks in the vicinity of the intra block;
16. The coding method conversion method according to claim 15, wherein the coding mode of an intra block in which a ratio that the estimation result of the neighboring control block is an intra mode is higher than a predetermined threshold is estimated as an intra mode. . The inter estimation procedure comprises:
A procedure for determining the reliability of the inter-block motion information;
A procedure for determining whether or not an edge in a predetermined direction is included in the inter block determined to have low reliability;
Determining whether or not the residual component of the orthogonal transform coefficient of the inter block determined not to include an edge in the predetermined direction is below a predetermined threshold,
The encoding method conversion method according to any one of claims 15 to 17, wherein an encoding mode of an inter block in which the residual component is below a predetermined threshold is estimated as an inter mode. The inter determination procedure further includes:
A step of determining an estimation result of other control blocks in the vicinity of the inter block in which the residual component is below a predetermined threshold;
19. The encoding method according to claim 18, wherein an encoding mode of an inter block whose ratio of the estimation results of the other plurality of control blocks being an inter mode is higher than a predetermined threshold is estimated as an inter mode. Conversion method.   An encoding method conversion program for causing a computer to execute the encoding method conversion method according to any one of claims 15 to 19.   A storage medium storing the encoding system conversion program according to claim 20 in a computer-readable manner.

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