JP2006295734A - Re-encoding apparatus, re-encoding method, and re-encoding program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a re-encoding apparatus capable of preventing an increase in a bit quantity and a deterioration in image quality even if there is an unsuitable motion vector when transcoding first encoded information into second encoded information while re-utilizing a motion vector of the first encoded information. <P>SOLUTION: A decoding section 100 decodes first encoded information, a motion vector analysis section 201 determines for each block whether or not a motion vector of the first encoded information can be re-utilized and based on a prediction mode of blocks around a block to be encoded, an in-image plane prediction mode decision section 202 changes a prediction mode of the block to be encoded for which it is determined by the motion vector analysis section 201 that the motion vector can not be re-utilized, from inter-image plane prediction to in-image plane prediction. In accordance with the set prediction mode, an in-image plane prediction section 204 and an inter-image plane prediction section 205 generate second encoded information by encoding the decoded image information for each block using inter-image plane prediction and in-image plane prediction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a re-encoding device, a re-encoding method, and a re-encoding program. Specifically, the first encoding information obtained by encoding image information by inter-screen prediction is used as the first encoding information. The present invention relates to a re-encoding device, a re-encoding method, and a re-encoding program that transcode into second encoded information using a motion vector used for decoding.

  In recent years, image information has been handled as digital data. At that time, for the purpose of efficient transmission and storage of information, compression is performed by orthogonal transform such as discrete cosine transform and motion prediction / compensation using redundancy unique to image information. An apparatus conforming to a system such as MPEG is widely used.

  In particular, MPEG2 (ISO / IEC 13818-2) is defined as a general-purpose image coding system, and is a standard that covers both interlaced and progressively scanned images, standard resolution images, and high-definition images. And widely used in a wide range of applications for consumer use. By using the MPEG2 compression method, for example, a standard resolution interlaced scanning image having 720 × 480 pixels is 4 to 8 Mbps, and a high resolution interlaced scanning image having 1920 × 1088 pixels is 18 to 22 Mbps. (Bit rate) can be assigned to achieve a high compression rate and good image quality.

  MPEG2 was mainly intended for high-quality encoding suitable for broadcasting, but did not support encoding methods with a lower code amount (bit rate) than MPEG1, that is, a higher compression rate. With the widespread use of mobile terminals, the need for such an encoding system is expected to increase in the future, and the MPEG4 encoding system has been standardized accordingly.

  Furthermore, in recent years, standardization of the H.264 (ITU-T Q6 / 16 VCEG) encoding method has been performed with the initial purpose of image encoding for video conferencing. H. H.264 is known to achieve higher encoding efficiency than a conventional encoding method such as MPEG2 or MPEG4, although a larger amount of calculation is required for encoding and decoding.

  Such H.P. In H.264, intra prediction encoding is used in which a prediction image is generated from pixels around a block and the difference is encoded. H. In the H.264 intra-frame prediction encoding, there are two types of intra 4 × 4 prediction mode in which prediction is performed in units of 4 × 4 pixel blocks and intra 16 × 16 prediction mode in which prediction is performed in units of 16 × 16 pixel blocks (macroblocks). Two prediction schemes are used.

  MPEG2 format encoding information is converted into H.264 format. When transcoding to H.264 format encoded information, after decoding the encoded information of MPEG2, a new H.264 format is added. When the H.264 encoding process is performed, the amount of calculation is large, so that there is a problem in that the process becomes complicated and the circuit scale increases. Therefore, the motion vector used in the MPEG2 decoding process is expressed as H.264. A technique has been proposed in which the amount of computation is reduced by reuse in the H.264 encoding process, and the processing speed is increased.

  However, H.C. Even when there is a motion vector (hereinafter also referred to as “inappropriate motion vector”) that cannot be used directly when reusing a motion vector used in a decoding process such as MPEG2 in the H.264 encoding process. Since encoding is performed as it is, there is a problem that the bit amount increases and the image quality deteriorates. Here, the inappropriate vector means, for example, a case where the motion vector is large. FIG. 10 is a diagram for explaining an inappropriate motion vector. In FIG. 10, in the motion vector search of MPEG2, the motion vector with the reference macroblock of the reference picture is detected, but the motion vector may become large. In addition, when transcoding is performed, a technique for switching inter-screen prediction to intra-screen prediction has been proposed (see, for example, Patent Document 1).

JP 11-46217 A

  The present invention has been made in view of the above, and when the motion vector of the first encoded information is reused and transcoded to the second encoded information, even when there is an inappropriate motion vector, An object of the present invention is to provide a re-encoding device, a re-encoding method, and a re-encoding program that can prevent an increase in bit amount and image quality deterioration.

  In order to solve the above-described problems and achieve the object, the present invention relates to first encoded information obtained by encoding image information using block prediction and intra prediction in units of blocks. In a re-encoding device that transcodes to second encoded information using a motion vector of information, decoding means for decoding the first encoded information, and a motion vector of the first encoded information A motion vector analyzing unit that determines whether or not the block can be used, and a prediction mode of the encoding target block that is determined by the motion vector analyzing unit that the motion vector is not reusable. In-screen prediction determination means for changing from inter-screen prediction to intra-screen prediction based on the prediction mode of the surrounding blocks, and the decoded image information is blocked according to the set prediction mode. Characterized by comprising encoding means for generating a second encoded information by encoding in inter prediction and intra prediction using the clock unit, the.

  The present invention also provides a first code information obtained by coding image information in units of blocks using inter-frame prediction and intra-screen prediction, using a motion vector of the first encoded information, In a re-encoding method for transcoding into encoded information, a decoding step for decoding the first encoded information and whether or not a motion vector of the first encoded information is reusable is determined in units of blocks A motion vector analysis step to be performed, and a prediction mode of a block to be encoded that is determined to be non-reusable in the motion vector analysis step based on a prediction mode of a block around the block to be encoded In-screen prediction determination process to change from inter-prediction to intra-screen prediction, and in accordance with the set prediction mode, the decoded image information is inter-block prediction and intra-screen prediction in block units. Characterized in that it comprises a coding step of generating second encoded information by Goka, the.

  In addition, the present invention uses the motion vector of the first encoded information, the first encoded information obtained by encoding the image information in block units using inter-frame prediction and intra-screen prediction, In a re-encoding program for transcoding to the second encoded information, a decoding step for decoding the first encoded information, and whether or not a motion vector of the first encoded information is reusable. The motion vector analysis step determined in units of blocks, and the prediction mode of the encoding target block determined that the motion vector is not reusable in the motion vector analysis step are changed to the prediction modes of blocks around the encoding target block. Based on the intra prediction prediction process for changing from inter prediction to intra prediction, the decoded image information is displayed in block units according to the set prediction mode. An encoding step of generating second encoded information by encoding between prediction and intra prediction, and characterized by causing a computer to execute the.

  Exemplary embodiments of a re-encoding device, a re-encoding method, and a re-encoding program according to the present invention will be explained below in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  FIG. 1 is a diagram illustrating a schematic configuration example of a re-encoding device 10 according to an embodiment of the present invention. In the re-encoding device 10 shown in the figure, as an example, MPEG-2 format encoding information is converted to H.264 format. A case of transcoding to H.264 format encoded information will be described. As shown in the figure, the re-encoding device 10 includes a decoding unit (MPEG2 decoder) 100 that decodes the first encoded information (MPEG2 bit stream), and image information decoded by the decoding unit 100. An encoding unit (H.264 encoder) 200 that encodes second encoded information (H.264 bit stream).

  The decoding unit 100 includes a variable length decoding unit 101, an inverse quantization unit 102, an inverse DCT (Discrete Cosine Transformation) unit 103, a calculation unit 104, a frame memory 105, and a motion compensation unit 106. Yes.

  The variable length decoding unit 101 performs variable length decoding on the input first encoded information (MPEG2 bit stream), converts the quantized DCT coefficients to the inverse quantization unit 102, and the motion vector MV to the motion compensation unit 106. , Output to the motion vector analysis unit 201 and motion compensation unit 214 of the encoding unit 200, and output the motion vector MV and the prediction mode to the intra prediction mode determination unit 202 of the encoding unit 200.

  The inverse quantization unit 102 inversely quantizes the quantized DCT coefficient and outputs the DCT coefficient to the inverse DCT unit 103. The inverse DCT unit 103 performs inverse DCT conversion on the DCT coefficient and outputs the result to the arithmetic unit 104.

  The motion compensation unit 106 reads the already decoded image information stored in the frame memory 105 according to the motion vector MV input from the variable length decoding unit 101, and outputs the read image information to the calculation unit 104 as predicted image information.

  The arithmetic unit 104 adds the output information from the inverse DCT unit 103 and the predicted image information from the motion compensation unit 106, thereby decoding the original image information and outputting the decoded image information to the encoding unit 200.

  The encoding unit 200 includes a motion vector analysis unit 201, an intra-screen prediction mode determination unit 202, an image switching unit 203, an intra-screen prediction unit 204, an inter-screen prediction unit 205, a DCT unit 206, and a quantization unit. 207 and a variable-length encoding unit 208.

  The motion vector analysis unit 201 analyzes the motion vector MV input from the variable length decoding unit 101, detects an inappropriate vector (a motion vector that cannot be reused), and determines the detection result of the inappropriate vector as an in-screen prediction mode. To the unit 202.

  The intra prediction mode determination unit 202 changes the prediction mode of the block detected as an inappropriate vector by the motion vector analysis unit 201 to intra prediction, and outputs the changed prediction mode to the image switching unit 203. The changing process to the intra prediction mode of the intra prediction mode determination unit 202 will be described later.

  Based on the prediction mode input from the in-screen prediction mode determination unit 202, the image switching unit 203 converts the image information input from the decoding unit 100 to the in-screen prediction unit 204 in the case of image information to be encoded in the screen. In the case of image information to be inter-screen encoded, it is output to the inter-screen prediction unit 205.

  In the case of image information to be subjected to intra-screen encoding, the intra-screen prediction unit 204 executes an intra 4 × 4 prediction mode or an intra 16 × 16 prediction mode, and has already been encoded in the vicinity of the block to be encoded. Prediction image information is generated from the value, and a difference value from the prediction image information is output to the DCT unit 206.

  In the case of image information to be subjected to inter-screen coding, the inter-screen prediction unit 205 generates predicted image information by performing motion prediction / compensation processing on the encoding target block, and calculates a difference value from the predicted image information. The data is output to the DCT unit 206.

  The DCT unit 206 performs DCT processing on the difference value input from the calculation unit 215 of the intra-screen prediction unit 204 or the inter-screen prediction unit 205, and outputs the resulting DCT coefficient to the quantization unit 207.

  The quantization unit 207 quantizes the input DCT coefficient, and outputs the quantized DCT coefficient to the variable length coding unit 208 and the inverse quantization unit 210 of the inter-screen prediction unit 205.

  The variable length coding unit 208 performs variable length coding on the quantized DCT coefficient and outputs the second coded information (H.264 bit stream).

  The inter-screen prediction unit 205 includes an inverse quantization unit 210, an inverse DCT unit 211, a calculation unit 212, a frame memory 213, a motion compensation unit 214, and a calculation unit 215.

  The calculation unit 215 calculates a difference value between the decoded image information input from the image switching unit 203 and the predicted image information input from the motion compensation unit 214 and outputs the difference value to the DCT unit 206.

  The inverse quantization unit 210 inversely quantizes the quantized DCT coefficient input from the quantization unit 207 and outputs the obtained DCT coefficient to the inverse DCT unit 211. The inverse DCT unit 211 performs inverse DCT processing on the DCT coefficient and outputs the result to the arithmetic unit 212.

  The calculation unit 212 adds the output information from the inverse DCT unit 211 and the predicted image information from the motion compensation unit 214, and locally decodes the original image information. This locally decoded image information is output to and stored in the frame memory 213, and is used when creating predicted image information.

  The motion compensation unit 214 uses the motion vector MV input from the variable length decoding unit 101 of the decoding unit 100 and the reference frame stored in the frame memory 213 to generate predicted image information, and To 215.

  With reference to FIGS. 2-6, the process of the prediction mode determination part 202 in a screen is demonstrated in detail. H. In the H.264 intra prediction encoding, there are two types of intra 4 × 4 prediction mode in which prediction is performed in units of 4 × 4 pixel blocks and intra 16 × 16 prediction mode in which prediction is performed in units of 16 × 16 pixel blocks (macroblocks). A prediction scheme is used.

  FIG. 2 is a diagram for explaining the intra 4 × 4 prediction mode. In the intra 4 × 4 prediction mode, as shown in FIG. 2, there are nine prediction modes shown below. (1) Mode 0 (Vertical prediction), (2) Mode 1 (Horizontal prediction), (3) Mode 2 (DC prediction), (4) Mode 3 (Diagonal down / left prediction), (5) Mod 4 (D) , (6) Mode5 (Vertical-right prediction), (7) Mode6 (Horizontal-down prediction), (8) Mode7 (Vertical-left prediction), (9) Mode8 (Horizontal-prediction). In addition, the intra 16 × 16 prediction mode includes the following four prediction modes. (1) Mode 0 (Vertical prediction), (2) Mode 1 (Horizontal prediction), (3) Mode 2 (DC prediction), (4) Mode 3 (Plane prediction).

  FIG. 3 is a diagram for explaining an encoding target block and an adjacent block to be referred to. In the case of an encoding target block in which the motion vector MV of the first encoding information cannot be reused, the intra prediction mode determination unit 202 determines the screen based on the prediction modes of the upper adjacent block and the left adjacent block of the encoding target block. The intra prediction mode is determined.

  FIG. 4 is a diagram for explaining a method for determining the prediction mode of the block to be encoded for which the motion vector of the first code information is determined to be unusable in the intra prediction mode determination unit 202. 4A is a diagram for explaining determination condition 1, FIG. 4-2 is a diagram for explaining determination condition 2, FIG. 4-3 is a diagram for explaining determination condition 3, and FIG.

(Judgment condition 1)
As shown in FIG. 4A, when the upper adjacent block of the encoding target block that cannot reuse the motion vector of the first encoded information is intra prediction, and the left adjacent block is inter prediction, Select the same prediction mode as the adjacent block.

(Judgment condition 2)
As shown in FIG. 4B, when the upper adjacent block of the encoding target block is inter prediction and the left adjacent block is intra prediction, the same prediction mode as that of the left adjacent block is selected.

(Judgment condition 3)
As shown in FIG. 4C, when the upper adjacent block to be encoded is intra prediction and the left adjacent block is intra prediction, the prediction mode number of the upper adjacent block and the left adjacent block is Select a smaller prediction mode. For example, when prediction mode A> prediction mode B, prediction mode B is selected.

(Judgment condition 4)
As shown in FIG. 4-4, when the upper adjacent block of the encoding target block is inter prediction and the left adjacent block is inter prediction, the inter prediction is selected.

  That is, when the upper adjacent block or the left adjacent block of the encoding target block is the intra prediction encoding, the same intra prediction encoding mode is selected, and both the upper adjacent block and the left adjacent block are in the intra screen. In the case of predictive coding, a prediction mode having a smaller prediction mode number is selected.

  FIG. 5 and FIG. 6 are flowcharts for explaining a method for determining a prediction mode of a block to be encoded in which the motion vector of the first encoded information is determined to be unusable. FIG. 5 is a flowchart for explaining the overall method of determining the prediction mode of the block to be encoded in which the motion vector of the first encoded information is determined to be unusable.

  In FIG. 5, the motion vector analysis unit 201 analyzes the motion vector input from the variable length decoding unit 101 to detect an inappropriate vector (motion vector that cannot be reused). Are output to the in-screen prediction mode determination unit 202 (step S1).

  Whether the intra prediction mode determination unit 202 can reuse the motion vector MV of the first encoded information based on the detection result input from the motion vector analysis unit 201 for each encoding target block. Whether or not the motion vector MV of the first encoded information is reusable (“Yes” in step S2), the inter-screen prediction is selected (step S3), and the first If the motion vector MV of the encoded information cannot be reused (“No” in step S2), intra prediction is selected (step S4).

  FIG. 6 is a flowchart for explaining details of the selection process for intra prediction in step S4 in FIG. In FIG. 6, the intra prediction mode determination unit 202 first determines whether the encoding target block satisfies the determination condition 1 (see FIG. 4A), that is, the upper adjacent block is intra prediction. Then, it is determined whether or not the left adjacent block is inter-screen prediction (step S11). When the determination condition 1 is satisfied (“Yes” in step S11), the same prediction mode as that of the upper adjacent block is set (step S12).

  When the determination condition 1 is not satisfied (“No” in step S11), whether the encoding target block satisfies the determination condition 2 (see FIG. 4-2 above), that is, the upper adjacent block is a screen. It is inter prediction, and it is determined whether the left adjacent block is intra prediction (step S13). When the determination condition 2 is satisfied (“Yes” in step S13), the same prediction mode as that of the left adjacent block is set (step S14).

  When the determination condition 2 is not satisfied (“No” in step S13), whether or not the encoding target block satisfies the determination condition 3 (see FIG. 4-3), that is, the upper adjacent block is predicted in the screen. It is determined whether the left adjacent block is intra prediction (step S15). When the determination condition 3 is satisfied (“Yes” in step S15), it is determined whether or not the prediction mode number of the upper adjacent block <the prediction mode number of the left adjacent block (step S16). When the mode number <prediction mode number of the left adjacent block (“Yes” in step S16), the prediction mode of the upper adjacent block is set (step S17), and the prediction mode number of the upper adjacent block <the left adjacent block If it is not the prediction mode number (“No” in step S16), the prediction mode of the left adjacent block is set (step S18).

  On the other hand, when the determination condition 3 is not satisfied (“No” in step S15), that is, when the determination condition 4 (see FIG. 4-4) is satisfied, inter-screen prediction is set (step S19). That is, when selecting inter-screen prediction, the prediction mode of the first encoded information is used as it is without being changed.

  The intra-screen prediction unit 204 and the inter-screen prediction unit 205 perform intra-screen prediction and inter-screen prediction according to the prediction mode set by the inter-screen prediction mode determination unit 202.

(Modification)
With reference to FIG. 7 and FIG. 8, the process of the prediction mode determination part 202 in a screen which concerns on a modification is demonstrated. In the above embodiment, when the determination condition 4 is satisfied, that is, when the upper adjacent block of the encoding target block is inter-screen encoding and the left adjacent block is inter-screen predictive encoding, the inter-screen In the modification, when the upper adjacent block of the encoding target block is the inter-screen prediction and the left adjacent block is the inter-screen prediction (judgment condition 4), the prediction encoding is selected. The prediction mode is determined based on the prediction mode of the block at the same position of the reference picture before the encoding target block.

  FIG. 7 is a diagram for explaining a prediction mode determination method when the determination condition 4 is satisfied. In FIG. 7, when the upper adjacent block of the encoding target block is inter-screen prediction and the left adjacent block is inter-screen prediction, the prediction of the block at the same position in the reference picture before the encoding target block is performed. When the mode is analyzed and the prediction mode of the block is intra prediction, the same intra prediction is selected as the encoding target block.

  FIG. 8 is a flowchart for explaining a prediction mode determination method when determination condition 4 is satisfied (modified example of the process of step S19 in FIG. 6). In FIG. 8, when the encoding target block satisfies the determination condition 4, the intra prediction mode determination unit 202 sets the prediction mode of the block at the same position of the reference picture before the encoding target block as intra prediction. It is determined whether or not there is (step S21), and in the case of intra prediction (“Yes” in step S21), the same intra prediction is set for the encoding target block (step S22), and inter prediction is performed. (No in step S21), inter-screen prediction is set for the encoding target block (step S23).

  As described above, according to the present embodiment, the first encoded information obtained by encoding the image information by inter-frame prediction in units of blocks is subjected to the second encoding using the motion vector of the first encoded information. In the re-encoding device 10 that transcodes information, the decoding unit 100 decodes the first encoded information, and the motion vector analysis unit 201 determines whether or not the motion vector of the first encoded information is reusable. The intra-screen prediction mode determination unit 202 determines the prediction mode of the encoding target block determined by the motion vector analysis unit 201 that the motion vector is not reusable and the surroundings of the encoding target block. Based on the prediction mode of the block, the inter-screen prediction is changed to the intra-screen prediction, and the intra-screen prediction unit 204 and the inter-screen prediction unit 205 are decoded according to the set prediction mode. Since the second encoded information is generated by encoding the image information by inter-frame prediction and intra-screen prediction on a block basis, the motion vector of the first encoded information cannot be reused, that is, an inappropriate vector. In this case, the prediction mode of the corresponding encoding target block can be switched to intra prediction, and even when there is an inappropriate motion vector, it is possible to prevent an increase in bit amount and deterioration in image quality.

  Further, the intra prediction mode determination unit 202 sets the prediction mode of the encoding target block that has been determined by the motion vector analysis unit 201 that the motion vector is not reusable, as the upper adjacent block and the left adjacent block of the encoding target block. Based on the prediction mode, the inter-screen prediction is changed to the intra-screen prediction, so that it is possible to reduce the amount of calculation when the prediction mode is changed by referring only to the upper adjacent block and the left adjacent block. It becomes.

  Further, the intra prediction mode determination unit 202 indicates the prediction mode of the encoding target block determined by the motion vector analysis unit 201 that the motion vector is not reusable, and (A) the upper adjacent block is the intra prediction. If the left adjacent block is inter-screen prediction, select the same prediction mode as the upper adjacent block, and (B) if the upper adjacent block is inter-screen prediction and the left adjacent block is intra-screen prediction, When the same prediction mode as the left adjacent block is selected, and (C) the upper adjacent block is the intra prediction and the left adjacent block is the intra prediction, the prediction mode number of the upper adjacent block and the left adjacent block is When a small prediction mode is selected and (D) the upper adjacent block is an inter-screen prediction and the left adjacent block is an inter-screen prediction, the inter-screen prediction is selected. It becomes possible to reduce the calculation amount in the case of changing the measurement mode, it is possible to change the prediction mode with high accuracy.

  Also, the intra prediction mode determination unit 202 (D) if the upper adjacent block is inter prediction and the left adjacent block is inter prediction, the same position of the reference picture before the encoding target block It is determined whether the prediction mode of the block is in-screen prediction. If the prediction mode is in-screen prediction, the same in-screen prediction is selected for the encoding target block. Since the inter-screen prediction is selected, the encoding efficiency can be further improved.

  In the above embodiment, MPEG2 to H.264 are used. Although the transcoding to H.264 has been described, the present invention is not limited to this. In the case of transcoding the first encoded information into the second encoded information using intra prediction and inter prediction. Applicable to all. For example, the first encoded information includes MPEG2, MPEG4, H.264. H.264 can be used, and the second encoded information includes MPEG4, H.264, and the like. H.264 or the like can be used.

  In the above embodiment, an example in which the upper adjacent block and the left adjacent block are referred to when the prediction mode of the encoding target block is changed has been described. However, the reference block is not limited to this. The prediction mode can be changed by referring to the surrounding blocks.

  In the above embodiment, the case where the block size of the encoding target block is the same as that of the upper adjacent block and the left adjacent block has been described. However, the present invention can also be applied to a case where the block sizes are different, When at least one of the upper adjacent block and the left adjacent block is intra prediction, the prediction mode of the encoding target block may be changed to the same intra prediction.

  Further, a program for realizing the function of the re-encoding device 10 is recorded on the computer-readable recording medium 500 shown in FIG. 9, and the program recorded on the recording medium 500 is shown in FIG. Each function may be realized by being read into 400 and executed.

A computer 400 shown in the figure has a CPU (Central Proc
essing Unit) 401, an input device 402 such as a keyboard and a mouse, a ROM (Read Only Memory) 403 for storing various data, and a RAM (Random for storing calculation parameters)
(Access Memory) 404, a reading device 405 for reading a program from the recording medium 500, and an output device 406 such as a display or a printer.

The CPU 401 implements the above-described functions by reading a program recorded on the recording medium 500 via the reading device 405 and then executing the program. In addition,
Examples of the recording medium 500 include an optical disk, a flexible disk, and a hard disk.

  As described above, the re-encoding device, the re-encoding method, and the re-encoding program according to the present invention are useful for various devices equipped with a re-encoding function, and are used for, for example, a DVD / HDD recorder. Is possible.

It is a figure which shows the structural example of the outline of the re-encoding apparatus which concerns on one Example of this invention. It is a figure for demonstrating intra 4x4 prediction mode. It is a figure for demonstrating the encoding object macroblock and the adjacent macroblock to refer. It is a figure for demonstrating the determination method of the prediction mode of the encoding object block determined with the motion vector of 1st code information being unusable (the 1). It is a figure for demonstrating the determination method of the prediction mode of the encoding object block determined with the motion vector of 1st code information being unusable (the 2). It is a figure for demonstrating the determination method of the prediction mode of the encoding object block determined with the motion vector of 1st code information being unusable (the 3). It is a figure for demonstrating the determination method of the prediction mode of the encoding object block determined with the motion vector of 1st code information being unusable (the 4). It is a flowchart for demonstrating the whole determination method of the prediction mode of the encoding object block determined with the motion vector of 1st encoding information being unusable. FIG. 6 is a flowchart for explaining details of selection processing of an intra prediction encoding mode in step S4 in FIG. It is a figure for demonstrating the determination method of the prediction mode in the case of the determination conditions 4. FIG. It is a flowchart for demonstrating the determination method of the prediction mode in the case of the determination conditions 4. It is a figure which shows the structural example of the outline of the re-encoding apparatus which concerns on the other Example of this invention. It is a figure for demonstrating an improper motion vector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Re-encoding apparatus 100 Decoding part 101 Variable length decoding part 102 Inverse quantization part

DESCRIPTION OF SYMBOLS 103 Inverse DCT part 104 Operation part 105 Frame memory 106 Motion compensation part 200 Encoding part 201 Motion vector analysis part 202 Intra-screen prediction mode determination part 203 Image switching part 204 In-screen prediction part 205 Inter-screen prediction part 206 DCT part 207 Quantization Unit 208 variable length encoding unit 210 inverse quantization unit 211 inverse DCT unit 212 calculation unit 213 frame memory 214 motion compensation unit 215 calculation unit 400 computer 401 CPU
402 Input device 403 ROM
404 RAM
405 Reading device 406 Output device 500 Recording medium

Claims (7)

Re-encoding device that transcodes first encoded information obtained by encoding image information in units of blocks using inter-screen prediction into second encoded information using a motion vector of the first encoded information In
Decoding means for decoding the first encoded information;
Motion vector analysis means for determining whether or not the motion vector of the first encoded information is reusable in units of blocks;
The prediction mode of the encoding target block determined that the motion vector is not reusable by the motion vector analysis means is changed from the inter-screen prediction to the intra-screen prediction based on the prediction modes of the blocks around the encoding target block. In-screen prediction determination means to be changed,
Encoding means for encoding the decoded image information by inter-frame prediction and intra-screen prediction in units of blocks according to the set prediction mode to generate second encoded information;
A re-encoding device comprising:   The intra-screen prediction determining means determines the prediction mode of the encoding target block determined by the motion vector analyzing means as not being reusable, and the prediction mode of the upper adjacent block and the left adjacent block of the encoding target block. The re-encoding apparatus according to claim 1, wherein the re-encoding apparatus changes from inter-screen prediction to intra-screen prediction based on the above. The in-screen prediction determination unit is configured to select a prediction mode of a block to be encoded that has been determined by the motion vector analysis unit that a motion vector cannot be reused.
(A) When the upper adjacent block is intra prediction and the left adjacent block is inter prediction, the same prediction mode as the upper adjacent block is selected,
(B) If the upper adjacent block is inter prediction prediction and the left adjacent block is intra prediction, select the same prediction mode as the left adjacent block,
(C) When the upper adjacent block is intra prediction and the left adjacent block is intra prediction, a prediction mode having a smaller prediction mode number is selected from the upper adjacent block and the left adjacent block.
(D) The re-encoding according to claim 2, wherein when the upper adjacent block is an inter-screen prediction and the left adjacent block is an inter-screen prediction, an inter-screen prediction encoding is selected. apparatus.   The intra-screen prediction determination means (D) if the upper adjacent block is inter-screen prediction and the left adjacent block is inter-screen prediction, the block at the same position of the reference picture before the encoding target block It is determined whether the prediction mode is intra prediction, and if it is intra prediction, the same intra prediction is selected as the encoding target block. The re-encoding device according to claim 3, wherein prediction is selected.   The first encoded information conforms to the MPEG2 format, and the second encoded information is H.264. The re-encoding device according to any one of claims 1 to 4, wherein the re-encoding device conforms to the H.264 format. Re-encoding method for transcoding first encoded information obtained by encoding image information in units of blocks using inter-screen prediction into second encoded information using a motion vector of the first encoded information In
A decoding step of decoding the first encoded information;
A motion vector analysis step of determining whether or not the motion vector of the first encoded information is reusable in units of blocks;
The prediction mode of the coding target block determined that the motion vector is not reusable in the motion vector analysis step is changed from inter-screen prediction to intra-screen prediction based on the prediction mode of the blocks around the coding target block. In-screen prediction determination process to be changed,
According to the set prediction mode, an encoding step of encoding the decoded image information by inter-screen prediction and intra-screen prediction in units of blocks to generate second encoded information;
A re-encoding method comprising: Re-transmission of causing the computer to transcode the first encoded information obtained by encoding the image information in units of blocks using inter-frame prediction into the second encoded information using the motion vector of the first encoded information. In the encoding program,
A decoding step of decoding the first encoded information;
A motion vector analysis step of determining whether or not the motion vector of the first encoded information is reusable in units of blocks;
The prediction mode of the coding target block determined that the motion vector is not reusable in the motion vector analysis step is changed from inter-screen prediction to intra-screen prediction based on the prediction mode of the blocks around the coding target block. In-screen prediction determination process to be changed,
According to the set prediction mode, an encoding step of encoding the decoded image information by inter-screen prediction and intra-screen prediction in units of blocks to generate second encoded information;
A re-encoding program that causes a computer to execute.

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