JP2009055124A - Encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an encoder which includes a mark not to be specified easily in a video stream without affecting a display image, and to provide an encoding method. <P>SOLUTION: The encoder includes an encoding section for outputting a first code on a first code table which matches input data according with the first code table or outputting a second code on a second code table which corresponds to input data not according with the first code table and a section for deciding whether input data accords with the first code table and satisfies predetermined conditions. When the condition decision section determines that the input data accords with the first code table and satisfies predetermined conditions, the encoder makes the encoding section output a second code in place of the first code. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention generally relates to an encoding apparatus, and more particularly to an encoding apparatus using variable-length encoding processing.

  FIG. 1 is a block diagram of a general video encoding apparatus based on the MPEG system. 1 includes a DCT unit 11, a quantization unit 12, a variable length coding unit 13, an inverse quantization unit 14, an inverse DCT unit 15, a frame memory 16, a motion prediction unit 17, and a subtractor 18. including.

  First, with respect to the input video signal, a difference between images based on the motion prediction process is calculated by the subtracter 18 to obtain a difference signal. The differential signal is subjected to DCT (Discrete Cosine Transform) conversion processing by the DCT unit 11 and quantization processing by the quantization unit 12, and then the quantized DCT coefficients are variable length encoded by the variable length encoding unit 13. By processing, a video stream is generated and output. In parallel with this processing, the quantized signal is subjected to inverse quantization processing by the inverse DCT unit 15 and inverse DCT conversion processing by the inverse DCT unit 15, and the obtained decoded image is temporarily stored in the frame memory 16. To do. The motion prediction unit 17 reconstructs the image by moving the decoded image stored in the frame memory 16 by the motion vector obtained by the operation, and the subtractor 18 reconstructs the reconstructed image and the original image of the input video signal. The motion prediction process is executed by obtaining the difference between the motion prediction process and the motion prediction process. Note that the intra-frame encoded picture in the input video signal is encoded only by the information of the picture, and is not a target of motion prediction processing.

  FIG. 2 is a block diagram of a general video decoding apparatus based on the MPEG system. 2 includes a variable length decoding unit 21, an inverse quantization unit 22, an inverse DCT unit 23, a frame memory 24, a motion compensation unit 25, and an addition unit 26.

  In the video decoding device 20, the received video stream is converted back to the quantized DCT coefficient signal by variable length decoding by the variable length decoding unit 21, and the quantized DCT coefficient signal is dequantized by the inverse quantization unit 22. The decoded difference image is restored by performing inverse DCT conversion processing by the processing and inverse DCT unit 23. In parallel with this process, the decoded image after the inverse DCT conversion process is temporarily stored in the frame memory 24. The motion compensation unit 25 reconstructs the image by moving the decoded image stored in the frame memory 24 by the motion vector, and the addition unit 26 adds the reconstructed image and the difference image to perform motion compensation processing. Execute. The signal after the addition by the adding unit 26 is output as a decoded video signal. Note that an intra-frame coded picture is decoded only by information about the picture, and is not a target of motion compensation processing.

  When distributing a video stream generated by the video encoding apparatus 10 as described above and to be decoded by the video decoding apparatus 20, the distribution of the video stream is given a right (license) by marking the distribution video stream. It is desirable to show that it has been encoded based on. If it is possible to determine whether or not the video stream is encoded based on legitimate rights based on the presence or absence of such a mark, a video stream generated using illegal means (illegal copy or the like) It becomes possible to eliminate.

For example, a method of inserting a logo such as a company name as a mark in a part of the original video or attaching individual information as a mark to a user data area of a video stream is conceivable. However, if the logo is inserted into the video, the logo is always displayed on the screen to be displayed, and there is a possibility that the viewability may be significantly impaired. In addition, since the individual information attached to the user data area may be easily tampered with by an editor or the like, the method of attaching such individual information is not optimal. That is, a method of inserting easily identifiable marks such as individual information at positions that are easily specified in a user data area or the like is not preferable because tampering is easy.
JP-A-6-105296 JP-A-9-128874

  In view of the above, an object of the present invention is to provide an encoding device and an encoding method that include in a video stream a mark that does not affect a displayed video and that is not easily specified.

  When the input data matches the first code table, the encoding device outputs the first code of the first code table corresponding to the input data, and the input data matches the first code table. An encoding unit that outputs the second code of the second code table corresponding to the input data when they do not match, and the input data is data that matches the first code table and satisfies a predetermined condition A condition determining unit that determines whether or not the input data is data that matches the first code table and satisfies the predetermined condition by the condition determining unit. The second code is output instead of the first code.

  The encoding method outputs a code of the first code table corresponding to the input data when the input data matches the first code table and does not satisfy a predetermined condition, and the input data is the first code table. If the code of the second code table corresponding to the input data is output when the input data does not match the code table, and the input data is data that matches the first code table and satisfies the predetermined condition Each step of outputting the code of the second code table corresponding to the input data is included.

  According to at least one embodiment of the present invention, a mark that is not easily identified, falsified, or imitated can be included in the video stream without affecting the displayed video. In addition, since the video stream generated by the embodiment of the present invention is completely compliant with the MPEG standard, it can be normally decoded without any problem by the decoding device on the receiving side.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 3 is a block diagram of a video encoding apparatus based on the MPEG system according to the present invention. 3, the same components as those in FIG. 1 are referred to by the same numerals, and a description thereof will be omitted.

  3 includes a DCT unit 11, a quantization unit 12, a variable length coding unit 33, an inverse quantization unit 14, an inverse DCT unit 15, a frame memory 16, a motion prediction unit 17, and a subtractor 18. including. Compared to the conventional video encoding apparatus 10 of FIG. 1, the variable length encoding unit 13 is replaced by a variable length encoding unit 33.

  In the variable length coding in the variable length coding unit 33, a zero run length code is assigned to the DCT coefficient after the quantization process. The zero run length code is a system in which one code is assigned to a combination of a continuous zero level signal and a subsequent non-zero level signal in a signal to be encoded. At this time, a first code table is created by combining a number of zero level signals (RUN), a signal value other than zero level (LEVEL), and a code. By assigning a Huffman code according to the frequency of the combination of RUN and LEVEL, a short code is assigned to a high-frequency combination, and a long code is assigned to a low-frequency combination. That is, the first code table is a variable length code table.

  FIG. 4 is a diagram illustrating an example of a variable length code table. As shown in FIG. 4, the variable length code table stores variable length codes in association with combinations of RUN and LEVL. For example, when RUN is 1 and LEVEL is 1, that is, the data to be encoded is “01”, a variable-length code 010s is assigned. Here, s at the end represents a sign. If s = 0, the LEVEL value is positive, and if s = 1, the LEVEL value is negative. Therefore, the variable length code corresponding to the encoding target data “0, +1” is 0100, and the variable length code corresponding to the encoding target data “0, −1” is 0101. For example, for example, when RUN is 0 and LEVEL is -3, that is, the data to be encoded is "-3", the variable length code is 01111. For example, when the RUN is 3 and the LEVEL is +1, that is, the encoding target data is “0, 0, 0, +1”, the variable length code is 001110.

  In general, since there are many combinations of RUN and LEVEL, only the combination of RUN and LEVEL with a high probability of occurrence is prepared as a variable length coding table as shown in FIG. For combinations of RUN and LEVEL that do not exist in the variable-length code table, an escape code, a fixed-length code corresponding to RUN that follows, and a fixed-length code corresponding to LEVEL that follows the escape code are used. A fixed-length code table for RUN and a fixed-length code table for LEVEL are prepared as a second code table.

  FIG. 5 is a diagram illustrating a fixed-length code table for RUN and a fixed-length code table for LEVEL. FIG. 5A shows a fixed-length code table for RUN. As shown in the figure, for example, when RUN is 2, a 6-bit fixed-length code 000010 is used. FIG. 5B shows a fixed-length code table for LEVEL. As shown in the figure, for example, when LEVEL is +2047, a 12-bit fixed length code 011111111111 is used. Therefore, when RUN is 2 and LEVEL is +2047, that is, when the data to be encoded is “0, 0, +2047”, the fixed-length code is 000010 + 0111111111111 (the “+” symbol is inserted for easy viewing). Yes, but not really) This 18-bit fixed length code is output following the escape code 000001 (defined in the variable length code table of FIG. 4).

  When the escape code is used in this way, there is a disadvantage that the code length becomes long. However, as long as escape codes are used, codes can be assigned to all combinations of RUN and LEVEL.

  In general, the fixed-length code table shown in FIG. 5 is used in the case of a combination of RUN and LEVEL whose data to be encoded does not exist in the variable-length code table shown in FIG. That is, in the conventional variable length encoding unit 13 shown in FIG. 1, when the input data to be encoded (quantized DCT coefficient of the input video signal) matches the variable length code table, the input data is handled. The code of the variable length code table is output, and when the input data does not match the variable length code table, the code of the fixed length code table corresponding to the input data is output.

  On the other hand, in the variable length coding unit 33 of the present invention, as described below, even if the data to be coded is a combination of RUN and LEVEL existing in the variable length code table of FIG. If the condition is satisfied, (escape code) + (RUN fixed length code) + (LEVEL fixed length code) is assigned to the encoding target data using the fixed length code table of FIG. That is, when it is determined that the input data is data that matches the variable length code table and satisfies a predetermined condition, the fixed length corresponding to the input data is used instead of the code of the variable length code table corresponding to the input data. It is configured to output the code of the code table.

  The predetermined condition may be at least a part of the condition that the input data is data that matches a specific pattern in the variable length code table. That is, in the variable length code table of FIG. 4, for example, a pattern (combination) in which RUN is 2 and LEVEL is −1 may be set as the predetermined condition. In this case, when the input data “0, 0, −1” (RUN is 2 and LEVEL is −1) appears in the input data stream, the variable length code corresponding to this input data is originally 001011. The variable-length encoding unit 33 outputs the fixed-length code 000010 + 1111111111111 extracted from the fixed-length code table of FIG. 5 following the escape code instead of the variable-length code.

  The predetermined condition may include a condition for designating a specific one of a plurality of input data matching a specific pattern in the input data stream. For example, in the above example, if all the input data “0, 0, −1” appearing in the input data stream is converted into a fixed-length code following the escape code, the deterioration of the encoding efficiency reaches an undesirable level. There is a possibility that. In addition, for those who intend to tamper or imitate a mark indicating whether or not the video stream is based on a legitimate right, the input data “0, 0, −1” originally corresponding to the variable length code table is always an escape code. If it is replaced with the following fixed-length code, the mark generation algorithm can be decoded relatively easily.

  Therefore, instead of assigning a fixed-length code following the escape code to all of the plurality of input data “0, 0, −1” appearing in the input data stream, it is specified among such a plurality of input data. A fixed-length code following an escape code may be assigned only to those, and a normal variable-length code may be assigned otherwise. For example, as described later, only the input data “0, 0, −1” that first appears in each picture (frame) is converted into a fixed-length code following the escape code, and the other input data “0, 0” , -1 "may be converted into a variable length code.

  FIG. 6 is a flowchart illustrating a procedure of variable length encoding processing executed by the variable length encoding unit 33. This variable length encoding process is performed on the DCT coefficient after the quantization process of the target block of the input video signal.

  In step S1, the DCT coefficient after the quantization process is scanned from the low frequency region side to the high frequency region side to determine whether a coefficient other than zero exists. When a coefficient other than zero appears (Yes in step S1), in step S2, a combination of RUN and LEVEL (RUN, LEVEL) is extracted.

  In step S3, it is determined whether or not the extracted (RUN, LEVEL) combination exists in the variable length code table. If it exists, it is determined in step S4 whether or not the extracted (RUN, LEVEL) combination satisfies the specified condition. If the specified condition is not satisfied, in step S5, a variable length code is assigned to the extracted (RUN, LEVEL) combination according to the variable length code table.

  If it is determined in step S3 that the extracted (RUN, LEVEL) combination does not exist in the variable-length code table, or if the extracted (RUN, LEVEL) combination satisfies the specified condition, step S4 When the determination is made in step S6, the process proceeds to step S6. In step S6, an escape code is inserted. Further, in step S7, a corresponding fixed-length code in the fixed-length code table is assigned to the extracted (RUN, LEVEL) combination. Through the processes in steps S6 and S7, encoded data is generated as an escape code and a fixed-length code following the escape code.

  When encoded data is generated in step S5 or step S7, the process returns to step S1 and the subsequent processing is repeated. If there is no coefficient other than zero in step S1, that is, if zero continues until the end of the block of interest, the process proceeds to step S8, and an EOB (End of Block) code is inserted. That is, a code corresponding to EOB shown in the variable length code table of FIG. 4 is output as encoded data. Thus, the encoding process for the block of interest ends.

  FIG. 7 is a block configuration diagram showing an example of the configuration of the variable length encoding unit 33 in FIG. 7 includes a coefficient position counter 41, a level detection unit 42, a zero run number detection unit 43, a fixed length code allocation unit 44, a variable length code allocation unit 45, a condition determination unit 46, a selector 47, A selector 48, an EOB code assigning unit 49, and a selector 50 are included.

  The variable length coding process by the variable length coding unit 33 is executed on the DCT coefficient after the quantization process of the target block of the input video signal. The DCT coefficients after the quantization processing of the block of interest are supplied in the order in which the block is scanned with a predetermined scanning pattern.

  First, the coefficient position counter 41 obtains the scan count position (0 to 63) by counting the input DCT coefficient, and outputs the obtained scan count position (0 to 63). Further, the level detection unit 42 detects the level (coefficient value) of the input DCT coefficient, and outputs a Zero_Enable instruction signal indicating a period during which the DCT coefficient value is zero level.

  The zero run number detection unit 43 generates and outputs a zero run number RUN according to the scan count position and the Zero_Enable instruction signal. The zero run number RUN is output when a non-zero coefficient appears in the DCT coefficient sequence supplied in the scanning order. When the current DCT coefficient is the last of the block of interest, the zero run number detection unit 43 asserts an EOB_Enable instruction signal.

  The fixed-length code assigning unit 44 identifies the corresponding fixed-length code according to the RUN from the zero-run number detecting unit 43 and the LEVEL from the level detecting unit 42, and the identified fixed-length code is arranged following the escape code. Output encoded data. Specifically, the fixed-length code assigning unit 44 includes a fixed-length code table shown in FIG. 5 and identifies a fixed-length code in the fixed-length code table that matches the input RUN and LEVEL. Further, the fixed-length code specified as the escape code is connected, and (escape code) + (RUN fixed-length code) + (LEVEL fixed-length code) is output.

  The variable length code assigning unit 45 collates the RUN from the zero run number detection unit 43 and the LEVEL from the level detection unit 42 with the variable length code table, and the combination of the input RUN and LEVEL is any of the variable length code tables. The VLC_Enable instruction signal is set to 1 when the combination of RUN and LEVEL matches, and the VLC_Enable instruction signal is set to 0 when they do not match. Further, the variable length code assigning unit 45 further includes a variable corresponding to the combination of the input RUN and LEVEL when the combination of the input RUN and LEVEL matches one of the combinations of RUN and LEVEL in the variable length code table. A long code is output as encoded data. Specifically, the variable-length code assigning unit 45 includes a variable-length code table shown in FIG. 4, and the combination of RUN and LEVEL that matches the input combination of RUN and LEVEL is included in the variable-length code table. If there is a match, a variable length code corresponding to the matched RUN and LEVEL combination is output.

  The condition determination unit 46 generates an ESC_Enable instruction signal according to the RUN from the zero-run number detection unit 43, the LEVEL from the level detection unit 42, and the designation condition and position information supplied from the outside to the variable length coding unit 33. Is set to 1 or 0. Specifically, for example, when the specified condition is satisfied, the ESC_Enable instruction signal is set to 1, and when the specified condition is not satisfied, the ESC_Enable instruction signal is set to 0.

  Here, the specification condition may include information indicating a combination of the RUN and LEVEL when a specific combination of RUN and LEVEL is a target of escape processing (processing for forcibly assigning a fixed-length code). . For example, when the input data “0, 0, −1” (RUN is 2 and LEVEL is −1) is the target of escape processing as in the above example, RUN is 2 and LEVEL is −1. Is included in the specified condition.

  In addition, for example, the designation condition may indicate that only a combination of a specific RUN and LEVEL that first appears in each picture (frame) is an object of escape processing. Alternatively, it may be instructed that only a combination of a specific RUN and LEVEL that first appears in each slice is an object of escape processing. As described above, when a plurality of input data corresponds to a combination of a specific RUN and LEVEL, only the specific input data among the plurality of input data may be specified as an escape process target. . In order to make such designation, it is necessary to specify the current position of the input data by referring to units such as a frame, a slice, a macroblock, and a block. For this purpose, the condition determining unit 46 may be supplied with position information indicating the current frame, current slice, current macroblock, and current block position (number).

  The selector 47 selects either the escape from the fixed length code assigning unit 44 and the fixed length code or the variable length code from the variable length code assigning unit 45 according to the output of the selector 48. When the output of the selector 48 is 1, the variable length code from the variable length code assigning unit 45 is selected. When the output of the selector 48 is 0, the escape from the fixed length code assigning unit 44 and the fixed length code are selected.

  The selector 48 selects and outputs either the VLC_Enable instruction signal output from the variable length code assigning unit 45 or 0 according to the ESC_Enable instruction signal from the condition determining unit 46. Specifically, when the ESC_Enable instruction signal is 0, the VLC_Enable instruction signal is selectively output, and when the ESC_Enable instruction signal is 1, 0 is selectively output.

  The output of the selector 47 is supplied to the selector 50. The selector 50 selects and outputs the EOB code supplied from the EOB code allocation unit 49 if the EOB_Enable instruction signal from the zero run number detection unit 43 is in the asserted state, and if the EOB_Enable instruction signal is in the negated state, the selector 47 Select an output to output.

  With the above configuration, when the input data matches the variable length code table, the variable length code of the variable length code table corresponding to the input data is output, and when the input data does not match the variable length code table, the input data In the encoding unit that outputs the fixed-length code of the fixed-length code table corresponding to, when it is determined that the input data is data that matches the variable-length code table and satisfies a predetermined condition, instead of the variable-length code A fixed-length code can be output.

  FIG. 8 is a diagram for explaining an example of the designation condition. In the example of FIG. 8, the specified condition is that a predetermined combination (RAN, LEVEL) that appears first in the picture is the target of the escape process. In the example shown in FIG. 8, one picture 60 is partitioned into a plurality of slices (Slice 1 to Slice 8), and each slice is further divided into a plurality of macro blocks (MB1 to MB12). In one macroblock, four luminance blocks are shown. In this example, for example, (RAN, LEVEL) specifies (2, -1) as a specific pattern, and input data that matches this pattern is a candidate for escape processing.

  The Δ mark in the figure indicates a location in the picture 60 where data with (RAN, LEVEL) of (2, −1) has appeared. Further, the x mark indicates the position of the first occurrence in the picture 60 among a plurality of data with (RAN, LEVEL) being (2, -1). In the example shown in FIG. 8, input data having (RAN, LEVEL) of (2, −1) at the position of the x mark is forcibly (escape code) + (fixed length code of RUN) + (LEVEL). Input data with (RAN, LEVEL) of (2, -1) at other positions is converted into a normal variable length code.

  FIG. 9 is a diagram for explaining another example of the designation condition. In the example of FIG. 9, the specified condition is that a predetermined combination (RAN, LEVEL) that first appears in the second macroblock in each slice is the target of the escape process. Similarly to FIG. 8, one picture 60 is partitioned into a plurality of slices (Slice 1 to Slice 8), and each slice is further divided into a plurality of macro blocks (MB1 to MB12). In one macroblock, four luminance blocks are shown. In this example, for example, (RAN, LEVEL) specifies (2, -1) as a specific pattern, and input data that matches this pattern is a candidate for escape processing.

  The Δ mark in the figure indicates a location in the picture 60 where data with (RAN, LEVEL) of (2, −1) has appeared. The cross indicates the position of the first occurrence of the second macroblock in each slice among a plurality of data with (RAN, LEVEL) being (2, -1). In the example shown in FIG. 9, input data having (RAN, LEVEL) of (2, −1) at the position of the × mark is forcibly (escape code) + (fixed length code of RUN) + (LEVEL). Input data with (RAN, LEVEL) of (2, -1) at other positions is converted into a normal variable length code.

  FIG. 10 is a diagram for explaining another example of the designation condition. In the example of FIG. 10, the specified condition is that a predetermined combination (RAN, LEVEL) in the block of block number 0 that appears first in the picture is the target of the escape process. Similar to FIG. 8, the picture 60 is divided into a plurality of slices and a plurality of macroblocks, and each macroblock includes four luminance blocks of block numbers 0 to 3. The upper left block of each macro block is the luminance block with block number 0. In this example, for example, (RAN, LEVEL) specifies (2, -1) as a specific pattern, and input data that matches this pattern is a candidate for escape processing.

  The Δ mark in the figure indicates a location in the picture 60 where data with (RAN, LEVEL) of (2, −1) has appeared. The cross indicates the position of the first occurrence in the picture in the block of block number 0 among the plurality of data with (RAN, LEVEL) being (2, -1). In the example shown in FIG. 9, input data having (RAN, LEVEL) of (2, −1) at the position of the × mark is forcibly (escape code) + (fixed length code of RUN) + (LEVEL). Input data with (RAN, LEVEL) of (2, -1) at other positions is converted into a normal variable length code.

  FIG. 11 is a flowchart showing the setting operation of the ESC_Enable instruction signal by the condition determination unit 46 shown in FIG.

  First, in step S1, ESC_Count and ESC_Enable are each initialized to 0. ESC_Count is a variable used to count the number of times that the specified condition is satisfied. ESC_Enable is a variable that is set to 1 when the specified condition is satisfied, and is set to 0 when the specified condition is not satisfied, and corresponds to the ESC_Enable instruction signal in FIG.

  In step S2, it is determined whether or not an ESC counter initialization condition is satisfied. That is, it is determined whether or not ESC_Count should be initialized to 0. This ESC counter initialization condition differs depending on the specified condition for executing the escape process. For example, in the case of the designation condition shown in FIG. 8, it is necessary to initialize the ESC counter at the beginning of each picture. Therefore, if the current input data position corresponds to the top of the picture, the ESC counter initialization condition is satisfied. Further, in the case of the designation condition shown in FIG. 9, it is necessary to initialize the ESC counter at the head of each slice. Therefore, if the current input data position corresponds to the head of each slice, the ESC counter initialization condition is satisfied. Further, in the case of the designation condition shown in FIG. 10, it is necessary to initialize the ESC counter at the head of each picture. Therefore, if the current input data position corresponds to the top of the picture, the ESC counter initialization condition is satisfied.

  In step S3, ESC_Count is set to 0. In step S4, it is determined whether or not the combination (RUN, LEVEL) of the input data matches the combination (RUN, LEVEL) specified in the specified condition. If they match, it is determined in step S5 whether or not the ESC use condition is satisfied. The ESC use condition varies depending on the designated condition for executing the escape process. For example, in the case of the designation condition of the example shown in FIG. 8, there is no designation of the ESC use condition, and the determination result in step S5 is always Yes. In addition, in the case of the specification condition of the example shown in FIG. 9, whether or not the current input data is that of the second macroblock of each slice is the ESC use condition. That is, when the current input data is the second macroblock of each slice, the determination result in step S5 is Yes. In addition, in the case of the designation condition shown in FIG. 10, whether the current input data is for the block with block number 0 is the ESC use condition. That is, if the current input data is for the block with block number 0, the determination result in step S5 is Yes.

  In step S6, it is determined whether ESC_Count is 0 or not. The determination result is Yes when the specified condition for executing the escape process is satisfied for the first time since the ESC counter initialization condition in step S2 is satisfied. Subsequent to step S6, ESC_Enable is set to 1 in step S7, ESC_Count is set to 1 in step S8, and the process returns to step S2. If the determination result is No in any of steps S4 to S6, ESC_Enable is set to 0 in step S9.

  The condition determination unit 46 executes the above process, thereby setting an ESC_Enable instruction signal. As a result, as shown in the examples of FIGS. 8 to 10, the ESC_Enable instruction signal can be set to 1 only at the portion marked with a cross.

  In the example of FIG. 10, the predetermined combination (RAN, LEVEL) that first appears in the second macroblock in each slice is the target of the escape process, but the macroblocks at other desired positions (not the second) ( Nth macroblock) may be the target. Further, in the example of FIG. 11, the predetermined combination (RAN, LEVEL) of the block of block number 0 that appears first in the picture is the target of the escape process, but the block at another desired position instead of block number 0 (Block of block number M) may be the target. Further, in each example of FIGS. 8 to 10, the condition such as the data that appears second may be used instead of the condition that the data appears first.

  Further, for example, when the remainder value when the picture count value is divided by 3 is 0, the specified condition shown in FIG. 8 is used, and when the remainder value when the picture count value is divided by 3 is 1, FIG. The designated condition may be changed for each picture, for example, when the remainder when the picture count value is divided by 3 is 2, the designated condition shown in FIG. 10 is used.

  As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to the said Example, A various deformation | transformation is possible within the range as described in a claim.

The present invention includes the following contents.
(Appendix 1)
When the input data matches the first code table, the first code of the first code table corresponding to the input data is output, and when the input data does not match the first code table, the An encoding unit that outputs the second code of the second code table corresponding to the input data;
A condition determination unit that determines whether the input data is data that matches the first code table and satisfies a predetermined condition, and the condition determination unit inputs the input data to the first code table; An encoding apparatus, characterized in that if the data match and the predetermined condition is determined, the encoding unit outputs the second code instead of the first code.
(Appendix 2)
The encoding apparatus according to appendix 1, wherein the predetermined condition includes at least part of the condition that the input data is data that matches a specific pattern in the first code table.
(Appendix 3)
The encoding apparatus according to claim 2, wherein the predetermined condition includes a condition for designating a specific one of a plurality of input data matching the specific pattern in the input data stream.
(Appendix 4)
The input data is video data in which each frame includes a plurality of slices and a plurality of blocks, and the predetermined condition refers to the plurality of input data with reference to at least one of the frames, the slices, and the blocks. The encoding apparatus according to appendix 3, wherein a specific one is designated.
(Appendix 5)
The encoding apparatus according to supplementary note 1, wherein the first code table is a variable-length code table, and the second code table is a fixed-length code table.
(Appendix 6)
The encoding apparatus according to appendix 1, wherein the encoding unit is configured to output the second code following an escape code.
(Appendix 7)
When the input data matches the first code table and does not satisfy a predetermined condition, the code of the first code table corresponding to the input data is output,
When the input data does not match the first code table, the code of the second code table corresponding to the input data is output,
And including each step of outputting a code of the second code table corresponding to the input data when the input data is data matching the first code table and satisfies the predetermined condition. Encoding method.
(Appendix 8)
The encoding method according to appendix 7, wherein the first code table is a variable length code table and the second code table is a fixed length code table.
(Appendix 9)
The encoding according to appendix 7, wherein when the code of the second code table is output, an escape code is output first, and then the code of the second code table is output following the escape code Method.

It is a block diagram of a general video encoding device based on the MPEG system. It is a block diagram of a general video decoding device based on the MPEG system. 1 is a block diagram of a video encoding apparatus based on an MPEG system according to the present invention. It is a figure which shows an example of a variable length code table. It is a figure which shows the fixed length code table with respect to RUN, and the fixed length code table with respect to LEVEL. It is a flowchart which shows the procedure of the variable length encoding process which the variable length encoding part of FIG. 3 performs. It is a block block diagram which shows an example of a structure of the variable length encoding part of FIG. It is a figure for demonstrating an example of designation | designated conditions. It is a figure for demonstrating another example of designation | designated conditions. It is a figure for demonstrating another example of designation | designated conditions. It is a flowchart which shows the setting operation | movement of the ESC_Enable instruction | indication signal by the condition determination part shown in FIG.

Explanation of symbols

11 DCT unit 12 Quantization unit 13 Variable length coding unit 14 Inverse quantization unit 15 Inverse DCT unit 16 Frame memory 17 Motion prediction unit 18 Subtractor 33 Variable length coding unit 41 Coefficient position counter 42 Level detection unit 43 Zero run number Detection unit 44 Fixed length code allocation unit 45 Variable length code allocation unit 46 Condition determination unit 47 Selector 48 Selector 49 EOB code allocation unit 50 Selector

Claims (5)

When the input data matches the first code table, the first code of the first code table corresponding to the input data is output, and when the input data does not match the first code table, the An encoding unit that outputs the second code of the second code table corresponding to the input data;
A condition determination unit that determines whether the input data is data that matches the first code table and satisfies a predetermined condition, and the condition determination unit inputs the input data to the first code table; An encoding apparatus, characterized in that if the data match and the predetermined condition is determined, the encoding unit outputs the second code instead of the first code.   2. The encoding apparatus according to claim 1, wherein the predetermined condition includes at least part of the condition that the input data is data that matches a specific pattern in the first code table.   3. The encoding apparatus according to claim 2, wherein the predetermined condition includes a condition for designating a specific one of the plurality of input data matching the specific pattern in the input data stream.   The input data is video data in which each frame includes a plurality of slices and a plurality of blocks, and the predetermined condition refers to the plurality of input data with reference to at least one of the frames, the slices, and the blocks. 4. The encoding apparatus according to claim 3, wherein a specific one is designated.   2. The encoding apparatus according to claim 1, wherein the first code table is a variable-length code table, and the second code table is a fixed-length code table.

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