JP2022140729A - Video decoding device and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the borderline of a coding block inconspicuous.

SOLUTION: A video coding device 1 encodes the signal of a video of each coding block by interframe prediction or intraframe prediction. A color-difference conversion part 201 of the video coding device 1 performs color-difference conversion processing for converting the pixel value in a first range around a prescribed pixel value, into the pixel value in a second range around a prescribed pixel value and narrower than the first range, for the color-difference signal of a local decoding image in the coding block used for interframe prediction or intraframe prediction.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a video encoding device, a video decoding device and a program.

FIG. 6 shows AVC (Advanced Video Coding)/H. 264 system, HEVC (High Efficiency Video Coding)/H. 1 is a diagram showing the configuration of a general video encoding device 9 based on the H.265 system. FIG. A frame of the input video is divided into coding blocks in the block dividing section 100 . Subsequent processing for the encoding target frame is performed for each encoding block. After subtraction section 101 subtracts the difference from the prediction signal, the encoding target frame is subjected to orthogonal transform such as DCT (discrete cosine transform) or DST (discrete sine transform) in orthogonal transform section 102, and is subjected to quantization section. Quantized at 103 . The quantized coefficients are entropy coded in entropy coding section 104 .

The quantized coefficients are inversely quantized in inverse quantization section 105 and then subjected to inverse orthogonal transform such as inverse DCT and inverse DST in inverse orthogonal transform section 106 . After that, the addition unit 107 adds the prediction signals to obtain a locally decoded image. The intra-frame prediction unit 110 predicts pixel values using a locally decoded image in the same frame as the encoding target frame. The inter-frame prediction unit 111 refers to the reference memory 109 that stores the locally decoded image after the loop filter 108 is applied, and performs pixel value prediction.

A prediction signal generated by the intra-frame prediction unit 110 or a prediction signal generated by the inter-frame prediction unit 111 is selected by the intra-frame prediction/inter-frame prediction switching unit 112 . The prediction signal is subtracted by subtraction section 101 in the next encoding process and is also used for addition by addition section 107 . Although not shown, the mode used by the intra-frame prediction unit 110, the motion vector used by the inter-frame prediction unit 111, and the switching signal used by the intra-frame prediction/inter-frame prediction switching unit 112 are also generated by the entropy coding unit 104. Entropy-encoded and sent.

Supervised by Sakae Okubo, "Impress Standard Textbook Series H.265/HEVC Textbook", Impress Japan Co., Ltd., 2013 "Recommendation ITU-T H.265", International Telecommunication Union, 2013

For example, an area with fine textures and almost uniform colors, such as images of a river with sparkling water or a choppy sea, can be captured using AVC/H.264 or HEVC/H.265. When encoded using , the otherwise uniform color may change, and the boundaries of encoded blocks may become conspicuous.

The present invention has been made in consideration of such circumstances, and provides a video encoding device, a video decoding device, and a program capable of making boundaries between encoding blocks inconspicuous.

One aspect of the present invention is a video encoding device that encodes a video signal for each encoding block by inter-frame prediction or intra-frame prediction, wherein the encoding block used for the inter-frame prediction or the intra-frame prediction With respect to the color difference signal of the local decoded image, the pixel values within a first range centered on a predetermined pixel value are set to a second range centered on the predetermined pixel value and narrower than the first range and a color-difference conversion unit that performs color-difference conversion processing to convert pixel values into values within the range of .

One aspect of the present invention is the video encoding device described above, wherein information indicating one or more of the predetermined pixel value, the first range, and the second range is encoded It is characterized by further comprising a first setting unit for setting an encoded stream for transmitting the signal.

One aspect of the present invention is the video encoding device described above, wherein information indicating whether or not the color difference conversion process is performed on the encoded block is set in an encoded stream for transmitting the encoded signal. It is characterized by further comprising a setting unit.

One aspect of the present invention is a video decoding device that decodes a signal of a video encoded for each decoded block by inter-frame prediction or intra-frame prediction, wherein the decoding used for the inter-frame prediction or the intra-frame prediction With respect to the color difference signal of the local decoded image of the block, a pixel value within a first range centered on a predetermined pixel value is set to a pixel value centered on the predetermined pixel value and narrower than the first range. and a color-difference conversion unit that performs color-difference conversion processing to convert pixel values into two ranges.

One aspect of the present invention is the video decoding device described above, wherein information indicating one or more of the predetermined pixel value, the first range, and the second range is encoded as the It is characterized by further comprising a first information acquisition unit that acquires from the encoded stream in which the signal is set.

An aspect of the present invention is the video decoding device described above, wherein the information indicating whether or not the color difference conversion process is performed on the decoded block is second information obtained from the encoded stream in which the encoded signal is set. It is characterized by further comprising an acquisition unit.

According to one aspect of the present invention, a computer used as a video encoding device that encodes a video signal for each encoding block by inter-frame prediction or intra-frame prediction is provided with the code used for inter-frame prediction or intra-frame prediction a pixel value within a first range centered on a predetermined pixel value for a color difference signal of a local decoded image of a localized block, centered on the predetermined pixel value and narrower than the first range. A program for executing a color-difference conversion step of converting to pixel values within a second range.

One aspect of the present invention is a computer used as a video decoding device that decodes a video signal encoded for each decoding block by inter-frame prediction or intra-frame prediction. With respect to the color difference signal of the local decoded image of the decoded block, the pixel values within a first range centered on a predetermined pixel value are set centered on the predetermined pixel value and more than the first range. A program for executing a color difference conversion step for converting pixel values within a narrow second range.

ADVANTAGE OF THE INVENTION According to this invention, the boundary of a coding block can be made inconspicuous.

1 is a block diagram showing the configuration of a video encoding device according to a first embodiment of this embodiment; FIG. It is a figure which shows the function used for the color difference conversion process by the same embodiment. FIG. 10 is a diagram showing functions used for color difference conversion processing according to the second embodiment; FIG. 10 is a diagram showing functions used for color difference conversion processing according to the third embodiment; FIG. 21 is a block diagram showing the configuration of a video decoding device according to an eighth embodiment; FIG. 1 is a block diagram showing the configuration of a conventional video encoding device; FIG.

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

[First Embodiment]
FIG. 1 is a block diagram showing the configuration of a video encoding device 1 according to an embodiment of the present invention. In the figure, the same reference numerals are given to the same parts as in the conventional video encoding device 9 shown in FIG. The video encoding device 1 shown in FIG. 107 , a color difference conversion unit 201 , a loop filter 108 , a reference memory 109 , an intra-frame prediction unit 110 , an inter-frame prediction unit 111 , and an intra-frame prediction/inter-frame prediction switching unit 112 . As described above, the video encoding device 1 of the present embodiment differs from the video encoding device 9 of the prior art in that it further includes a color difference conversion unit 201 and an entropy encoding unit instead of the entropy encoding unit 104. 202 is provided.

The block division unit 100 divides a frame of an input video into encoding blocks. Coding blocks are, for example, AVC/H. In the H.264 system, it is a macroblock, and in HEVC/H.264. In the H.265 system, it is a coding unit (CU) or a prediction unit (PU). The video encoding device 1 performs subsequent processing on the encoding target frame for each encoding block.

Subtraction section 101 outputs a prediction residual signal, which is the difference between the encoding target frame and the prediction signal selected by intra-frame prediction/inter-frame prediction switching section 112 , to orthogonal transformation section 102 . Orthogonal transformation section 102 performs orthogonal transformation on the prediction residual signal input from subtraction section 101 . Quantization section 103 quantizes transform coefficients obtained as a result of the orthogonal transform by orthogonal transform section 102 and outputs the quantized transform coefficients to entropy coding section 202 and inverse quantization section 105 .

The inverse quantization unit 105 inversely quantizes the transform coefficients quantized by the quantization unit 103 . The inverse orthogonal transform unit 106 inverse orthogonal transforms the transform coefficients inversely quantized by the inverse quantization unit 105 . The addition unit 107 adds the result of the inverse orthogonal transformation by the inverse orthogonal transformation unit 106 and the prediction signal selected by the intra-frame prediction/inter-frame prediction switching unit 112 to obtain a locally decoded image. A color difference conversion unit 201 performs color difference conversion processing on color difference signals of a local decoded image. In the chrominance conversion process, when the chrominance signal is within a predetermined range around an arbitrarily determined value, conversion is performed so that the value of the chrominance signal approaches a predetermined pixel value.

The loop filter 108 performs filter processing such as reduction of block boundary distortion and pixel value correction based on adjacent pixel values from the locally decoded image subjected to the color difference conversion processing. A reference memory 109 stores the locally decoded image after the loop filter 108 has been applied. The intra-frame prediction unit 110 predicts pixel values using a locally decoded image in the same frame as the encoding target frame. The inter-frame prediction unit 111 refers to the reference memory 109 that stores the locally decoded image after the loop filter 108 is applied, and performs pixel value prediction. The intra-frame prediction/inter-frame prediction switching unit 112 selects either the prediction result of the intra-frame prediction unit 110 or the prediction result of the inter-frame prediction unit 111, and outputs it to the subtraction unit 101 and the addition unit 107 as a predicted image. do.

The entropy coding unit 202 converts the transform coefficients quantized by the quantization unit 103, the mode used by the intra-frame prediction unit 110, the motion vector used by the inter-frame prediction unit 111, and the intra-frame prediction/inter-frame prediction switching unit 112. The switching signal to be used is entropy-encoded and sent. The entropy encoding unit 202 may further entropy-encode parameters for performing color difference conversion processing similar to that of the color difference conversion unit 201 in the video decoding device 3 described in the eighth embodiment described later, and send the parameters.

When a region having a fine texture and a substantially uniform color is coded using AVC/H.264, HEVC/H.265, or the like, the originally uniform color changes, resulting in a change in the code. In some cases, a phenomenon occurs where the boundary between blocks becomes conspicuous. This phenomenon occurs because, for example, an almost achromatic area in the original image changes to light green, purple, or the like due to encoding, and the change differs depending on the encoded block. Therefore, the video encoding device 1 performs color difference transform processing on the color difference signal of the locally decoded image obtained by inverse orthogonal transforming the color difference signal and adding the prediction signal. The video encoding device 1 applies this chrominance conversion processing only to the chrominance signal, not to the luminance signal. That is, the video encoding device 1 does not apply the color difference conversion processing by the color difference conversion unit 201 to the y signal, which is the luminance signal of the locally decoded image, and performs the same operation as in the conventional art. On the other hand, the video encoding device 1 applies color difference conversion processing by the color difference conversion unit 201 to the u signal and v signal, which are the color difference signals of the locally decoded image, to change the color difference values.

The color difference conversion processing performed by the color difference conversion unit 201 suppresses a color difference signal having a value near a predetermined color difference value from greatly changing in color due to prediction processing or quantization processing. As a result, when coding an area having a substantially uniform color and fine texture, the phenomenon that the boundary between coding blocks becomes conspicuous due to a change in color is suppressed.

FIG. 2 is a diagram showing functions used in the color difference conversion process of this embodiment. The chrominance conversion unit 201 of this embodiment uses the functions shown in the figure in the chrominance conversion process. In the function shown in the figure, the horizontal axis represents the input signal and the vertical axis represents the output signal. When the value of the color difference signal is M and the width of the value of the color difference signal is w (w>0), the color difference conversion unit 201 converts the pixel M is output as the value, and when the value is outside this range, the value s of the input signal is output as is.

Each of M and w may be a predetermined value or a value set by a user, and may be one or more predetermined feature values obtained from a frame to be encoded or a plurality of frames including the frame to be encoded, or It may be a value determined according to the result of performing a predetermined calculation on the feature amount. Also, the video encoding device 1 may notify the video decoding device 3 (see FIG. 5 of the eighth embodiment described later) of at least one of M and w applied to the frame to be encoded as a parameter. good. In this case, entropy coding section 202 embeds parameters in the coded stream that transmits the entropy coding result.

A color difference conversion unit 302 (see FIG. 5 of an eighth embodiment, which will be described later) of the video decoding device 3, which will be described later, uses the same M and w as those of the video encoding device 1, which are predetermined or set by the user. , performs color difference conversion processing similar to that of the color difference conversion unit 201 . When the chrominance conversion unit 302 of the video decoding device 3 reads a parameter in which one or more of M and w is set from the encoded stream, it uses the read parameter to perform processing similar to the chrominance conversion unit 201 of the present embodiment. color difference conversion processing.

[Second embodiment]
The configuration of the video encoding device according to the second embodiment is the same as that of the video encoding device 1 of the first embodiment shown in FIG. However, in this embodiment, the color difference conversion unit 201 performs color difference conversion processing using the functions shown in FIG.

FIG. 3 is a diagram showing functions used in the color difference conversion process of this embodiment. As in FIG. 2, the function shown in FIG. 2 represents the input signal on the horizontal axis and the output signal on the vertical axis. Note that s _max is the maximum value that the color difference signal can take.

(1) If the value s of the input signal is less than (M−w), output s×((M−k)/(M−w)).
(2) Output M+(s−M)×(k/w) when the value s of the input signal is in the range of (M−w, M+w).
(3) Output (M+k)+(s−(M+w))×(s _max −(M+k))/(s _max −(M+w)) when the value s of the input signal is greater than or equal to (M+w).

Thus, values in the range (M−w, M+w) of the input signal are converted to values in the range (M−k, M+k). Note that 0<k<w.

Each of M, w, and k may be a predetermined value, or may be a value set by a user. It may be a value determined according to the result of performing a predetermined calculation on the feature amount. Values obtained in the same manner as in the first embodiment may be used for M and w. The entropy encoding unit 202 of the video encoding device 1 may use one or more of the values of M, w, and k as a parameter and embed it in the encoded stream for transmission.

The color difference conversion unit 302 of the video decoding device 3, which will be described later, uses the same M, w, and k as those of the video encoding device 1, which are predetermined or set by the user, and perform the same operations as the color difference conversion unit 201 of the present embodiment. color difference conversion processing. When the color difference conversion unit 302 of the video decoding device 3 reads a parameter in which one or more of M, w, and k is set from the encoded stream, the color difference conversion unit 201 of the present embodiment uses the read parameter. performs the same color difference conversion processing as

In the first embodiment, when the value of the color difference signal is other than the value near M, the original value is maintained, but the output value of the color difference conversion unit 201 becomes discontinuous. Therefore, discontinuity may be conspicuous when applied to a frame having an area where the color difference signal changes gently due to gradation or the like. In this embodiment, all the color difference signals change from their original values, but the values output from the color difference conversion unit 201 do not become discontinuous, so it is suitable for application to such regions.

[Third Embodiment]
The configuration of the video encoding device according to the third embodiment is the same as that of the video encoding device 1 of the first embodiment shown in FIG. However, in this embodiment, the color difference conversion unit 201 performs color difference conversion processing using the functions shown in FIG.

FIG. 4 is a diagram showing functions used in the color difference conversion process of this embodiment. In the function shown in the figure, the horizontal axis represents the input signal and the vertical axis represents the output signal, as in FIGS. The color difference conversion unit 201 outputs the following values. However, 0<k<w<d.

(1) Output s when the input signal value s is less than (M−d) or greater than (M+d).
(2) When the input signal value s is in the range of (Md, Mw), (Md)+(s-(Md))×(dk)/(dw) output.
(3) Output M+(s−M)×(k/w) when the input signal value s is in the range of (M−w, M+w).
(4) Output (M+k)+(s−(M+w))×(d−k)/(d−w) when the input signal value s is in the range of (M+w, M+d).

Each of M, w, k, and d may be a predetermined value or a value set by a user, and may be one or more predetermined values obtained from a frame to be encoded or a plurality of frames including the frame to be encoded. It may be a value determined according to the feature amount or the result of performing a predetermined calculation on the feature amount. M, w and k may be values obtained in the same manner as in the second embodiment. The entropy encoding unit 202 of the video encoding device 1 may use one or more of the values of M, w, k, and d as a parameter and embed it in the encoded stream for transmission.

The color difference conversion unit 302 of the video decoding device 3, which will be described later, uses the same M, w, k, and d as those of the video encoding device 1, which are predetermined or set by the user, to perform the color difference conversion unit 201 of the present embodiment. performs the same color difference conversion processing as When the chrominance conversion unit 302 of the video decoding device 3 reads a parameter in which one or more of M, w, k, and d is set from the encoded stream, the chrominance conversion unit 302 of the present embodiment uses the read parameter. Color difference conversion processing similar to that of the unit 201 is performed.

Compared to the second embodiment, this embodiment has the effect of suppressing the range in which the color difference signal changes from the original value to (M−d, M+d).

[Fourth embodiment]
This embodiment independently determines the value of M for each of the u signal and the v signal in the first to third embodiments described above.

[Fifth Embodiment]
In this embodiment, when the pixel value M for the u signal is Mu and the pixel value M for the v signal is Mv, the color difference conversion unit 201 determines that the value of the u signal is within the range of (Mu−w, Mu+w). If the condition that there is and the value of the v signal is within the range of (Mv−w, Mv+w) is not satisfied, the input signal is output as is.

For example, in a region where the u signal is uniform and has a value close to Mu, but the v signal varies greatly depending on the position, when viewed as a color image, it has "substantially uniform color." It is an area with various colors that cannot be said to be ". In the first to third embodiments, since the two color difference signals of the u signal and the v signal are processed independently of each other, the color difference conversion process is applied even to such a region, and the encoded image quality deteriorates. may decrease. In this embodiment, since the signal is not changed for such a region, deterioration of the encoded image quality is suppressed.

[Sixth Embodiment]
In the present embodiment, the values of parameters such as M, Mu, Mv, w, k, and d can be changed for each encoding block in the first to fifth embodiments described above. When changing the parameter applied to the encoding block from the parameter applied to the immediately preceding encoding block, the video encoding device 1 sets a flag indicating that the value of the parameter is to be changed, and parameters after the change (M, Mu , Mv, w, k, d). The color difference transform unit 201 of the video encoding device 1, for example, converts one or more feature values obtained from the encoding block to be encoded or a plurality of encoding blocks including the encoding block to be encoded, or the feature values It may be determined whether or not to change the parameter based on the result of performing a predetermined calculation in . For example, if the feature amount or the result of performing a predetermined calculation on the feature amount between the encoding block to be encoded and the encoding block that has already been encoded changes more than a predetermined value, the parameter value is changed. Then, it may be determined.

The video decoding device 3, which will be described later, receives from the video encoding device 1 a flag indicating that a parameter value is to be changed, and for the decoded block, the changed parameters such as M, Mu, Mv, w, k, and d are also changed. receive. The color difference conversion unit 302 described later updates the values with the received parameters, and uses the updated parameters to perform color difference conversion processing similar to that of the color difference conversion unit 201 of the video encoding device 1 . Note that the color difference conversion unit 302 performs the color difference conversion process using the same values as when the previous color difference conversion process was performed for the parameters for which the change was not notified. Also, the color difference conversion unit 302 performs the color difference conversion process using the same parameters as when the previous color difference conversion process was performed for the decoded blocks for which the flag indicating that the parameter value is to be changed has not been received.

[Seventh Embodiment]
In the present embodiment, the presence or absence of color difference conversion processing is switched for each encoded block in the above-described third to sixth embodiments. The color difference transform unit 201 of the video encoding device 1, for example, converts one or more feature amounts obtained from an encoding block to be encoded or a plurality of encoding blocks including the encoding block to be encoded, or the feature amounts It is determined whether or not to perform color difference conversion processing for each encoded block based on the result of performing a predetermined calculation. The chrominance conversion unit 201 performs the chrominance conversion processing of the third to sixth embodiments on the blocks determined to be the target of the chrominance conversion processing, and performs the chrominance conversion processing on the blocks determined not to be the target of the chrominance conversion processing. do not The entropy encoding unit 202 of the video encoding device 1 embeds information indicating whether each encoded block is to be subjected to color difference conversion processing in the encoded stream and transmits the encoded stream. Note that the flag may be set only for the encoding blocks targeted for the color difference conversion process, or may be set only for the encoding blocks not targeted for the color difference conversion process.

The chrominance conversion unit 302 of the video decoding device 3, which will be described later, performs chrominance conversion processing on decoded blocks for which a flag indicating the presence of chrominance conversion processing is set or for which a flag indicating the absence of chrominance conversion processing is not set. Also, the chrominance conversion unit 302 does not perform chrominance conversion processing on a decoded block for which a flag indicating no chrominance conversion processing is set or for which a flag indicating that chrominance conversion processing is not set is set.

The video encoding device 1 may set a flag for an encoding block that changed from being subjected to color difference conversion processing to being performed last time and to an encoding block that was changed to being subjected to color difference conversion processing from being performed last time. In this case, the chrominance conversion unit 302 of the video decoding device 3 switches between the presence/absence of chrominance conversion processing from the previous time when the decoded block with the flag set is received.

[Eighth Embodiment]
This embodiment is a video decoding device for decoding video signals encoded by the video encoding devices according to the first to seventh embodiments.

FIG. 5 is a block diagram showing the configuration of the video decoding device 3 according to this embodiment. In the figure, the same reference numerals are given to the same parts as in the video encoding apparatus 1 according to the first embodiment shown in FIG. The video decoding device 3 shown in FIG. It comprises an inter-frame prediction unit 111 and an intra-frame prediction/inter-frame prediction switching unit 112 .

The entropy decoding unit 301 receives the encoded stream received from the video encoding device 1 according to the first to seventh embodiments, and entropy-decodes the quantized transform coefficients of the decoded block, which is the encoding block to be decoded. Furthermore, the entropy decoding unit 301 decodes information about intra-frame prediction, information about inter-frame prediction, and parameters and flags for color difference conversion processing. Entropy decoding section 301 outputs the result of entropy decoding to inverse quantization section 105 , outputs information about intra-frame prediction to intra-frame prediction section 110 , and outputs information about inter-frame prediction to inter-frame prediction section 111 . The entropy decoding unit 301 outputs to the color difference conversion unit 302 when parameters and flags for color difference conversion processing are obtained by decoding.

An inverse quantization unit 105 inversely quantizes the quantized transform coefficients and outputs transform coefficients. The inverse orthogonal transform unit 106 inverse orthogonal transforms the transform coefficients inversely quantized by the inverse quantization unit 105 . The addition unit 107 adds the result of the inverse orthogonal transformation by the inverse orthogonal transformation unit 106 and the prediction signal selected by the intra-frame prediction/inter-frame prediction switching unit 112 to obtain a locally decoded image. The chrominance conversion unit 302 uses predetermined parameters, parameters set by the user, or parameters and flags obtained from the encoded stream by the entropy decoding unit 301 to perform the same operations as in the first to seventh embodiments. Perform color difference conversion processing.

The loop filter 108 performs filter processing such as reduction of block boundary distortion and pixel value correction based on adjacent pixel values from the locally decoded image subjected to the color difference conversion processing. A reference memory 109 stores the locally decoded image after the loop filter 108 has been applied. The intra-frame prediction unit 110 predicts pixel values using a locally decoded image within the same frame as the decoding target frame. The inter-frame prediction unit 111 refers to the reference memory 109 that stores the locally decoded image after the loop filter 108 is applied, and performs pixel value prediction. The intra-frame prediction/inter-frame prediction switching unit 112 selects either the prediction result of the intra-frame prediction unit 110 or the prediction result of the inter-frame prediction unit 111, and outputs it to the addition unit 107 as a predicted image.

According to the embodiments described above, the video encoding device that encodes video signals for each encoding block by inter-frame prediction or intra-frame prediction includes a color difference conversion unit. For example, the video encoding device is the video encoding device 1 of the embodiment, and the color difference conversion section is the color difference conversion section 201 . The chrominance transform unit performs chrominance transform processing on a chrominance signal of a locally decoded image of an encoding block used for inter-frame prediction or intra-frame prediction. In the color-difference conversion process, among the pixel values of the color-difference signal, pixel values within a first range centered on a predetermined pixel value are converted to a pixel value centered on the predetermined pixel value and narrower than the first range. Convert to a pixel value within the range of two.

Note that the chrominance conversion unit may not convert pixel values outside the first range of the chrominance signal of the local decoded image. Alternatively, the chrominance conversion unit may also convert pixel values outside the first range of the chrominance signal of the local decoded image. In this case, for example, as shown in FIGS. 3 and 4, the chrominance conversion unit increases the pixel value after conversion as the pixel value before conversion increases, and also converts the pixel value from the minimum pixel value that the color difference signal can take to the maximum pixel value. conversion such that the pixel values after converting the pixel values outside the first range and the pixel values after converting the pixel values within the first range change continuously A rule transforms pixel values outside the first range. Also, the first range and the second range may be determined independently for each of the u signal and the v signal of the color difference signal. That is, the predetermined pixel value may be the same or different between the u signal and the v signal. At this time, pixel value conversion may be performed only when the u signal and the v signal are within independently determined first ranges.

The video encoding device performs first setting for setting information indicating one or more of a predetermined pixel value, a first range, and a second range in an encoded stream for transmitting an encoded video signal. You may further provide a part. For example, the information indicating the predetermined pixel value is M, the information representing the first range is w or M and w, and the information representing the second range is k or M and k. The video encoding device may further include a second setting unit that sets information indicating whether or not color difference conversion processing is performed on the encoded block in the encoded stream that transmits the encoded video signal. The first setting unit and the second setting unit are, for example, the entropy coding unit 104 in the embodiment described above.

A video decoding device that decodes a video signal encoded for each decoding block by inter-frame prediction or intra-frame prediction includes a color difference conversion unit. For example, the video decoding device is the video decoding device 3 of the embodiment, and the color difference conversion section is the color difference conversion section 302 . The chrominance transform unit performs chrominance transform processing similar to that of the chrominance transform unit of the video encoding device on the chrominance signal of the locally decoded image of the decoded block used for inter-frame prediction or intra-frame prediction.

The video decoding device acquires information indicating one or more of a predetermined pixel value, a first range, and a second range from the encoded stream in which the encoded signal is set. You may further provide a part. Also, the video decoding device may further include a second information acquiring unit that acquires information indicating whether or not color difference conversion processing is performed on the decoded block from the encoded stream in which the encoded signal is set. The first setting unit and the second setting unit are, for example, the entropy decoding unit 301 .

According to the above-described embodiments, it is possible to make the boundaries of coding blocks inconspicuous.

All or part of the functions of the video encoding device 1 and the video decoding device 3 described above may be implemented using hardware or may be implemented using software. When realizing all or part of each function of the video encoding device 1 and the video decoding device 3 by software, the video encoding device 1 and the video decoding device 3 are connected by a bus with a CPU (Central Processing Unit) and a memory. , auxiliary storage, etc., and executes a program to realize this function. Note that this program may be recorded on a computer-readable recording medium. Computer-readable recording media include portable media such as magneto-optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks incorporated in computer systems. Also, this program may be transmitted via an electric communication line.

Reference Signs List 1, 9 Video coding device 3 Video decoding device 100 Block division unit 101 Subtraction unit 102 Orthogonal transformation unit 103 Quantization units 104, 202 Entropy coding unit 105 Inverse quantization unit 106 Inverse orthogonal Conversion unit 107 Addition units 201, 302 Color difference conversion unit 108 Loop filter 109 Reference memory 110 Intra-frame prediction unit 111 Inter-frame prediction unit 112 Intra-frame prediction/inter-frame prediction switching unit 301 Entropy decoding unit

Claims (6)

an entropy decoding unit that entropy-decodes the quantized transform coefficients of the blocks to be decoded that have been divided into blocks from the encoded stream;
an inverse quantization unit that inversely quantizes the quantized transform coefficients and outputs transform coefficients;
an inverse transform unit that inverse transforms the transform coefficients;
an adding unit for obtaining a decoded image block by adding a result of the inverse transform by the inverse transform unit and a prediction signal corresponding to the block;
a pixel value conversion unit that performs a pixel value conversion process in which each pixel value of the color component of the decoded image block output from the addition unit is used as an input signal and converted by a piecewise linear function on a block-by-block basis;
a loop filter that performs filtering on the decoded image block that has undergone the pixel value conversion process;
Under the condition that the pixel value conversion unit does not convert the minimum value and the maximum value of the input/output signal of the pixel value conversion unit,
identifying an input section to which the value of the input signal belongs from among a plurality of input sections each associated with a linear function;
A video decoding device that transforms the value of the input signal by the linear function corresponding to the specified input segment and outputs the result. an entropy decoding unit that entropy-decodes quantized transform coefficients of a block to be decoded that has been divided into blocks from an encoded stream, and acquires from the encoded stream information indicating whether pixel value conversion processing is necessary for the block;
an inverse quantization unit that inversely quantizes the quantized transform coefficients and outputs transform coefficients;
an inverse transform unit that inverse transforms the transform coefficients;
an adding unit for obtaining a decoded image block by adding a result of the inverse transform by the inverse transform unit and a prediction signal corresponding to the block;
When the obtained information indicates that the pixel value conversion process is to be used, the pixel value converted by a piecewise linear function using each pixel value of the color component of the decoded image block output by the adding unit as an input signal. a pixel value conversion unit that performs conversion processing on a block-by-block basis;
a loop filter that performs filtering on the decoded image block that has undergone the pixel value conversion process;
The pixel value conversion unit
identifying an input segment to which the value of the input signal belongs from among a plurality of input segments each associated with a linear function;
A video decoding device that transforms the value of the input signal by the linear function corresponding to the identified input segment and outputs the result. each of the plurality of input segments is associated with an output segment that is a range of possible values of the input signal transformed by the linear function;
3. The video decoding apparatus according to claim 1, wherein the slope of said linear function is determined by the width of an input section corresponding to said linear function and the width of an output section corresponding to said linear function. 4. The video decoding device according to any one of claims 1 to 3, wherein the entropy decoding unit acquires information defining each input segment from the encoded stream. 5. The video decoding device according to any one of claims 1 to 4, wherein the entropy decoding unit acquires information defining each output division from the encoded stream. A program that causes a computer to function as the video decoding device according to any one of claims 1 to 5.

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