Coding apparatus, coding method, decoding apparatus, decoding method, transmitting apparatus, and receiving apparatus
Moving image data of a wide viewing angle image is divided into blocks to obtain a coding target block. A motion-compensated reference block is extracted for each coding target block. The reference block is subjected to adjustment processing of rotation and/or scaling. A residual signal is calculated on the basis of a pixel value of the coding target block and a pixel value of the reference block subjected to the adjustment processing for each coding target block, and the residual signal of the coding target block is coded to obtain an encoded stream. Adjustment processing information is inserted into the encoded stream together with the motion vector for each coding target block. The residual can be reduced, the coding bit rate can be reduced, and consequently the coding performance of motion prediction can be improved.
1. A coding apparatus, comprising:
processing circuitry configured to:
divide moving image data of an image into blocks to obtain coding target blocks,
extract a motion-compensated reference block for each coding target block,
perform adjustment processing of rotation by an angle of rotation on the reference block, the angle of rotation being formed between a first imaginary line connecting a position of the reference block and a target point centered in the image, and a second imaginary line connecting a corresponding position of the coding target block and the target point,
calculate a residual signal based on (i) a pixel value of a coding target block that corresponds to the reference block, and (ii) a pixel value of the reference block after the adjustment processing is performed on the reference block,
encode the calculated residual signal of each coding target block to obtain an encoded stream, and
insert information of the adjustment processing into the encoded stream for each coding target block.
2. The coding apparatus according to claim 1 , wherein the processing circuitry is further configured to perform, before block matching is performed, rotation processing on each candidate in which the reference block is extracted.
3. The coding apparatus according to claim 1 , wherein the processing circuitry is further configured to perform, after block matching is performed, rotation processing on each candidate in which the reference block is extracted.
4. The coding apparatus according to claim 1 , wherein the image is a panoramic 360 degree image and the processing circuitry is further configured to perform the adjustment processing based on the target point, which is at a center of the panoramic 360 degree image.
5. A decoding apparatus, comprising:
decoding circuitry configured to decode an encoded stream, which includes a coding signal of each coding target block obtained by dividing moving image data of an image into blocks to obtain a residual signal for each decoding target block,
the encoded stream including adjustment processing information of rotation by an angle of rotation inserted into the encoded stream to obtain a reference block for each coding target block, the angle of rotation being formed between a first imaginary line connecting a position of the reference block and a target point centered in the image, and a second imaginary line connecting a corresponding position of the coding target block and the target point, and
the decoding apparatus further including processing circuitry configured to:
extract a reference block for each decoding target block based on the adjustment processing information for each block, and
add a pixel value of the reference block to the residual signal for each decoding target block to obtain the moving image data.
6. A transmitting apparatus, comprising:
a coding apparatus configured to encode moving image data of an image to obtain an encoded stream; and
transmission circuitry configured to transmit a container including the encoded stream in a predetermined format, wherein
the coding apparatus includes processing circuitry configured to:
divide the moving image data into blocks to obtain coding target blocks,
extract a motion-compensated reference block for each coding target block,
perform adjustment processing of rotation by an angle of rotation, on the reference block, the angle of rotation being formed between a first imaginary line connecting a position of the reference block and a target point centered in the image, and a second imaginary line connecting a corresponding position of the coding target block and the target point,
calculate a residual signal based on (i) a pixel value of a coding target block that corresponds to the reference block, and (ii) a pixel value of the reference block after the adjustment processing is performed on the reference block,
encode the calculated residual signal of each coding target block to obtain the encoded stream, and
insert information of the adjustment processing into the encoded stream for each coding target block.
7. The transmitting apparatus according to claim 6 , wherein the processing circuitry is further configured to perform, before block matching is performed, rotation processing on each candidate in which the reference block is extracted.
8. The transmitting apparatus according to claim 6 , wherein the processing circuitry is further configured to perform, after block matching is performed, rotation processing one each candidate in which the n block is extracted.
9. The transmitting apparatus according to claim 6 , wherein the moving image data is a panoramic 360 degree image and the processing circuitry is further configured to perform the adjustment processing based on the target point, which is at a center of the panoramic 360 degree image.
10. A receiving apparatus, comprising:
receiving circuitry configured to receive a container in a predetermined format including an encoded stream obtained by encoding moving image data of an image, the encoded stream including adjustment processing information of rotation, by an angle of rotation inserted into the encoded stream to obtain a reference block for each coding target block, the angle of rotation being formed between a first imaginary line connecting a position of the reference block and a target point centered in the image, and a second imaginary line connecting a corresponding position of the coding target block and the target point; and
a decoding apparatus configured to decode the encoded stream to obtain the moving image data, wherein
the decoding apparatus includes processing circuitry configured to:
decode the encoded stream to obtain a residual signal for each decoding target block,
extract a reference block for each decoding target block based on the adjustment processing information for each block, and
add a pixel value of the reference block to the residual signal for each decoding target block to obtain the moving image data.
11. The coding apparatus of claim 1 , wherein the processing circuitry is further configured to perform an adjustment process of scaling on the reference block prior to calculating the residual signal.