ENCODER AND DECODER FOR CODED PICTURES HAVING REGIONS WITH COMMON MOTION MODELS

1 . A video encoder configured to encode a bitstream to be decoded by a compliant decoder:

the encoder generating the encoded bitstream comprising a sequence parameter set and a coded picture, the coded picture comprising a first contiguous region comprising a first plurality of coding blocks and a second contiguous region comprising a second plurality of coding blocks, and an intra-predicted coding block; and

the decoder being configured to:

receive the encoded bitstream;

decode the first contiguous region of the coded picture by:

for each coding block of the first plurality of coding blocks in the first contiguous region, utilize a motion model, the motion model being the same for all of the first plurality of coding blocks in the first contiguous region, the motion model being one of 4-parameter affine motion, and 6-parameter affine motion, the sequence parameter set containing information about the motion model;

when the motion model is 4-parameter affine motion, construct for each of the first plurality of coding blocks in the first contiguous region, a motion vector candidate list including a 4-parameter candidate comprising two control point motion vectors, wherein each of the two control point motion vectors is a motion vector of a nearest neighbor block in the coded picture, and decode each of the first plurality of coding blocks in first contiguous region using the 4-parameter candidate for 4-parameter affine motion compensation;

when the motion model is 6-parameter affine motion, construct for each of the first plurality of coding blocks in the first contiguous region, a motion vector candidate list including a 6-parameter candidate comprising three control point motion vectors, wherein each of the three control point motion vectors is a motion vector of a nearest neighbor block in the coded picture, and decode each of the first plurality of coding blocks in first contiguous region using the 6-parameter candidate for 6-parameter affine motion compensation;

decode the second contiguous region of the coded picture by decoding each of the coding blocks in the second plurality using individual motion information contained in the bitstream for each of the second plurality of coding blocks;

decode the intra-predicted block using intra-prediction from within the picture; and

store the decoded picture in a decoded picture buffer.

2 . The encoder of claim 1 wherein each of said blocks is part of a coding tree unit.

3 . The encoder of claim 1 , wherein at least one block is a symmetric block.

4 . The encoder of claim 3 wherein each of the blocks is N×N where N is one of 32, 64 or 128.

5 . A video decoder having circuitry configured to:

receive an encoded bitstream comprising a sequence parameter set and a coded picture, the coded picture comprising a first contiguous region comprising a first plurality of coding blocks and a second contiguous region comprising a second plurality of coding blocks, and an intra-predicted coding block;

decode the first contiguous region of the coded picture by:

for each coding block of the first plurality of coding blocks in the first contiguous region, utilize a motion model, the motion model being the same for all of the first plurality of coding blocks in the first contiguous region, the motion model being one of 4-parameter affine motion, and 6-parameter affine motion, the sequence parameter set containing information about the motion model;

when the motion model is 4-parameter affine motion, construct for each of the first plurality of coding blocks in the first contiguous region, a motion vector candidate list including a 4-parameter candidate comprising two control point motion vectors, wherein each of the two control point motion vectors is a motion vector of a nearest neighbor block in the coded picture, and decode each of the first plurality of coding blocks in first contiguous region using the 4-parameter candidate for 4-parameter affine motion compensation;

when the motion model is 6-parameter affine motion, construct for each of the first plurality of coding blocks in the first contiguous region, a motion vector candidate list including a 6-parameter candidate comprising three control point motion vectors, wherein each of the three control point motion vectors is a motion vector of a nearest neighbor block in the coded picture, and decode each of the first plurality of coding blocks in first contiguous region using the 6-parameter candidate for 6-parameter affine motion compensation;

decode the second contiguous region of the coded picture by decoding each of the coding blocks in the second plurality using individual motion information contained in the bitstream for each of the second plurality of coding blocks;

decode the intra-predicted block using intra-prediction from within the picture; and

store the decoded picture in a decoded picture buffer.

6 . The decoder of claim 5 wherein each of said blocks is part of a coding tree unit.

7 . The decoder of claim 5 , wherein at least one block is a symmetric block.

8 . The decoder of claim 7 wherein each of the blocks is N×N where N is one of 32, 64 or 128.

9 . A method of transmitting an encoded video signal comprising:

receiving a video signal;

generate an encoded bitstream a bitstream to be decoded by a compliant decoder, the encoded bitstream comprising a sequence parameter set and a coded picture, the coded picture comprising a first contiguous region comprising a first plurality of coding blocks and a second contiguous region comprising a second plurality of coding blocks, and an intra-predicted coding block; and

transmitting the encoded bitstream to a decoder a configured to:

receive the encoded bitstream;

decode the first contiguous region of the coded picture by:

for each coding block of the first plurality of coding blocks in the first contiguous region, utilize a motion model, the motion model being the same for all of the first plurality of coding blocks in the first contiguous region, the motion model being one of 4-parameter affine motion, and 6-parameter affine motion, the sequence parameter set containing information about the motion model;

when the motion model is 4-parameter affine motion, construct for each of the first plurality of coding blocks in the first contiguous region, a motion vector candidate list including a 4-parameter candidate comprising two control point motion vectors, wherein each of the two control point motion vectors is a motion vector of a nearest neighbor block in the coded picture, and decode each of the first plurality of coding blocks in first contiguous region using the 4-parameter candidate for 4-parameter affine motion compensation;

when the motion model is 6-parameter affine motion, construct for each of the first plurality of coding blocks in the first contiguous region, a motion vector candidate list including a 6-parameter candidate comprising three control point motion vectors, wherein each of the three control point motion vectors is a motion vector of a nearest neighbor block in the coded picture, and decode each of the first plurality of coding blocks in first contiguous region using the 6-parameter candidate for 6-parameter affine motion compensation;

decode the second contiguous region of the coded picture by decoding each of the coding blocks in the second plurality using individual motion information contained in the bitstream for each of the second plurality of coding blocks;

decode the intra-predicted block using intra-prediction from within the picture; and

store the decoded picture in a decoded picture buffer.

10 . The method of claim 9 , wherein each of said blocks is part of a coding tree unit.

11 . The method of claim 9 , wherein at least one block is a symmetric block.

12 . The method of claim 11 wherein each of the blocks is N×N where N is one of 32, 64 or 128.