SYSTEMS AND METHODS FOR ENCODING AND DECODING VIDEO WITH REGIONS OF GLOBAL MOTION

1 . A decoder comprising circuitry configured to:

receive a bitstream, the bitstream comprising a coded picture, the coded picture comprising a first region with global motion and a second region with local motion bordering the first region, the first region with global motion comprising a first plurality of coding units with most of the coding units of the picture, the second region with local motion comprising a second plurality of coding units of the picture, the first plurality of coding units all having the same affine motion motion model,

for each block in the first region,

determine, a motion model, the motion model being the same for all of the blocks in the first region and being one of 4-parameter affine motion or 6-parameter affine motion, the parameters of the motion model for each block in the first region being determined from at least one motion vector signaled in the bitstream; and

decode each block in the first region using the parameters of the motion model to reconstruct the global motion in the first region; and

for each block in the second region, decode each block using motion information determined individually for each block to reconstruct the local motion in the second region.

2 . The decoder of claim 1 , wherein the motion model in the 1 first region is 4-parameter affine motion.

3 . The decoder of claim 1 , wherein the motion model in the first region is 6-parameter affine motion.

4 . The decoder of claim 1 , wherein the at least one motion vector is a control point motion vector.

5 . The decoder of claim 1 , wherein the motion model in the first region is 4-parameter affine motion and the at least one motion vector includes two control point motion vectors.

6 . The decoder of claim 1 , wherein the motion model in the first region is 6-parameter affine motion and the at least one motion vector includes three control point motion vectors.

7 . A method of transmitting an encoded bitstream comprising:

receiving a video signal;

generating an encoded bitstream representing the video signal comprising a coded picture, the coded picture having a first region with global motion and a second region with local motion bordering the first region, the first region with global motion comprising a first plurality of coding units with most of the coding units of the picture, the second region with local motion comprising a second plurality of coding units of the picture, the first plurality of coding units all having the same affine motion motion model;

the bitstream being further configured to be decodable by a decoding method comprising:

for each block in the first region determine a motion model, the motion model being the same for all of the blocks in the first region and being one of 4-parameter affine motion or 6-parameter affine motion, the parameters of the motion model for each block in the first region being determined from at least one motion vector signaled in the bitstream; and

decode each block in the first region using the parameters of the motion model to reconstruct the global motion in the first region; and

for each block in the second region, decode each block using motion information determined individually for each block to reconstruct the local motion in the second region; and

transmit the encoded bitstream over a channel to a decoder.

8 . The method of claim 7 , wherein the motion model in the first region is 4-parameter affine motion.

9 . The method of claim 7 , wherein the motion model in the first region is 6-parameter affine motion.

10 . The decoder of claim 7 , wherein the at least one motion vector is a control point motion vector.

11 . The decoder of claim 7 , wherein the motion model in the first region is 4-parameter affine motion and the at least one motion vector includes two control point motion vectors.

12 . The decoder of claim 7 , wherein the motion model in the first region is 6-parameter affine motion and the at least one motion vector includes three control point motion vectors.

13 . An encoder comprising circuitry configured to:

receive a video signal;

generate an encoded bitstream representing the video signal, the encoded bitstream

including a coded picture, the coded picture having a first region with global motion and a second region with local motion bordering the first region, the first region with global motion comprising a first plurality of coding units with most of the coding units of the picture, the second region with local motion comprising a second plurality of coding units of the picture, the first plurality of coding units all having the same affine motion motion model;

the bitstream being further configured by the encoder to be decodable by a decoding method comprising:

for each block in the first region determine a motion model, the motion model being the same for all of the blocks in the first region and being one of 4-parameter affine motion or 6-parameter affine motion, the parameters of the motion model for each block in the first region being determined from at least one motion vector signaled in the bitstream; and

decode each block in the first region using the parameters of the motion model to reconstruct the global motion in the first region; and

for each block in the second region, decode each block using motion information determined individually for each block to reconstruct the local motion in the second region; and

transmit the encoded bitstream over a channel.

14 . The encoder of claim 13 , wherein the motion model in the first region is 4-parameter affine motion.

15 . The encoder of claim 13 , wherein the motion model in the first region is 6-parameter affine motion.

16 . The encoder of claim 13 , wherein the at least one motion vector is a control point motion vector.

17 . The encoder of claim 13 , wherein the motion model in the first region is 4-parameter affine motion and the at least one motion vector includes two control point motion vectors.

18 . The encoder of claim 13 , wherein the motion model in the first region is 6-parameter affine motion and the at least one motion vector includes three control point motion vectors.