Adaptive motion vector prediction candidate in frames with global motion
A decoder includes circuitry configured to receive a bitstream; determine, for a current block and using the bitstream, a global motion vector candidate utilized by an adjacent block; construct a motion vector candidate list including adding the determined global motion vector candidate to the motion vector candidate list; and reconstruct pixel data of the current block and using the motion vector candidate list. Related apparatus, systems, techniques and articles are also described.
1. A method of transmitting video data in an encoded bitstream, comprising:
receiving a video signal;
generating an encoded bitstream representing the video signal, the bitstream including a coded picture, the coded picture including a first region having global motion and comprising a first contiguous plurality of coding units and a second region having local motion different from the global motion and comprising a second contiguous plurality of coding units, the first plurality of coding units all having the same affine motion model, wherein the bitstream is configured to be decodable by a decoder performing a decoding method comprising:
constructing, for each of the coding units in the first plurality of coding units, a motion vector candidate list, each motion vector candidate list comprising one or more motion vector candidates generated using motion vector information of a neighboring coding unit;
decoding each of the first plurality of coding units of the first region using a selected one of the motion vector candidates from the coding unit's motion vector candidate list, the selected motion vector candidate being a candidate generated using motion vector information of a neighboring coding unit, wherein the affine motion model is a 6-parameter affine motion model characterizable by the parameters a, b, c, d, e, and f where
x′=ax+by+c
y′=dx+ey+f
(x,y) is a pixel location in the first region of the coded picture and (x′, y′) is a pixel location in a reference picture, wherein each selected motion vector candidate comprises three control point motion vectors, and wherein the selected motion vector candidates implement a, b, c, d, e, and f with substantially the same values in all of the coding units of the first region, whereby the global motion in the first region is reconstructed; and
decoding the coding units in the second plurality of coding units, whereby the local motion is reconstructed and;
transmit the encoded bitstream over a channel to a decoder.
2. A method of transmitting video data in an encoded bitstream comprising:
receiving a video signal;
generating an encode bitstream including a coded picture, the coded picture including a first region having global motion and comprising a first contiguous plurality of coding units and a second region having local motion different from the global motion and comprising a second contiguous plurality of coding units, the first plurality of coding units all having the same affine motion model, wherein the encode bitstream is configured to be decodable by a decoder performing a decoding method comprising:
constructing, for each of the coding units in the first plurality of coding units, a motion vector candidate list, each motion vector candidate list comprising one or more motion vector candidates generated using motion vector information of a neighboring coding unit;
decoding each of the first plurality of coding units of the first region using a selected one of the motion vector candidates from the coding unit's motion vector candidate list, the selected motion vector candidate being a candidate generated using motion vector information of a neighboring coding unit, wherein the affine motion model is a 4-parameter affine motion model characterizable by the parameters a, b, c, and f where
x′=ax+by+c
y′=−bx+ay+f
(x,y) is a pixel location in the first region of the coded picture and (x′,y′) is a pixel location in a reference picture, wherein each selected motion vector candidate comprises two control point motion vectors, and wherein the selected motion vector candidates implement a, b, c, and f with substantially the same values in all of the coding units of the first region, whereby the global motion in the first region is reconstructed; and
decoding the coding units in the second plurality of coding units, whereby the local motion is reconstructed; and
transmitting the encoded bitstream.