CN-121985123-A - Signaling of global motion vectors in image headers

Abstract

A decoder includes circuitry configured to receive a bitstream, extract a header, determine a global motion model using the header, and decode a current block of a current frame using the global motion model. Related apparatus, systems, techniques, and articles are also described.

Inventors

• H. Kava
• B. Fulcht
• V. Ajic

Assignees

• OP方案有限责任公司

Dates

Publication Date

20260505

Application Date

20200424

Priority Date

20190425

Claims (18)

1. 1. A decoder, the decoder comprising circuitry configured to: Receiving a bitstream, the bitstream comprising an encoded image, the encoded image comprising a first region having global motion and a second region adjacent to the first region having local motion, the first region having global motion comprising a first plurality of encoding units having a majority of the encoding units of the image, the second region having local motion comprising a second plurality of encoding units of the image, the first plurality of encoding units all having the same affine motion model, Determining, for each block in the first region, a motion model which is the same for all blocks in the first region and which is one of a four-parameter affine motion or a six-parameter affine motion, the parameters of the motion model of each block in the first region being determined from at least one motion vector signaled in the bitstream, and Decoding 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, decoding each block using motion information determined separately for each block to reconstruct the local motion of the second region.
2. 2. The decoder of claim 1, wherein the motion model in the first region is a four parameter affine motion.
3. 3. The decoder of claim 1, wherein the motion model in the first region is a six parameter affine motion.
4. 4. The decoder of claim 1, wherein the at least one motion vector is a control point motion vector.
5. 5. The decoder of claim 1, wherein the motion model in the first region is a four parameter affine motion and the at least one motion vector comprises two control point motion vectors.
6. 6. The decoder of claim 1, wherein the motion model in the first region is a six parameter affine motion and the at least one motion vector comprises three control point motion vectors.
7. 7. A method of transmitting an encoded bitstream, comprising: receiving a video signal; Generating an encoded bitstream representing the video signal comprising an encoded picture having a first region with global motion and a second region adjacent to the first region with local motion, the first region with global motion comprising a first plurality of coding units with a majority of 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 model, The bitstream is further configured to be decodable by a decoding method comprising: Determining, for each block in the first region, a motion model which is the same for all blocks in the first region and which is one of a four-parameter affine motion or a six-parameter affine motion, the parameters of the motion model of each block in the first region being determined from at least one motion vector signaled in the bitstream, and Decoding 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, decoding each block using motion information determined separately for each block to reconstruct the local motion of the second region, and The encoded bit stream is transmitted to a decoder over a channel.
8. 8. The method of claim 7, wherein the motion model in the first region is a four parameter affine motion.
9. 9. The method of claim 7, wherein the motion model in the first region is a six parameter affine motion.
10. 10. The method of claim 7, wherein the at least one motion vector is a control point motion vector.
11. 11. The method of claim 7, wherein the motion model in the first region is a four parameter affine motion and the at least one motion vector comprises two control point motion vectors.
12. 12. The method of claim 7, wherein the motion model in the first region is a six parameter affine motion and the at least one motion vector comprises three control point motion vectors.
13. 13. An encoder, the encoder comprising circuitry configured to: receiving a video signal; Generating an encoded bitstream representing the video signal, the encoded bitstream comprising an encoded image having a first region with global motion and a second region adjacent to the first region with local motion, the first region with global motion comprising a first plurality of encoding units with a majority of encoding units of the image, the second region with local motion comprising a second plurality of encoding units of the image, the first plurality of encoding units all having the same affine motion model; the bitstream is further configured by the encoder to be decodable by a decoding method comprising: Determining, for each block in the first region, a motion model which is the same for all blocks in the first region and which is one of a four-parameter affine motion or a six-parameter affine motion, the parameters of the motion model of each block in the first region being determined from at least one motion vector signaled in the bitstream, and Decoding 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, decoding each block using motion information determined separately for each block to reconstruct the local motion of the second region, and The encoded bit stream is transmitted over a channel.
14. 14. The encoder of claim 13, wherein the motion model in the first region is a four parameter affine motion.
15. 15. The encoder of claim 13, wherein the motion model in the first region is a six parameter affine motion.
16. 16. The encoder of claim 13, wherein the at least one motion vector is a control point motion vector.
17. 17. The encoder of claim 13, wherein the motion model in the first region is a four parameter affine motion and the at least one motion vector comprises two control point motion vectors.
18. 18. The encoder of claim 13, wherein the motion model in the first region is a six parameter affine motion and the at least one motion vector comprises three control point motion vectors.

Description

Signaling of global motion vectors in image headers The application is a divisional application of China national application No. 2020800458545, entitled "Signal Transmission of Global motion vectors in image header", filed on 24 th month 4 in 2020. Cross Reference to Related Applications The present application claims priority from U.S. provisional patent application 62/838,509 entitled "signaling of global motion vectors in image headers," filed on 25 th 2019, which is incorporated herein by reference in its entirety. Technical Field The present invention relates generally to the field of video compression. In particular, the invention relates to the signaling of global motion vectors in an image header. Background The video codec may include electronic circuitry or software that compresses or decompresses digital video. It can convert uncompressed video into compressed format and vice versa. In the case of video compression, the device that compresses video (and/or performs some of the functions of the compressed video device) may be generally referred to as an encoder, while the device that decompresses video (and/or performs some of the functions of the compressed video) may be referred to as a decoder. Disclosure of Invention In one aspect, a decoder includes circuitry configured to receive a bitstream, extract a header, determine a global motion model using the header, and decode a current block of a current frame using the global motion model. In another aspect, a method includes receiving, by a decoder, a bitstream. The method includes extracting a header from a bitstream. The method includes determining a global motion model using the header. The method includes decoding a current block of a current frame using the global motion model. The details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims. Drawings For the purpose of illustrating the invention, the drawings show various aspects of one or more embodiments of the invention. However, it should be understood that the invention is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein: FIG. 1 is a motion vector diagram illustrating an example frame with global and local motion; FIG. 2 illustrates three example motion models that may be used for global motion, including index values (0, 1, or 2) for the three example motion models; FIG. 3 is a process flow diagram of some example implementations consistent with the present subject matter; FIG. 4 is a system block diagram of an example decoder according to some example implementations of the present subject matter; FIG. 5 is a process flow diagram of some example implementations consistent with the present subject matter; FIG. 6 is a system block diagram of an example encoder in accordance with some example implementations of the present subject matter, and FIG. 7 is a block diagram of a computing system that may be used to implement any one or more of the methods disclosed herein and any one or more portions thereof. The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In some instances, details that are not necessary for an understanding of the embodiments or that render other details difficult to perceive may have been omitted. Like reference symbols in the various drawings indicate like elements. Detailed Description Global motion in video refers to motion that occurs throughout a frame. Global motion may be caused by camera motion, such as, but not limited to, camera panning and zooming may produce motion in a frame that generally affects the entire frame. The motion that exists in the video portion may be referred to as local motion. Local motion may be caused by moving objects in the scene, such as, but not limited to, objects moving from left to right in the scene. The video may contain a combination of local and global motion. Some implementations of the present subject matter may provide efficient methods to communicate global motion to a decoder, as well as use global motion vectors to improve the compression efficiency. Fig. 1 is a diagram of an exemplary embodiment illustrating motion vectors of an example frame 100 with global and local motion. Frame 100 may include a plurality of blocks of pixels, shown as squares, and motion vectors associated with them, shown as arrows. The squares (e.g., pixel blocks) pointed to the top and left by the arrows indicate blocks with what can be considered global motion, and the squares (indicated by 104) pointed to the other directions by the arrows indicate blocks with local motion. In the illustrated example of fig. 1, many blocks have the same global motion. Transmitting a global motion signal (e.g., pictu