Method and apparatus for encoding/decoding images using adaptive motion vector resolution

Patent metadata

Field	Value
Publication number	US-11622124-B2
Application number	US-201013391509-A
Country	US
Kind code	B2
Filing date	Aug 21, 2010
Priority date	Aug 21, 2009
Publication date	Apr 4, 2023
Grant date	Apr 4, 2023

Abstract

The present disclosure relates to a method and apparatus for improving the encoding efficiency by adaptively changing the resolution of the motion vector in the inter prediction encoding and inter prediction decoding of a video. The video encoding/decoding apparatus includes: a video encoder for determining a motion vector resolution of each area or motion vector of a video and performing an inter prediction encoding of the video by using a motion vector according to the motion vector resolution determined for each area or motion vector; and a video decoder for reconstructing a resolution by extracting resolution information from a bitstream, and then performing an inter prediction decoding by using a motion vector according to the motion vector resolution of each reconstructed area or motion vector.

First claim

The invention claimed is:

1. A video encoding apparatus for inter-predicting a current block and encoding, into a bitstream, a motion vector of the current block based on a predicted motion vector which is derived from one or more neighboring blocks of the current block, the apparatus comprising a microprocessor configured to:
derive the predicted motion vector of the current block from the neighboring blocks which have been already encoded; and
encode a value of a current motion vector difference corresponding to a difference between the predicted motion vector and the motion vector of the current block, in a motion vector resolution selected among:
(a) a reference motion vector resolution which is set in an entirety of an image area to which the current block belongs, the image area being one of a picture, a sequence of pictures and a slice of a picture, and
(b) a first motion vector resolution dedicated to the current block among blocks which belong to the image area,
wherein the motion vector resolution selected among the reference motion vector resolution and the first motion vector resolution represents a pixel interval by which a reference picture is interpolated, and the first motion vector resolution dedicated to the current block is variably selected from a group of pixel intervals comprising at least two of 1 pixel interval, 1/2 fractional pixel interval, 1/4 fractional pixel interval and 1/8 fractional pixel interval,

wherein the microprocessor is further configured to
determine whether to apply the reference motion vector resolution in the entirety of the image area, the reference motion vector resolution being a predetermined fractional pixel interval corresponding to one of pixel intervals included in the group, wherein the reference motion vector resolution is used as a default motion vector resolution to encode all motion vectors in the image area, when it is determined that the reference motion vector resolution is applied in the entirety of the image area;
encode, into a header of the image area, first information for indicating whether the reference motion vector resolution is applied in the entirety of the image area; and
when the first information indicates that the reference motion vector resolution is not applied in the entirety of the image area and thereby motion vector resolutions are to be encoded respectively in the unit of the blocks which belong to the image area,
determine the first motion vector resolution dedicated to the current block, from among the group of pixel intervals,
encode a resolution identification information which is dedicated to the current block and indicates the first motion vector resolution, and
generate a predicted block of the current block by interpolating pixels in the reference picture of the current block, wherein the interpolation of the pixels in the reference picture of the current block are allowed up to a pixel position corresponding to the first motion vector resolution, wherein a filter for interpolating the pixels in the reference picture is variably decided among a plurality of filters depending on the first motion vector resolution, and the pixels in the reference picture are interpolated using the decided filter,

wherein the predicted motion vector is generated by rounding a motion vector candidate corresponding to a motion vector of one of the neighboring blocks of the current block such that the rounded motion vector candidate has the same motion vector resolution as the first motion vector resolution when the motion vector resolution of the motion vector candidate is higher than the first motion vector resolution, and then the predicted motion vector is subtracted from the motion vector of the current block to thereby generate the value of the current motion vector difference at the first motion vector resolution, and
wherein, when the first information indicates that the reference motion vector resolution is applied in the entirety of the image area, the resolution identification information is not encoded and a predetermined filter is used as the filter for interpolating the pixels in the reference picture.

2. The video encoding apparatus of claim 1 , wherein the microprocessor is further configured to
generate, in the unit of the image area, a resolution change flag for indicating whether the first motion vector resolution is determined for (i) the motion vector of the current block to be encoded or (ii) the current block to be encoded, as the first information.

3. The video encoding apparatus of claim 1 , wherein when the group of pixel intervals comprises 1/1 pixel interval, the microprocessor is configured to generate the predicted block from integer pixels of the reference picture.

4. The video encoding apparatus of claim 1 , wherein the value of the current motion vector difference is encoded by using one of multiple entropy coding methods according to the first motion vector resolution.

5. The video encoding apparatus of claim 1 , wherein the microprocessor is further configured to
generate, in the unit of the image area, a resolution appointment flag indicating a motion vector resolution set available for the image area, as the first information.

6. The video encoding apparatus of claim 1 , wherein, when it is available to obtain the first motion vector resolution by using a reference picture index, the microprocessor is further configured to encode, as the resolution identification information, the reference picture index.

7. The video encoding apparatus of claim 5 , wherein, when using multiple reference pictures, the microprocessor is configured to set the motion vector resolution set to be different according to reference pictures based on a predetermined criterion without encoding a resolution identification flag.

8. The video encoding apparatus of claim 7 , wherein the predetermined criterion comprises one of a distance between a reference picture and a current picture, an error value between motion vector resolutions measured by an error measurement means, and a table including motion vector resolution sets corresponding to reference pictures.

9. The video encoding apparatus of claim 7 , wherein the microprocessor is configured to set different motion vector resolution sets for a picture to be used as a reference picture and a picture not to be used as a reference picture, respectively.

10. The video encoding apparatus of claim 1 , wherein the microprocessor is further configured to
generate a resolution conversion flag which indicates a change between (i) the first motion vector resolution and (ii) a motion vector resolution corresponding to one of neighboring blocks of the current block or a previous block.

11. A video decoding apparatus for decoding, from a bitstream, a motion vector of a current block based on a predicted motion vector which is derived from one or more neighboring blocks of the current block and inter-predicting the current block, the apparatus comprising a microprocessor configured to:
decode, from the bitstream, a value of a current motion vector difference of the current block in a motion vector resolution selected among:
(a) a reference motion vector resolution which is set in an entirety of an image area to which the current block belongs, the image area being one of a picture, a sequence of pictures and a slice of a picture, and
(b) a first motion vector resolution dedicated to the current block among blocks which belong to the image area,
wherein the motion vector resolution selected among the reference motion vector resolution and the first motion vector resolution represents a pixel interval by which a reference picture is interpolated, and the first motion vector

Assignees

• Kim Sunyeon
• Lim Jeongyeon
• Moon Joohee
• Lee Yunglyul
• Kim Haekwang
• Jeon Byeungwoo
• Lee Juock
• Kim Dongwon
• Sk Telecom Co Ltd

Inventors

• Kim Sunyeon
• Lim Jeongyeon
• Moon Joohee
• Lee Yunglyul
• Kim Haekwang
• Jeon Byeungwoo
• Lee Juock
• Kim Dongwon

Classifications

• H04N19/523

  with sub-pixel accuracy · CPC title

• H04N19/91

  Entropy coding, e.g. variable length coding [VLC] or arithmetic coding · CPC title

• H04N19/463

  by compressing encoding parameters before transmission · CPC title

• H04N19/46

  Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) · CPC title

• H04N19/517 Primary

  by encoding · CPC title