Video encoding and decoding method and apparatus

Patent metadata

Field	Value
Publication number	US-2018152728-A1
Application number	US-201815882346-A
Country	US
Kind code	A1
Filing date	Jan 29, 2018
Priority date	Jul 30, 2015
Publication date	May 31, 2018
Grant date	—

Abstract

A video encoding and decoding method and apparatus are provided. The video encoding method includes: obtaining a first statistical characteristic of previous K frames of images of a video sequence; determining a first background frame; determining, according to the first statistical characteristic, a QP used for encoding the first background frame; encoding the first background frame according to the QP, to obtain a first background long-term reference frame; and encoding the (K+1) th frame of image of the video sequence to the (K+L) th frame of image of the video sequence according to the first background long-term reference frame. When encoding is performed on the (K+1) th frame of image of the video sequence to the (K+L) th frame of image of the video sequence, the used QP for encoding the background long-term reference frame is determined according to the first statistical characteristic related to video content of the previous K frames of images.

First claim

1 . A video encoding method, comprising:
obtaining a first statistical characteristic of previous K frames of images of a video sequence, wherein K is a positive integer; determining a first background frame, wherein the first background frame is used as a reference when encoding is performed on the (K+1) th frame of image of the video sequence to the (K+L) th frame of image of the video sequence, wherein L is a positive integer; determining, according to the first statistical characteristic, a quantization parameter (QP) used for encoding the first background frame; encoding the first background frame according to the QP, to obtain a first background long-term reference frame; and encoding the (K+1) th frame of image of the video sequence to the (K+L) th frame of image of the video sequence according to the first background long-term reference frame.

2 . The method according to claim 1 , wherein determining the QP used for encoding the first background frame comprises:
obtaining, according to the first statistical characteristic, a first probability that an image block in each of the (K+1) th frame of image of the video sequence to the (K+L) th frame of image of the video sequence uses the first background frame as a reference; and obtaining, according to the first probability, the QP used for encoding the first background frame.

3 . The method according to claim 1 , wherein the first statistical characteristic comprises a variance of K centroid values corresponding to K image blocks and an average coding distortion of K coding distortions corresponding to the K image blocks, wherein the K image blocks are image blocks located at same locations in all of the previous K frames of images, the variance of the K centroid values is a variance of a centroid value sequence constituted by the K centroid values, and the average coding distortion of the K coding distortions is an average value of a coding distortion sequence constituted by the K coding distortions.

4 . The method according to claim 3 , wherein
the K image blocks are the i th image blocks in all of the previous K frames of images, wherein i is a positive integer; and wherein obtaining the first statistical characteristic of the previous K frames of images of the video sequence comprises: performing iteration calculation according to an order from the second frame of image of the previous K frames of images to the K th frame of image of the previous K frames of images, to obtain the variance of the K centroid values corresponding to the i th image blocks in all of the previous K frames of images, and the average coding distortion of the K coding distortions corresponding to the i th image blocks in all of the previous K frames of images, wherein the iteration calculation comprises: determining whether the i th image block in the j th frame of image of the video sequence belongs to a background region; and when the i th image block in the j th frame of image of the video sequence belongs to the background region, obtaining, according to B j,i =B j−1,i +1, a quantity B j,i of image blocks that are of previous j image blocks and that belong to the background region, wherein the previous j image blocks are the i th image blocks in all of previous j frames of images of the video sequence; and obtaining, according to B j,i , a variance of j centroid values corresponding to the i th image blocks in all of the previous j frames of images and an average coding distortion of j coding distortions corresponding to the i th image blocks in all of the previous j frames of images, wherein K≥j≥2, and when the i th image block in the first frame of image of the video sequence belongs to the background region, B 1,i is 1, or when the ith image block in the first frame of image of the video sequence does not belong to the background region, B 1,i is 0; or when the i th image block in the j th frame of image of the video sequence does not belong to the background region, obtaining, according to B j,i =B j−1,i , a quantity B j,i of image blocks that are of previous j image blocks and that belong to the background region, wherein the previous j image blocks are the i th image blocks in all of previous j frames of images, using a variance of j−1 centroid values corresponding to the i th image blocks in all of previous j−1 frames of images of the video sequence as a variance of j centroid values corresponding to the i th image blocks in all of the previous j frames of images, and using an average coding distortion of j−1 coding distortions corresponding to the i th image blocks in all of the previous j−1 frames of images of the video sequence as an average coding distortion of j coding distortions corresponding to the i th image blocks in all of the previous j frames of images of the video sequence, wherein when j is 2, the variance of the j−1 centroid values corresponding to the i th image blocks in all of the previous j−1 frames of images is a first preset value, and the average coding distortion of the j−1 coding distortions corresponding to the i th image blocks in all of the previous j−1 frames of images is a second preset value or a coding distortion of the first frame of image of the video sequence.

5 . The method according to claim 4 , wherein
determining whether the i th image block in the j th frame of image of the video sequence belongs to the background region comprises: determining whether a horizontal component of a minimum motion vector in motion vectors of an image subblock of the i th image block in the j th frame of image is less than a first preset threshold, and whether a vertical component of the minimum motion vector is less than a second preset threshold; and when the horizontal component is less than the first preset threshold, and the vertical component is less than the second preset threshold, determining that the i th image block in the j th frame of image belongs to the background region; or when the horizontal component is not less than the first preset threshold or the vertical component is not less than the second preset threshold, determining that the i th image block in the j th frame of image does not belong to the background region.

6 . The method according to claim 4 , wherein
obtaining, according to B j,i , a variance of j centroid values and the average coding distortion of j coding distortions comprises: obtaining a centroid value and a coding distortion of the i th image block in the j th frame of image; obtaining, according to the centroid value of the i th image block in the j th frame of image and B j,i , the variance of the j centroid values corresponding to the i th image blocks in all of the previous j frames of images; and obtaining, according to the coding distortion of the i th image block in the j th frame of image and B j,i , the average coding distortion of the j coding distortions corresponding to the i th image blocks in all of the previous j frames of images.

7 . The method according to claim 6 , wherein
the average coding distortion of the j coding distortions corresponding to the i th image blocks in all of the previous j frames of images is obtained through the following:

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Assignees

• Huawei Tech Co Ltd
• Univ Science & Technology China

Inventors

• Chen Fangdong
• Lin Sixin
• Li Houqiang
• Li Li

Classifications

• H04N19/192

  the adaptation method, adaptation tool or adaptation type being iterative or recursive · CPC title

• H04N19/124

  Quantisation · CPC title

• H04N19/176

  the region being a block, e.g. a macroblock · CPC title

• H04N19/14

  Coding unit complexity, e.g. amount of activity or edge presence estimation (H04N19/146 takes precedence) · CPC title

• H04N19/139

  Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability · CPC title