Tile copying for video compression

• US 10,542,258 B2
• Filed: 01/25/2016
• Issued: 01/21/2020
• Est. Priority Date: 01/25/2016
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google LLC (Alphabet Inc.)
• Inventors: Wang, Yunqing
• Primary Examiner(s): Anderson, II, James M
• Application Number:
  US15/005,545
• Publication Number:
  US 20170214920A1
• Time in Patent Office: 1,457 Days
• Field of Search: 37524024
• CPC Class Codes: H04N 19/119 Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks
• CPC Class Codes: H04N 19/129 Scanning of coding units, e.g. zig-zag scan of transform coefficients or flexible macroblock ordering [FMO]
• CPC Class Codes: H04N 19/167 Position within a video image, e.g. region of interest [ROI]
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques

Abstract

Tile copying may include decoding a current frame from an encoded video bitstream by decoding, from the encoded video bitstream, tile information for a current tile of the current frame. Decoding the tile information for the current tile of the current frame includes decoding a reference tile offset, and the tile information for the current tile omits encoded tile content information corresponding to the current tile. From the encoded video bitstream, encoded tile content information corresponding to the reference tile is identified based on the reference tile offset, a decoded tile corresponding to the current tile is generated by decoding the encoded tile content information corresponding to the reference tile as the current tile, and the decoded tile is output or stored.

Claims

1. A method comprising:

receiving an encoded bitstream including information representing a current frame of video data;

decoding, by a processor in response to instructions stored on a non-transitory computer readable medium, the current frame, wherein decoding the current frame includes;

decoding a current tile from the current frame, wherein the current tile comprises two or more blocks, and wherein decoding the current tile includes;

decoding, from the encoded bitstream, a header for the current tile, wherein decoding the header includes decoding a tile copy mode indicator, and wherein;

on a condition that the tile copy mode indicator indicates a tile-copy mode of copy, wherein the tile-copy mode of copy indicates that the encoded bitstream does not include entropy coded content data for the current tile;

 

decoding the header for the current tile includes decoding offset information from the header, wherein the offset information indicates a spatial difference between a location of the current tile in the current frame and a location of a reference tile in the current frame, and wherein the offset information includes at least one of a reference tile row offset or a reference tile column offset;

 

locating reference tile content information representing the reference tile in the encoded bitstream based on the offset information, the reference tile content information comprising at least one of motion information and residuals of blocks of the reference tile; and

 

omitting decoding current tile content information from the encoded bitstream;

 

generating a decoded tile corresponding to the current tile by using the reference tile content information;

 

including the decoded tile in a decoded output video stream; and

outputting or storing the decoded current frame.

2. The method of claim 1, wherein the location of the reference tile in the current frame is spatially adjacent to the location of the current tile in the current frame, and wherein a tile scan order position of the reference tile precedes a tile scan order position of the current tile.

3. The method of claim 1, wherein a location of a neighbor tile in the current frame is spatially adjacent to the location of the current tile in the current frame, wherein a tile copy mode indicator for the neighbor tile indicates a tile-copy mode of copy, a tile scan order position of the neighbor tile precedes a tile scan order position of the current tile, and offset information for the neighbor tile indicates the reference tile.

19. The method of claim 1, further comprising:

on a condition that the tile copy mode indicator indicates a tile-copy mode other than copy;

generating a decoded tile corresponding to the current tile by decoding tile content information from the encoded bitstream subsequent to the header for the current tile.

4. A method comprising:

decoding, by a processor in response to instructions stored on a non-transitory computer readable medium, a current frame from an encoded video bitstream, wherein decoding the current frame includes;

decoding, from the encoded video bitstream, tile information for a current tile of the current frame, wherein the current tile comprises two or more blocks; and

wherein decoding the tile information for the current tile of the current frame includes;

decoding a reference tile offset, wherein the tile information for the current tile omits encoded tile content information corresponding to the current tile and wherein the reference tile offset indicates at least one of a row spatial difference or a column spatial difference between a location of the current tile in the current frame and a location of a reference tile in the current frame, and wherein decoding the tile information for the current tile includes decoding a tile header for the current tile, wherein the tile header includes the reference tile offset;

identifying, from the encoded video bitstream, encoded tile content information corresponding to the reference tile based on the reference tile offset, wherein the tile content information corresponding to the reference tile comprising at least one of motion information or residuals of blocks of the reference tile;

generating a decoded tile corresponding to the current tile by decoding the encoded tile content information corresponding to the reference tile as the current tile; and

including the decoded tile in a decoded output video stream; and

outputting or storing the decoded current frame.

5. The method of claim 4, wherein the location of the reference tile in the current frame is spatially adjacent to the location of the current tile in the current frame, and wherein a tile scan order position of the reference tile precedes a tile scan order position of the current tile.

6. The method of claim 4, wherein a location of a neighbor tile in the current frame is spatially adjacent to the location of the current tile in the current frame, and wherein a tile copy mode indicator for the neighbor tile indicates a tile-copy mode of copy, a tile scan order position of the neighbor tile precedes a tile scan order position of the current tile, and reference tile offset information for the neighbor tile indicates the reference tile.

7. The method of claim 4, wherein decoding the tile information for the current tile includes decoding a tile copy mode indicator indicating a tile-copy mode for the current tile of copy.

8. The method of claim 4, wherein decoding the tile information for the current tile includes:

decoding a tile copy mode indicator indicating a tile-copy mode for the current tile; and

decoding the reference tile offset is performed in response to determining that the tile copy mode indicator indicates a tile-copy mode of copy.

9. The method of claim 4, wherein decoding the current frame includes:

decoding, from the encoded video bitstream, tile information for a second tile of the current frame, wherein the tile information for the second tile includes encoded tile content information corresponding to a second frame, wherein the tile information for the second frame is located prior to the tile information for the current frame in the encoded video bitstream, and wherein the second tile is the reference tile.

10. A method, comprising:

encoding, by a processor in response to instructions stored on a non-transitory computer readable medium, a frame from an input video stream by;

identifying tiles from the frame;

generating a first encoded tile by encoding a first tile from the tiles, wherein the first tile comprises two or more first blocks;

including the first encoded tile in an output bitstream;

generating a second encoded tile by encoding a second tile from the tiles, wherein the second tile comprises two or more second blocks;

determining whether a difference between encoded tile content of the first encoded tile and encoded tile content of the second encoded tile is within a threshold;

on a condition that the difference is within the threshold;

identifying an offset indicating a difference between a spatial location of the first tile in the frame and the second tile in the frame,

including the offset in the output bitstream, and

omitting the encoded tile content of the second encoded tile from the output bitstream; and

transmitting or storing the output bitstream.

11. The method of claim 10, wherein including the offset comprises:

defining a header for the second encoded tile; and

including the offset within the header.

12. The method of claim 10, wherein encoding the first tile and encoding the second tile comprises encoding motion information and residuals of each of the first tile and the second tile, and wherein omitting the encoded tile content comprises omitting the encoded motion information and the residuals of the second tile from the output bitstream.

13. The method of claim 10, wherein including the offset in the output bitstream comprises encoding without using entropy coding.

14. The method of claim 10, wherein including the offset in the output bitstream comprises:

including spatial offset information related to the first tile within a header of the second tile written to the output bitstream.

15. The method of claim 10, further comprising:

identifying previously coded tiles spatially proximate to a current tile as candidate tiles; and

selecting the first encoded tile from the candidate tiles.

16. The method of claim 15, wherein the candidate tiles include at least one of a first candidate tile that is located above the current tile, a second candidate tile that is located left of the current tile, a third candidate tile that is located above-left of the current tile, or a fourth candidate tile that is located above-right of the current tile.

17. The method of claim 15, wherein the candidate tiles are located immediately adjacent to the current tile.

18. The method of claim 10, further comprising:

generating a tile-copy mode indicator that indicates whether the second encoded tile in the output bitstream is a copy tile, wherein on a condition that the second encoded tile is the copy tile, the encoded tile content for the second encoded tile is omitted from the output bitstream and a tile header for the second encoded tile includes the tile-copy mode indicator and the offset for locating a reference tile having the encoded tile content for the second encoded tile.