Palette mode coding for video coding

Patent metadata

Field	Value
Publication number	US-2016227239-A1
Application number	US-201615004508-A
Country	US
Kind code	A1
Filing date	Jan 22, 2016
Priority date	Jan 29, 2015
Publication date	Aug 4, 2016
Grant date	—

Abstract

Receiving a plurality of syntax elements that are indicative of a palette that was used to encode a block of video data, the plurality of syntax elements including a first syntax element that indicates a number of palette values for the palette that are explicitly signaled in the encoded video bitstream, wherein the first syntax element is encoded using one or more Golomb codes such that the length of the encoded first syntax element is less than or equal to a predetermined maximum number of bits, decoding the plurality of syntax elements, including decoding the first syntax element using the one or more Golomb codes, reconstructing the palette based on the decoded plurality of syntax elements, and decoding the block of video data using the reconstructed palette.

First claim

What is claimed is:

1 . A method of decoding video data, the method comprising:
receiving a block of video data in an encoded video bitstream, the block of video data having been encoded using a palette-based coding mode; receiving a plurality of syntax elements that are indicative of a palette that was used to encode the block of video data, the plurality of syntax elements including a first syntax element that indicates a number of palette values for the palette that are explicitly signaled in the encoded video bitstream, wherein the first syntax element is encoded using one or more Golomb codes such that the length of the encoded first syntax element is less than or equal to a predetermined maximum number of bits; decoding the plurality of syntax elements, including decoding the first syntax element using the one or more Golomb codes; reconstructing the palette based on the decoded plurality of syntax elements; and decoding the block of video data using the reconstructed palette.

2 . The method of claim 1 , wherein the first syntax element is a num_signalled_palette_entries syntax element.

3 . The method of claim 1 , wherein the predetermined maximum number of bits is 32, and wherein the one or more Golomb codes is an exponential Golomb code of order 0.

4 . The method of claim 1 , wherein the predetermined maximum number of bits is 32, and wherein the one or more Golomb codes is a concatenation of a truncated Rice code and an exponential Golomb code.

5 . The method of claim 1 , wherein the plurality of syntax elements includes the palette values indicated as being explicitly signaled by the first syntax element.

6 . The method of claim 1 , wherein a maximum value of the first syntax element is defined relative to a second syntax element that indicates a maximum size of the palette, and a third syntax element that indicates a maximum size of a palette predictor, the method further comprising:
defining the second syntax element to be a value from 0 to a first threshold; and defining the third syntax element to be a value from 0 to a second threshold.

7 . The method of claim 6 , wherein the first threshold is one of 4095 or 4096 and the second threshold is one of 4095, 8191, or 8192.

8 . The method of claim 1 , wherein a maximum value of the first syntax element is defined relative to a second syntax element, of the plurality of syntax elements, that indicates a maximum size of the palette, and a third syntax element, of the plurality of syntax elements, that indicates a maximum size of a palette predictor, the method further comprising:
defining the second syntax element to be less than or equal to a number of pixels in a largest possible block of the video data in the encoded video bitstream; and defining the third syntax element to be less than or equal to K*a value of the second syntax element, where K is a positive constant and * indicates a multiplication operation.

9 . The method of claim 8 , wherein K is 2.

10 . The method of claim 1 , further comprising:
displaying the decoded block of video data.

11 . The method of claim 1 , further comprising:
receiving a syntax element indicating a palette run type in the case that a current pixel of the block of video data is not a first pixel in a scanning order of the block of video data; and inferring the syntax element as indicating a palette run type in the case that the current pixel is the first pixel in the scanning order.

12 . An apparatus configured to decode video data, the apparatus comprising:
a memory configured to store an encoded video bitstream; and a video decoder configured to:
receive a block of video data in the encoded video bitstream, the block of video data having been encoded using a palette-based coding mode;
receive a plurality of syntax elements that are indicative of a palette that was used to encode the block of video data, the plurality of syntax elements including a first syntax element that indicates a number of palette values for the palette that are explicitly signaled in the encoded video bitstream, wherein the first syntax element is encoded using one or more Golomb codes such that the length of the encoded first syntax element is less than or equal to a predetermined maximum number of bits;
decode the plurality of syntax elements, including decoding the first syntax element using the one or more Golomb codes;
reconstruct the palette based on the decoded plurality of syntax elements; and
decode the block of video data using the reconstructed palette.

13 . The apparatus of claim 12 , wherein the first syntax element is a num_signalled_palette_entries syntax element.

14 . The apparatus of claim 12 , wherein the predetermined maximum number of bits is 32, and wherein the one or more Golomb codes is an exponential Golomb code of order 0.

15 . The apparatus of claim 12 , wherein the predetermined maximum number of bits is 32, and wherein the one or more Golomb codes is a concatenation of a truncated Rice code and an exponential Golomb code.

16 . The apparatus of claim 12 , wherein the plurality of syntax elements includes the palette values indicated as being explicitly signaled by the first syntax element.

17 . The apparatus of claim 12 , wherein a maximum value of the first syntax element is defined relative to a second syntax element that indicates a maximum size of the palette, and a third syntax element that indicates a maximum size of a palette predictor, and wherein the video decoder is further configured to:
define the second syntax element to be a value from 0 to a first threshold; and define the third syntax element to be a value from 0 to a second threshold.

18 . The apparatus of claim 17 , wherein the first threshold is one of 4095 or 4096 and the second threshold is one of 4095, 8191, or 8192.

19 . The apparatus of claim 12 , wherein a maximum value of the first syntax element is defined relative to a second syntax element, of the plurality of syntax elements, that indicates a maximum size of the palette, and a third syntax element, of the plurality of syntax elements, that indicates a maximum size of a palette predictor, and wherein the video decoder is further configured to:
define the second syntax element to be less than or equal to a number of pixels in a largest possible block of the video data in the encoded video bitstream; and define the third syntax element to be less than or equal to K*a value of the second syntax element, where K is a positive constant and * indicates a multiplication operation.

20 . The apparatus of claim 19 , wherein K is 2.

21 . The apparatus of claim 12 , further comprising:
a display configured to display the decoded block of video data.

22 . The apparatus of claim 12 , wherein the video decoder is further configured to:
receive a syntax element indicating a palette run type in the case that a current pixel of the block of video data is not a first pixel in a scanning order of the block of video data; and infer the syntax element as indicating a palette run type in the case that the current pixel is the first pixel in the scanning order.

23 . An apparatus configured to decode video data, the apparatus comprising:
means for receiving a block of video data in an encoded video bitstream, the block of video data having been encoded using a palette-based coding mode; means for receiving a plurality of syntax elements that are indicative of a palette that

Assignees

• Qualcomm Inc

Inventors

• Pu Wei
• Karczewicz Marta
• Joshi Rajan Laxman
• Zou Feng
• Seregin Vadim

Classifications

• H04N19/44 Primary

  Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder · CPC title

• H04N19/176 Primary

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

• H04N19/70

  characterised by syntax aspects related to video coding, e.g. related to compression standards · CPC title

• H04N19/593 Primary

  involving spatial prediction techniques · CPC title

• H04N19/196

  being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters (processing of motion vectors H04N19/513) · CPC title