Edge-selective intra coding

• US 9,756,346 B2
• Filed: 10/02/2015
• Issued: 09/05/2017
• Est. Priority Date: 10/08/2012
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Gu, Qunshan, Xu, Yaowu
• Primary Examiner(s): HUANG, FRANK F
• Application Number:
  US14/873,688
• Publication Number:
  US 20160029034A1
• Time in Patent Office: 704 Days
• CPC Class Codes: H04N 19/11 among a plurality of spatial predictive coding modes
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock

Abstract

Edge-selective intra coding may include encoding a first input block, generating a first reconstructed block by decoding the first encoded block, determining a reconstruction error block based on a difference between the first input block and the first reconstructed block, identifying a second input block from the first input frame, and determining a plurality of refined context pixels. Determining a plurality of refined context pixels may include identifying a plurality of context pixels from the reconstruction error block, generating a plurality of encoded context pixels by encoding the plurality of context pixels, generating a plurality of reconstructed context pixels by decoding the plurality of encoded context pixels, and adding at least a portion of the reconstruction error block and the plurality of reconstructed context pixels. The method may include generating a second encoded block by encoding the second input block based on the plurality of refined context pixels.

Claims

1. A method comprising:

generating a first encoded block by encoding a first input block from a first input frame from an input video stream;

generating a first reconstructed block by decoding the first encoded block;

determining a reconstruction error block based on a difference between the first input block and the first reconstructed block;

identifying a second input block from the first input frame;

determining a plurality of refined context pixels by;

identifying a plurality of context pixels from the reconstruction error block,

generating a plurality of encoded context pixels by encoding the plurality of context pixels,

generating a plurality of reconstructed context pixels by decoding the plurality of encoded context pixels, and

adding at least a portion of the reconstruction error block and the plurality of reconstructed context pixels;

generating, by a processor in response to instructions stored on a non-transitory computer readable medium, a second encoded block by encoding the second input block based on the plurality of refined context pixels;

including the second encoded block in an output bitstream; and

transmitting or storing the output bitstream.

2. The method of claim 1, wherein encoding the first input block includes:

identifying a prediction block based on the first input block;

generating a residual block based on a difference between the first input block and the prediction block;

determining a transform block by transforming the residual block, the transform block including a plurality of transform coefficients; and

generating a quantized block by quantizing the transform block.

3. The method of claim 2, wherein decoding the first encoded block includes:

generating a dequantized block by dequantizing the quantized block;

generating an inverse-transform block by inverse-transforming the dequantized block; and

generating the reconstructed block based on a sum of the inverse-transform block and the prediction block.

4. The method of claim 1, wherein encoding the plurality of context pixels includes:

generating a plurality of quantized context pixels by quantizing the plurality of context pixels.

5. The method of claim 4, wherein decoding the plurality of encoded context pixels includes:

dequantizing the plurality of quantized context pixels.

6. The method of claim 1, wherein encoding the first input block includes intra-prediction coding the first input block.

7. The method of claim 1, wherein encoding the first input block includes using a first quantization value and encoding the plurality of context pixels includes using a second quantization value.

8. The method of claim 1, wherein encoding the first input block includes using transform domain quantization and encoding the plurality of context pixels includes using spatial domain quantization.

9. The method of claim 1, wherein identifying the plurality of context pixels includes:

identifying the right most column of the reconstruction error block as the plurality of context pixels, on a condition that encoding the first input block includes using horizontal intra prediction; and

identifying the bottom most row of the reconstruction error block as the plurality of context pixels, on a condition that encoding the first input block includes using vertical intra prediction.

10. The method of claim 1, wherein encoding the second input block include intra-coding the second input block.

11. A method comprising:

identifying a first input block from a first input frame from an input video stream;

generating a first encoded block by;

identifying a prediction block based on the first input block,

generating a residual block based on a difference between the first input block and the prediction block,

generating a transform block by transforming the residual block, the transform block including a plurality of transform coefficients, and

generating a quantized block by quantizing the transform block using a transform domain quantization value;

generating a first reconstructed block by decoding the first encoded block;

determining a reconstruction error block based on a difference between the first input block and the first reconstructed block;

identifying a second input block from the first input frame;

determining a plurality of refined context pixels by;

identifying a plurality of context pixels from the reconstruction error block,

generating a plurality of encoded context pixels by quantizing the plurality of context pixels using a spatial domain quantization value,

generating a plurality of reconstructed context pixels by decoding the plurality of encoded context pixels, and

adding at least a portion of the reconstruction error block and the plurality of reconstructed context pixels;

generating, by a processor in response to instructions stored on a non-transitory computer readable medium, a second encoded block by encoding the second input block based on the plurality of refined context pixels;

including the second encoded block in an output bitstream; and

transmitting or storing the output bitstream.

12. The method of claim 11, wherein decoding the first encoded block includes:

generating a dequantized block by dequantizing the quantized block;

generating an inverse-transform block by inverse-transforming the dequantized block; and

generating the reconstructed block based on a sum of the inverse-transform block and the prediction block.

13. The method of claim 11, wherein decoding the plurality of encoded context pixels includes:

dequantizing the plurality of quantized context pixels.

14. The method of claim 11, wherein encoding the first input block includes intra-prediction coding the first input block.

15. The method of claim 11, wherein identifying the plurality of context pixels includes:

identifying the right most column of the reconstruction error block as the plurality of context pixels, on a condition that encoding the first input block includes using horizontal intra prediction; and

identifying the bottom most row of the reconstruction error block as the plurality of context pixels, on a condition that encoding the first input block includes using vertical intra prediction.

16. The method of claim 11, wherein encoding the second input block include intra-coding the second input block.

17. A method comprising:

identifying a current input block from a first input frame from an input video stream;

generating, by a processor in response to instructions stored on a non-transitory computer readable medium, a current encoded block by encoding the current input block, wherein encoding the current input block includes identifying a prediction block based on the current input block and a plurality of refined context pixels;

including the current encoded block in an output bitstream; and

transmitting or storing the output bitstream.

18. The method of claim 17, identifying the prediction block includes:

generating a reconstructed block by decoding an encoded block;

generating a reconstruction error block for the reconstructed block;

identifying a plurality of context pixels from the reconstruction error block;

generating a plurality of encoded context pixels by encoding the plurality of context pixels;

generating a plurality of reconstructed context pixels by decoding the plurality of encoded context pixels; and

identifying the plurality of refined context pixels by adding at least a portion of the reconstruction error block and the plurality of reconstructed context pixels.

19. The method of claim 18, wherein decoding the encoded block includes using a transform domain quantization value and decoding the plurality of encoded context pixels includes using a spatial domain quantization value.

20. The method of claim 18, wherein identifying the plurality of context pixels includes:

identifying the right most column of the reconstruction error block as the plurality of context pixels, on a condition that encoding the first input block includes using horizontal intra prediction; and

identifying the bottom most row of the reconstruction error block as the plurality of context pixels, on a condition that encoding the first input block includes using vertical intra prediction.