Edge-selective intra coding

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.