Video coder providing implicit coefficient prediction and scan adaptation for image coding and intra coding of video
A predictive video coder performs gradient prediction based on previous blocks of image data. For a new block of image data, the prediction determines a horizontal gradient and a vertical gradient from a block diagonally above the new block (vertically above a previous horizontally adjacent block). Based on these gradients, the encoder predicts image information based on image information of either the horizontally adjacent block or a block vertically adjacent to the new block. The encoder determines a residual that is transmitted in an output bitstream. The decoder performs the identical gradient prediction and predicts image information without need for overhead information. The decoder computes the actual information based on the predicted information and the residual from the bitstream.
1. A method for decoding coded signals of a block X of new image data associated with a video object plane, the method comprising:
identifying via a decoder a block A horizontally adjacent to and temporally prior to the block X, a block B vertically adjacent to the block A, and a block C vertically adjacent to the block X; and
if any of the block A, the block B or the block C is outside a boundary of the video object plane, to yield an outside block, assigning a value to an inverse quantized DC coefficient for the outside block, to yield an assigned value, and using the assigned value to compute a prediction value for the block X.
2. The method of claim 1 , wherein the value is 128.
3. The method of claim 1 , wherein the prediction value for the block X is computed by steps comprising:
determining a first block-based gradient between data of the block A and data of the block B;
determining a second block-based gradient between data of the block B and the data of the block C; and
predicting the prediction value for the block X, based on the first block-based gradient and the second block-based gradient.
4. The method of claim 3 , wherein predicting the prediction value for the block X is performed without reference to any other gradient.
5. The method of claim 3 , further comprising:
in the event that the first block-based gradient is less than the second block-based gradient, predicting the prediction value for the block X based on the data of the block C; and
in the event that the first block-based gradient is not less than the second block-based gradient, predicting the prediction value for the block X based on the data of the block A.
6. A non-transitory computer-readable storage medium storing instructions for controlling a decoder to decode coded signals of a block X of new image data associated with a video object plane, the instructions comprising:
identifying a block A horizontally adjacent to and temporally prior to the block X, a block B vertically adjacent to the block A, and a block C vertically adjacent to the block X; and
if any of the block A, the block B or the block C is outside a boundary of the video object plane, to yield an outside block, assigning a value to an inverse quantized DC coefficient for the outside block, to yield an assigned value, and using the assigned value to compute a prediction value for the block X.
7. The non-transitory computer-readable storage medium of claim 6 , wherein the assigned value is 128.
8. The non-transitory computer-readable storage medium of claim 6 , wherein the prediction value for the block X is computed by steps comprising:
determining a first block-based gradient between data of the block A and data of the block B;
determining a second block-based gradient between data of the block B and the data of the block C; and
predicting the prediction value for the block X, based on the first block-based gradient and the second block-based gradient.
9. The non-transitory computer-readable storage medium of claim 8 , wherein predicting the prediction value for the block X is performed without reference to any other gradient.
10. The non-transitory computer-readable storage medium of claim 8 , wherein the instructions further comprise:
in the event that the first block-based gradient is less than the second block-based gradient, predicting the prediction value for the block X based on the data of the block C; and
in the event that the first block-based gradient is not less than the second block-based gradient, predicting the prediction value for the block X based on the data of the block A.
11. A system for decoding coded signals of a block X of new image data associated with a video object plane, the system comprising:
a processor;
a first module configured to control the processor to identify a block A horizontally adjacent to and temporally prior to the block X, a block B vertically adjacent to the block A, and a block C vertically adjacent to the block X; and
a second module configured to control the processor, if any of the block A, the block B or the block C is outside a boundary of the video object plane, yielding an outside block, to assign a value to an inverse quantized DC coefficient for the outside block, to yield an assigned value, and use the assigned value to compute a prediction value for the block X.
12. The system of claim 11 , wherein the assigned value is 128.
13. The system of claim 11 , wherein the system further comprises a third module configured to control the processor to compute the prediction value for the block X by:
determining a first block-based gradient between data of the block A and data of the block B;
determining a second block-based gradient between data of the block B and the data of the block C; and
predicting the prediction value for the block X, based on the first block-based gradient and the second block-based gradient.
14. The system of claim 13 , wherein predicting the prediction value for the block X is performed without reference to any other gradient.
15. The system of claim 13 , wherein the third module computes the prediction value by:
in the event that the first block-based gradient is less than the second block-based gradient, predicting the prediction value for the block X based on the data of the block C; and
in the event that the first block-based gradient is not less than the second block-based gradient, predicting the prediction value for the block X based on the data of the block A.
16. A system for decoding coded signals of a block X of new image data associated with a video object plane, the system comprising:
a processor;
a first module configured to control the processor to identify a block A horizontally adjacent to, left of, and temporally prior to the block X, a block B vertically adjacent to and above the block A, and a block C vertically adjacent to and above the block X; and
a second module configured to control the processor, if any of the block A, the block B or the block C is outside a boundary of the video object plane to yield an outside block, to assume a value to an inverse quantized DC coefficient for the outside block, to yield an assumed value, and use the assumed value to compute a prediction value for the block X.
17. The system of claim 16 , wherein the assumed value is 128.
18. The system of claim 16 , wherein the system further comprises a third module configured to control the processor to compute the data for the block X by:
determining a first block-based gradient between data of the block A and data of the block B;
determining a second block-based gradient between data of the block B and the data of the block C; and
predicting the prediction value for the block X, based on the first block-based gradient and the second block-based gradient.
19. The system of claim 18 , wherein predicting the prediction value for the block X is performed without reference to any other gradient.
20. The system of claim 18 , wherein the third module computes the prediction value for the block X by:
in the event that the first block-based gradient is less than the second block-based gradient, predicting the prediction value for the block X based on the data of the block C; and
in the event that the first block-based gradient is not less than the second block-based gradient, predicting the prediction value for the block X based on the data of the block A.
21. A decoder that decodes coded signals of a block X of new image data associated with a video object plane, the decoder performing steps comprising:
identifying a block A horizontally adjacent to and temporally prior to the block X, a block B vertically adjacent to the block A, and a block C vertically adjacent to the block X; and
if any of the block A, the block B or the block C is outside a boundary of the video object plane, to yield an outside block, assigning a value to an inverse quantized DC coefficient for the outside block, to yield an assigned value, and using the assigned value to compute a prediction value for the block X.
22. The decoder of claim 21 , wherein the assigned value is 128.
23. The decoder of claim 21 , wherein the decoder further performs a step comprising computing the prediction value for the block X by:
determining a first block-based gradient between data of the block A and data of the block B;
determining a second block-based gradient between data of the block B and the data of the block C; and
predicting the prediction value for the block X, based on the first block-based gradient and the second block-based gradient.
24. The decoder of claim 23 , wherein predicting the prediction value for the block X is performed without reference to any other gradient.
25. The decoder of claim 23 , wherein the decoder further performs steps comprising:
in the event that the first block-based gradient is less than the second block-based gradient, predicting the prediction value for the block X based on the data of the block C; and
in the event that the first block-based gradient is not less than the second block-based gradient, predicting the prediction value for the block X based on the data of the block A.