Method and device for encoding and decoding videos using a best transformation matrix among multiple transformation matrices
The embodiments of the present invention provide a method and a device for encoding and decoding videos, and relate to the communication field, and an efficient transformation matrix corresponding to features of each residual block is selected for transformation, which therefore improves encoding efficiency. The solution provided in an embodiment of the present invention is: generating a prediction residual according to input video data; selecting a set of best transformation matrixes among multiple candidate transformation matrixes according to an intra-frame prediction mode and rate-distortion criteria to perform transform-coding on the prediction residual and obtain a transformation result; and generating an encoded stream according to the transformation result and selected transformation matrix index information.
1. A method for encoding video data, comprising:
generating a prediction residual according to input video data;
performing transform-coding on the prediction residual using a plurality of candidate transformation matrices and obtaining a transformation result for each of the plurality of candidate transformation matrices;
selecting a set of best transformation matrices among the plurality of candidate transformation matrices according to optimization criteria; and
encoding a selected transformation matrix index according to the transformation result corresponding to the set of best transformation matrices and an intra-frame prediction mode to generate an encoded stream.
2. The method for encoding video data according to claim 1 , wherein:
the set of best transformation matrices is a non-separate transformation matrix; or
the set of best transformation matrices are a pair of transformation matrices that comprise a column transformation matrix and a row transformation matrix.
3. The method for encoding video data according to claim 1 , wherein:
the optimization criteria comprise: rate-distortion criteria, sum of absolute difference (SAD), code bits, or distortion.
4. The method for encoding video data according to claim 1 , further comprising:
selecting a scan order of a set of coefficients according to the transformation matrix index to scan a transformed coefficient.
5. The method for encoding video data according to claim 1 , further comprising:
encoding the prediction residual in various encoding modes, selecting a mode with a minimum optimization criteria cost as the intra-frame prediction mode, and obtaining an encoding result.
6. The method for encoding video data according to claim 1 , wherein: the encoding the selected transformation matrix index according to the transformation result and the intra-frame prediction mode to generate the encoded stream comprises:
selecting a method for encoding the transformation matrix index according to a selected intra-frame prediction mode to write the transformation matrix index into the encoded data.
7. The method for encoding video data according to claim 6 , wherein: if the set of best transformation matrices are a pair of transformation matrices, the selecting a method for encoding the transformation matrix index according to the selected intra-frame prediction mode to write the transformation matrix index into the encoded data comprises:
encoding index of a pair of transformation matrices jointly, or encoding index of a pair of transformation matrices separately; and
selecting a method for encoding the transformation matrix index according to the selected intra-frame prediction mode to write the transformation matrix index into the encoded data.
8. The method for encoding video data according to claim 1 , wherein: the selecting a set of best transformation matrices among the plurality of candidate transformation matrices according to the optimization criteria to perform transform-coding on the prediction residual and obtain a transformation result comprises:
traversing all combinations of a column transformation matrix and a row transformation matrix in the plurality of candidate transformation matrices, selecting a transformation combination with a minimum optimization criteria cost after residual transform-coding as a best transformation matrix, and obtaining a transformation result.
9. A video decoding method, comprising:
resolving an encoded video stream to obtain a transformation result, and obtaining a transformation matrix index according to an intra-frame prediction mode; and
determining a transformation matrix among a plurality of candidate transformation matrices according to the transformation matrix index, using the determined transformation matrix to perform inverse transformation on the transformation result to obtain residual data, and reconstructing video data according to the residual data.
10. The video decoding method according to claim 9 , wherein:
the determined transformation matrix is a non-separate transformation matrix; or
the determined transformation matrix is a pair of transformation matrices that comprise a column transformation matrix and a row transformation matrix.
11. The video decoding method according to claim 9 , wherein the obtaining the transformation matrix index according to the intra-frame prediction mode comprises:
selecting a method for decoding the transformation matrix index according to the intra-frame prediction mode to obtain the transformation matrix index.
12. The video decoding method according to claim 9 , further comprising:
selecting a scan order of a set of coefficients according to the transformation matrix index to perform inverse coefficient scanning on a transformed coefficient.
13. The video decoding method according to claim 9 , wherein:
the transformation matrix is determined among a set of candidate row transformation matrices and column transformation matrices according to row transformation matrix index information and column transformation matrix index in the transformation matrix index.
14. A video data encoder, comprising:
a hardware processor configured to:
generate a prediction residual according to input video data;
perform transform-coding on the prediction residual using a plurality of candidate transformation matrices and obtain a transformation result for each of the plurality of candidate transformation matrices;
select a set of best transformation matrices among the plurality of candidate transformation matrices according to optimization criteria; and
encode a selected transformation matrix index according to the transformation result corresponding to the set of best transformation matrices and an intra-frame prediction mode to generate an encoded stream.
15. The video data encoder according to claim 14 , the hardware processor further configured to select a scan order of a set of coefficients according to the transformation matrix index to scan a transformed coefficient.
16. The video data encoder according to claim 14 , the hardware processor further configured to determine a mode with a minimum optimization criteria cost as an intra-frame prediction mode after the prediction residual is encoded in various encoding modes, and obtain an encoding result.
17. The video data encoder according to claim 14 , the hardware processor further configured to select a method for encoding the transformation matrix index according to a selected intra-frame prediction mode to write the transformation matrix index into encoded data.
18. The video data encoder according to claim 14 , the hardware processor further configured to: traverse all combinations of a column transformation matrix and a row transformation matrix in the plurality of candidate transformation matrices, select a transformation combination with a minimum optimization criteria cost after residual transform-coding as a best transformation matrix, and obtain a transformation result.
19. A video decoder, comprising:
a hardware processor configured to:
resolve a video stream to obtain a transformation result, and obtain a transformation matrix index according to an intra-frame prediction mode;
determine a transformation matrix among a plurality of candidate transformation matrices according to the transformation matrix index information; and
use the determined transformation matrix to perform inverse transformation on the transformation result to obtain residual data, and reconstruct video data according to the residual data.
20. The video decoder according to claim 19 , the hardware processor further configured to select a scan order of a set of coefficients according to the transformation matrix index to perform inverse coefficient scanning on a transformed coefficient.
21. The video decoder according to claim 19 , the hardware processor further configured to determine a transformation matrix among a set of candidate row transformation matrices and column transformation matrices according to row transformation matrix index and column transformation matrix index in the transformation matrix index.