RU2021129277A - ENCODER, DECODER AND CORRESPONDING METHODS OF INTER-FRAME PREDICTION - Google Patents

Claims (48)

1. A method for predicting a bidirectional optical flow, comprising steps in which obtaining an initial pair of motion vectors for the current block, where the initial pair of motion vectors contains a forward motion vector and a reverse motion vector; obtaining a forward prediction block corresponding to the forward motion vector and a backward prediction block corresponding to the backward motion vector; calculating gradient parameters for the current sample in the current block based on the forward prediction sample and for the reverse prediction sample corresponding to the current sample, where the forward prediction sample is a forward prediction block and the reverse prediction sample is in a reverse prediction block; obtaining at least two optical flow sample parameters for the current sample based on the gradient parameters, the optical flow sample parameters comprising a first parameter and a second parameter; the parameters of the optical flow block are obtained based on the parameters of the optical flow samples in the current block, wherein one of the parameters of the optical flow block is obtained by multiplying the value of the first parameter and the value of the sign function of the second parameter, the sign function being a piecewise function with at least three subranges ; obtaining a prediction value of the current block based on the parameters of the forward prediction block, the backward prediction block, the parameters of the optical flow block, and the parameters of the samples of the optical flow. 2. The method according to claim 1, in which the sign function has the form: Sign( x ) =

, where T is a non-negative real number. 3. The method according to p. 2, where T is 0; accordingly, the sign function has the form: Sign( x ) =

. 4. The method according to paragraphs. 1-3, wherein the initial motion vector pair is obtained according to the motion information of at least one spatial and/or temporal block adjacent to the current block. 5. The method according to any one of paragraphs. 1-4, in which the current block is a coding block or a subblock of a coding block. 6. The method according to any one of paragraphs. 1-5, in which the gradient parameters comprise a forward horizontal gradient, a reverse horizontal gradient, a forward vertical gradient, and a reverse vertical gradient. 7. The method of claim 6, wherein the direct horizontal gradient is the difference between a right sample and a left sample adjacent to the forward prediction sample. 8. The method of claim 6 or 7, wherein the inverse horizontal gradient is the difference between a right sample and a left sample adjacent to the inverse prediction sample. 9. The method according to any one of paragraphs. 6-8, in which the direct vertical gradient is the difference between the bottom sample and the top sample adjacent to the forward prediction sample. 10. The method according to any one of paragraphs. 6-9, in which the inverse vertical gradient is the difference between the lower sample and the upper sample adjacent to the inverse prediction sample. 11. The method according to any one of paragraphs. 6-10, in which the optical flow sampling parameters comprise a sampling difference, a horizontal average gradient, and a vertical average gradient. 12. The method of claim 11, wherein the first parameter is a sample difference, a horizontal mean gradient, or a vertical mean gradient. 13. The method of claim 12, wherein the second parameter is a sample difference, a horizontal mean gradient, or a vertical mean gradient, and the second parameter is not equal to the first parameter. 14. Device for bidirectional prediction of the optical flow, containing an acquisition module, configured to obtain an initial motion vector pair for the current block, the initial motion vector pair comprising a forward motion vector and a reverse motion vector; a correction module, configured to obtain a forward prediction block corresponding to the forward motion vector and a backward prediction block corresponding to the reverse motion vector; the gradient module, configured to calculate gradient parameters for the current sample in the current block based on the forward prediction sample and the reverse prediction sample corresponding to the current sample, where the forward prediction sample is in the forward prediction block and the reverse prediction sample is in the reverse prediction block; a calculation module configured to obtain at least two optical flow sampling parameters for the current sample based on the gradient parameters, the optical flow sampling parameters comprising a first parameter and a second parameter; a learning module configured to obtain the parameters of the optical flow block based on the parameters of the samples of the optical flow for the samples in the current block, wherein one of the parameters of the optical flow block is obtained by an operation comprising multiplying the value of the first parameter and the value of the sign function of the second parameter, wherein the sign function is a piecewise function with at least three subranges; And a prediction module configured to obtain a prediction value of the current block based on the parameters of the forward prediction block, the backward prediction block, the optical flow block, and the parameters of the optical flow samples. 15. The device according to claim 14, in which the sign function has the form: Sign( x ) =

, where T is a non-negative real number. 16. The device according to p. 15, in which T is equal to 0; accordingly, the sign function is Sign( x ) =

. 17. The device according to any one of paragraphs. 14-16, in which the initial pair of motion vectors is obtained in accordance with the motion information of at least one spatial and/or temporal block adjacent to the current block. 18. The device according to any one of paragraphs. 14-17, in which the current block is a coding block or a subblock of a coding block. 19. The device according to any one of paragraphs. 14-18, in which the gradient parameters comprise a forward horizontal gradient, a reverse horizontal gradient, a forward vertical gradient, and a reverse vertical gradient. 20. The apparatus of claim 19, wherein the forward horizontal gradient is the difference between a right sample and a left sample adjacent to the forward prediction sample. 21. The apparatus of claim 19 or 20, wherein the inverse horizontal gradient is the difference between a right sample and a left sample adjacent to the inverse prediction sample. 22. The device according to any one of paragraphs. 19-21, in which the forward vertical gradient is the difference between the bottom sample and the top sample adjacent to the forward prediction sample. 23. The device according to any one of paragraphs. 19-22, where the inverse vertical gradient is the difference between the bottom sample and the top sample adjacent to the inverse prediction sample. 24. The device according to any one of paragraphs. 19-23, in which the optical flow sampling parameters comprise a sampling difference, a horizontal average gradient, and a vertical average gradient. 25. The apparatus of claim 24, wherein the first parameter is a sample difference, a horizontal mean gradient, or a vertical mean gradient. 26. The apparatus of claim 25, wherein the second parameter is a sample difference, a horizontal mean gradient, or a vertical mean gradient, wherein the second parameter is not equal to the first parameter. 27. Device for bidirectional prediction of the optical flow, containing one or more processors; And a computer-readable, non-volatile storage medium coupled to the processors and storing programming executed by the processors, wherein the programming, when executed by the processors, causes the execution of a method according to any one of claims. 1-13. 28. Computer software product containing a control program for performing the method according to any one of paragraphs. 1-13.