The disclosure discloses a method for processing video signals and an apparatus therefor. Specifically, the method of processing video signals based on inter prediction, comprising: configuring a merge candidate list based on a spatial neighboring block and a temporal neighboring block to a current block; adding a history-based merge candidate of the current block to the merge candidate list; obtaining a merge index indicating a merge candidate used for an inter prediction of the current block within the merge candidate list; generating a prediction sample of the current block based on motion information of the merge candidate indicated by the merge index; and updating a history-based merge candidate list based on the motion information.

The disclosure discloses a method for processing video signals and an apparatus therefor. Specifically, the method of processing video signals based on inter prediction, comprising: configuring a merge candidate list based on a spatial neighboring block and a temporal neighboring block to a current block; adding a history-based merge candidate of the current block to the merge candidate list; obtaining a merge index indicating a merge candidate used for an inter prediction of the current block within the merge candidate list; generating a prediction sample of the current block based on motion information of the merge candidate indicated by the merge index; and updating a history-based merge candidate list based on the motion information.

An image processing method includes: downsizing a current frame and a reference frame; dividing the down-sized current frame and the down-sized reference frame into multiple first current blocks and multiple first reference blocks, respectively; performing a first motion estimation to the first current blocks and the first reference blocks to generate multiple first motion vectors; dividing the current picture and the reference picture into multiple second current blocks and multiple second reference blocks, respectively; performing a second motion estimation to the second current blocks and the second reference blocks to generate multiple second motion vectors; and generating a compensated frame between the current frame and the reference frame according to the second motion vectors. The second motion estimation includes: performing a 3D recursive search for each second current block; and adjusting multiple estimation parameters in the 3D recursive search according to the first motion vector.

Embodiments of video coding systems and methods are described for reducing coding latency introduced by decoder-side motion vector refinement (DMVR). In one example, two non-refined motion vectors are identified for coding of a first block of samples (e.g. a first coding unit) using bi-prediction. One or both of the non-refined motion vectors are used to predict motion information for a second block of samples (e.g. a second coding unit). The two non-refined motion vectors are refined using DMVR, and the refined motion vectors are used to generate a prediction signal of the first block of samples. Such embodiments allow the second block of samples to be coded substantially in parallel with the first block without waiting for completion of DMVR on the first block. In additional embodiments, optical-flow-based techniques are described for motion vector refinement.

A method operates within an integrated circuit having a plurality of processing lanes. For each of a first and second processing lanes, the method determines a number of packed data words among one or more packed data words associated with the respective processing lane, associates the number of packed data words with a used field of the processing lane, wherein the used field indicates the number of packed data words in the processing lane; and stores the one or more packed data words in a variable record length memory based, at least in part, on the used field of the processing lane.

A method operates within an integrated circuit having a plurality of processing lanes. For each of a first and second processing lanes, the method determines a number of packed data words among one or more packed data words associated with the respective processing lane, associates the number of packed data words with a used field of the processing lane, wherein the used field indicates the number of packed data words in the processing lane; and stores the one or more packed data words in a variable record length memory based, at least in part, on the used field of the processing lane.

A method for video encoding includes generating a first syntax element indicating a maximum number of merge motion vector prediction (MVP) candidates, and encoding the first syntax element at a first coding level in a coded video bitstream, the first coding level being higher than a picture parameter set (PPS) level. The video encoding method also includes transmitting the coded video bitstream including the first syntax element. The maximum number of merge MVP candidates indicated by the first syntax element is applicable for reconstructing coding blocks of the coded video bitstream associated with the first coding level.

A method for video encoding includes generating a first syntax element indicating a maximum number of merge motion vector prediction (MVP) candidates, and encoding the first syntax element at a first coding level in a coded video bitstream, the first coding level being higher than a picture parameter set (PPS) level. The video encoding method also includes transmitting the coded video bitstream including the first syntax element. The maximum number of merge MVP candidates indicated by the first syntax element is applicable for reconstructing coding blocks of the coded video bitstream associated with the first coding level.

Method and apparatus of video coding using decoder derived motion information based on bilateral matching or template matching are disclosed. According to one method, merge index for merge candidate group comprising bilateral matching merge candidate and/or template matching merge candidate are signalled using different codewords. According to another method, the first-stage MV or the first-stage MV pair is used as an only initial MV or MV pair or used as a central MV of search window for second-stage search. According to yet another method, after the reference template for a first reference list is found, the current template is modified for template search in the other reference list. According to yet another method, the sub-PU search is disabled for the template search. According to yet another method, block difference calculation is based on reduced bit depth during MV search associated with the decoder-side MV derivation process.

Method and apparatus of video coding using decoder derived motion information based on bilateral matching or template matching are disclosed. According to one method, merge index for merge candidate group comprising bilateral matching merge candidate and/or template matching merge candidate are signalled using different codewords. According to another method, the first-stage MV or the first-stage MV pair is used as an only initial MV or MV pair or used as a central MV of search window for second-stage search. According to yet another method, after the reference template for a first reference list is found, the current template is modified for template search in the other reference list. According to yet another method, the sub-PU search is disabled for the template search. According to yet another method, block difference calculation is based on reduced bit depth during MV search associated with the decoder-side MV derivation process.