Google Inc.

Lester Lu

Debargha Mukherjee

Elliott Karpilovsky

Rohit Shankar Singh

Yue Chen

Onur Gonen Guleryuz

Zeyu Deng

Transform prediction with parsing independent coding includes generating a reconstructed frame and outputting the reconstructed frame. Generating the reconstructed frame includes entropy decoding transform blocks for the reconstructed frame, entropy decoding decoded transform identifiers for the transform blocks, obtaining transform-specific probability distributions for available transforms, and, for a current transform block from the transform blocks, identifying a current remapped transform identifier from the decoded transform identifiers, identifying a current transform identifier in accordance with the current remapped transform identifier, the transform coefficients from the current transform block, and the transform-specific probability distributions, identifying a current transform in accordance with the current transform identifier; inverse transforming, in accordance with the current transform, the current transform block to obtain a current residual block and obtaining a current reconstructed block using the current residual block. Generating the reconstructed frame includes including the current reconstructed block in the reconstructed frame.

Transform prediction with parsing independent coding

Residual coding using vector quantization (VQ) is described. A flag indicating whether a residual block for the current block is encoded using VQ. In response to the flag indicating that the residual block is encoded using VQ, a parameter indicating an entry in a codebook is decoded, and the residual block is decoded using the entry. In response to the flag indicating that the residual block is not encoded using VQ, the residual block is decoded based on a skip flag indicating whether the current block is encoded using transform skip. The current block is reconstructed using the residual block.

Vector quantization for prediction residual coding

Transform modes are derived for inter-predicted blocks using side information. A prediction residual is generated for a current video block using a reference frame. Side information associated with one or both of the current video block or the reference frame is identified. A trained transform is determined from amongst multiple trained transforms based on the side information, in which each of the trained transforms is determined using individual side information types and combinations of the individual side information types and the side information represents values of one of the individual side information types or one of the combinations of the individual side information types. The prediction residual is transformed according to the trained transform, and data associated with the transformed prediction residual and the side information are encoded to a bitstream.

Inter-prediction mode-dependent transforms for video coding

Decoding video data includes, for a block encoded using a prediction mode, determining a transform mode for the block using the prediction mode. The transform mode is a first mode when the prediction mode is an inter-prediction mode and is a second mode when the prediction mode is an intra-prediction mode. The first mode is an available first transform type that is a combination of transforms selected from first fixed transforms and first learned transforms that each comprise a respective transformation matrix generated iteratively using blocks predicted using the inter-prediction mode. The second mode is an available second transform type that is a combination of transforms selected from second fixed transforms, which is a proper subset of the first fixed transforms, and a second learned transform comprising a transformation matrix that is generated iteratively using blocks predicted using the intra-prediction mode. Decoding the block uses the prediction and transform modes.

Combination of mode-dependent and fixed transform types in video coding

Coding a block of video data includes determining a prediction mode for the block, which is an inter-prediction or intra-prediction mode, determining a transform type for the block, and coding the block using the prediction mode and the transform type. The transform type is one of a first plurality of transform types when the prediction mode is the inter-prediction mode, and is one of a second plurality of transform types when the prediction mode is the intra-prediction mode. The first plurality of transform types includes first fixed transform types and first mode-dependent transform types that are based on a first learned transform generated using inter-predicted blocks. The second plurality of transform types includes second fixed transform types and second mode-dependent transform types that are based on a second learned transform generated using intra-predicted blocks. The first and second fixed transform types have at least some fixed transform types in common.

Transform modes are derived for inter-predicted blocks using side information available within a bitstream. An inter-predicted encoded video block and side information are identified within a bitstream. Based on the side information, a trained transform is determined for inverse transforming transform coefficients of the inter-predicted encoded video block from amongst multiple trained transforms. The transform coefficients of the inter-predicted encoded video block are inverse transformed according to the trained transform to produce a prediction residual. A video block is reconstructed using the prediction residual and the reference frame. The video block is then output within an output video stream for storage or display. To determine the trained transforms, a learning model uses individual side information types and combinations of the individual side information types processed against a training data set.

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Lester Lu