Google Inc.

General Instrument Corporation

Terayon Communication Systems, Inc.

Joseph Young

Dake He

Jane Perera

Aki Kuusela

Claudionor Coelho

Shan Li

Todd Nguyen

An apparatus for encoding an image block includes a processor that presents, to a machine-learning model, the image block, obtains the partition decision for encoding the image block from the model, and encodes the image block using the partition decision. The model is trained to output a partition decision for encoding the image block by using training data for a plurality of training blocks as input, the training data including for a training block, partition decisions for encoding the training block, and, for each partition decision, a rate-distortion value resulting from encoding the training block using the partition decision. The model is trained using a loss function combining a partition loss function based upon a relationship between the partition decisions and respective predicted partitions, and a rate-distortion cost loss function based upon a relationship between the rate-distortion values and respective predicted rate-distortion values.

Using rate distortion cost as a loss function for deep learning

An apparatus for decoding a current block includes a processor that is configured to obtain a transform class of a transform type used for decoding a transform block of the current block; select, based on the transform class, a template for coding a value related to a transform coefficient at a row and a column of the transform block; obtain, using the template, an index of a probability distribution in a table of probability distributions; and decode, from a compressed bitstream, the value using the probability distribution.

Entropy coding using transform class

A method for coding a frame of a video stream includes selecting a first initial probability distribution for coding at least a first portion of the frame; updating, to obtain an updated first initial probability distribution and using backward adaptivity, the first initial probability distribution while coding the first portion of the frame; mapping the updated first initial probability distribution to a second initial probability distribution; and coding a second portion of the frame using the second initial probability distribution as an initial probability distribution. The first values of the first initial probability distribution are described using M bits, wherein M is a first positive integer. Second values of the updated first initial probability distribution are described using N bits, where N is a second positive integer that is greater than M. Third values of the second initial probability distribution are described using M bits.

Probability mapping for entropy coding

Coding a current block using a directional intra-prediction mode is described. A filter to apply to reference pixels peripheral to the current block is determined using a prediction angle of the intra-prediction mode and a size of the current block. The reference pixels are filtered using the filter to generate modified reference pixels, and a prediction block is generated for the current block using the intra-prediction mode and the modified reference pixels.

Directional intra-prediction coding

An apparatus includes a memory and a processor. The processor is configured to execute instructions stored in the memory to obtain a transform type for decoding a transform block for the current block; select, based on the transform type, a template for coding a value of a non-zero map; select, based on the template, a context for entropy decoding the value of the non-zero map; and decode the value of the non-zero map based on the context. The non-zero map indicates which coefficients of the transform block have non-zero values. A method includes obtaining a transform class for coding a transform block for the current block, wherein the transform class corresponding to a transform type and a direction; selecting, based on the transform class, a coding context for coding a value of a non-zero map; and coding the value of the non-zero map based on the coding context.

Refined entropy coding for level maps

A method for coding a current block using an intra-prediction mode includes defining a mapping from available intra-prediction modes to intra-prediction classes; determining, using the mapping, a first intra-prediction class of a first intra-prediction mode used for decoding a first neighboring block of the current block; determining, using the mapping, a second intra-prediction class of a second intra-prediction mode used for decoding a second neighboring block of the current block; using the first intra-prediction class and the second intra-prediction class as indices into a list of available context models to select a context model for coding the intra-prediction mode; and coding the intra-prediction mode using the context model. A first number of the intra-prediction classes is smaller than a second number of the available intra-prediction modes. each class is an ordinal value, and each available intra-prediction mode uniquely maps to one class of the intra-prediction classes.

Context modeling for intra-prediction modes

Efficient noise reduction coding may include generating, by a processor, an encoded frame by encoding an input video frame. Encoding the input frame includes determining an estimated noise level for the input video frame, determining a minimum quantization parameter level based on the estimated noise level for the input video frame, determining a quantization parameter value for encoding the input frame such that the quantization parameter value is at least the minimum quantization parameter level, obtaining the encoded frame by encoding the input frame in accordance with the quantization parameter level, including the encoded frame in an output bitstream, and outputting the output bitstream.

Efficient noise reduction coding

Coding a current block using a directional intra prediction mode is disclosed. The intra prediction mode includes a prediction angle and uses pixels peripheral to the current block to generate a prediction block. An apparatus determines, using the prediction angle, a filter to apply to the pixels peripheral to the current block; filters, using the filter, at least some of the pixels peripheral to the current block resulting in modified pixels; and generates a prediction block for the current block using the intra prediction mode and the modified pixels.

Intra-prediction edge filtering

Coding using level maps is disclosed. A method includes coding a scan position, in a forward scan direction, corresponding to an end-of-block and coding, in a backward scan direction, a non-zero map indicating positions of the transform block containing non-zero transform coefficients. The method also includes coding, in the backward scan direction, lower-range level maps, each lower-range level map having a respective map level up to a maximum map level, the lower-range level map indicating which absolute values of the non-zero transform coefficients are equal to the respective map level and which absolute values of the non-zero transform coefficients are greater than the respective map level. The method also includes coding a coefficient residual map, each residual coefficient of the coefficient residual map corresponding to a respective non-zero transform coefficient of the transform block having an absolute value exceeding the maximum map level.

A method for intra-coding a current block using an intra-prediction mode includes determining a left intra-mode of a left neighbor block and determining an above intra-mode of an above neighbor block. The method also includes, on condition that the left intra-mode and the above intra-mode are a same mode, using that same mode to determine a probability distribution for coding the intra-prediction mode and, on condition that at least one of the left intra-mode or the above intra-mode is a smooth intra-prediction mode, using the other of the left intra-mode and the above intra-mode to determine the probability distribution for coding the intra-prediction mode. The method also includes coding the intra-prediction mode using the probability distribution.

Coding a current block using a directional intra prediction mode is disclosed. The intra prediction mode includes a prediction angle and uses pixels peripheral to the current block to generate a prediction block. A method includes determining, using the prediction angle, a filter to apply to the pixels peripheral to the current block, filtering, using the filter, at least some of the pixels peripheral to the current block resulting in modified pixels, and generating a prediction block for the current block using the intra prediction mode and the modified pixels.

A crawl motion vector is determined based on a speed and direction of the crawling text to be displayed in a text crawl area. A determination whether to re-encode macroblocks in the plurality of pictures is made. The macroblocks in the plurality of pictures that are to be re-encoded are either macroblocks having motion vectors pointing to the text crawl area or macroblocks within the text crawl area. A lowest bit rate coding option for each macroblock to be re-encoded is determined, and each macroblock is re-encoded using the lowest bit rate coding option for the macroblock.

Method and apparatus for managing bit rate

A method and apparatus transfer digital data between a coder/decoder circuit and a signal processor. The transfer of the digital data includes (a) obtaining, at a first circuit, a block of data values having certain statistical characteristics, the first circuit being one of the coder/decoder circuit and the signal processor, (b) generating, at the first circuit, a data stream by encoding the block of data values based on the statistical characteristics thereof, (c) transferring the data stream to a second circuit via a data bus connecting the first circuit and the second circuit, the second circuit being the other of the coder/decoder circuit and the signal processor, and (d) reconstructing, at the second circuit, the block of data values by decoding the data stream received from the first circuit.

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Mountain View, CA, United States of America

Joseph Young