Qualcomm Incorporated

Rahul P Panchal

Marta Karczewicz

Yan Ye

Rajan Laxman Joshi

Muhammed Zeyd Coban

Peisong Chen

Seyfullah Halit Oguz

Amit Rohatgi

This disclosure describes techniques for calculating values of sub-integer pixels applied by an encoder and a decoder to encode blocks of video data. In one example, a video encoder is configured to receive values for a full integer pixel positions of a reference sample, apply an interpolation filter to a first set of the values for the full integer pixel positions to calculate a value for a first sub-integer pixel of one of the full integer pixel positions, apply the interpolation filter to a second, different set of the values for the full integer pixel positions to calculate a value for a second, different sub-integer pixel of the one of the full integer pixel positions, encode a current block of pixels using a motion vector that points to one of the first sub-integer pixel and the second sub-integer pixel.

Adaptive support for interpolating values of sub-pixels for video coding

A receiver receives coded coefficient values of enhancement layer video blocks. A control unit defines one or more vectors of transform coefficients for decoding of the enhancement layer blocks, and selects a prediction mode for the enhancement layer blocks based on the vectorized entropy decoding. Each of the vectors comprises one or more of the transform coefficients in a scan order having an end position indicated by a vector control signal. The control unit selects weighted prediction when the vectorized entropy decoding establishes two or more vectors, and selects non-weighted prediction when the defined vectorized entropy coding establishes a single vector. A prediction unit performs predictive decoding based on the prediction mode. An entropy decoding unit performs the vectorized entropy decoding. A scanning unit scans the enhancement layer video blocks from the vectors into two-dimensional blocks of transform coefficients, and separately entropy decodes the vectors.

Weighted prediction based on vectorized entropy coding

This disclosure describes techniques for adaptively coding video block header information based on previously encoded video blocks. A video encoder may adaptively select a coding table for use in encoding a syntax element of a current video block based on corresponding syntax elements of one or more previously encoded blocks. In one aspect, the video encoder may adaptively select the coding table for use in encoding a block type of the current block based on block types of one or more video blocks adjacent to the current video block, i.e., neighboring video blocks. The video encoder may also predict one or more other header syntax elements of the current block based on at least one of the previously encoded video blocks. If prediction is successful, the video encoder may encode a flag to indicate the success of prediction.

Adaptive coding of video block header information

In one example, an encoder may apply a plurality of pre-defined interpolation filters to units of video data, such as frames of reference video, in order to generate a plurality of different interpolated prediction data. The encoder may also at times determine that a new interpolation filter or set of interpolation filters might improve coding quality by either improving video compression or improving reconstructed image quality. The encoder may also signal to a video decoder whether one of the pre-defined interpolation filters was used or a new set of interpolation filters was used. The encoder may also signal to a video decoder whether to continue using the new set of interpolation filters, or whether to revert back to using the pre-defined set of interpolation filters. A video decoder can decode video data based on data received from the video encoder.

Inclusion of switched interpolation filter coefficients in a compressed bit-stream

In one example, this disclosure describes video encoding and decoding techniques applicable to bi-directional prediction. For signaling from an encoder to a decoder a block type for a video block, an encoder can transmit to the decoder two or more separate syntax elements, where one of the two or more separate syntax elements identifies a partition size for the video block and another of the two or more separate syntax elements identifies a prediction direction for a partition of the video block. The separate syntax elements can be individually encoded and transmitted from the encoder to the decoder.

Block type signalling in video coding

In one aspect of this disclosure, techniques are described for the decoupling of uni-directional and bi-directional prediction weights, particularly for explicit weighted predictions of video blocks within a B-unit. According to this disclosure, explicit weights communicated in the bitstream may be applied by a decoder for explicit bi-directional prediction, but different weights (which may be default weights or separately defined explicit uni-directional weights) may be used for explicit uni-directional prediction. The described techniques may improve video quality relative to techniques that use the same explicit weights for explicit bi-directional prediction and explicit uni-directional prediction within a B-unit.

Different weights for uni-directional prediction and bi-directional prediction in video coding

This disclosure describes techniques for generating a layered encoded bitstream structure that exploits correlation in header information among video blocks of a coded unit of video data. A video encoder configured to operate in accordance with the techniques of this disclosure separates header information of the video blocks of a slice (or other coded unit) from the residual information of the video blocks of the slice. The video encoder run-length encodes the header information of the video blocks to better exploit the correlation of the header information among the blocks of the slice. After encoding the header information of the blocks of the slice, the video encoder encodes the residual information for each of the blocks of the slice. The video encoder transmits the encoded header information as a first sequence of bits and transmits the encoded residual information as second sequence of bits.

Layered encoded bitstream structure

This disclosure describes scalable video coding techniques. In particular, the techniques may be used to encode refinements of a video block for enhancement layer bit streams in a single coding pass, thereby reducing coding complexity, coding delay and memory requirements. In some instances, the techniques encode each nonzero coefficient of a coefficient vector of the enhancement layer without knowledge of any subsequent coefficients. Coding the enhancement layer in a single pass may eliminate the need to perform a first pass to analyze the coefficient vector and a second pass for coding the coefficient vector based on the analysis.

Enhancement layer coding for scalable video coding

In generally, techniques are described for efficiently selecting a prediction mode by which to predict predictive video data from reference video data. In particular, an apparatus may include a memory that stores at least a first and second reference coded unit that each includes a first and second reference video data unit, respectively. The apparatus may further comprise a motion compensation unit that performs default weighted prediction to predict a first version of a predictive video data unit from the first and second reference video data units and calculates an offset value for the first version of the predictive video data unit. The motion compensation unit may then perform, based on the calculated offset value, either implicit weighted prediction or explicit weighted prediction to predict a second version of the predictive video data unit and encode the predictive video data unit as either the first or second version.

Efficient prediction mode selection

Techniques are described for efficient transcoding from a first format that supports I-units, P-units and B-units to a second format that supports I-units and P-units but does not support the B-units. In particular, techniques are described for converting B-frames or B-slices of the first format into P-frames or P-slices of the second format. The techniques avoid the need to decode and re-encode that frames or slices. Instead, residuals associated with the B-video blocks in the first format are augmented and made to be dependent upon only one of the two lists associated with the B-video blocks so that such B-video blocks in the first format can be redefined as P-video blocks in the second format.

Growing community of inventors

San Diego, CA, United States of America

Rahul P Panchal