Google Inc.

On2 Technologies, Inc.

Yaowu Xu

James Bankoski

Paul Gordon Wilkins

Jingning Han

Adrian Grange

Ching-Han Chiang

Eric Ameres

Debargha Mukherjee

Hui Su

Tim Murphy

Qunshan Gu

Bohan Li

Yuxin Liu

Cheng Che Chen

Jia Feng

Linfeng Zhang

Scott Lavarnway

James Zern

Ronald Sebastiaan Bultje

Di Chen

Dake He

Anil Christopher Kokaram

Aki Kuusela

Francis William Galligan

Dan Miller

Jim Bankoski

Stanislav Vitvitskyy

John Koleszar

Wei-Ting Lin

Scott J La Varnway

Yue Sun

An encoded bitstream is decodable by a processor configured to execute instructions to store, in a first line buffer, first values of a first scan-order diagonal line scanned immediately before a current scan-order diagonal line of a transform block; and store, in a second line buffer, second values of a second scan-order diagonal line scanned immediately before the first scan-order diagonal line. The first values of the first line buffer and the second values of the second line buffer are interleaved in a destination buffer. Using the destination buffer, a probability distribution is selected for coding a current value of the current scan-order diagonal line. The current value is entropy decoded from the bitstream using the probability distribution. One of the second line buffer or the first line buffer is replaced with current values of the current scan-order diagonal line for coding values of an immediately subsequent scan-order diagonal line.

Efficient context model computation design in transform coefficient coding

A motion vector for a current block of a current frame is decoded from a compressed bitstream. A location of a reference block within an un-generated reference frame is identified. The reference block is generated using a forward reference frame and a backward reference frame without generating the un-generated reference frame. The reference block is generated by identifying an extended reference block by extending the reference block at each boundary of the reference block by a number of pixels related to a filter length of a filter used in sub-pixel interpolation; and generating pixel values of only the extended reference block by performing a projection using the forward reference frame and the backward reference frame without generating the whole of the un-generated reference frame. The current block is then decoded based on the reference block and the motion vector.

Selective reference block generation without full reference frame generation

Entropy coding a sequence of symbols is described. A first probability model for entropy coding is selected. At least one symbol of the sequence is coded using a probability determined using the first probability model. The probability according to the first probability model is updated with an estimation of a second probability model to entropy code a subsequent symbol. The combination may be a fixed or adaptive combination.

Probability estimation for video coding

A motion field estimate determined using motion vector information of two or more reference frames of a current/encoded frame is used to derive a motion vector for inter-prediction of the current/encoded frame. Motion trajectory information, including concatenated motion vectors and locations of the current/encoded frame at which those concatenated motion vectors point, is determined by concatenating motion vectors of the reference frames. A motion field estimate is determined using the motion trajectory information and, in some cases, by interpolating unavailable motion vectors using neighbors. The motion field estimate is used to determine a co-located reference frame for the current/encoded frame, and an inter-prediction process is performed for the current/encoded frame using a motion vector derived using the co-located reference frame. During decoding, the motion field estimate may be determined using motion vectors signaled within a bitstream and without additional side information, thereby improving prediction coding efficiency.

Motion field estimation based on motion trajectory derivation

Video coding using constructed reference frames may include generating, by a processor in response to instructions stored on a non-transitory computer readable medium, a reconstructed video. Generating the reconstructed video may include receiving an encoded bitstream. Video coding using constructed reference frames may include generating a reconstructed non-showable reference frame. Generating the reconstructed non-showable reference frame may include decoding a first encoded frame from the encoded bitstream. Video coding using constructed reference frames may include generating a reconstructed frame. Generating the reconstructed frame may include decoding a second encoded frame from the encoded bitstream using the reconstructed non-showable reference frame as a reference frame. Video coding using constructed reference frames may include including the reconstructed frame in the reconstructed video and outputting the reconstructed video.

Video coding using constructed reference frames

A system, apparatus, and method for encoding and decoding a video image having a plurality of frames is disclosed. Encoding and decoding the video image can include selecting, for a current block, a prediction mode from a plurality of prediction modes; identifying, for the current block, a quantization value; selecting, for the current block, a probability distribution from a plurality of probability distributions based on the identified quantization value using a processor; and entropy encoding the selected prediction mode using the selected probability distribution.

Adaptive coding of prediction modes using probability distributions

Transform kernel candidates including a vertical transform type associated with a vertical motion and a horizontal transform type associated with a horizontal motion can be encoded or decoded. During a decoding operation, a probability model for decoding encoded bitstream video data associated with a transform kernel candidate for an encoded transform block is identified based on one or both of a first transform kernel candidate selected for an above neighbor transform block of the encoded transform block or a second transform kernel candidate selected for a left neighbor transform block of the encoded transform block. The encoded bitstream video data associated with the transform kernel candidate is decoded using the probability model.

Transform kernel selection and entropy coding

A transform type is obtained for decoding the transform block of transform coefficients. A template for entropy-decoding values related to the transform coefficients is selected based on the transform type. The template indicates, for a to-be-coded value, positions of already coded values. A context for selecting a probability distribution for entropy decoding a current value of the values is determined using the template. The current value is entropy decoded from a compressed bitstream using the probability distribution.

Motion prediction using optical flow is determined to be available for a current frame in response to determining that a reference frame buffer includes, with respect to the current frame, a forward reference frame and a backward reference frame. A flag indicating whether a current block is encoded using optical flow is decoded. Responsive to determining that the flag indicates that the current block is encoded using optical flow, a motion vector is decoded for the current block; a location of an optical flow reference block is identified within an optical flow reference frame based on the motion vector; subsequent to identifying the location of the optical flow reference block, the optical flow reference block is generated using the forward reference frame and the backward reference frame without generating the optical flow reference frame; and the current block is decoded based on the optical flow reference block.

Block-based optical flow estimation for motion compensated prediction in video coding

Techniques for encoding and decoding image data are described. An image is reconstructed and deblocked. A respective deblocking filter is identified for different color planes of the image. The deblocking filters may include those having different lengths for a luma plane as compared to one or more chroma planes of the image. One or more of the color planes, such as the luma plane, may have different filters for filtering reconstructed pixels vertically as compared to filtering the reconstructed pixels horizontally.

Deblocking filtering

An apparatus for decoding frames of a compressed video data stream having at least one frame divided into partitions, includes a memory and a processor configured to execute instructions stored in the memory to read partition data information indicative of a partition location for at least one of the partitions, decode a first partition of the partitions that includes a first sequence of blocks, decode a second partition of the partitions that includes a second sequence of blocks identified from the partition data information using decoded information of the first partition.

System and method for decoding using parallel processing

Decoding a current block of a current frame includes obtaining motion trajectories between the current frame and at least one previously coded frame by projecting motion vectors from the at least one previously coded frame onto the current frame. A motion field is obtained between the current frame and a reference frame used for coding the current frame. The motion field is obtained by extending the motion trajectories from the current frame towards the reference frame. A motion vector for the current block is identified based on the motion field. A prediction block is obtained for the current block using a reference block of the reference frame identified using the motion vector.

Constrained motion field estimation for hardware efficiency

Adaptive composite intra-prediction may include in response to a determination that a first prediction pixel from a first block immediately adjacent to a first edge of a current block is available for predicting a current pixel of the current block, determining whether a second prediction pixel from a second block immediately adjacent to a second edge of the current block is available for predicting the current pixel, wherein the second edge is opposite the first edge, and, in response to a determination that the second prediction pixel is available, generating a prediction value for the current pixel based on at least one of the first prediction pixel or the second prediction pixel. Adaptive composite intra-prediction may include generating a reconstructed pixel corresponding to the current pixel based on the prediction value, including the reconstructed pixel in the decoded current block, and outputting or storing the decoded current block.

Adaptive composite intra prediction for image and video compression

Decoding a video stream may include decoding a first block of a current frame by decoding a first motion vector from the encoded video stream, decoding an identifier of a first interpolation filter from the encoded video stream, and reconstructing the first block using the first motion vector and the first interpolation filter. Decoding a second block of the current frame may include identifying the first motion vector from the first block as a selected motion vector for predicting the second block in response to decoding an inter-prediction mode identifier for decoding the second block, identifying the first interpolation filter as a selected interpolation filter for predicting the second block in response to identifying the first motion vector from the first block as the selected motion vector for predicting the second block, and reconstructing the second block using the first motion vector and the first interpolation filter.

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Saratoga, CA, United States of America

Yaowu Xu