Microsoft Technology Licensing, LLC

Jizheng Xu

Jian Li

Gary Joseph Sullivan

Feng Wu

Lihua Zhu

B Anil Kumar

Sridhar Sankuratri

Xiulian Peng

Chih-Lung Lin

You Zhou

Jiahao Li

Cuiling Lan

Bin Li

J Gary Sullivan

Weijia Zhu

Innovations in the area of prediction of block vector ('By') values improve encoding or decoding of blocks using intra block copy (“BC”) prediction. For example, some of the innovations relate to use of a default BV predictor with a non-zero value. Other innovations relate to use of a selected one of multiple BV predictor candidates for a current block. Still other innovations relate to use of a skip mode in which a current intra-BC-predicted block uses a predicted BV value.

Block vector prediction in video and image coding/decoding

Innovations in adaptive encoding and decoding for units of a video sequence can improve coding efficiency when switching between color spaces during encoding and decoding. For example, some of the innovations relate to adjustment of quantization or scaling when an encoder switches color spaces between units within a video sequence during encoding. Other innovations relate to adjustment of inverse quantization or scaling when a decoder switches color spaces between units within a video sequence during decoding.

Adjusting quantization/scaling and inverse quantization/scaling when switching color spaces

Disclosed herein are representative embodiments of generating representative motion information that can be used during processing of a video frame. In one exemplary embodiment disclosed herein, a reference frame comprising a group of blocks is processed, and motion information for the group of blocks is compressed at least by buffering representative motion-vector information and representative reference-frame index information for the group of blocks. The representative reference-frame index information comprises reference-frame index information of a representative block of the group of blocks, and the representative reference-frame index information represents reference-frame index information for the group of blocks during processing of a current frame.

Representative motion information for temporal motion prediction in video encoding and decoding

Innovations in intra-picture prediction with multiple candidate reference lines available are described herein. For example, intra-picture prediction for a current block uses a non-adjacent reference line of sample values to predict the sample values of the current block. This can improve the effectiveness of the intra-picture prediction when the reference line of sample values that is adjacent the current block includes significant capture noise, significant quantization error, or significantly different values (compared to the current block) due to an occlusion. Innovations described herein include, but are not limited to, the following: intra-picture prediction with multiple candidate reference lines available; encoding/decoding of reference line indices using prediction; filtering of reference sample values; residue compensation; weighted prediction; mode-dependent padding to replace unavailable reference sample values; using in-loop-filtered reference sample values; encoder-side decisions for selecting reference lines; and post-filtering of predicted sample values.

Intra-picture prediction using non-adjacent reference lines of sample values

Non-transform blocks of video content may be coded by selectively changing a scanning order. In some implementations, an encoder or decoder may perform a scanning process on a block according to a scanning order. When the block has not been transformed, the encoder or decoder may selectively change the scanning order to a different order. For example, if the block is associated with a particular type of prediction, the scanning order may be changed to a different order. In another example, if the non-transform block has a size that is smaller than a predetermined size, the scanning order may be changed to a different order.

Scanning orders for non-transform coding

Innovations in adaptive encoding and decoding for units of a video sequence can improve coding efficiency. For example, some of the innovations relate to encoding/decoding that includes adaptive switching of color spaces between units within a video sequence. Other innovations relate encoding/decoding that includes adaptive switching of color sampling rates between units within a video sequence. Still other innovations relate encoding/decoding that includes adaptive switching of bit depths between units within a video sequence.

Adaptive switching of color spaces, color sampling rates and/or bit depths

Innovations in intra block copy ('BC') prediction mode facilitate intra BC prediction that is more effective in terms of rate-distortion performance and/or computational efficiency of encoding and decoding. For example, some of the innovations provide ways to select block vector (“BV”) values more effectively. Other innovations provide ways to encode/decode BV values more efficiently. Still other innovations address how to perform in-loop deblock filtering when a block has intra BC prediction mode, or address how to perform intra BC prediction when constrained intra prediction is enabled.

Features of intra block copy prediction mode for video and image coding and decoding

Techniques for coding and deriving (e.g., determining) one or more coded-block-flags associated with video content are described herein. A coded-block-flag of a last node may be determined when coded-block-flags of preceding nodes are determined to be a particular value and when a predetermined condition is satisfied. In some instances, the predetermined condition may be satisfied when log(size of current transform unit) is less than log(size of maximum transform unit) or log(size of current coding unit) is less than or equal to log(size of maximum transform unit)+1. The preceding nodes may be nodes that precede the last node on a particular level in a residual tree.

Coded-block-flag coding and derivation

Techniques for selectively transforming one or more coding units when coding video content are described herein. The techniques may include determining whether or not to transform a particular coding unit. The determination may be based on a difference in pixel values of the particular coding unit and/or one or more predefined rate-distortion constraints. When it is determined to not perform a transform, the particular coding unit may be coded without transforming the particular coding unit.

Non-transform coding

Innovations in encoder-side options for intra block copy ('BC') prediction mode facilitate intra BC prediction that is more effective in terms of rate-distortion performance and/or computational efficiency of encoding. For example, some of the innovations relate to concurrently performing block vector (“BV”) estimation and making block splitting decisions for a block. Other innovations relate to selectively merging blocks into a larger block during BV estimation.

Encoder-side options for intra block copy prediction mode for video and image coding

Innovations in flexible reference picture management are described. For example, a video encoder and video decoder use a global reference picture set ('GRPS') of reference pictures that remain in memory, and hence are available for use in video encoding/decoding, longer than conventional reference pictures. In particular, reference pictures of the GRPS remain available across random access boundaries. Or, as another example, a video encoder and video decoder clip a reference picture so that useful regions of the reference picture are retained in memory, while unhelpful or redundant regions of the reference picture are discarded. Reference picture clipping can reduce the amount of memory needed to store reference pictures or improve the utilization of available memory by providing better options for motion compensation. Or, as still another example, a video encoder and video decoder filter a reference picture to remove random noise (e.g., capture noise due to camera imperfections during capture).

Flexible reference picture management for video encoding and decoding

Innovations in adaptive encoding for units of a video sequence can improve coding efficiency. For example, some of the innovations relate to encoding that includes adaptive switching of color spaces between units within a video sequence. Other innovations relate encoding that includes adaptive switching of color sampling rates between units within a video sequence. Still other innovations relate encoding that includes adaptive switching of bit depths between units within a video sequence.

Encoding strategies for adaptive switching of color spaces, color sampling rates and/or bit depths

Innovations in the use of base color index map ('BCIM') mode dining encoding and/or decoding simplify implementation by reducing the number of modifications made to support BCIM mode and/or improve coding efficiency of BCIM mode. For example, some of the innovations involve reuse of a syntax structure that is adapted for transform coefficients to instead signal data for elements of an index map in BCIM mode. Other innovations relate to mapping of index values in BCIM mode or prediction of elements of an index map in BCIM mode. Still other innovations relate to handling of exception values in BCIM mode.

Features of base color index map mode for video and image coding and decoding

Various innovations facilitate the use of intra-picture prediction modes such as palette prediction mode, intra block copy mode, intra line copy mode and intra string copy mode by an encoder or decoder when wavefront parallel processing ('WPP') is enabled. For example, for a palette coding/decoding mode, an encoder or decoder predicts a palette for an initial unit in a current WPP row of a picture using previous palette data from a previous unit in a previous WPP row of the picture. Or, as another example, for an intra copy mode (e.g., intra block copy mode, intra string copy mode, intra line copy mode), an encoder enforces one or more constraints attributable to the WPP, or a decoder receives and decodes encoded data that satisfies one or more constraints attributable to WPP.

Rules for intra-picture prediction modes when wavefront parallel processing is enabled

Innovations in encoding or decoding when switching color spaces are presented. For example, some of the innovations relate to signaling of control information for adaptive color space transformation ('ACT'). Other innovations relate to ACT operations. These innovations can improve coding efficiency when switching between color spaces during encoding and decoding.

Growing community of inventors

Beijing, China

Jizheng Xu