Microsoft Technology Licensing, LLC

Polycom, Inc.

Microsoft Corporation

Gary Joseph Sullivan

Sandeep Kanumuri

Yongjun Wu

Lihua Zhu

Jian Li

Chih-Lung Lin

You Zhou

Jizheng Xu

Feng Wu

Shyam Sadhwani

Ming-Chieh Lee

B Anil Kumar

Sridhar Sankuratri

Sridhar Srinivasan

Shankar Lakshmi Regunathan

Stephen Estrop

Chad Edward Fogg

Shipeng Li

Chengjie Tu

Sergey Sablin

Sergey Silkin

Alexandros Michael Tourapis

Shijun Sun

Glenn Frederick Evans

Jeffrey G Bernstein

Stephen C Botzko

Brian A Howell

Elizabeth M Comstock

William L Kruger

Robert V Seiler

Yifu Zhang

Stephen C Rowe

Donald J Munsil

Leon Bottou

Anand Ganesh

Henrique Sarmento Malvar

Adriana Dumitras

Mei-Hsuan Lu

Alexandros Tourapis

Robin C B Speed

Zhi Zhou

Timothy E Onders

Jeremy S De Bonet

Daniel Schonberg

Jian Lou

Dragos C Avadanei

Stephen J Estrop

Bin Li

Anil B Kumar

Innovations in signaling of reference picture list ('RPL') modification information. For example, a video encoder evaluates a condition that depends at least in part on a variable indicating a number of total reference pictures. Depending on the results of the evaluation, the encoder signals in a bitstream a flag that indicates whether an RPL is modified according to syntax elements explicitly signaled in the bitstream. A video decoder evaluates the condition and, depending on results of the evaluation, parses from a bitstream a flag that indicates whether an RPL is modified according to syntax elements explicitly signaled in the bitstream. The condition can be evaluated as part of processing for an RPL modification structure that includes the flag, or as part of processing for a slice header. The encoder and decoder can also evaluate other conditions that affect syntax elements for list entries of the RPL modification information.

Conditional signaling of reference picture list modification information

Disclosed herein are innovations for bitstreams having clean random access (CRA) pictures and/or other types of random access point (RAP) pictures. New type definitions and strategic constraints on types of RAP pictures can simplify mapping of units of elementary video stream data to a container format. Such innovations can help improve the ability for video coding systems to more flexibly perform adaptive video delivery, production editing, commercial insertion, and the like.

Constraints and unit types to simplify video random access

Techniques and tools for reducing latency in video encoding and decoding by constraining latency due to reordering of video frames, and by indicating the constraint on frame reordering latency with one or more syntax elements that accompany encoded data for the video frames. For example, a real-time communication tool with a video encoder sets a syntax element that indicates a constraint on frame reordering latency, which is consistent with inter-frame dependencies between multiple frames of a video sequence, then outputs the syntax element. A corresponding real-time communication tool with a video decoder receives the syntax element that indicates the constraint on frame reordering latency, determines the constraint on frame reordering latency based on the syntax element, and uses the constraint on frame reordering latency to determine when a reconstructed frame is ready for output (in terms of output order).

Reducing latency in video encoding and decoding

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 for signaling state of a decoded picture buffer ('DPB') and reference picture lists (“RPLs”). In example implementations, rather than rely on internal state of a decoder to manage and update DPB and RPLs, state information about the DPB and RPLs is explicitly signaled. This permits a decoder to determine which pictures are expected to be available for reference from the signaled state information. For example, an encoder determines state information that identifies which pictures are available for use as reference pictures (optionally considering feedback information from a decoder about which pictures are available). The encoder sets syntax elements that represent the state information. In doing so, the encoder sets identifying information for a long-term reference picture (“LTRP”), where the identifying information is a value of picture order count least significant bits for the LTRB. The encoder then outputs the syntax elements as part of a bitstream.

Signaling of state information for a decoded picture buffer and reference picture lists

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

Innovations in encoder-side search ranges having horizontal bias or vertical bias are described herein. For example, a video encoder determines a block vector ('BV') for a current block of a picture, performs intra prediction for the current block using the BV, and encodes the BV. The BV indicates a displacement to a region within the picture. When determining the BV, the encoder checks a constraint that the region is within a BV search range having a horizontal bias or vertical bias. The encoder can select the BV search range from among multiple available BV search ranges, e.g., depending at least in part on BV values of one or more previous blocks, which can be tracked in a histogram data structure.

Encoder-side search ranges having horizontal bias or vertical bias

A format for use in encoding moving image data, comprising: a sequence of frames including plurality of the frames in which at least a region is encoded using motion estimation; a respective set of motion vector values representing motion vectors of the motion estimation for each respective one of these frames or each respective one of one or more regions within each of such frames; and at least one respective indicator associated with each of the respective frames or regions, indicating whether the respective motion vector values of the respective frame or region are encoded at a first resolution or a second resolution.

Representing motion vectors in an encoded bitstream

Innovations in control and use of chroma quantization parameter ('QP') values that depend on hum QP values. More generally, the innovations relate to control and use of QP values for a secondary color component that depend on QP values for a primary color component. For example, during encoding, an encoder determines a QP index from a primary component QP and secondary component QP offset. The encoder maps the QP index to a secondary component QP, which has an extended range. The encoder outputs at least part of a bitstream including the encoded content. A corresponding decoder receives at least part of a bitstream including encoded content. During decoding, the decoder determines a QP index from a primary component QP and secondary component QP offset, then maps the QP index to a secondary component QP, which has an extended range.

Control and use of chroma quantization parameter values

Innovations in syntax and semantics of coded picture buffer removal delay ('CPBRD') values potentially simplify splicing operations. For example, a video encoder sets a CPBRD value for a current picture that indicates an increment value relative to a nominal coded picture buffer removal time of a preceding picture in decoding order, regardless of whether the preceding picture has a buffering period SEI message. The encoder can signal the CPBRD value according to a single-value approach in which a flag indicates how to interpret the CPBRD value, according to a two-value approach in which another CPBRD value (having a different interpretation) is also signaled, or according to a two-value approach that uses a flag and a delta value. A corresponding video decoder receives and parses the CPBRD value for the current picture. A splicing tool can perform simple concatenation operations to splice bitstreams using CPBRD value for the current picture.

Syntax and semantics for buffering information to simplify video splicing

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Gary Joseph Sullivan