Zoom Communications, Inc.

Zoom Video Communications, Inc.

Zhejiang University

Zhichu He

Jing Wu

Yi Guo

Yichen Zhang

Rui Li

Bo Ling

Minxia Yang

Shiyan Zhang

Lu Yu

Methods, systems, and apparatus, including computer programs encoded on computer storage media for fast search of transform kernel selection. A set of transform kernels are selected. Multiple images are encoded via the AV1 coded using the selected transform kernels. The encoded images are transmitted to another computing device.

Fast search and selection of a transform kernel for AV1 encoding

In one example, a video encoder divides a superblock of a video frame into subblocks. The dividing includes dividing the superblock according to a first and second partitioning schemes to generate a first and second combination of subblocks, respectively. The number of non-zero residuals in each subblock in the first and second combinations of subblocks is less than a corresponding threshold set for a size of the subblock. The encoder determines the subblocks for the superblock as the first combination of subblocks based on a first cost value associated with the first combination of subblocks being lower than a second cost value associated with the second combination of subblocks. The encoder further encodes the superblock into a video bitstream representing the video by encoding the subblocks.

Reducing grid artifacts in video frames

Fast parameter search for chroma from luma (CFL) intra prediction in video encoding is provided. A video encoder determines a value of a parameter of a linear CFL predictor for a coding block of a frame of a video. The determining includes dividing a search range within a value range of the parameter into three portions by a starting value: the starting value and values on two sides of the starting value. The encoder determines cost values of parameter values from the three portions and select the value of the parameter that corresponds to the lowest cost value. The encoder further encodes the coding block of the frame into a bitstream representing the video using the CFL predictor with the selected value of the parameter.

Fast parameter search for chroma from luma intra prediction in video coding

Deriving in-loop filter parameters via training for video encoding is provided. A video encoder performs inter prediction for a frame in a set of frames of the video to generate prediction residuals for the frame. The inter prediction for the frame is performed based on a reconstructed frame in the set of frames filtered using an in-loop filter. The value of a parameter of the in-loop filter is determined by determining, for each candidate in-loop filter parameter value, a visual quality metric for a set of training frames in training video sequences filtered by the in-loop filter. The candidate in-loop filter parameter value that corresponds the highest visual quality metric can be selected as the value of the parameter of the in-loop filter. The video encoder further encodes the prediction residues of the frame and the parameter of the in-loop filter into a bitstream representing the video.

Deriving in-loop filter parameters for video coding

Constructing a motion vector candidate list for inter-prediction in video coding is provided. A video encoder performs inter prediction for a frame of the video to generate prediction residuals. The inter prediction is performed using motion vectors (MVs) for blocks of the frame. To determine the motion vector of a block, the encoder determines an integer-valued MV for the block based on a reference frame and selects, based on the integer-valued MV, a subset of candidate MVs from a list of MVs including MVs of neighboring blocks. The encoder identifies a MV from the subset of candidate MVs for the block and searches in a neighborhood of the identified MV for a refined MV. The encoder calculates the prediction residuals for the block based on a reference block in the reference frame pointed by the refined MV and encodes the prediction residuals into a bitstream representing the video.

Constructing motion vector candidates list for video coding

Methods, systems, and apparatus, including computer programs encoded on computer storage media related to multi-stream video encoding for screen sharing a communications session. The system may determine an active pixel area and a remaining pixel area of a video region. of a video region. A first video stream of the active pixel area is generated at a first frame rate. A second video stream of the remaining pixel area is generated at second frame rate, where the second frame rate is a frame rate lower than the first frame rate. A client device may transmit the first video stream and the second video stream to a second client device.

Multiple video stream generation based on different pixel sets within an initial video stream

Methods, systems, and apparatus, including computer programs encoded on computer storage media related to multi-stream video encoding for screen sharing a communications session. The system may determine a sub-area and a remaining area of a display region. A first video stream of the sub-area is generated at a first frame rate. A second video stream of the remaining area is generated at second frame rate, where the second frame rate is a frame rate lower than the first frame rate. A client device may transmit the first video stream and the second video stream to a second client device.

Multi-stream video encoding for screen sharing within a communications session

The invention provides an information preserving coding method based on possibility distribution of value of a sample. The possibility distribution of value of a sample refers to evaluation of the possibility of various values of the sample. The information preserving coding method provided is more in line with the non-stationary probability property of an actual source, and a coding code length is the overhead caused by a prediction error of the possibility distribution of value of the sample. The invention further provides multiple coding methods based on possibility distribution of value of a sample. Through improving the prediction accuracy of the possibility distribution of value of the sample, the coding efficiency is greatly improved.

Growing community of inventors

Hangzhou, China

Zhichu He