A first predictor is applied to an input image to generate first-stage predicted codewords approximating prediction target codewords of a prediction target image. Second-stage prediction target values are created by performing an inverse cascade operation on the prediction target codewords and the first-stage predicted codewords. A second predictor is applied to the input image to generate second-stage predicted values approximating the second-stage prediction target values. Multiple sets of cascade prediction coefficients are generated to comprise first and second sets of cascade prediction coefficients specifying the first and second predictors. The multiple sets of cascade prediction coefficients are encoded, in a video signal, as image metadata. The video signal is further encoded with the input image.

Systems, methods and apparatus for encoding, decoding or transcoding digital video are described. One example method of processing video data includes performing a conversion between a video and a bitstream of the video according to a format rule, wherein the format rule specifies that a supplemental enhancement information field included in the bitstream indicates whether the bitstream comprises one or more video layers that represent auxiliary information.

Embodiments of this application provide an image transmission method and apparatus. The method includes: converting a first high-resolution image into a first low-resolution image, where first resolution of the first high-resolution image is higher than second resolution of the first low-resolution image; encoding the first low-resolution image to obtain a first bitstream; obtaining a second high-resolution image, where third resolution of the second high-resolution image is higher than the second resolution, and the second high-resolution image includes high-frequency information of the first high-resolution image and excludes low-frequency information of the first high-resolution image; obtaining an image residual between the first high-resolution image and the second high-resolution image, where the image residual is used to reflect the low-frequency information of the first high-resolution image; encoding the image residual to obtain a second bitstream; and sending the first bitstream and the second bitstream.

Embodiments of this application provide an image transmission method and apparatus. The method includes: converting a first high-resolution image into a first low-resolution image, where first resolution of the first high-resolution image is higher than second resolution of the first low-resolution image; encoding the first low-resolution image to obtain a first bitstream; obtaining a second high-resolution image, where third resolution of the second high-resolution image is higher than the second resolution, and the second high-resolution image includes high-frequency information of the first high-resolution image and excludes low-frequency information of the first high-resolution image; obtaining an image residual between the first high-resolution image and the second high-resolution image, where the image residual is used to reflect the low-frequency information of the first high-resolution image; encoding the image residual to obtain a second bitstream; and sending the first bitstream and the second bitstream.

A video processing method includes performing a conversion between a video having one or more video layers including one or more video pictures and a bitstream of the video according to a rule. The rule specifies a condition under which no picture that has been generated by a decoding process for generating an unavailable reference picture is referred to by an active entry in a reference picture list of a current slice of a current picture.

A three-dimensional data encoding method includes: obtaining an attribute information item of a three-dimensional point; executing an encoding process that executes a transform process on a numerical value indicated by the attribute information item and encodes the attribute information item or that encodes the attribute information item without executing the transform process, the transform process performing at least one of scaling or offset, the scaling performing at least one of a multiplication and division operation or a shift operation, the offset performing an addition and subtraction operation; and generating a bitstream including the attribute information item encoded and a transform identification information item indicating whether the transform process has been executed.

A three-dimensional data encoding method includes: obtaining an attribute information item of a three-dimensional point; executing an encoding process that executes a transform process on a numerical value indicated by the attribute information item and encodes the attribute information item or that encodes the attribute information item without executing the transform process, the transform process performing at least one of scaling or offset, the scaling performing at least one of a multiplication and division operation or a shift operation, the offset performing an addition and subtraction operation; and generating a bitstream including the attribute information item encoded and a transform identification information item indicating whether the transform process has been executed.

Methods, devices and systems for configuring different access units in scalable video coding are described. In one example aspect, a method of video processing include performing a conversion between a video comprising one or more pictures in one or more video layers and a bitstream of a video, wherein the bitstream comprises a coded video sequence that includes one or more access units, and wherein the bitstream further comprises a first syntax element indicating whether an access unit includes a picture for each video layer making up the coded video sequence.

Methods, systems, and devices are described for communicating data from multiple data terminals to an aggregator terminal over a communication link having changing link conditions. In some embodiments, source data is received at multiple data terminals, each in communication with an aggregator terminal over a communication link. For example, during a live newscast, one mobile camera may receive live video of an event from a first position while another mobile camera receives live video of the event from a second position. For various reasons (e.g., as the cameras move) each communication link may experience independently changing link conditions. Each data terminal encodes the source data (or store source data for later encoding) as a function of its respective link conditions and transmits encoded source data over its respective communication link to the aggregator terminal.

Methods, systems, and devices are described for communicating data from multiple data terminals to an aggregator terminal over a communication link having changing link conditions. In some embodiments, source data is received at multiple data terminals, each in communication with an aggregator terminal over a communication link. For example, during a live newscast, one mobile camera may receive live video of an event from a first position while another mobile camera receives live video of the event from a second position. For various reasons (e.g., as the cameras move) each communication link may experience independently changing link conditions. Each data terminal encodes the source data (or store source data for later encoding) as a function of its respective link conditions and transmits encoded source data over its respective communication link to the aggregator terminal.