Abstract: This application discloses an image encoding and decoding method and apparatus, an encoder, a decoder, and a system, and relates to the multimedia field. An example method includes: after encoding of a previous coding unit and decoding of the previous coding unit end, a number of lossless bits of a current coding unit and an average number of lossless bits of the current coding unit are updated based on a number of coded bits of the previous coding unit and a used quantization parameter. When an expected number of bits obtained by performing lossy coding on the coding unit is adaptively allocated based on the image content of the coding unit, a quantization parameter used for encoding or decoding the current coding unit is determined based on the number of coded bits of the previous coding unit.

Abstract: A method includes determining an adjustment value of a number of lossy bits based on an approximate value of a number of remaining coding units. An averaging stage, related to division in a process of calculating the number of lossy bits may be implemented by a shift operation at both an encoder side and a decoder side.

Abstract: A coding device estimates a number of coded bits of an (i+k)th coding unit based on a number of coded bits of an ith coding unit, where k is a positive integer greater than or equal to 2. The coding device further uses image content of the (i+k)th coding unit as an input of the QP decision.

Abstract: An encoding method and apparatus, and a decoding method and apparatus are disclosed, and relate to the field of video coding technologies. A decoding device may decode a coding unit based on a number of coded bits corresponding to the coding unit and a number of estimated bits indicating substream header bits corresponding to a plurality of substreams. This avoids a problem that accuracy of rate control is affected because an error occurs when a rate control module performs rate control only based on the number of coded bits corresponding to the coding unit, and helps improve video decoding quality. In addition, because the decoding device considers a number of bits occupied by the substream header bits, the substream header bits are also considered in a video decoding process.

Abstract: Embodiments of this application provide a decoding method. The method includes: obtaining a bitstream of a first coding unit, where the first coding unit is at least one coding unit in a plurality of coding units; determining an end decrease step, wherein the end decrease step is used to update a virtual padding amount of the plurality of coding units; determining the virtual padding amount of the plurality of coding units based on the end decrease step, where the virtual padding amount is used to reduce storage space of a buffer in a decoding device; determining that an encoding mode of the first coding unit in the plurality of coding units is a fallback mode; and decoding the bitstream of the first coding unit based on the virtual padding amount and the fallback mode, to obtain first data.

Abstract: Embodiments of this application disclose example encoding methods and apparatuses, and example decoding methods and apparatuses. One example method includes encoding a plurality of picture blocks of media content to obtain a plurality of syntax elements; encoding the plurality of syntax elements to obtain a plurality of substreams; and interleaving a plurality of data packets into a bitstream based on target values of the data packets. Each substream includes at least one data packet, and the target value represents an encoding ranking of a target picture block corresponding to the data packet.

Abstract: The present application discloses example encoding methods and apparatuses, and decoding methods and apparatuses, and relate to the field of media technologies. One example method includes obtaining a bitstream, and obtaining a plurality of data packets based on the bitstream. Based on identifiers of the plurality of data packets, the plurality of data packets is sent to a plurality of entropy decoders for decoding, to obtain a plurality of syntax elements. Media content is restored based on the plurality of syntax elements.

Abstract: This application provides example encoding methods and example encoders. One example method includes performing bit truncation on a to-be-encoded block when a bit rate control condition is satisfied. A first cost value corresponding to the bit truncation can then be calculated. The to-be-encoded block can then be predicted to determine a prediction residual of the to-be-encoded block when the bit rate control condition is satisfied. A second cost value corresponding to the prediction can then be calculated based on the prediction residual. The first cost value can then be compared with the second cost value to determine an encoded bit.

Abstract: An image encoding and decoding method includes obtaining a to-be-encoded image, where the to-be-encoded image is divided into a base layer and at least one enhancement layer; when feedback information sent by a decoder side is received, determining a reconstructed image corresponding to a frame sequence number and a layer sequence number indicated in the feedback information as a first reference frame, and performing inter encoding on the base layer based on the first reference frame to obtain a bitstream of the base layer; encoding the at least one enhancement layer to obtain a bitstream of the at least one enhancement layer; and sending the bitstream of the base layer and the bitstream of the at least one enhancement layer to the decoder side, where the bitstream of the base layer carries coding reference information.

Abstract: Embodiments of this application provide a video transmission method, apparatus, and system, to reduce an end-to-end transmission delay of video data. The method includes: A transmit end obtains a first frame of image of the video data, where the first frame of image includes a plurality of sub-images, and the plurality sub-images include a first sub-image and a second sub-image; the transmit end performs layered encoding on the first sub-image to obtain a plurality of layers of bitstreams of the first sub-image; the transmit end sends the plurality of layers of bitstreams of the first sub-image to a receive end; the receive end decodes the plurality of layers of bitstreams of the first sub-image to obtain the first sub-image.

Abstract: This application relates to the image processing field, and provides an encoding method and an encoder. The method includes: determining an encoding quantization parameter QP; precoding a to-be-encoded block by using the encoding QP to obtain encoding result information; adjusting the encoding QP based on the encoding result information; and performing real encoding on the to-be-encoded block by using an adjusted encoding QP. This can improve image compression performance.

Abstract: This application relates to the image processing field, and provides an encoding method and an encoder. The method includes: when a forcible bit rate control condition is satisfied, performing bit truncation of a spatial-domain branch and coefficient discarding of a frequency domain branch on a to-be-encoded block at the same time, calculating cost values respectively corresponding to the bit truncation and the coefficient discarding, and determining a final encoded bit based on the two cost values, so as to improve image decoding quality as much as possible while preventing bitstream buffer overflow.