There are provided methods and apparatus for transform selection in video coding. An apparatus includes a video encoder for encoding at least a block in a picture by selecting a transform to apply to a residue of the block from a set of two or more available transforms. The transform is selected based on at least one of an inter prediction mode used to predict at least one reference for the block, one or more values corresponding to a motion vector, a value of a residue of one or more previously encoded blocks, a value of prediction data for the block, one or more transform selections of one or more neighboring reconstructed blocks, and a quantization step applied to transform coefficients for the residue of the block.

An image decoding method, according to the present invention, includes the steps of: deriving an MPM candidate mode from neighboring blocks adjacent to a target block to be decoded; generating an MPM list using the MPM candidate mode derived from the neighboring blocks; and deriving an intra prediction mode for the target block to be decoded using the generated MPM list. According to the present invention, image compression efficiency can be improved.

A method and a device for assessing video encoding quality. The method includes: acquiring a quantization parameter of a slice of a video frame and a quantity of bytes per pixel of the slice of the video frame of the video stream; determining complexity of content of the video according to the quantity of bytes per pixel of the slice of the video frame of the video stream; and predicting the video encoding quality according to the complexity of content of the video and the quantization parameter of the video. In the present invention, the complexity of content of the video is also considered in predicting the video encoding quality. Therefore, encoding quality predicted by a model that is obtained by considering the complexity of content of the video better satisfies subjective feelings of human eyes, thereby improving accuracy of prediction.

Methods and apparatus are provided for embedded quantization parameter adjustment in video encoding and decoding. An apparatus includes an encoder for encoding picture data for at least a block in a picture. A quantization parameter, applied to one or more transform coefficients obtained by transforming a difference between an original version of the block and at least one reference block, is derived from reconstructed data corresponding to at least the block.

In general, techniques are described for performing motion vector prediction for video coding. A video coding device comprising a processor may perform the techniques. The processor may be configured to determine a plurality of candidate motion vectors for a current block of the video data so as to perform the motion vector prediction process and scale one or more of the plurality of candidate motion vectors determined for the current block of the video data to generate one or more scaled candidate motion vectors. The processor may then be configured to modify the scaled candidate motion vectors to be within a specified range.

Techniques are described for sub-prediction unit (PU) based motion prediction for video coding in HEVC and 3D-HEVC. In one example, the techniques include an advanced temporal motion vector prediction (TMVP) mode to predict sub-PUs of a PU in single layer coding for which motion vector refinement may be allowed. The advanced TMVP mode includes determining motion vectors for the PU in at least two stages to derive motion information for the PU that includes different motion vectors and reference indices for each of the sub-PUs of the PU. In another example, the techniques include storing separate motion information derived for each sub-PU of a current PU predicted using a sub-PU backward view synthesis prediction (BVSP) mode even after motion compensation is performed. The additional motion information stored for the current PU may be used to predict subsequent PUs for which the current PU is a neighboring block.

A prediction information deriving unit derives the inter-prediction information candidates from inter-prediction information of a prediction block neighboring to a coding target prediction block or a prediction block present at the same position as or near the coding target prediction block in a coded picture at a temporally different position from the coding target prediction block. A candidate supplementing unit supplements inter-prediction information candidates having the same prediction mode, reference index, and motion vector until the number of inter-prediction information candidates reaches the designated number of candidates when the number of inter-prediction information candidates is smaller than the designated number of candidates.

A method of encoding input data to generate corresponding encoded data is provided. The method includes encoding the input data into a plurality of symbols in the encoded data, wherein the plurality of symbols represent data as defined by a plurality of palettes indicated and/or included in the encoded data. The method further includes determining mutually different palettes to be used for encoding mutually different parts of the input data, and using the mutually different palettes for encoding the mutually different parts of the input data. Moreover, the method also includes including, within the encoded data, information associating the mutually different palettes with their respective parts of the input data encoded into the encoded data, wherein the information includes palette selection indices for referencing the mutually different palettes on a block-by-block basis.

Systems and methods for hinting an encoder are disclosed in which a server monitors for information related to changes in frame rendering, calculates tolerance boundaries, rolling average frame time and/or short-term trends in frame time, and uses those calculations to identify a frame time peak. The server then hints a codec (encoder) to modulate the quality settings of frame output in proportion to the size of the frame time peak. In certain embodiments, a renderer records one or more playthroughs in a game environment, sorts a plurality of frames from one or more playthroughs into a plurality of cells on a heatmap, and collects the list of sorted frames. A codec may then encode one or more frames from the list of sorted frames to calculate an average encoded frame size for each cell in the heatmap, and associate each average encoded frame size with a per-cell normalized encoder quality setting.

Provided are methods and apparatuses for improving compression efficiency in directional intra-prediction. A video encoding apparatus, which does not need to record intra mode information, includes a mode selector that selects one from among a plurality of intra modes on the basis of a directionality of at least one neighboring block that has already been reconstructed before a current block is reconstructed, an intra predictor that obtains a prediction block of the current block from the at least one neighboring block according to the directionality of the selected mode, and obtains a residual block by subtracting the prediction block from the current block, and a unit for encoding the obtained residual block.