Abstract: Techniques are described for initializing a Rice parameter used to define codes for coefficient level coding. According to the techniques, the initial value of the Rice parameter is determined for a coefficient group (CG) in a transform block of video data based on statistics of coefficient levels that are gathered for previously coded coefficients of the video data. The statistics may be statistics of absolute values of coefficient levels or remaining absolute values of coefficient levels of previously coded coefficients. A value of the statistics may be initialized to zero at a beginning of a video slice and updated based on coefficient levels coded in each CG of the slice. The statistics may be updated once per CG. In some cases, statistics may be gathered separately for each of a plurality of different categories of CGs that are defined based on characteristics of transform blocks that include the CGs.

Abstract: Techniques coding video data, including a mode for intra prediction of blocks of video data from predictive blocks of video data within the same picture, may include determining a predictive block of video data for the current block of video data, wherein the predictive block of video data is a reconstructed block of video data within the same picture as the current block of video data. A two-dimensional vector, which may be used by a video coder to identify the predictive block of video data, includes a horizontal displacement component and a vertical displacement component relative to the current block of video data. The mode for intra prediction of blocks of video data from predictive blocks of video data within the same picture may be referred to as Intra Block Copy or Intra Motion Compensation.

Abstract: A device configured to code video data includes: a memory configured to store video data, and at least one processor. The at least one processor is configured to: code information indicating whether a block from a current picture will flicker. A determination of whether the block from the current picture will flicker is based on the block in the current picture in a display order and a collocated block from a next picture in the display order.

Abstract: Receiving a plurality of syntax elements that are indicative of a palette that was used to encode a block of video data, the plurality of syntax elements including a first syntax element that indicates a number of palette values for the palette that are explicitly signaled in the encoded video bitstream, wherein the first syntax element is encoded using one or more Golomb codes such that the length of the encoded first syntax element is less than or equal to a predetermined maximum number of bits, decoding the plurality of syntax elements, including decoding the first syntax element using the one or more Golomb codes, reconstructing the palette based on the decoded plurality of syntax elements, and decoding the block of video data using the reconstructed palette.

Abstract: In one example, there is provided a method that includes coding a block within a slice of video data. The slice may comprise one or more blocks of the video data. The method further includes storing bits corresponding to the block in a buffer, determining information indicative of a position of the block within the slice, and determining fullness of the buffer based at least in part on the position of the block within the slice.

Abstract: A device for decoding video data may be configured to determine a block of the video data is coded using a palette-based coding mode; determine a sample of the block of video data is coded using a copy from top mode or an index mode; and decode a greater than zero flag to indicate whether a run value is greater than zero, wherein the run value specifies a number of samples subsequent to the sample that have a same mode as the sample.

Abstract: A video coder may determine a palette predictor list comprising one or more candidates. Each respective candidate in the palette predictor list specifies a value of a different respective reconstructed neighboring pixel from among one or more reconstructed neighboring pixels. Each of the one or more reconstructed neighboring pixels is in a line above or a column left of a current block of the video data. The video coder may include, in a palette for the current block, at least one candidate in the palette predictor list.

Abstract: In an example, a method of decoding video data may include receiving a palette mode encoded block of video data of a picture. The method may include receiving encoded palette mode information for the palette mode encoded block of video data. The encoded palette mode information may include a plurality of instances of a first syntax element and a plurality of syntax elements that are different from the first syntax element. The method may include decoding, using bypass mode, the plurality of instances of the first syntax element before decoding the plurality of syntax elements that are different from the first syntax element using context mode. The method may include decoding, using context mode, the plurality of syntax elements that are different from the first syntax element after decoding the plurality of instances of the first syntax element using bypass mode.

Abstract: A method and apparatus for detecting a complex region of an image are disclosed. In one example, the method may involve calculating complexity values for a current block, a next block, and a previous block. The method may involve: (i) detecting that the previous complexity value is less than a first threshold value, and that the next complexity value is greater than a second threshold value; and (ii) determining that neither a transition to the current block nor a transition to the previous block is a flat-to-complex region transition. The method may involve detecting a flat-to-complex region transition when transitioning to the next block in response to (i) and (ii).

Abstract: Techniques are described for updating a value of a Rice parameter used to define Golomb codes for coefficient level coding. The Golomb codes defined by the Rice parameter may be used to code a remaining absolute value of a coefficient level for at least one coefficient in a coefficient group (CG). According to the techniques, the value of the Rice parameter is updated based on a selection of a minimum of either a maximum value of the Rice parameter or a variable increment of the value of the Rice parameter. The variable increment is determined based on the value of the Rice parameter and an absolute value of the coefficient level for the current coefficient being coded. Techniques are also described for adjusting the value of the Rice parameter used to define Golomb codes for coefficient level coding based on whether a transform is applied to a transform block.

Abstract: A system and method for flatness detection for display stream compression (DSC) is disclosed. In one aspect, the method includes determining a first complexity value for a previous block of video data, a second complexity value for a current block of the video data, and a third complexity value for a next block of the video data. The method also includes determining whether the current block includes a transition from a complex region to a flat region based at least in part on the first, second, and third complexity values.

Abstract: A device for coding video data includes a memory configured to store video data, and at least one processor configured to: determine a maximum number of bits to be used when coding a syntax element indicating absolute values of transform coefficients of a coding unit of the video data, determine a maximum number of suffix bits to be used when coding a Golomb-Rice/Exponential-Golomb coding suffix codeword of the syntax element, determine a maximum number of prefix bits to be used when coding a unary Golomb-Rice/Exponential-Golomb coding prefix codeword of the syntax element, determine the absolute values of transform coefficients for the coding unit, code a prefix codeword for one of the absolute values, and code a suffix codeword for the one of the absolute values, and code the coding unit based on the prefix codeword and the suffix codeword.

Abstract: Techniques are described for palette-based video coding. In palette-based coding, a video coder may form a so-called “palette” as a table of colors for representing video data of a given block of video data. Rather than coding actual pixel values or their residuals for the given block, the video coder may code index values for one or more of the pixels. The index values map the pixels to entries in the palette representing the colors of the pixels. Techniques are described for determining the application of deblocking filtering for pixels of palette coded blocks at a video encoder or a video decoder. In addition, techniques are described for determining quantization parameter (QP) values and delta QP values used to quantize escape pixel values of palette coded blocks at the video encoder or the video decoder.

Abstract: An example method of decoding video data includes determining a palette for decoding a block of video data, where the palette includes one or more palette entries each having a respective palette index, determining a first plurality of palette indices for first pixels of the block of video data, enabling a palette coding mode based on a run length of a run of a second plurality of palette indices for second pixels of the block of video data being decoded relative to the first plurality of palette indices meeting a run length threshold, and decoding the run of the second plurality of palette indices relative to the first plurality of palette indices using the palette coding mode.

Abstract: Techniques are described for palette-based video coding. In palette-based coding, a video coder may form a “palette” as a table of colors for representing video data of a particular area (e.g., a given block). Rather than coding actual pixel values (or their residuals), the video coder may code palette index values for one or more of the pixels that correspond to entries in the palette representing the colors of the pixels. A palette may be explicitly encoded, predicted from previous palette entries, or a combination thereof. In this disclosure, techniques are described for coding a block of video data that has a single color value using a single color mode as a sub-mode of a palette coding mode. The disclosed techniques enable a block having a single color value to be coded with a reduced number of bits compared to a normal mode of the palette coding mode.

Abstract: A device for decoding video data is configured to determine for one or more blocks of the video data that adaptive color transform is enabled; determine a quantization parameter for the one or more blocks; in response to a value of the quantization parameter being below a threshold, modify the quantization parameter to determine a modified quantization parameter; and dequantize transform coefficients based on the modified quantization parameter.

Abstract: Entropy coding techniques for display stream compression (DSC) are disclosed. In one aspect, a method of entropy coding video data includes partitioning a block of the video data into a plurality of groups of samples based at least in part on a coding mode of the block. The method further includes entropy coding the block via performing a group-wise skip on at least one of the groups in response to all of the samples in the at least one group being equal to a predetermined value.

Abstract: An example method of coding video data includes determining, for a current block of video data, a palette that includes a plurality of entries that each corresponds to a respective color value; determining a particular entry in the palette that is predicted to correspond to a color value of a current pixel of the current block; selecting a binarization from a plurality of binarizations; and coding, using the selected binarization, an index that indicates which entry in the palette corresponds to a color value for a current pixel of the current block, wherein coding the index using a first binarization of the plurality of binarizations comprises coding a syntax element that indicates whether the index is equal to the particular entry, and wherein coding the index using a second binarization of the plurality of binarizations comprises coding the index using a variable length code without coding the syntax element.

Abstract: In an example, system and method for coding encoded video data. A quantized residue differences block associated with a current block of a picture is generated and a reconstructed prediction residue for each quantized residue difference in the block of quantized residue differences is generated. Each reconstructed prediction residue is added to its corresponding original prediction value to produce a current block of a picture. Generating the reconstructed prediction residue includes performing inverse quantization on blocks of quantized residue differences, wherein the inverse quantization reconstructs data to which uniform quantization residue differential pulse code modulation (RDPCM) has been applied and wherein the quantization is of the form: ?Xq=floor((X+?Q)/Q) where Q is quantization step and ? is quantization offset.

Abstract: A video decoder receives local quantization information for a current quantization group. The video decoder determines a partitioning of a coding tree unit (CTU) of a picture of the video data into a plurality of coding units (CUs). Additionally, the video decoder derives, based at least in part on the local quantization information for the current quantization group, a quantization parameter. The current quantization group is defined as a group of successive CUs so that boundaries of the current quantization group must be boundaries of the CUs. The current quantization group may or may not be square. Additionally, the video decoder inverse quantizes, based on the quantization parameter, at least one transform coefficient of a current CU being in the current quantization group. The video decoder reconstructs, based on inverse quantized transform coefficients of the current CU, a coding block of the current CU.