Abstract: A method of reducing blocking artifacts associated with pixels of a block boundary of an image. Pixel values of pixels from a first block and a neighboring block, being located on opposite sides of a block boundary, are evaluated. A first offset for the two pixels of each block located next to the block boundary is calculated, after which the first offset is compared to a first threshold value. If abs[first offset]<first threshold, the pixel values of consecutive pixels from the first block and the pixel values of consecutive pixels from the second block are modified by applying normal filtering on the respective pixels, while if instead abs[first offset]>=first threshold, the pixel values of consecutive pixels from the first block and the pixel values of consecutive pixels from the second block are modified by applying weak filtering or no filtering at all on the respective pixels.

Abstract: A method performed by a decoder for decoding a bitstream comprising a picture parameter set, PPS, and a first set of slices. The method includes obtaining the picture parameter set. The method also includes decoding a syntax element included in the picture parameter set to obtain an indicator value. The decoder is configured such that if the indicator value is set to a first value then the decoder determines that a picture header included in the bitstream comprises a parameter value corresponding to a particular parameter, otherwise the decoder determines that each slice included in the first set of slices comprises a parameter value corresponding to the particular parameter. If the picture header comprises the parameter value corresponding to the particular parameter, then this parameter value is used to decode slice data of each slice included in the first set of slices.

Abstract: A process for selecting a transform set for a prediction block. The process can be used in both an encoder and a decoder. For example, the process can be used in both an encoder and a decoder for a prediction block that has been predicted from a reference block. In some embodiments, both the prediction block and the reference block are intra blocks.

Abstract: A method for decoding a picture from a bitstream. In one embodiment, The method includes: receiving a slice header for a slice of the picture, wherein the slice header comprises a state syntax element; decoding a state value from the state syntax element in the slice header, wherein a) if the state value is not equal to a first value, then the state value indicates that i) the bitstream includes for the picture a picture header comprising a set of picture syntax elements and ii) the slice header does not comprise the set of picture syntax elements and b) if the state value is equal to the first value, then the state value indicates that i) the slice header contains said set of picture syntax elements and ii) the bitstream does not include a picture header for the picture; and using the set of picture syntax elements to decode the slice of the picture.

Abstract: A method for decoding a picture from a bitstream, includes decoding a first part of the bitstream to form an address mapping that maps a segment group index value to a segment group address; and decoding a second part of the bitstream. The second part of the bitstream includes code words representing the plurality of segment groups. Decoding the second part of the bitstream includes decoding a first segment group. Decoding the first segment group includes: 1) decoding a first segment group index value for the first segment group; 2) determining a first segment group address for the first segment group; 3) determining a first spatial location for the first segment group; and 4) decoding at least one sample value for the first segment group and assigning the at least one sample value to a location in the decoded picture given by the first spatial location.

Abstract: Method for decoding a picture, comprising: decoding information that the picture is partitioned into more than one segment based on one or more syntax elements in a bitstream; decoding information that the spatial segmentation is uniform based on the one or more syntax elements; determining a segment unit size based on the one or more syntax elements or based on a predefined segment unit size; decoding a first value indicating a segment width from one or more code words in the bitstream; decoding a second value indicating a segment height from the one or more code words; deriving segment column widths based on a picture width in number of segment units and the first value; deriving segment row heights based on a picture height in number of segment units and the second value; deriving a spatial location for a current block based on the derived segment column widths and the derived segment heights; and decoding the current block based on the derived spatial location.

Abstract: An encoded representation of a picture of a video stream is decoded by retrieving buffer description from the encoded representation. The buffer description information is used to determine at least one picture identifier identifying a respective reference picture as decoding reference for the picture. A decoded picture buffer is updated based on the determined picture identifier. The encoded representation of the picture itself comprises the information needed by a decoder to identify the reference pictures required to decode the encoded representation.

Abstract: A method for decoding a video bitstream comprising a sequence of pictures comprising a picture A and a picture B, wherein picture A starts a recovery point period and picture B ends the recovery point period. The method includes obtaining the video bitstream and decoding from the video bitstream a normative indication of the recovery point period. The normative indication of the recovery point period indicates that picture A starts the recovery point period and/or that picture B ends the recovery point period.

Abstract: A decoder can be configured to obtain a current inter block and a plurality of previously decoded inter blocks. Each inter block of the plurality of inter blocks can include a motion vector having a resolution. The decoder generates a list of motion vector predictor candidates that is used to predict the motion vector that is associated with the current inter block. Generating the list of motion vector predictor candidates can include defining a set of inter blocks that includes a number of previously decoded inter blocks; scanning the inter blocks in the set of inter blocks in a scanning order; and for each of the inter blocks in the set of inter blocks: deriving a motion vector prediction candidate using the motion vector of the inter block; and determining whether a criterion is satisfied.

Abstract: A method for decoding a picture from a bitstream. The picture comprising a number of units, and the picture being partitioned into a number of spatial segments by a partition structure. The method includes decoding one or more code words in the bitstream; determining that the partition structure is uniform based on the one or more code words; determining the number of spatial segments based on the one or more code words; determining a segment unit size; and deriving the sizes and/or locations for spatial segments in the picture from the one or more code words. Deriving the sizes and/or locations for spatial segments in the picture comprises a first loop over the number of spatial segments in a first dimension or direction. A number of remaining segment units in the first dimension or direction to be segmented is calculated inside the first loop.

Abstract: A method for decoding a current block in a current picture of a video bitstream includes decoding, from the video bitstream, a first motion vector for the current block relative to a first reference block of a first reference picture having a first picture order count, and decoding, from the video bitstream, a second motion vector for the current block relative to a second reference block of a second reference picture having a second picture order count. A similarity metric is generated based on a comparison of the first motion vector and the second motion vector. The method further includes determining whether to refine the first motion vector based on the similarity metric, generating a first refined motion vector from the first motion vector, and performing motion compensation to derive a first reference block from the first reference picture using the first refined motion vector.

Abstract: A first filter decision value is calculated for a block of pixels in a video frame based on pixel values of pixels in a first line (12) of pixels in the block. A second filter decision value is also calculated for the block based on pixel values of pixels in a corresponding first line of pixels in a neighboring block in the video frame. The first filter decision value is used to determine how many pixels in a line of pixels in the block to filter relative to a block boundary between the block and the neighboring block. The second filter decision value is used to determine how many pixels in a corresponding line of pixels in the neighboring block to filter relative to the block boundary.

Abstract: A process for selecting a transform set for a prediction block. The process can be used in both an encoder and a decoder. For example, the process can be used in both an encoder and a decoder for a prediction block that has been predicted from a reference block. In some embodiments, both the prediction block and the reference block are intra blocks.

Abstract: Methods and apparatuses for applying a deblocking to a coding unit in video pictures. In one aspect, the deblocking is applied to sub-block boundaries in the coding unit and to implicit transform unit boundaries in the coding unit.

Abstract: A method decodes one or more code words in a loop that is run N times by decoding an indication of whether a picture is a long-term picture or not and deriving a positive integer K[i]>0 for each long-term picture. An indicator value V[i] is derived for each long-term picture by subtracting the value of the positive integer K[i] from a picture indicator value P of the current picture. For each of the indicator values V[i], the indicator value V[i] is compared with values associated with pictures stored in the DPB. The method keeps the pictures stored in the DPB marked as short-term or long-term for which there is a match with one of the indicator values V[i] in the DPB as long-term pictures, and marks long-term pictures for which there is no match with any indicator value V[i] as unused for reference in the DPB.

Abstract: Providing backward compatibility in terms of a media bitstream and a media player conforming to different versions of a media bitstream syntax specification. In one embodiment, a bitstream is made backward compatible by including in the bitstream a first entry for a feature available in the media bitstream and second entry for an updated feature available in the media bitstream, where the first entry is understood both by a media player supporting a first version of a syntax specification and a media player supporting an updated version of the syntax specification, and the second entry is understood by the media player supporting the updated version of the syntax specification, but is not understood by the media player supporting the first version of the syntax specification.

Abstract: A method of processing a video sequence including images, wherein each image includes blocks of sample values, is provided. The method includes determining input and output lengths for deblocking filtering of the sample values for a first and second side of a potential blocking boundary. The input and output lengths are a number of consecutive sample values, from a sample value closest to the potential blocking boundary to one or more other sample values spaced from the potential blocking boundary. The input and output lengths are determined based on determining whether the potential blocking boundary is identified as an internal sub-block boundary. The method includes deblocking filtering of the sample values on the at least one of the first and second side of the potential blocking boundary, using the input and output lengths, to generate deblocked sample values.

Abstract: A method (400) performed by a decoder (260, 600, 701) for decoding a bitstream comprising a picture parameter set, PPS, and a first set of slices. The method includes obtaining (s402) the picture parameter set. The method also includes decoding (s404) a syntax element included in the picture parameter set to obtain an indicator value. The decoder is configured such that if the indicator value is set to a first value then the decoder determines that a picture header included in the bitstream comprises a parameter value corresponding to a particular parameter, otherwise the decoder determines that each slice included in the first set of slices comprises a parameter value corresponding to the particular parameter. If the picture header comprises the parameter value corresponding to the particular parameter, then this parameter value is used to decode slice data of each slice included in the first set of slices.

Abstract: An encoder is configured to encode a representation of a current picture of a video stream of multiple pictures. The encoder is further configured to encode, for each of a plurality of reference pictures included in a buffer description for the current picture, a respective one-bit flag according to one of two available values for the one-bit flag. The two available values for the one-bit flag include a first value explicitly indicating to a decoder to include the reference picture in a reference picture list for decoding the current picture. The two available values for the one-bit flag further include a second value explicitly indicating to the decoder not to include the reference picture in the reference picture list for decoding the current picture. The encoder is further configured to output the representation of the current picture and the one-bit flags.

Abstract: A method for decoding a picture from a bitstream. In one embodiment, The method includes: receiving a slice header for a slice of the picture, wherein the slice header comprises a state syntax element; decoding a state value from the state syntax element in the slice header, wherein a) if the state value is not equal to a first value, then the state value indicates that i) the bitstream includes for the picture a picture header comprising a set of picture syntax elements and ii) the slice header does not comprise the set of picture syntax elements and b) if the state value is equal to the first value, then the state value indicates that i) the slice header contains said set of picture syntax elements and ii) the bitstream does not include a picture header for the picture; and using the set of picture syntax elements to decode the slice of the picture.