Abstract: A method of using a base layer to predict an enhancement layer is disclosed. The method may include using a block of multimedia data to generate a base residual including base quantized coefficients, using the block of multimedia data to generate an enhancement residual including enhancement quantized coefficients, determining a first value based on the base quantized coefficients, determining a second value based on the enhancement quantized coefficients, and determining the enhancement layer using at least one of the base quantized coefficients or the enhancement quantized coefficients. A method of decoding a multimedia bitstream may include receiving a multimedia bitstream having a base layer and an enhancement layer and decoding the base layer to determine whether the enhancement layer should be decoded using intralayer prediction or interlayer prediction.

Abstract: In general, techniques are described for performing motion vector prediction for video coding. An apparatus comprising a motion compensation unit may implement the techniques. The motion compensation unit determines spatial candidate motion vectors (MVPs) associated with a current portion of a video frame and prunes the spatial candidate motion vectors to remove duplicates without removing a temporal candidate motion vector. The motion compensation unit selects one of the temporal candidate motion vector or one of the spatial candidate motion vectors remaining after pruning as a selected candidate motion vector based on a motion vector predictor (MVP) index signaled in a bitstream and performs motion compensation based on the selected candidate motion vector.

Abstract: The example techniques described in this disclosure provide for an efficient manner to encode or decode a video block of a picture using a single reference picture list. The single reference picture list may include identifiers for reference picture or pictures used to encode or decode the video block. In some examples, a video encoder or decoder may encode or decode a video block that is predicted from two reference pictures using the single reference picture list, and encode or decode a video block that is predicted from one reference picture using the same, single reference picture list.

Abstract: A method of coding video data includes determining a candidate motion vector for each of one or more candidate portions of a video frame and determining a current motion vector for a current portion of a current frame. The current motion vector identifies a portion of a reference frame that at least partially matches the current portion of the current frame. The method also includes calculating a motion vector difference between the current motion vector and each of the candidate motion vectors, selecting one of the candidate motion vectors based on the calculated motion vector differences, signaling an index identifying the candidate portion having the selected one of the candidate motion vectors, and signaling the corresponding motion vector difference calculated with respect to the selected one of the candidate motion vectors.

Abstract: This disclosure relates to techniques for constructing a combined reference picture list, List C, based on List 0 and List 1, used for uni-directional prediction of video blocks in any direction. The techniques include coding one or more syntax elements defined to indicate construction information for List C, and performing reference picture list construction for List C from List 0 and List 1 based on the syntax elements. The one or more syntax elements may indicate that List C is used for uni-directional prediction, and may also indicate a number of reference pictures identified in List C and a reference index of a reference picture for each entry in List C. Each coded video block of a B slice may have an associated syntax element, i.e., inter_pred_idc, to indicate whether the video block is bi-predicted from List 0 and List 1 (Bi) or uni-directional predicted from List C (Pred_LC).

Abstract: Methods and apparatus to process multimedia data enabling faster channel acquisitions, improved error recovery and improved efficiency. An encoder device encodes a first portion of multimedia data using inter-coding to generate a first version, and encodes the first portion of multimedia data using intra-coding to generate a second version. A decoder device receives a first version of a first portion of multimedia data, wherein the first version is inter-coded, receives a second version of the first portion of multimedia data, wherein the second version is intra-coded, and selectively decodes the first and second received versions.

Abstract: During a video encoding or decoding process, a predicted prediction block is generated for a CU. The CU may have two or more prediction units (PUs). A computing device selects a neighbor region size. After the computing device selects the neighbor region size, samples in a transition zone of the prediction block are identified. Samples associated with a first PU are in the transition zone if neighbor regions that contain the samples also contain samples associated with a second PU. Samples associated with the second PU may be in the transition zone if neighbor regions that contain the samples also contain samples associated with the first PU. The neighbor regions have the selected neighbor region size. A smoothing operation is then performed on the samples in the transition zone.

Abstract: During a video coding process, a prediction block is generated for a CU. The CU has two or more prediction units. A computing device determines, based on sizes of one or more of the prediction units, whether to perform a smoothing operation on samples in a transition zone of the prediction block. The transition zone is located at a boundary between samples of the prediction block associated with different prediction units. If the computing device makes the determination to perform the smoothing operation, the smoothing operation is performed to smooth samples of the prediction block in the transition zone.

Abstract: In one example, this disclosure describes a method of decoding a frame of video data comprising a plurality of block-sized coding units including one or more largest coding units (LCUs) that include a hierarchically arranged plurality of relatively smaller coding units. In this example, the method includes determining a granularity at which the hierarchically arranged plurality of smaller coding units has been split when forming independently decodable portions of the frame. The method also includes identifying an LCU that has been split into a first section and a second section using the determined granularity. The method also includes decoding an independently decodable portion of the frame that includes the first section of the LCU without the second section of the LCU.

Abstract: A video encoder may transform residual data by using a transform selected from a group of transforms. The transform is applied to the residual data to create a two-dimensional array of transform coefficients. A scanning mode is selected to scan the transform coefficients in the two-dimensional array into a one-dimensional array of transform coefficients. The combination of transform and scanning mode may be selected from a subset of combinations that is based on an intra-prediction mode. The scanning mode may also be selected based on the transform used to create the two-dimensional array. The transforms and/or scanning modes used may be signaled to a video decoder.

Abstract: This disclosure describes techniques for calculating values of sub-integer pixels applied by an encoder and a decoder to encode blocks of video data. In one example, a video encoder is configured to receive values for a full integer pixel positions of a reference sample, apply an interpolation filter to a first set of the values for the full integer pixel positions to calculate a value for a first sub-integer pixel of one of the full integer pixel positions, apply the interpolation filter to a second, different set of the values for the full integer pixel positions to calculate a value for a second, different sub-integer pixel of the one of the full integer pixel positions, encode a current block of pixels using a motion vector that points to one of the first sub-integer pixel and the second sub-integer pixel.

Abstract: During a video encoding process, rectangular prediction units (PUs) for a coding unit (CU) are generated. Furthermore, a geometric partitioning mode is used to generate a first and a second geometric PU for the CU. The first and second geometric PUs are associated with different geometric partitions of a sample block of the CU. One of the rectangular PUs is identified as overlapping the first geometric PU. The motion vector of the identified rectangular PU is used to identify a given area of a reference frame. The given area of a reference frame is then used as a starting point of a search to identify a reference sample for the first geometric PU. A motion vector for the first geometric PU indicates a position of the reference sample relative to a position of the first geometric PU. A prediction block is generated using the motion vector for first geometric PU.

Abstract: In one example, a video decoder is configured to determine whether a component of a transform unit of a coding unit of video data includes at least one non-zero coefficient based on a codeword for the transform unit, determine whether the transform unit is split into sub-transform units based on the codeword, and decode the transform unit based on the determinations. In another example, a video encoder is configured to determine whether a component of a transform unit of a coding unit of video data includes at least one non-zero coefficient, determine whether the transform unit is split into sub-transform units, select a codeword from a variable length code table, wherein the variable length code table provides an indication that the codeword corresponds to the determinations, and provide the codeword for the transform unit.

Abstract: A video encoder may be configured to adaptively select a sub-pixel precision for motion vectors used to encode video data. The video encoder may further entropy encode an indication of the sub-pixel precision using context adaptive binary arithmetic coding, where the context may correspond to the size of a block of video data for the motion vector. For example, the size may correspond to the depth of a coding unit, the size of a prediction unit of the coding unit, and/or a type for the prediction unit. The video encoder may also interpolate values for one-sixteenth pixel positions of chrominance data using bilinear interpolation. The video encoder may further encode a motion vector difference value for the motion vector using an encoding scheme corresponding to the sub-pixel precision of the motion vector. A video decoder may use similar, reciprocal techniques for decoding the video data.

Abstract: During a video encoding process, a video encoder may transform the residual data of a coding unit (CU) using a single transform if the CU only has a single prediction unit (PU). If the CU has multiple PUs, the video encoder may transform the residual data using multiple transforms. The video encoder outputs an indication of the size of a transform used to transform residual data of the CU only when the CU has more than one PU. If a video decoder receives such an indication, the video decoder may reconstruct residual data of the CU using a transform of the indicated size. Otherwise, the video decoder may reconstruct the residual data of the CU using a transform having same size as the CU.

Abstract: A method and system for coding mode selection using estimated coding costs. To provide high compression efficiency, for example, an encoding device may attempt to select a coding mode for coding blocks of pixels that codes the data of the blocks with high efficiency. To this end, the encoding device may perform coding mode selection based on estimates of coding cost for at least a portion of the possible modes. The encoding device may estimate the coding cost for the different modes without actually coding the blocks. In fact, in some aspects, the encoding module device may estimate the coding cost for the modes without quantizing the data of the block for each mode. In this manner, the coding cost estimation techniques may reduce the amount of computationally intensive calculations needed to perform effective mode selection.

Abstract: This disclosure relates to techniques for efficient coding of video parameters for weighted motion compensated prediction in video encoding and decoding. A video coding device may code a video block using weighted motion compensated prediction with respect to prediction data generated based on at least one motion vector and video parameter values. The video parameter values may include scale and/or offset parameter values. The techniques reduce signaling overhead by only signaling video parameter values when the motion vector points to a predefined sub-pixel position of a reference block. The techniques include storing a list of predefined sub-pixels associated with the video parameters. When the motion vector points to a sub-pixel position included in the list of predefined sub-pixels, the video coding device may code the video parameter values. The list of predefined sub-pixels may be signaled to a video decoder at a video coding unit or higher level.

Abstract: Video coding devices may signal or determine sub-integer pixel precision for motion vectors based on a direction of prediction for the motion vector, e.g., whether a reference frame is to be displayed earlier or later than a current frame. In one example, an apparatus includes a video encoder configured to encode a block of video data using a motion vector that refers to a reference frame in one of a plurality of sets of reference frames with a selected sub-integer pixel precision, generate a value representative of the selected precision for the motion vector based on the one of the plurality of sets of reference frames referred to by the motion vector, and output the encoded block and the generated value representative of the selected precision for the motion vector. A video decoder may determine a sub-integer pixel precision for the motion vector based on the value.

Abstract: In one example, an apparatus for signaling information for video data includes a processor configured to receive video data for two or more views of a scene, form a representation comprising a subset of the two or more views, and send, to a client device, as a part of a manifest of the representation, information indicative of a maximum number of views in the representation that can be targeted for output. An apparatus for receiving information for video data may receive the manifest including the information indicating the maximum number of views and request at least a portion of the video data of the representation based at least in part on a maximum number of views that can be output by the apparatus and the information indicative of the maximum number of views in the representation that can be targeted for output.

Abstract: In one example, an apparatus includes a processor configured to receive video data for two or more views of a scene, determine horizontal locations of camera perspectives for each of the two or more views, assign view identifiers to the two or more views such that the view identifiers correspond to the relative horizontal locations of the camera perspectives, form a representation comprising a subset of the two or more views, and, in response to a request from a client device, send information indicative of a maximum view identifier and a minimum view identifier for the representation to the client device.