摘要:
Techniques are described that can be used to either compress or expand video. Color compression techniques are described that can be used to compress the wide color gamut content into lower color gamut for inclusion in a baseline layer. Color expansion techniques are described that convert lower color gamut data into wider color gamut format for inclusion in an enhancement layer. Both of the baseline video stream and enhancement layer video streams may be transmitted through a channel or stored in a memory device to be viewed later. Accordingly, both baseline and enhancement video layers are available so that either lower or higher quality displays can be used to display video.
摘要:
Systems, devices and methods for performing low memory access candidate-based decoder-side motion vector determination (DMVD) are described. The number of candidate motion vectors (MVs) searched may be confined by limiting the range of pixels associated with candidate MVs to a pre-defined window. Reference windows may then be loaded into memory only once for both DMVD and motion compensation (MC) processing. Reference window size may be adapted to different PU sizes. Further, various schemes are described for determining reference window positions.
摘要:
Video compression encoding includes intra and inter prediction to reduce spatial and temporal redundancies in video. Prediction results or residuals represent differences between original video pixel values and predicted pixel values. The prediction residuals may be transformed into coefficients, referred to as transform coefficients, in the frequency domain. The transform coefficients may be quantized and entropy encoded. The transform coefficients can be sub-sampled prior to quantization to reduce their number. For example, sub-sampling may reduce more high frequency components than low frequency components represented in the transform coefficients. Therefore, sub-sampling reduces the number of transform coefficients that need to be quantized, reduces quantization complexity, and correspondingly increases throughput in the encoding.
摘要:
Systems, devices and methods for performing luma-based chroma ultra prediction are described. Down-sample filters may be applied to luma values of luma pixel positions to generate reconstructed luma values for chroma pixel positions in a prediction unit of an intra frame. The down-sampled reconstructed luma values may then be used to predict chroma values for the chroma pixel positions. In some implementations, a reconstructed luma value of a chroma position may be used to predict that position's chroma value. In other implementations, reconstructed luma values of neighboring chroma pixel positions may be analyzed to adaptively predict a chroma value for a chroma pixel position.
摘要:
Techniques are described that can be used to either compress or expand video. Color compression techniques are described that can be used to compress the wide color gamut content into lower color gamut for inclusion in a baseline layer. Color expansion techniques are described that convert lower color gamut data into wider color gamut format for inclusion in an enhancement layer. Both of the baseline video stream and enhancement layer video streams may be transmitted through a channel or stored in a memory device to be viewed later. Accordingly, both baseline and enhancement video layers are available so that either lower or higher quality displays can be used to display video.
摘要:
Adaptive control can use hierarchical motion estimation (HME) and/or multiple reference motion estimation (MRME) for the motion estimation of current encoding blocks. Both HME and MRME are allowed in the motion estimation to achieve a high coding gain. Control consists of slice level control and macro-block (MB) level control. A slice is one or more contiguous macroblocks. In slice level control, it is decided to use only one reference frame or use multiple reference frames to coding current slice based on the motion vectors obtained in coarse level motion estimation. In MB level control, it is decided to perform MRME or perform HME for the MB and its subblocks based on the coarse level motion vectors of the MB.
摘要:
Systems, methods, and computer program products that can be used to determine a search range (SR) when performing motion estimation at, for example, a video encoder or decoder. Determining a motion vector for a current block during motion estimation may involve searching within a search window that may reside in a reference frame, or in a previously decoded block that spatially or temporally neighbors the current block. Such a search seeks a motion vector that minimizes a metric, such as a sum of absolute differences between corresponding blocks of reference frames. A motion vector that minimizes such a metric may be a good candidate for use in motion estimation. The search may become more efficient if a search range is determined such that the extent of the search is bounded. A search range may be determined at the block level or at the picture level.
摘要:
Method and apparatus for deriving a motion vector at a video decoder. A block-based motion vector may be produced at the video decoder by utilizing motion estimation among available pixels relative to blocks in one or more reference frames. The available pixels could be, for example, spatially neighboring blocks in the sequential scan coding order of a current frame, blocks in a previously decoded frame, or blocks in a downsampled frame in a lower pyramid when layered coding has been used.
摘要:
An adaptive Wiener filter may be applied to improve coding efficiency because of information lost during quantization of the video encoding process. The Wiener filter may be selectively applied globally to an entire picture or locally to portions of the picture. Histogram segmentation may be used to select pixels for Wiener filtering in some embodiments. The Wiener filter may be adaptively applied to histogram bins, improving coding efficiency in some cases.