Abstract: Embodiments are provided for compressing a color index map in video coding applications including screen content images. An embodiment method includes obtaining, at a video codec device, an image block, and generating a color index map comprising a plurality of entries and representing the image block. Each one of the entries is assigned a color index indicating a respective color. The method further includes assigning, in a correct prediction map, a first bit-value for each one of the entries that is predictable by a neighboring entry in the color index map, and a second bit-value for each one of the entries that is unpredictable by any neighboring entry in the color index map. Further, an actual value from the color index map for the each one of the entries that is unpredictable by any neighboring entry is added in a sequence of non-predictable color indices.

Abstract: A video codec comprising a processor configured to generate a prediction block for a current block, compute a difference between the current block and the prediction block to generate a residual block, scan a plurality of prediction residuals located in the residual block following a scanning order, and if the plurality of residual values comprise at least one non-zero prediction residual, entropy encode the at least one non-zero prediction residual. A method comprising generating a prediction block for a current block, computing a difference between the current block and the prediction block to generate a residual block, scanning a plurality of prediction residuals located in the residual block, and if the plurality of residual values comprise at least one non-zero prediction residual, entropy encoding the at least one non-zero prediction residual.

Abstract: A method and device for generating a predicted value of image that are mostly used to generate a predicted value of a current block during image encoding or decoding. The method includes: determining a searching scope, wherein multiple motion vectors are included in the searching scope; performing up-sampling interpolations on first reference blocks, corresponding to the motion vector in the searching scope, in a reference image of the current block by using a first filter to obtain up-sampled first reference blocks; by using the up-sampled first reference blocks, obtaining at least one candidate motion vector corresponding to the current block; performing up-sampling interpolations on second reference blocks, corresponding to the at least one candidate motion vector, in the reference image of the current block by using a second filter to obtain up-sampled second reference blocks; combining the up-sampled second reference blocks to obtain a predicted value of the current block.

Abstract: A video codec including a memory and a processor operably coupled to the memory. The processor is configured to compute a reconstructed pixel based on a residual pixel and a first prediction pixel and compute a second prediction pixel in a directional intra prediction mode based on the reconstructed pixel, where the first and second prediction pixels are located in a same block of a video frame. A method for intra prediction including computing a prediction pixel adaptively based on a plurality of reconstructed neighboring pixels, where a distance between the prediction pixel and each of the plurality of reconstructed neighboring pixels is one.

Abstract: An encoding apparatus, decoding apparatus, and coding methods. The encoding apparatus includes a processor configured to receive a video frame including screen content, generate a block containing an index map of colors for screen content in the video frame, wherein the block includes strings of index values sharing a same escape color index value, wherein the escape color index value represents an escape color, encode each of the strings of index values in the block, and sequentially encode the escape colors after each of the strings of index values in the block has been encoded. A transmitter operably coupled to the processor is configured to transmit the strings of index values and the escape colors in a bitstream to a decoding apparatus.

Abstract: Embodiments of the present invention provide a motion prediction or compensation method during a video coding and decoding process. A motion prediction or compensation method provided in the embodiments of the present invention includes: acquiring a candidate motion vector set; conducting a refined search for an optimal motion vector based on information of the candidate motion vector set; and performing motion prediction or compensation by using the motion vector acquired by the refined search. This improves coding performance and meanwhile maintains reasonable complexity.

Abstract: There are provided methods and apparatus for using syntax for the coded_block_flag syntax element for the CAVLC 4:4:4 Intra, High 4:4:4 Intra, and High 4:4:4 Predictive profiles in MPEG-4 AVC high level coding. An apparatus includes an encoder (100) for encoding image data into a resultant bitstream in accordance with an encoding profile that encodes a sample of the image data such that the sample includes two chrominance arrays and a luminance array. Each of the two chrominance arrays has a same height and a same width as the luminance array. The encoder (100) indicates a presence of at least one 8×8 block in the resultant bitstream using a syntax element.

Abstract: A method including adaptively updating a value of an Exponential-Golomb (EG) parameter according to a value of an encoded prediction residual value, and encoding a prediction residual value in a lossless mode using an EG code based on the value of the EG parameter.

Abstract: A video codec comprising a processor configured to compute a reconstructed pixel based on a residual pixel and a first prediction pixel and compute a second prediction pixel in a directional intra prediction mode based on the reconstructed pixel, wherein the first and second prediction pixels are located in a same block of a video frame. A method for intra prediction comprising computing a prediction pixel adaptively based on a plurality of reconstructed neighboring pixels, wherein a distance between the prediction pixel and each of the plurality of reconstructed neighboring pixels is one.

Abstract: An apparatus is configured to perform a method for screen content coding. The method includes deriving a color index map based on a current coding unit (CU). The method also includes encoding the color index map, wherein at least a portion of the color index map is encoded using a first coding technique, wherein a first indicator indicates a significant distance of the first coding technique. The method further includes combining the encoded color index map and the first indicator for transmission to a receiver.

Abstract: There are provided methods and apparatus for using syntax for the coded_block_flag syntax element for the CAVLC 4:4:4 Intra, High 4:4:4 Intra, and High 4:4:4 Predictive profiles in MPEG-4 AVC high level coding. An apparatus includes an encoder (100) for encoding image data into a resultant bitstream in accordance with an encoding profile that encodes a sample of the image data such that the sample includes two chrominance arrays and a luminance array. Each of the two chrominance arrays has a same height and a same width as the luminance array. The encoder (100) indicates a presence of at least one 8×8 block in the resultant bitstream using a syntax element.

Abstract: An apparatus is configured to perform a method for screen content encoding. The method includes deriving a palette table and a color index map based on a coding unit (CU). The method also includes encoding the palette table and encoding the color index map. The method further includes combining the encoded palette table and the encoded color index map for transmission to a receiver, where the palette table and index map are decoded to reconstruct a pixel block.

Abstract: An apparatus is configured to perform a method for screen content encoding. The method includes deriving a palette table and a color index map based on a coding unit (CU). The method also includes encoding the palette table and encoding the color index map. The method further includes combining the encoded palette table and the encoded color index map for transmission to a receiver, where the palette table and index map are decoded to reconstruct a pixel block.

Abstract: There are provided video encoders, video decoders, and corresponding methods. A video encoder for encoding video signal data for an image block includes an encoder (100) for encoding all color components of the video signal data using a common predictor (315). A video decoder for decoding video signal data for an image block includes a decoder (200) for decoding all color components of the video signal data using a common predictor (430). Additionally, an apparatus and method for encoding and decoding signal data for an image block includes an encoder and decoder for encoding/decoding color components of the video signal data without applying a residual color transform thereto. Furthermore, a video encoder and decoder for encoding/decoding video signal data for an image block includes an encoder and decoder for encoding/decoding the video signal data using unique predictors for each of color components of the video signal data.

Abstract: Coding of screen content includes identifying corresponding areas in one or more previously coded frames to code unchanged areas in current frames. An unchanged area in a current frame is coded by copying a corresponding area from a previously coded frame or several previously coded frames. Usage of a copy mode to be applied to the unchanged areas is signaled in an encoding bitstream. The copy mode can be signaled for each unchanged area or a single copy mode is signaled for a group of unchanged areas. The copy mode can be automatically applied to one or more unchanged areas contiguous to the group of unchanged areas without further signaling the copy mode. Copying the corresponding area from the previously coded frame includes copying palette entries from the previously coded frame. Palette entries copied from the previously coded frame are reordered according to frequency of appearance.

Abstract: A method and device for coding screen content into a bitstream by selecting a color palette table for a coding unit (CU) of screen content, creating a color index map having indices for the coding unit (CU), and encoding the selected color palette table and the color index map for the CU into a bitstream.

Abstract: A framework for a screen content sharing system with generalized screen descriptions is described. In one approach, a screen content update message is sent from a client device to a control plane where the client device wishes to share its screen content with a remote device. The remote device sends a message indicating an interest in receiving said update. The control plane subsequently retrieves a detailed description from the client device. Based on the computational context of the remote device, the detailed description may be trimmed to a more compatible format. In some embodiments, the detailed description is sent to the remote device and includes a screen description and a content description. The content of the shared screen is described and the content is subsequently retrieved from a service router. A shared screen content is assembled based on the screen description and the content retrieved from the service router.

Abstract: An apparatus used in video encoding comprising a processor configured to generate a prediction block for a current block, compute a difference between the current block and the prediction block to generate a residual block, wherein the residual block comprises a plurality of residual values, and if the plurality of residual values include at least one non-zero residual value comprising at least one sign and at least one residual level, perform entropy encoding on the at least one sign; and perform entropy encoding on the at least one residual level, wherein one non-residual value comprises one sign and one residual level.

Abstract: There are provided video encoders, video decoders, and corresponding methods. A video encoder for encoding video signal data for an image block includes an encoder (100) for encoding all color components of the video signal data using a common predictor (315). A video decoder for decoding video signal data for an image block includes a decoder (200) for decoding all color components of the video signal data using a common predictor (430). Additionally, an apparatus and method for encoding and decoding signal data for an image block includes an encoder and decoder for encoding/decoding color components of the video signal data without applying a residual color transform thereto. Furthermore, a video encoder and decoder for encoding/decoding video signal data for an image block includes an encoder and decoder for encoding/decoding the video signal data using unique predictors for each of color components of the video signal data.

Abstract: Presented systems and methods facilitate screen content coding. A system can comprises: a processing component configured to execute coding operations and a storage component configured to store information for the processing component, including the color table and color index map. The coding operations can include: receiving information associated with a plurality of pixels; creating a color table, the color table includes color values (e.g., of the pixels) and corresponding indices; creating a color index map wherein each index of the color map maps a pixel to an index value of the color table; and performing coding operations corresponding to the color table and color index map. In one exemplary implementation, index values of the color table are encoded/decoded during color table and index map coding rather than the actual raw color values for each pixel. Various types of compression and coding can be implemented (e.g., lossless, lossy, intra-prediction, inter-prediction, etc.).