Transformed coefficient ordering for entropy coding
The present disclosure provides a method for encoding input data in an encoder to generate encoded output data, wherein the method includes: instructing the conversion of the input data into base-layer reconstruction data using a down-sampled version of the input data; and generating enhancement-layer data that provides instructions for enhancing the base-layer reconstruction data, wherein the enhancement-layer data comprises residual data representing a difference between a reconstruction generated from the base-layer reconstruction data and data derived from the input data, wherein the residual data are subjected to at least one transform and at least one data compression method to generate the encoded output data, characterized in that the method includes: arranging for the at least one transform to include a Hadamard transform to convert the residual data to corresponding transform coefficients, wherein different output elements of the Hadamard transform are arranged as different surfaces to be encoded, and selecting an output order for the transform coefficients in the surfaces to provide a sequence of transform coefficients for the at least one data compression method to generate the encoded output data, wherein the output order is selected as one of at least a tile raster order and a n-by-n block “Z”-order.
1 . A method for encoding input data in an encoder to generate encoded output data, the method comprising:
converting input data into base-layer reconstruction data using a down-sampled version of the input data;
generating enhancement-layer data that provides instructions for enhancing the base-layer reconstruction data, wherein the enhancement-layer data comprises residual data representing a difference between a reconstruction generated from the base-layer reconstruction data and data derived from the input data;
subjecting the residual data to a Hadamard transform to convert the residual data to corresponding transform coefficients, wherein different output elements of the Hadamard transform are arranged as different surfaces to be encoded, each surface corresponding to a respective directional component of the transform, and wherein an output order traverses transform coefficients across multiple ones of the surfaces;
selecting the output order for the transform coefficients in the surfaces to provide an ordered sequence of transform coefficients for at least one data compression method, wherein the selected output order is one of a tile raster order and an n-by-n block “Z”-order, and wherein the selected output order operates over groups of coefficients spanning multiple surfaces and multiple coding units and is chosen based on content-dependent spatial-correlation characteristics of the residual data; and
subjecting the ordered sequence of transform coefficients to the at least one data compression method to generate encoded output data.
2 . The method of claim 1 , wherein the at least one data compression method includes run-length encoding (RLE) followed by Huffman encoding.
3 . The method of claim 1 , wherein method includes arranging for the tile raster order to include encoding tiles having a size in a range of 8×8 elements to 64×64 elements, wherein transform coefficients are selected in raster order within each tile.
4 . The method of claim 3 , wherein the tile raster order includes encoding tiles having a size of 8×8 elements, 16×16 elements, or 32×32 elements.
5 . The method of claim 1 , wherein the n-by-n block “Z”-order includes one or more n-by-n “Z”-order readouts from top-left coefficient to top-right coefficient to bottom-left coefficient to bottom-right coefficient in a given group of coefficients, wherein the n-by-n “Z”-order readouts are repeated in a recursive n-by-n “Z”-order across different groups of transformed coefficients.
6 . The method of claim 1 , wherein the method is implemented to be compatible with one of the VC-6 and LCEVC standards.
7 . A computer program product comprising a non-transitory computer-readable storage medium having computer-readable instructions stored thereon, the computer-readable instructions being executable by a computerized device comprising processing hardware to execute the method of claim 1 .
8 . An encoder that, when in operation, encodes input data to generate corresponding encoded output data,
wherein the encoder converts input data into base-layer reconstruction data using a down-sampled version of the input data,
wherein the encoder generates enhancement-layer data that provides instructions for enhancing the down-sampled version of the input data,
wherein the enhancement-layer data comprises residual data that represents a difference between a reconstruction generated from the base-layer reconstruction data and data derived from the input data,
wherein the residual data are subjected in the encoder to a Hadamard transform to convert the residual data to corresponding Hadamard transform coefficients,
wherein different output elements of the Hadamard transform are arranged as different surfaces to be encoded, each surface corresponding to a respective directional component of the transform, and wherein an output order traverses transform coefficients across multiple ones of the surfaces,
wherein the encoder is configured to select an output order for the transform coefficients in the surfaces to provide an ordered sequence of transform coefficients for at least one data compression method,
wherein the selected output order is one of a tile raster order and an n-by-n block “Z”-order, and wherein the selected output order operates over groups of coefficients spanning multiple surfaces and multiple coding units and is chosen based on content-dependent spatial-correlation characteristics of the residual data, and
wherein the ordered sequence of transform coefficients are subjected to the at least one data compression method to generate the encoded output data.
9 . The encoder of claim 8 , wherein the at least one data compression transform includes run-length encoding (RLE) followed by a Huffman encoding.
10 . The encoder of claim 8 , wherein the tile raster order includes encoding tiles having a size in a range of 8×8 elements to 64×64 elements, wherein transform coefficients are selected in raster order within each tile.
11 . The encoder of claim 10 , wherein the tile manner includes encoding tiles having a size of 8×8 elements, 16×16 elements, or 32×32 elements.
12 . The encoder of claim 8 , the n-by-n block “Z”-order includes one or more n-by-n “Z”-order readouts from top-left coefficient to top-right coefficient to bottom-left coefficient to bottom-right coefficient in a given group of coefficients, wherein the n-by-n “Z order readouts are repeated in a recursive n-by-n “Z”-order across different groups of transformed coefficients.
13 . The encoder of claim 8 , wherein the encoder is implemented to be compatible with one of the VC-6 or LCEVC standards.
14 . A method for decoding encoded data in a decoder to generate decoded output data, wherein the method comprises:
(i) receiving encoded data at the decoder;
(ii) applying an inverse transform to convert the received encoded data into enhancement-layer data that provides instructions for enhancing a base-layer reconstruction derived from a down-sampled version of the input data, wherein the enhancement-layer data comprises residual data to provide its enhancement, wherein the residual data are subjected to at least one transform and at least one data compression method to generate the received encoded data;
(iii) decompressing the received encoded data according to the at least one data compression method to generate intermediate decoded data; and
(iv) arranging for the inverse transform to include an inverse Hadamard transform to convert transform coefficients derived from the intermediate decoded data into the residual data, wherein different output elements of the Hadamard transform represent different encoded surfaces, each surface corresponding to a respective directional component of the transform, and wherein an output order traverses transform coefficients across multiple ones of the surfaces,
wherein a content-dependent readout order has been communicated to the decoder to allow a corresponding readout order by the decoder, and
wherein the transform coefficients are decoded by being read according to the corresponding readout order, the corresponding readout order comprising a tile raster manner or an n-by-n block “Z”-order, the readout output order operating over groups of coefficients spanning multiple surfaces and multiple coding units and is based on content-dependent spatial-correlation characteristics of the residual data.
15 . A computer program product comprising a non-transitory computer-readable storage medium having computer-readable instructions stored thereon, the computer-readable instructions being executable by a computerized device comprising processing hardware to execute the method of claim 14 .
16 . A decoder for decoding encoded data to generate decoded output data, wherein the decoder includes:
(i) an input for receiving encoded data;
(ii) a data processing arrangement for applying an inverse transform to convert the received encoded data into enhancement-layer data that provides instructions for enhancing a base-layer reconstruction derived from a down-sampled version of the input data, wherein the enhancement-layer data comprises residual data to provide its enhancement, wherein the residual data are subjected to at least one transform and at least one data compression method to generate the encoded data;
(iii) a decompression arrangement for decompressing the received encoded data using according to the at least one data compression method to generate intermediate decoded data; and
(iv) an inverse transformation arrangement to apply the inverse transform as an inverse Hadamard transform to convert transform coefficients derived from the intermediate decoded data into the residual data, wherein different output elements of the Hadamard transform represent different encoded surfaces, each surface corresponding to a respective directional component of the transform, and wherein an output order traverses transform coefficients across multiple ones of the surfaces
wherein the decoder is configured to receive a content-dependent readout order to allow a corresponding readout order by the decoder, and
wherein the transform coefficients are decoded by being read according to the corresponding readout order, the corresponding readout order comprising a tile raster manner or a n-by-n block “Z”-order, the readout output order operating over groups of coefficients spanning multiple surfaces and multiple coding units and is based on content-dependent spatial-correlation characteristics of the residual data.