Methods and devices for coding and decoding the position of the last significant coefficient
AssigneeResearch In Motion Limited
InventorsDake He, Jing Wang
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Abstract
Methods and devices are described for entropy coding data using an entropy coder to encode quantized transform domain coefficient data. Last significant coefficient information is signaled in the bitstream using two-dimensional coordinates for the last significant coefficient. The context for bins of one of the coordinates is based, in part, upon the value of the other of the coordinates. In one case, instead of signaling last significant coefficient information, the number of non-zero coefficients is binarized and entropy encoded.
Claims31
A method for encoding quantized transform domain coefficient data including last significant coefficient information, the method comprising:
- binarizing, with a processor, each of two positions of two-dimensional coordinates of the last significant coefficient;
- determining, with the processor, a context for each bin of one of the positions;
- determining, with the processor, a context for each bin of the other of the positions, wherein the context of each bin of the other of the positions is based, in part, upon said one of the positions;
- and
- entropy encoding the binarized positions based upon the context determined for each of the bins of the binarized positions to produce encoded data.
An encoder for encoding quantized transform domain coefficient data, the encoder comprising:
- a processor;
- a memory;
- and
- an encoding application stored in memory and containing instructions for configuring the processor to
- binarize each of two positions of two-dimensional coordinates of the last significant coefficient;
- determine a context for each bin of one of the positions;
- determine a context for each bin of the other of the positions, wherein the context of each bin of the other of the positions is based, in part, upon said one of the positions;
- and
- entropy encode the binarized positions based upon the context determined for each of the bins of the binarized positions to produce encoded data.
A method for decoding a bitstream of encoded data to reconstruct quantized transform domain coefficient data, the method comprising:
- entropy decoding, with a processor, a portion of the encoded data to produce two binarized positions defining two-dimensional coordinates of a last significant coefficient, wherein entropy decoding the portion of the data includes
- determining a context for each bin of one of the positions, and
- determining a context for each bin of the other of the positions, wherein the context of each bin of the other of the positions is based, in part, upon said one of the positions;
- entropy decoding, with the processor, a significant coefficient sequence based upon the two-dimensional coordinates of the last significant coefficient;
- entropy decoding, with the processor, level information based upon the significant coefficient sequence;
- and
- reconstructing, with the processor, the quantized transform domain coefficient data using the level information and the significant coefficient sequence.
A decoder for decoding a bitstream of encoded data to reconstruct a sequence of symbols, the symbols belonging to a finite alphabet, the decoder comprising:
- a processor;
- a memory;
- and
- a decoding application stored in memory and containing instructions for configuring the processor to
- entropy decode a portion of the encoded data to produce two binarized positions defining two-dimensional coordinates of a last significant coefficient, wherein entropy decoding the portion of the data includes
- determining a context for each bin of one of the positions, and
- determining a context for each bin of the other of the positions, wherein the context of each bin of the other of the positions is based, in part, upon said one of the positions;
- entropy decode a significant coefficient sequence based upon the two-dimensional coordinates of the last significant coefficient;
- entropy decode level information based upon the significant coefficient sequence;
- and
- reconstruct the quantized transform domain coefficient data using the level information and the significant coefficient sequence.
Dependencies are inferred from the claim text.