Decoding apparatus and control method thereof
AssigneeCanon Kabushiki Kaisha
InventorsYuji Hara, Hisashi Ishikawa
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Abstract
The invention provides a decoding apparatus which guarantees a decoding speed of a predetermined unit. To this end, the decoding apparatus includes a shifter which detects a start bit of a codeword from coded data, a table which stores decode values of a plurality of symbol data at one address, a table which is used to store a shift amount of the shifter, a table which generates a data length of the decode values of the plurality of symbol data, a decoder which is used to generate an address of the first table from the coded data, a decoder which is used to generate an address of the second and third tables from the coded data, and a packer which couples or separates the decoded values of the plurality of symbol data to data for the predetermined fixed number of bits.
Claims15
A decoding apparatus, comprising:
- a shifter which detects a start bit of a codeword from coded data;
- a memory which stores a first table, a second table and a third table, wherein the first table stores decode values of a plurality of symbol data at one address, the second table stores a shift amount of the shifter, and the third table is used to generate a data length of the decode values of the plurality of symbol data;
- a first decoder which is used to generate an address of the first table from the coded data;
- a second decoder which is used to generate an address of the second and third tables from the coded data;
- and
- an output unit which is used to couple or separate the decode values of the plurality of symbol data to data for a predetermined fixed number of bits;
- wherein the decoding apparatus decodes coded data generated by executing variable length coding to have a pixel block including a plurality of pixels (the number of pixels N) as a unit, and
- wherein letting P (bits) be a code size of the pixel block, T (pixels/clock cycle) be a target throughput, x (bits/clock cycle) be a code size to be processed per clock cycle, and y (pixels/clock cycle) be the number of pixels to be processed per clock cycle, at least either of:
- x≧(P/N)×T
- and
- y≧T
- is satisfied.
A method of controlling a decoding apparatus, comprising:
- a shift step of detecting a start bit of a codeword from coded data;
- a first decode step of generating an address of a first table from the coded data;
- a second decode step of generating an address of second and third tables from the coded data;
- and
- an output step of coupling or separating decode values of a plurality of symbol data to data for a predetermined fixed number of bits;
- wherein the first table stores the decode values of the plurality of symbol data at one address, the second table stores a shift amount of a shifter, and the third table is used to generate a data length of the decode values of the plurality of symbol data;
- wherein the method decodes coded data generated by executing variable length coding to have a pixel block including a plurality of pixels (the number of pixels N) as a unit, and
- wherein letting P (bits) be a code size of the pixel block, T (pixels/clock cycle) be a target throughput, x (bits/clock cycle) be a code size to be processed per clock cycle, and y (pixels/clock cycle) be the number of pixels to be processed per clock cycle, at least either of:
- x≧(P/N)×T
- and
- y≧T
- is satisfied.
A decoding apparatus for decoding coded data, which is generated by variable length coding, and outputting a plurality of pixel data, the decoding apparatus comprising:
- a shifter which detects a start bit of a codeword from coded data;
- a memory storing a first table which stores decode values of a plurality of symbol data at one address, a second table which stores a shift amount of the shifter, and a third table which is used to generate a data length of the plurality of symbol data;
- a first decoder which is used to generate an address of the first table from the coded data;
- a second decoder which is used to generate an address of the second and third tables from the coded data;
- and
- an output unit which is used to couple or separate the decode values of the plurality of symbol data to data for a predetermined fixed number of bits.
A method of controlling a decoding apparatus for decoding coded data, which is generated by variable length coding, and outputting a plurality of pixel data, wherein the decoding apparatus includes:
- a first table which stores decode values of a plurality of symbol data at one address;
- a second table which stores a shift amount of a shifter;
- and
- a third table which is used to generate a data length of the plurality of symbol data;
- the method comprising:
- a shift step of detecting a start bit of a codeword from coded data;
- a first decode step of generating an address of the first table from the coded data;
- a second decode step of generating an address of the second and third tables from the coded data;
- and
- an output step of coupling or separating the decode values of the plurality of symbol data to data for a predetermined fixed number of bits.
Dependencies are inferred from the claim text.