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US 6,687,304 B1Granted
Efficient video data data access using fixed ratio compression
AssigneeKoninklijke Philips Electronics N.V.
InventorShaomin Peng
Life of this patent
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Abstract
A data organization and access scheme for permitting easier location of a reference macroblock during motion compensation and for providing a video output system with output data. The frames are segmented into coding blocks comprising a small number of horizontally adjunct blocks compressed to a fixed length. Within each coding block, only two quantization strategies are employed so that the start and end position of any coding block is easily ascertained as well as the location of any individual block within the coding block.
Claims15
A method of coding digital video data comprised of one or more frames, the method comprising:
- dividing each frame into adjunct coding blocks compressed to a fixed length, each coding block being coded independently and including a fixed number of miniblocks having a respective value of bits that is variable, with a sum of a total number of bits of all the miniblocks being equal to the fixed length of the coding block;
- identifying a maximum and a minimum value for each of the miniblocks in each coding block;
- calculating a dynamic range for each miniblock within each coding block by subtracting the minimum value from the maximum value for each miniblock within each coding block;
- quantizing each miniblock in accordance with a selected quantization strategy such that each coding block is encoded with a fixed compression ratio, the number of bits in each coding block is less than the original number, and the start and end of each coding block can be readily ascertained;
- and
- outputting the compressed coding blocks comprising the minimum value data, the dynamic range data, and the encoded compressed video data.
3 more elements
An apparatus for coding video data input comprised of one or more frames, the apparatus comprising:
- a block dividing portion for dividing the input video signal into adjunct coding blocks compressed to a fixed length, each coding block being coded independently and including a fixed number of miniblocks having a respective value of bits that is variable, with a sum of a total number of bits of all the miniblocks being equal to the fixed length of the coding block;
- a maximum/minimum identifying portion for identifying a maximum and a minimum value for each of the miniblocks in each coding block;
- a dynamic range calculating portion for calculating a dynamic range for each miniblock based upon the maximum and minimum values;
- a quantizing portion for quantizing each miniblock with a selected quantization strategy such that each coding block is encoded with a fixed compression ratio, the number of bits in each coding block is less than the original number, and the start and end of each coding block can be readily ascertained;
- and
- an outputting means for outputting the compressed coding blocks comprising minimum value data, dynamic range data, and the compressed video data.
3 more elements
Computer-executable process steps to code digital video data comprised of one or more frames, the computer-executable process steps being stored on a computer-readable medium and comprising:
- dividing each frame into miniblocks of adjacent vertical and horizontal bits;
- grouping a fixed number of the miniblocks into coding blocks of fixed length, wherein each miniblock having a respective value of bits that is variable, with a sum of a total number of bits of all the miniblocks being equal to the fixed length each of the respective coding blocks;
- identifying a fixed compression ratio for each coding block, such that the number of bits in each coding block is less than the original number, and the start and end of each coding block can be readily ascertained;
- identifying a maximum and a minimum value for each of the miniblocks in each coding block;
- calculating a dynamic range for each miniblock by subtracting the minimum value from the maximum value for each miniblock within each coding block;
- dividing the dynamic range into a plurality of sub-ranges, each sub-range corresponding to a unique quantization strategy;
- associating each sub-range with an identifier;
- selecting the sub-range and a first quantization strategy which corresponds to the dynamic range of the miniblock;
- identifying a second quantization strategy which will provide the compression ratio and a picture which, when decoded, will be of a predetermined picture quality;
- selecting the second quantization strategy when the first quantization strategy, associated with the selected sub-range, will not provide the required compression ratio;
- quantizing each miniblock in accordance with the selected quantization strategy;
- and
- outputting the compressed video data.
10 more elements
A signal, embodied in a carrier wave, representing digital video data comprising frames of units of adjacent vertical and horizontal bytes, grouped into a fixed number of coding blocks of fixed length, each of the coding block comprised of a plurality of miniblocks having a respective value of bits that is variable, with a sum of a total number of bits of all the miniblocks being equal to the fixed length of the coding block;
- each coding block encoded with a fixed compression ratio such that the number of bits in each coding block is less than the original uncompressed number, and the start and end of each coding block can be readily ascertained, each unit having an identified maximum and minimum value, each coding block having a dynamic range calculated by subtracting the minimum value from the maximum value for each unit within the coding block, each dynamic range being divided into a plurality of sub-ranges, each sub-range corresponding to an unique quantization strategy and associated with an identifier, a first sub-range being selected in accordance with the dynamic range of the unit and being replaced by a second sub-range which will provide the required compression ratio when the first sub-range cannot do so, and the selected quantization strategy being applied to quantize the data.
An apparatus for coding video data input comprised of one or more frames, the apparatus comprising:
- means for dividing the input video signal into coding blocks of fixed length, each coding block being further comprised of a fixed number of miniblocks having a respective value of bits that is variable, with a sum of a total number of bits of all the miniblocks being equal to the fixed length of the coding block;
- means for identifying a maximum and a minimum value for each of the miniblocks in each coding block;
- means for calculating a dynamic range for each miniblock based upon the maximum and minimum values;
- means for quantizing each miniblock with a selected quantization strategy such that each coding block is encoded with a fixed compression ratio, the number of bits in each coding block is less than the original number, and the start and end of each coding block can be readily ascertained;
- and
- means for outputting the compressed coding blocks comprising minimum value data, dynamic range data, and the compressed video data.
3 more elements
A method of coding digital video data comprised of one or more frames, the method comprising;
- dividing each frame into coding units, each of the coding units further comprising a plurality of miniblocks having a respective value of bits that is variable, with a sum of a total number of bits of all the miniblocks being equal to the fixed length of each respective coding unit;
- identifying a maximum and a minimum value for each of the coding units;
- calculating a dynamic range for each coding unit by subtracting the minimum value from the maximum value for each coding unit;
- dividing each dynamic range into a plurality of sub-ranges, each sub-range corresponding to a unique quantization step;
- associating each sub-range with an identifier;
- selecting the sub-range and a first corresponding quantization strategy which corresponds to the dynamic range of each coding unit;
- identifying a second, coarser quantization strategy for each coding unit, which will provide a required compression ratio and a picture which, when decoded, will exhibit a predetermined picture quality;
- quantizing each coding unit in accordance with a selected quantization strategy such that each coding unit is encoded with a fixed compression ratio, the number of bits in each coding unit is less than the original number, and the start and end of each coding unit can be readily ascertained;
- and
- outputting the compressed coding units comprising the minimum value data, the dynamic range data, and the encoded compressed video data.
7 more elements
Dependencies are inferred from the claim text.