Method to control the generated bit rate in MPEG-4 shape coding
First Claim
1. In a digital video compression system comprising a real buffer having a maximum buffer capacity and virtual buffer having a virtual buffer capacity, said virtual buffer capacity being less than said maximum buffer capacity, a method for controlling the generated bit rate of compressed video information to keep within said maximum buffer capacity comprising the steps of:
- (a) receiving one or more blocks of digital information, each block representing at least one identifiable characteristicfor a portion of a frame of video;
(b) determining whether a current received block can be compressed by one of one or more shortcuts, and if so, compressing said current received block with one of said shortcuts;
(c) if said current received block cannot be compressed with said shortcuts, determining whether said virtual buffer capacity will be exceeded if said current received block is compressed only by arithmetic coding, and if not, compressing said current received block with only arithmetic coding;
(d) if said current received block cannot be compressed with said shortcuts and if said virtual buffer capacity would be exceeded with only arithmetic coding, determining whether said virtual buffer capacity will be exceeded if said current received block is compressed with both downsampling and arithmetic coding, and if not, compressing said current received block with both said downsampling and said arithmetic coding; and
(e) if said current received block cannot be compressed with said shortcuts and if said virtual buffer capacity would be exceeded with only arithmetic coding or with both downsampling and arithmetic coding, compressing said current received block with a default mode of compression even if said virtual buffer capacity is exceeded with such compression.
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Accused Products
Abstract
In a digital video compression system that includes both a real buffer of size Bmax, and a smaller virtual buffer of size Bvirtual, a method for controlling the generated bit rate of compressed video information to keep within the maximum buffer capacity is disclosed. The method includes the steps of (a) receiving blocks of digital information, (b) determining whether a current block can be compressed by one of one or more shortcuts and using the shortcut if possible; (c) if the current block cannot be compressed with any shortcut, determining whether the virtual buffer capacity will be exceeded if the current received block is compressed only by arithmetic coding and using only arithmetic coding if possible; (d) if the current block cannot be compressed with any shortcut and the virtual buffer capacity would be exceeded with only arithmetic coding, determining whether the virtual buffer capacity will be exceeded if the current block is compressed with both downsampling and arithmetic coding and using both downsampling and arithmetic coding if possible; and (e) if all else fails, compressing the current block with a default mode of compression even if the virtual buffer capacity is exceeded with such compression.
49 Citations
20 Claims
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1. In a digital video compression system comprising a real buffer having a maximum buffer capacity and virtual buffer having a virtual buffer capacity, said virtual buffer capacity being less than said maximum buffer capacity, a method for controlling the generated bit rate of compressed video information to keep within said maximum buffer capacity comprising the steps of:
- (a) receiving one or more blocks of digital information, each block representing at least one identifiable characteristicfor a portion of a frame of video;
(b) determining whether a current received block can be compressed by one of one or more shortcuts, and if so, compressing said current received block with one of said shortcuts; (c) if said current received block cannot be compressed with said shortcuts, determining whether said virtual buffer capacity will be exceeded if said current received block is compressed only by arithmetic coding, and if not, compressing said current received block with only arithmetic coding; (d) if said current received block cannot be compressed with said shortcuts and if said virtual buffer capacity would be exceeded with only arithmetic coding, determining whether said virtual buffer capacity will be exceeded if said current received block is compressed with both downsampling and arithmetic coding, and if not, compressing said current received block with both said downsampling and said arithmetic coding; and (e) if said current received block cannot be compressed with said shortcuts and if said virtual buffer capacity would be exceeded with only arithmetic coding or with both downsampling and arithmetic coding, compressing said current received block with a default mode of compression even if said virtual buffer capacity is exceeded with such compression. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- (a) receiving one or more blocks of digital information, each block representing at least one identifiable characteristicfor a portion of a frame of video;
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11. A method for compressing digital video information by downsampling and arithmetic encoding while controlling the generated bit rate of compressed video information to keep within a maximum buffer capacity by employing a virtual buffer having a capacity being less than said maximum buffer capacity, comprising the steps of:
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(a) receiving one or more blocks of digital information, each block representing at least one identifiable characteristic for a portion of a frame of video; (b) determining whether a current received block can be compressed by one of one or more shortcuts, and if so, compressing said current received block with one of said shortcuts; (c) if said current received block cannot be compressed with said shortcuts;
determining whether said virtual buffer capacity will be exceeded if said current received block is compressed only by arithmetic coding, and if not, compressing said current received block with only arithmetic coding;(d) if said current received block cannot be compressed with said shortcuts and if said virtual buffer capacity would be exceeded with only arithmetic coding, determining whether said virtual buffer capacity will be exceeded if said current received block is compressed with both downsampling and arithmetic coding, and if not, compressing said current received block with both said downsampling and said arithmetic coding; and (e) if said current received block cannot be compressed with said shortcuts and if said virtual buffer capacity would be exceeded with only arithmetic coding or with both downsampling and arithmetic coding, compressing said current received block with a default mode of compression even if said virtual buffer capacity is exceeded with such compression. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for compressing digital video information by downsampling and arithmetic encoding while controlling the generated bit rate of compressed video information to keep within a maximum buffer capacity, comprising the steps of:
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(a) receiving one or more blocks of digital information, each block representing at least one identifiable characteristic for a portion of a frame of video; (b) determining whether a current received block can be compressed by one of one or more shortcuts, and if so, compressing said current received block with one of said shortcuts; (c) if said current received block cannot be compressed with said shortcuts, determining a measure of distortion if said current received block is only arithmetic encoded or first downsampled and then arithmetic encoded and (1) compressing said current received block by first downsampling and then arithmetic encoding if such encoding yields acceptable distortion and if said maximum buffer capacity is not exceeded; (2) if downsampling and then arithmetic encoding does not yield acceptable distortion, compressing said current received block with only arithmetic encoding if said maximum buffer capacity is not exceeded; and (3) if said maximum buffer capacity is exceeded, recompressing a previous block in order to reduce buffer occupancy.
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Specification