Multimedia signal processing using fixed-point approximations of linear transforms
First Claim
1. A method of multi-media signal processing using a processor, the method comprising using the processor to perform actions of:
- separating an input multi-media signal into possibly overlapping data blocks; and
applying a fixed-point approximation of an ideal linear transformation to at least some of the blocks, where the fixed-point approximation of the ideal linear transformation is structured as a decomposition of the ideal linear transformation formed by factoring one or more parts of the ideal linear transformation into a cascade of simpler transformations, the simpler transformations comprising one or more primitive operations that can be performed by a multiplication of the input data by a constant fixed-point number, where the value of one or more of the constant fixed-point numbers differs from the closest fixed-point approximation of an ideal constant multiplier value in the simpler transformation in a manner having the effect of increasing the precision of the approximation relative to the ideal linear transformation.
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Abstract
Close approximations of ideal linear transforms, such as the forward and inverse discrete cosine transformation (DCT), are formed with minimum complexity using fixed-point arithmetic. The transformation is decomposed into a smaller set of transformations (e.g., the LLM decomposition of the DCT). The multiplication factors of the decomposition are then approximated by a fixed-point representation. However, instead of simply applying scaling and rounding operations to produce fixed-point approximations closest to the multiplication factors themselves, fixed-point multiplication factors are chosen that have the effect (after the cascaded operations of the various stages of decomposition) of being the closest feasible approximations of the entries in the resulting complete ideal transformation matrix.
76 Citations
21 Claims
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1. A method of multi-media signal processing using a processor, the method comprising using the processor to perform actions of:
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separating an input multi-media signal into possibly overlapping data blocks; and applying a fixed-point approximation of an ideal linear transformation to at least some of the blocks, where the fixed-point approximation of the ideal linear transformation is structured as a decomposition of the ideal linear transformation formed by factoring one or more parts of the ideal linear transformation into a cascade of simpler transformations, the simpler transformations comprising one or more primitive operations that can be performed by a multiplication of the input data by a constant fixed-point number, where the value of one or more of the constant fixed-point numbers differs from the closest fixed-point approximation of an ideal constant multiplier value in the simpler transformation in a manner having the effect of increasing the precision of the approximation relative to the ideal linear transformation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A multi-media signal processing system comprising:
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means for separating a multi-media signal into block data; means for applying a fixed-point approximation of an ideal linear transformation to the block data, the fixed-point approximation structured as a decomposition of the linear transformation into a cascade of simpler transformations comprising one or more primitive operations that can be performed by a multiplication of the input data by a constant fixed-point number, where the value of one or more of the constant fixed-point numbers differs from the closest fixed-point approximation of an ideal constant multiplier value in the simpler transformation in a manner having the effect of increasing the precision of the approximation relative to the ideal linear transformation; means for coding the transformed block data into a processed bitstream. - View Dependent Claims (13, 14, 15, 16)
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17. A computer readable storage medium having programming instructions of a multi-media signal processing program stored thereon that is executable on a processor of a signal processing system to process a digital multimedia signal according to a method comprising:
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separating an input multi-media signal into possibly overlapping data blocks; and applying a fixed-point approximation of an ideal linear transformation to at least some of the blocks, where the fixed-point approximation of the ideal linear transformation is structured as a decomposition of the ideal linear transformation formed by factoring one or more parts of the ideal linear transformation into a cascade of simpler transformations, the simpler transformations comprising one or more primitive operations that can be performed by a multiplication of the input data by a constant fixed-point number, where the value of one or more of the constant fixed-point numbers differs from the closest fixed-point approximation of an ideal constant multiplier value in the simpler transformation in a manner having the effect of increasing the precision of the approximation relative to the ideal linear transformation. - View Dependent Claims (18, 19, 20, 21)
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Specification