Digital audio compression system

Claim 1

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks each block having a maximum signal value; scaling each signal block by a constant value selected such that the maximum absolute signal value in each block equals a predetermined value within a preset range and setting a scale factor equal to said constant value for each signal block; transforming each said signal block into transform blocks comprising a plurality of transform values representative of the audio signal in its associated signal block; quantizing said transform blocks; and recording said quantized transform blocks and said scale factors as digital data on the data storage medium.

Claim 2

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks each block having a maximum signal value; scaling each signal block by a constant value selected such that the maximum absolute signal value in each block equals a predetermined value within a preset range and setting a scale factor equal to said constant value for each signal block; transforming each said signal block into transform blocks comprising a plurality of transform values representative of the audio signal in its associated signal block; quantizing said transform blocks; and recording said quantized transform blocks and said scale factors as digital data on the data storage medium.

Claim 7

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks; dividing said signal blocks into a plurality of subblocks; detecting transients in said subblocks and setting a transient flag associated with said signal block to a predetermined value if a transient greater than a predetermined threshold is detected; if the transient flag is set to said predetermined value, scaling each subblock in accordance with transients detected to produce processed signal blocks and generating a scale factor for each subblock; said scaling step further comprising the step of scaling at least one subblock occurring a predetermined time before a detected transient differently than scaling the subblock containing the transient; transforming said processed signal blocks into transform blocks each comprising a plurality of transform values representative of the audio signal in its associated block; quantizing said transform blocks; and recording said quantized transform blocks, transient flags and scale factors as digital data on the data storage medium.

Claim 8

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks; dividing said signal blocks into a plurality of subblocks; detecting transients in said subblocks and setting a transient flag associated with said signal block to a predetermined value if a transient greater than a predetermined threshold is detected; if the transient flag is set to said predetermined value, scaling each subblock in accordance with transients detected to produce processed signal blocks and generating a scale factor for each subblock; said scaling step further comprising the step of scaling at least one subblock occurring a predetermined time before a detected transient differently than scaling the subblock containing the transient; transforming said processed signal blocks into transform blocks each comprising a plurality of transform values representative of the audio signal in its associated block; quantizing said transform blocks; and recording said quantized transform blocks, transient flags and scale factors as digital data on the data storage medium.

Claim 13

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising; dividing said wideband digital audio signal into signal blocks; detecting if a transient occurs in each signal block and setting a transient flag to a predetermined value when a transient is detected; when said transient flag equals said predetermined value, dividing said signal blocks into a plurality of subblocks; scaling each subblock in accordance with transients detected to produce processed signal blocks and generating a scale factor for each subblock; said scaling step further comprising the step of scaling at least one subblock occurring a predetermined time before a detected transient differently than scaling the subblock containing the transient; transforming said processed signal blocks into transform blocks each comprising a plurality of transform values representative of the magnitude and phase of the audio signal as a function of frequency in its associated block; quantizing said transform blocks; and recording said quantized transform blocks, transient flags and scale factors as digital data on a data storage medium.

Claim 14

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising; dividing said wideband digital audio signal into signal blocks; detecting if a transient occurs in each signal block and setting a transient flag to a predetermined value when a transient is detected; when said transient flag equals said predetermined value, dividing said signal blocks into a plurality of subblocks; scaling each subblock in accordance with transients detected to produce processed signal blocks and generating a scale factor for each subblock; said scaling step further comprising the step of scaling at least one subblock occurring a predetermined time before a detected transient differently than scaling the subblock containing the transient; transforming said processed signal blocks into transform blocks each comprising a plurality of transform values representative of the magnitude and phase of the audio signal as a function of frequency in its associated block; quantizing said transform blocks; and recording said quantized transform blocks, transient flags and scale factors as digital data on a data storage medium.

Claim 15

A method of processing a wideband digital audio signal and for storing the processed signal on a dam storage medium comprising; dividing said wideband digital audio signal into signal blocks; Fourier transforming said signal blocks into transformed blocks representative of the magnitude and phase of the audio signal in its associated block as a function of frequency; extracting from said transformed blocks magnitude data blocks and phase data blocks as a function of frequency; grouping said magnitude data blocks and phase data blocks into a plurality of adjacent frequency bands, said frequency bands extending from low frequency bands to high frequency bands; applying a first quantization process upon said magnitude data blocks in each frequency band to develop quantized magnitude blocks; applying a second quantization process upon said phase dam blocks in each frequency band to develop quantized phase blocks, said second quantization process developing higher precision quantization in said low frequency bands than in said high frequency bands; recording said quantized magnitude blocks and said quantized phase blocks as digital data on the data storage medium wherein said first quantization process includes two-stage vector quantization of said magnitude data blocks.

Claim 16

A method of processing a wideband digital audio signal and for storing the processed signal on a dam storage medium comprising; dividing said wideband digital audio signal into signal blocks; Fourier transforming said signal blocks into transformed blocks representative of the magnitude and phase of the audio signal in its associated block as a function of frequency; extracting from said transformed blocks magnitude data blocks and phase data blocks as a function of frequency; grouping said magnitude data blocks and phase data blocks into a plurality of adjacent frequency bands, said frequency bands extending from low frequency bands to high frequency bands; applying a first quantization process upon said magnitude data blocks in each frequency band to develop quantized magnitude blocks; applying a second quantization process upon said phase dam blocks in each frequency band to develop quantized phase blocks, said second quantization process developing higher precision quantization in said low frequency bands than in said high frequency bands; recording said quantized magnitude blocks and said quantized phase blocks as digital data on the data storage medium wherein said first quantization process includes two-stage vector quantization of said magnitude data blocks.

Claim 26

A method of processing a wideband digital audio signal and for storing the processed signal in a data storage medium comprising the steps of: dividing said wideband audio signal into signal blocks, Fourier transforming each said block into transform blocks representative of the magnitude and phase of the audio signal as a function of frequency in its associated block, grouping said transform blocks into a plurality of adjacent frequency bands, each frequency band having a predetermined magnitude quantizer factor and predetermined phase quantizer factors, said quantizer factors determining the degree of precision of a subsequent quantization, quantizing the magnitudes and phases of each transform block in each frequency band in accordance with its respective quantizer factor to develop quantized magnitude blocks and quantized phase blocks, and recording said quantized magnitude blocks and quantized phase blocks as digital data on the data storage medium.

Claim 27

A method of processing a wideband digital audio signal and for storing the processed signal in a data storage medium comprising the steps of: dividing said wideband audio signal into signal blocks, Fourier transforming each said block into transform blocks representative of the magnitude and phase of the audio signal as a function of frequency in its associated block, grouping said transform blocks into a plurality of adjacent frequency bands, each frequency band having a predetermined magnitude quantizer factor and predetermined phase quantizer factors, said quantizer factors determining the degree of precision of a subsequent quantization, quantizing the magnitudes and phases of each transform block in each frequency band in accordance with its respective quantizer factor to develop quantized magnitude blocks and quantized phase blocks, and recording said quantized magnitude blocks and quantized phase blocks as digital data on the data storage medium.

Claim 30

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks; dividing said signal blocks into a plurality of subblocks; detecting transients in said subblocks and setting a transient flag associated with said signal block to a predetermined value if a transient greater than a predetermined threshold is detected; if the transient flag is set to said predetermined value, scaling each subblock in accordance with transients detected to produce processed signal blocks and generating a scale factor for each subblock; said scaling step further comprising the step of scaling at least one subblock occurring a predetermined time after a detected transient differently than scaling the subblock containing the transient; transforming said processed signal blocks into transform blocks each comprising a plurality of transform values representative of the audio signal in its associated block; quantizing said transform blocks; and recording said quantized transform blocks, transient flags and scale factors as digital data on the data storage medium.

Claim 31

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks; dividing said signal blocks into a plurality of subblocks; detecting transients in said subblocks and setting a transient flag associated with said signal block to a predetermined value if a transient greater than a predetermined threshold is detected; if the transient flag is set to said predetermined value, scaling each subblock in accordance with transients detected to produce processed signal blocks and generating a scale factor for each subblock; said scaling step further comprising the step of scaling at least one subblock occurring a predetermined time after a detected transient differently than scaling the subblock containing the transient; transforming said processed signal blocks into transform blocks each comprising a plurality of transform values representative of the audio signal in its associated block; quantizing said transform blocks; and recording said quantized transform blocks, transient flags and scale factors as digital data on the data storage medium.

Claim 32

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising; dividing said wideband digital audio signal into signal blocks; detecting if a transient occurs in each signal block and setting a transient flag to a predetermined value when a transient is detected; when said transient flag equals said predetermined value, dividing said signal blocks into a plurality of subblocks; scaling each subblock in accordance with transients detected to produce processed signal blocks and generating a scale factor for each subblock; said scaling step further comprising the step of scaling at least one subblock occurring a predetermined time after a detected transient differently than scaling the subblock containing the transient; transforming said processed signal blocks into transform blocks each comprising a plurality of transform values representative of the magnitude and phase of the audio signal as a function of frequency in its associated block; quantizing said transform blocks; and recording said quantized transform blocks, transient flags and scale factors as digital data on a data storage medium.

Claim 33

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising; dividing said wideband digital audio signal into signal blocks; detecting if a transient occurs in each signal block and setting a transient flag to a predetermined value when a transient is detected; when said transient flag equals said predetermined value, dividing said signal blocks into a plurality of subblocks; scaling each subblock in accordance with transients detected to produce processed signal blocks and generating a scale factor for each subblock; said scaling step further comprising the step of scaling at least one subblock occurring a predetermined time after a detected transient differently than scaling the subblock containing the transient; transforming said processed signal blocks into transform blocks each comprising a plurality of transform values representative of the magnitude and phase of the audio signal as a function of frequency in its associated block; quantizing said transform blocks; and recording said quantized transform blocks, transient flags and scale factors as digital data on a data storage medium.

Claim 34

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks; Fourier transforming said signal blocks into transformed blocks representative of the magnitude and phase of the audio signal in its associated block as a function of frequency; extracting from said transformed blocks magnitude data blocks and phase data blocks as a function of frequency; grouping said magnitude data blocks and phase data blocks into a plurality of adjacent frequency bands, said frequency bands extending from low frequency bands to high frequency bands; applying a first quantization process upon said magnitude data blocks in each frequency band to develop quantized magnitude blocks; applying a second quantization process upon said phase data blocks in each frequency band to develop quantized phase blocks, said second quantization process developing higher precision quantization in said low frequency bands than in said high frequency bands; recording said quantized magnitude blocks and said quantized phase blocks as digital data on the data storage medium wherein said first quantization process includes tree-structured vector quantization of said magnitude data blocks.

Claim 35

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks; Fourier transforming said signal blocks into transformed blocks representative of the magnitude and phase of the audio signal in its associated block as a function of frequency; extracting from said transformed blocks magnitude data blocks and phase data blocks as a function of frequency; grouping said magnitude data blocks and phase data blocks into a plurality of adjacent frequency bands, said frequency bands extending from low frequency bands to high frequency bands; applying a first quantization process upon said magnitude data blocks in each frequency band to develop quantized magnitude blocks; applying a second quantization process upon said phase data blocks in each frequency band to develop quantized phase blocks, said second quantization process developing higher precision quantization in said low frequency bands than in said high frequency bands; recording said quantized magnitude blocks and said quantized phase blocks as digital data on the data storage medium wherein said first quantization process includes tree-structured vector quantization of said magnitude data blocks.

Claim 37

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks; Fourier transforming said signal blocks representative of the magnitude and phase of the audio signal in its associated block as a function of frequency; extracting from said transformed blocks magnitude data blocks and phase data blocks as a function of frequency; grouping said magnitude data blocks and phase data blocks into a plurality of adjacent frequency bands, said frequency bands extending from low frequency bands to high frequency bands; applying a first quantization process upon said magnitude data blocks in each frequency band to develop quantized magnitude blocks; applying a second quantization process upon said phase data blocks in each frequency band to develop quantized phase blocks, said second quantization process developing higher precision quantization in said low frequency bands than in said high frequency bands; recording said quantized magnitude blocks and said quantized phase blocks as digital data on the data storage medium wherein each phase data block comprises a plurality of phase coefficients and wherein said second quantization process comprises the step of applying a scalar quantizer to each phase coefficient with a level spacing inversely proportional to the frequency of each coefficient.

Claim 38

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks; Fourier transforming said signal blocks representative of the magnitude and phase of the audio signal in its associated block as a function of frequency; extracting from said transformed blocks magnitude data blocks and phase data blocks as a function of frequency; grouping said magnitude data blocks and phase data blocks into a plurality of adjacent frequency bands, said frequency bands extending from low frequency bands to high frequency bands; applying a first quantization process upon said magnitude data blocks in each frequency band to develop quantized magnitude blocks; applying a second quantization process upon said phase data blocks in each frequency band to develop quantized phase blocks, said second quantization process developing higher precision quantization in said low frequency bands than in said high frequency bands; recording said quantized magnitude blocks and said quantized phase blocks as digital data on the data storage medium wherein each phase data block comprises a plurality of phase coefficients and wherein said second quantization process comprises the step of applying a scalar quantizer to each phase coefficient with a level spacing inversely proportional to the frequency of each coefficient.

Claim 39

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks; Fourier transforming said signal blocks into transformed block representative of the magnitude and phase of the audio signal in its associated block as a function of frequency; extracting from said transformed blocks magnitude data blocks and phase data blocks as a function of frequency; grouping said magnitude data blocks and phase data blocks into a plurality of adjacent frequency bands, said frequency banks extending from low frequency bands to high frequency bands; applying a first quantization process upon said magnitude data blocks in each frequency band to develop quantized magnitude blocks; applying a second quantization process upon said phase data blocks in each frequency band to develop quantized phase blocks, said second quantization process developing higher precision quantization in said low frequency bands than in said high frequency bands; recording said quantized magnitude blocks and said quantized phase blocks as digital data on the data storage medium; detecting a transient in said transformed blocks and, when detected, decreasing the level spacing with respect to said second quantization process.

Claim 40

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising: dividing said wideband digital audio signal into signal blocks; Fourier transforming said signal blocks into transformed block representative of the magnitude and phase of the audio signal in its associated block as a function of frequency; extracting from said transformed blocks magnitude data blocks and phase data blocks as a function of frequency; grouping said magnitude data blocks and phase data blocks into a plurality of adjacent frequency bands, said frequency banks extending from low frequency bands to high frequency bands; applying a first quantization process upon said magnitude data blocks in each frequency band to develop quantized magnitude blocks; applying a second quantization process upon said phase data blocks in each frequency band to develop quantized phase blocks, said second quantization process developing higher precision quantization in said low frequency bands than in said high frequency bands; recording said quantized magnitude blocks and said quantized phase blocks as digital data on the data storage medium; detecting a transient in said transformed blocks and, when detected, decreasing the level spacing with respect to said second quantization process.

Claim 42

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising; dividing said wideband digital audio signal into signal blocks; Fourier transforming said signal blocks into transformed blocks representative of the magnitude and phase of the audio signal in its associated block as a function of frequency; extracting from said transformed blocks magnitude data blocks and phase data blocks as a function of frequency; grouping said magnitude data blocks and phase data blocks into a plurality of adjacent frequency bands, said frequency bands extending from low frequency bands to high frequency bands; scaling each said frequency band by a constant value selected such that the energy of the frequency band equals a predetermined value within a preset range; applying a first quantization process upon said magnitude data blocks in each frequency band to develop quantized magnitude blocks; applying a second quantization process upon said phase data blocks in each frequency band to develop quantized phase blocks, said second quantization process developing higher precision quantization in said low frequency bands than in said high frequency bands; recording said quantized magnitude blocks said constant values and said quantized phase blocks as digital data on the data storage medium wherein said first quantization process includes two-stage vector quantization of said magnitude data blocks.

Claim 43

A method of processing a wideband digital audio signal and for storing the processed signal on a data storage medium comprising; dividing said wideband digital audio signal into signal blocks; Fourier transforming said signal blocks into transformed blocks representative of the magnitude and phase of the audio signal in its associated block as a function of frequency; extracting from said transformed blocks magnitude data blocks and phase data blocks as a function of frequency; grouping said magnitude data blocks and phase data blocks into a plurality of adjacent frequency bands, said frequency bands extending from low frequency bands to high frequency bands; scaling each said frequency band by a constant value selected such that the energy of the frequency band equals a predetermined value within a preset range; applying a first quantization process upon said magnitude data blocks in each frequency band to develop quantized magnitude blocks; applying a second quantization process upon said phase data blocks in each frequency band to develop quantized phase blocks, said second quantization process developing higher precision quantization in said low frequency bands than in said high frequency bands; recording said quantized magnitude blocks said constant values and said quantized phase blocks as digital data on the data storage medium wherein said first quantization process includes two-stage vector quantization of said magnitude data blocks.