EP0655876A1
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EP
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Perceptual coding of audio signals
Assignee: AT&T Inc
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Filing: 1994-11-16
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Granted: —
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Expires: 2014-11-16
Abstract
Abstract A five-channel perceptual audio compression system which encodes five matrixed channels switches among a fourteen encoding modes each utilizing a respective different set of matrixed channels. Six of the modes are for encoding the three front channels and eight of the modes are for encoding the two back channels. A number of the modes have as at least one of their respective matrixed channels a matrixed channel which is a function of a) one of the input channels or a sum or difference of two of them, and b) a predicted value of a).
Inventors
- 👤 James David Johnston
- 👤 Deepen Sinha
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 17:21
CPC Classifications
H; H03; H03M; H03M7/00; H04; H04S; H04S3/00; H04S3/02; H04B; H04B1/00; H04B1/66; H04B1/665
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
85 words
A method of perceptually encoding an audio signal comprising a set of input channels, the method comprising the steps of generating a set of matrixed channels in response to said input channels, and perceptually encoding said matrixed channels, characterized in that at least an individual one of the matrixed channels of said set of matrixed channels is a function of a) an individual one of said input channels or the sum of, or the difference between, two of them, and b) a prediction of a).
Claim 2
Dependent Claim
30 words
The invention of claim 1 comprising the further step of alternatively applying to an output a) said perceptually encoded matrixed channels and b) a perceptual encoding of said input channels.
Claim 3
Dependent Claim
35 words
The invention of claim 1 comprising the further step of alternatively applying to a communication channel or a storage medium a) said perceptually encoded matrixed channels and b) a perceptual encoding of said input channels.
Claim 4
Dependent Claim
63 words
The invention of claim 1 wherein in said audio signal, said input channels are represented in the frequency domain and wherein said generating step comprises the step of generating said set of matrixed channels from said input channels in such a way that each of said matrixed channels is represented, for each of a series of time domain blocks, by frequency spectrum lines.
Claim 5
Dependent Claim
50 words
The invention of claim 4 wherein said frequency spectrum lines are divided into a plurality of coder bands and wherein the magnitudes of the frequency spectrum lines of each coder band are represented by values that are quantized as a function of a noise threshold associated with that coder band.
Claim 6
Dependent Claim
130 words
Apparatus for processing an audio signal comprising a set of input channels, said apparatus comprising means (205) for perceptually encoding one of a predetermined plurality of sets of matrixed channels generated in response to said input channels, and means (206, 208) for applying the perceptually encoded matrixed channels to a selected one of a) a communications channel, and b) a storage medium, characterized in that the channels of an individual one of said sets of matrixed channels are said input channels and the channels of others of said sets of matrixed channels include at least an individual one matrixed channel which is a function of a) an individual one of said input channels or the sum of, or the difference between, two of them, and b) a prediction of a).
Claim 7
Dependent Claim
65 words
The invention of claim 6 wherein in said audio signal, said input channels are represented for each of a series of time domain blocks, by frequency spectrum lines divided into a plurality of coder bands, the magnitudes of the frequency spectrum lines of each coder band being represented by values that are quantized as a function of a noise threshold associated with that coder band.
Claim 8
Independent Claim
152 words
A method for processing a perceptually encoded audio signal, said perceptually encoded audio signal having been generated by generating a set of matrixed channels in response to a set of input channels; perceptually encoding said matrixed channels; and applying said perceptually encoded matrixed channels to a communication channel or a storage medium, said method comprising the steps of receiving said perceptually encoded matrixed channels from said communications channel or storage medium, decoding the received perceptually encoded matrixed channels, and recovering said input channels from the decoded matrixed channels, characterized in that said set of matrixed channels comprises a selected one of i) said input channels, and ii) a set of matrixed channels in which at least an individual one of the matrixed channels is a function of a) an individual one of said input channels or the sum of, or the difference between, two of them, and b) a prediction of a).
Claim 9
Dependent Claim
30 words
The invention of claim 8 wherein said recovering step includes the step of determining how said set of matrixed channels was generated in response to said set of input channels.
Claim 10
Dependent Claim
140 words
Apparatus for processing a perceptually encoded audio signal, said perceptually encoded audio signal having been generated by generating a set of matrixed channels in response to a set of input channels; perceptually encoding said matrixed channels; and applying the perceptually encoded matrixed channels to a communication channel or a storage medium; said apparatus comprising means (801) for receiving said perceptually encoded matrixed channels from said communications channel or storage medium, means (804) for decoding the received perceptually encoded matrixed channels, and means (807) for recovering said input channels from the decoded matrixed channels, characterized in that at least an individual one of the matrixed channels of said set of matrixed channels being a function of a) an individual one of said input channels or the sum of, or the difference between, two of them, and b) a prediction of a).
Claim 11
Dependent Claim
27 words
The invention of claim 10 wherein said means for recovering determines how said set of matrixed channels was generated in response to said set of input channels.
Claim 12
Dependent Claim
97 words
An article (700) in which is stored information representing a perceptually encoded audio signal comprising a set of input channels, said perceptually encoded audio signal having been generated by the steps of generating a set of matrixed channels in response to said input channels, and perceptually encoding said matrixed channels, characterized in that at least an individual one of the matrixed channels of said set of matrixed channels is a function of a) an individual one of said input channels or the sum of, or the difference between, two of them, and b) a prediction of a).
Claim 13
Dependent Claim
28 words
The invention of claim 12 wherein said perceptually encoded audio signal was generated by the further step of perceptually encoding said input channels alternatively with said matrixed channels.
Claim 14
Dependent Claim
35 words
The invention of claim 1 or claim 6 or claim 8 or claim 10 or claim 12 wherein said individual one of said matrixed channels is a function of the difference between a) and b).
Claim 15
Dependent Claim
17 words
The invention of claim 1 wherein said set of input channels includes left, right and center channels.
Claim 16
Dependent Claim
72 words
The invention of claim 15 wherein a first one of said matrixed channels is a function of said left channel and a prediction of said left channel; wherein a second one of said matrixed channels is a function of said right channel and a prediction of said right channel; and wherein a third one of said matrixed channels is said center channel; each said prediction being a function of said center channel.
Claim 17
Dependent Claim
21 words
The invention of claim 16 wherein each said prediction is a function of a perceptually encoded version of said center channel.
Claim 18
Dependent Claim
31 words
The invention of claim 16 wherein each said prediction is a function of the product of a) a perceptually encoded version of said center channel, with b) a respective prediction coefficient.
Claim 19
Dependent Claim
63 words
The invention of claim 15 wherein a first one of said matrixed channels is said left channel; wherein a second one of said matrixed channels is said right channel; and wherein a third one of said matrixed channels is a function of said center channel and a prediction of said center channel, that prediction being a function of said left and right channels.
Claim 20
Dependent Claim
21 words
The invention of claim 19 wherein said prediction is a function of perceptually encoded versions of said left and right channels.
Claim 21
Dependent Claim
54 words
The invention of claim 19 wherein said prediction is a function of the product of a) a perceptually encoded version of said left channel with b) a respective prediction coefficient, and is further a function of the product of a) a perceptually encoded version of said right channel, with b) a respective prediction coefficient.
Claim 22
Dependent Claim
58 words
The invention of claim 15 wherein a first one of said matrixed channels is a function of the sum of said left and right channels; wherein a second one of said matrixed channels is a function of the difference between said left and right channels; and wherein a third one of said matrixed channels is said center channel.
Claim 23
Dependent Claim
103 words
The invention of claim 15 wherein a first one of said matrixed channels is a function of a sum channel and a prediction of said sum channel; wherein a second one of said matrixed channels is a function of a difference channel and a prediction of said difference channel; and wherein a third one of said matrixed channels is said center channel; said sum channel being a function of the sum of said left and right channels, said difference channel being a function of the difference between said left and right channels, and each said prediction being a function of said center channel.
Claim 24
Dependent Claim
21 words
The invention of claim 23 wherein each said prediction is a function of a perceptually encoded version of said center channel.
Claim 25
Dependent Claim
31 words
The invention of claim 23 wherein each said prediction is a function of the product of a) a perceptually encoded version of said center channel, with b) a respective prediction coefficient.
Claim 26
Dependent Claim
94 words
The invention of claim 15 wherein a first one of said matrixed channels is a sum channel; wherein a second one of said matrixed channels is a difference channel; and wherein a third one of said matrixed channels is a function of said center channel and a prediction of said center channel; said sum channel being a function of the sum of said left and right channels, said difference channel being a function of the difference between said left and right channels, and said prediction being a function of said left and right channels.
Claim 27
Dependent Claim
21 words
The invention of claim 26 wherein said prediction is a function of perceptually encoded versions of said left and right channels.
Claim 28
Dependent Claim
54 words
The invention of claim 26 wherein said prediction is a function of the product of a) a perceptually encoded version of said left channel with b) a respective prediction coefficient, and is further a function of the product of a) a perceptually encoded version of said right channel, with b) a respective prediction coefficient.
Claim 29
Dependent Claim
19 words
The invention of claim 15 wherein said set of input channels further includes left surround and right surround channels.
Claim 30
Dependent Claim
54 words
The invention of claim 29 wherein an individual one of said matrixed channels is a function of said left surround channel and a prediction of said left surround channel, and wherein a further one of said matrixed channels is a function of said right surround channel and a prediction of said right surround channel.
Claim 31
Dependent Claim
31 words
The invention of claim 30 wherein said left surround channel prediction and said right surround channel prediction are respective functions of one or more of said left, right and center channels.
Claim 32
Dependent Claim
35 words
The invention of claim 30 wherein said left surround channel prediction and said right surround channel prediction are respective functions of perceptually encoded versions of one or more of said left, right and center channels.
Claim 33
Dependent Claim
50 words
The invention of claim 29 wherein an individual one of said matrixed channels is a function of the sum of said left surround and right surround channels; and wherein a further one of said matrixed channels is a function of the difference between said left surround and right surround channels.
Claim 34
Dependent Claim
91 words
The invention of claim 29 wherein an individual one of said matrixed channels is a function of a sum surround channel and a prediction of said sum surround channel; and wherein a further one of said matrixed channels is a function of a difference surround channel and a prediction of said difference surround channel; said sum surround channel being a function of the sum of said left surround and right surround channels, and said difference surround channel being a function of the difference between said left surround and right surround channels.
Claim 35
Dependent Claim
31 words
The invention of claim 34 wherein said sum surround channel prediction and said difference surround channel prediction are respective functions of one or more of said left, right and center channels.
Claim 36
Dependent Claim
35 words
The invention of claim 34 wherein said sum surround channel prediction and said difference surround channel prediction are respective functions of perceptually encoded versions of one or more of said left, right and center channels.
References Cited (Backward Citations)
WO1990016136A1
Cited
EP0564089A1
Cited
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