Efficiency improvements in scalable audio coding
First Claim
1. An audio encoding method of coding audio signal into a layered data stream having a first layer and a second layer, said second layer serving as an enhancement of said first layer, the method comprising the steps of forming an original digital audio signal;
- encoding said original signal to obtain a first layer signal;
producing a residual signal to reflect a difference between the original signal and the first layer signal;
evaluating the residual signal; and
, in case the result of the evaluation meets given criteria, selecting a predetermined low-entropy signal to be encoded as a second layer signal, and, otherwise, selecting either said original signal or said residual signal to be encoded as said second layer signal; and
producing said second layer signal by encoding said selected signal.
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Abstract
An audio encoding method of coding audio signals into a layered data stream having a first layer and a second layer is presented. The second layer serves as an enhancement of the first layer. The method involves forming an original digital audio signal, encoding the original signal to obtain a first layer signal, producing a residual signal to reflect a difference between the original signal and the first layer signal, selecting either the original signal or the residual signal for encoding, and producing a second layer signal by encoding the selected signal. Moreover, the residual signal is evaluated and, in case the result of the evaluation meets given criteria, a predetermined low-entropy signal is selected to be encoded as the second layer signal, instead of the original signal or the residual signal.
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Citations
36 Claims
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1. An audio encoding method of coding audio signal into a layered data stream having a first layer and a second layer, said second layer serving as an enhancement of said first layer, the method comprising the steps of
forming an original digital audio signal; -
encoding said original signal to obtain a first layer signal;
producing a residual signal to reflect a difference between the original signal and the first layer signal;
evaluating the residual signal; and
, in case the result of the evaluation meets given criteria,selecting a predetermined low-entropy signal to be encoded as a second layer signal, and, otherwise, selecting either said original signal or said residual signal to be encoded as said second layer signal; and
producing said second layer signal by encoding said selected signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An audio encoder for coding audio signals into a layered data stream having a first layer and a second layer, said second layer serving as an enhancement of said first layer, the encoder comprising
a first encoder element, capable of encoding an original digital audio signal into a first layer signal; -
a subtracting unit adapted to produce a residual signal to reflect a difference between the original signal and the first layer signal;
a first selector adapted to select either said original signal or said residual signal for encoding as a second layer signal;
a second encoder element, capable of producing said second layer signal by encoding said selected signal;
an evaluating unit adapted to evaluate the residual signal and provide an indication that the result of the evaluation meets given criteria; and
a second selector, said second selector being associated with said evaluating unit and being adapted, upon receiving said indication, to select, instead of said original signal or said residual signal, a predetermined low-entropy signal to be encoded by said second encoder element. - View Dependent Claims (20, 21, 22, 23, 28, 29, 30, 34, 35, 36)
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24. An audio decoder, comprising:
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means for receiving a layered data stream containing an encoded first layer signal and at least one encoded second layer signal;
a first decoder element capable of decoding the first layer signal;
a second decoder element capable of decoding the second layer signal;
means for determining a perceptual quality measure for the second layer signal;
means for deciding whether the perceptual quality measure meets predetermined criteria;
means for combining the second layer signal with the first layer signal to produce a decoded output signal, if said perceptual quality measure meets said criteria; and
means for producing the decoded output signal from the first layer signal alone, if said perceptual quality measure does not meet said criteria. - View Dependent Claims (25, 26, 27, 31, 32, 33)
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Specification