Method for time-scale modification of signals
DCFirst Claim
1. A method for time-scale modification of a signal comprised of an input stream of signal representations to form an output stream of signal representations, the method comprising the steps of:
- determining an input block of W signal representations from the input stream for use in overlapping signal representations from the input block with signal representations in the output stream; and
overlapping WOV signal representations from the beginning of the input block with WOV signal representations from the end of the output stream, where WOV is determined by W and the time-scale modification.
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Abstract
Method for time-scale modification ("TSM") of a signal, for example, a voice signal, wherein starting positions of blocks in an input signal, referred to as analysis windows, are varied and an output signal is reconstructed by overlapping analysis windows using fixed window offsets, i.e., the duration of overlap between analysis windows is fixed during reconstruction. This is done by searching for segments of the input signal which are similar to the previous portion of the output signal. In one embodiment of the present invention a cross-correlation is used as a similarity measure to evaluate such similarity and the cross-correlation uses a fixed, predetermined minimum number of samples. The starting position of the analysis window which results in the greatest similarity in overlapping regions is determined as the starting position which provides the largest value of cross-correlation in the overlapping regions. Several cross-correlations are evaluated by shifting the analysis window over a predetermined number of samples, removing the first shifted samples in the evaluation each time, and using the same, predetermined number of samples in the evaluation to determine the "best" starting position for an analysis window. Finally, the predetermined number of samples from the beginning of the analysis window are averaged with the predetermined number of samples from the end of the previous portion of the output signal and the remaining samples in the window are appended to the averaged segment of the previous portion of the output signal.
202 Citations
20 Claims
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1. A method for time-scale modification of a signal comprised of an input stream of signal representations to form an output stream of signal representations, the method comprising the steps of:
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determining an input block of W signal representations from the input stream for use in overlapping signal representations from the input block with signal representations in the output stream; and overlapping WOV signal representations from the beginning of the input block with WOV signal representations from the end of the output stream, where WOV is determined by W and the time-scale modification. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 20)
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10. A method for time-scale modification of a signal comprised of an input stream of signal representations to form an output stream of signal representations, the method comprising the steps of:
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determining a number of signal representations for use in overlapping signal representations from the input stream to the output stream, WOV ; determining an input block of W signal representations from the input stream for use in overlapping signal representations from the input block with signal representations in the output stream; and overlapping WOV signal representations from the beginning of the input block with WOV signal representations from the end of the output stream. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method which comprises the steps of:
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time-scale modifying a signal comprised of an input stream of signal representations to form an output stream of signal representations wherein at least one of the steps of time-scale modifying comprises; determining an input block of signal representations from the input stream for use in appending signal representations from the input block to signal representations in the output stream, where the number appended is determined by the time-scale modification; and appending the signal representations to the end of the output stream.
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Specification