Fixed-size cross-correlation computation method for audio time scale modification
AssigneeTexas Instruments Incorporated
InventorsAtsuhiro Sakurai, Yoshihide Iwata
Life of this patent
Estimating the term…
Abstract
A time-domain time-scale modification method based on the synchronous overlap-and-add method consists of a generalization of the envelope-matching time-scale modification method. The cross-correlation function employs a fixed-size cross-correlation buffer to eliminate the need for normalization inside the search loop. This fixed-size cross-correlation buffer is the center of the overlap region corresponding to the case where the fine overlap adjustment value is set to zero. The computational cost of this invention is lower than any other method with a comparable quality.
Claims6
A method of time scale modification of a digital audio signal comprising the steps of:
- analyzing an input signal in a set of first equally spaced, overlapping time windows having a first overlap amount Sa;
- selecting a base overlap Ss for output synthesis corresponding to a desired time scale modification;
- calculating a cross-correlation R[k] for index value k between overlapping frames for a range of overlaps between Ss+kmin to Ss+kmax for a fixed length overlap region;
- selecting a value K yielding the greatest cross-correlation value R[k];
- synthesizing an output signal in a set of second equally spaced, overlapping time windows having a second overlap amount equal to Ss+K.
A digital audio apparatus comprising:
- a source of a digital audio signal;
- a digital signal processor connected to said source of a digital audio signal programmed to perform time scale modification on the digital audio signal by
- analyzing an input signal in a set of first equally spaced, overlapping time windows having a first overlap amount,
- selecting a base overlap Ss for output synthesis corresponding to a desired time scale modification,
- calculating a cross-correlation R[k] for index value k between overlapping frames for a range of overlaps between Ss+kmin to Ss+kmax for a fixed length overlap region;
- selecting a value K yielding the greatest cross-correlation value R[k],
- synthesizing an output signal in a set of second equally spaced, overlapping time windows having a second overlap amount equal to Ss+K;
- and
- an output device connected to the digital signal processor for outputting the time scale modified digital audio signal.
Dependencies are inferred from the claim text.