Download An efficient audio time-scale modification algorithm for use in a subband implementation
The PAOLA algorithm is an efficient algorithm for the timescale modification of speech. It uses a simple peak alignment technique to synchronise synthesis frames and takes waveform properties and the desired time-scale factor into account to determine optimum algorithm parameters. However, PAOLA has difficulties with certain waveform types and can result in poor synchronisation for subband implementations. SOLA is a less efficient algorithm but resolves the issues associated with PAOLA’s implementation. We present an algorithm that is a combination of the two approaches that proves to be an efficient and effective algorithm for a subband implementation.
Download An Efficient Phasiness Reduction Technique for Moderate Audio Time-Scale Modification
Phase vocoder approaches to time-scale modification of audio introduce a reverberant/phasy artifact into the time-scaled output due to a loss in phase coherence between short-time Fourier transform (STFT) bins. Recent improvements to the phase vocoder have reduced the presence of this artifact, however, it remains a problem. A method of time-scaling is presented that results in a further reduction in phasiness, for moderate time-scale factors, by taking advantage of some flexibility that exists in the choice of phase required so as to maintain horizontal phase coherence between related STFT bins. Furthermore, the approach leads to a reduction in computational load within the range of time-scaling factors for which phasiness is reduced.
Download Time and pitch scale modification: A real-time framework and tutorial
A framework is presented which is designed to address the issues related to the real-time implementation of time-scale and pitchscale modification algorithms. This framework can be used as the basis for the developments of applications which allow for a seamless real-time transition between continually varying timescale and pitch-scale parameters which arise as a result of manual or automatic intervention.