The time scaling module allows speech files to be played back at a different speed, from the speed at which they were recorded. If this were done by simply speeding up or slowing down replay, the pitch of the voice would change, and sound very odd. This modules keeps the pitch of the voice normal.
The time scaling module is based on the Pointer Interval Controlled OverLap and Add (PICOLA) method, developed by Morita Naotaka. Mikio Ikeda has an excellent web page on this subject at http://keizai.yokkaichi-u.ac.jp/~ikeda/research/picola.html There is also working code there. This implementation uses exactly the same algorithms, but the code is a complete rewrite. Mikio's code batch processes files. This version works incrementally on streams, and allows multiple streams to be processed concurrently.
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