Improvement of SoundTouch variable speed Wsola algorithm

SoundTouch variable speed algorithm is similar to Sola algorithm, a closer look only know is Wsola algorithm.

Last week there was a need to apply this variable speed to live packet processing, somewhat similar to the WEBRTC NETEQ processing mechanism.

Using SoundTouch directly, there are some problems:

1. A normal, a variable speed, the middle will appear discontinuous, there is impact. or switching at different rates.

The more frequent, the more obvious the phenomenon, the de,de sound.

2.soundtouch each processing, there will be remnants, if flush, the sound quality will be affected, the general to the end of the use of the function.

This means that the input sample has a residue.

The length of the 3.soundtouch variable can not be accurate to the sample point level, because when stitching back to find the best position, so this is a change,

The final variable speed length is still likely to have a hundreds of millisecond deviation.

Through a one-week study, the above three problems were finally solved.

Does not appear contiguous, the input sample point is completely processed, there is no residue, the exact output length to the sample point level.

Figure one: Primitive, figure II: SoundTouch Switch between different rates three: improved effect.

Improvement of SoundTouch variable speed Wsola algorithm