AF’s Weblog

November 28, 2008

Time Stretching and Pitch Shifting: Comparison

Time Stretching & Pitch Shifting: Comparison Part I
Software Comparison
OK, here we go! This is the first of our comparative software tests on time-stretching and pitch-shifting. The competitors: 26 Mac and PC programs, from big sequencers to small applications, plug-ins to audio editors
Digital audio has brought about many changes to the audio world when compared to analog. Is this good or bad? Everyone has their own opinion; but certain features have been improved, some totally new ones have emerged, while others are less effective or successful (knowing that many opinions are primarily subjective).

But the goal here is not to make (empty) comparisons between the two worlds. We’ll be dealing with two important features that have more or less created a revolution in music since their arrival with the earliest samplers: time-stretching and pitch-shifting. The first can speed up or slow down an audio file without changing its pitch, the second change its pitch without changing its tempo (otherwise, it’s back to tapes and vari-speed …).

With a lot of reverb, sustained chords, resonance, slides, transients, this file is not easy. And it already shows at 75%: Kontakt can’t do it at all, TimeFactory 2 Clear Scale and SampleTank Stretch have problems with lows, DSP Quattro gives us tremolo, while SampleTank PS/TS adds an expression pedal (no transients). Melodyne has a phase issue, same with Peak which decreases transients, which are also damaged in Pitch’n Time and Live. And as for their part, Logic, Pro Tools TS and X-Form, TimeFactory 2 MPEX3, and UVIWorkstation smear up the sound …

At 90%, it’s the same, except for Time Pitch’n which fared a little better with transients. At 110%, things change: Melodyne alters one or two attacks, Peak and Live still eat up a few transients, SampleTank Stretch, PS/TS and DSP Quattro “tremble”, Kontakt, Pro Tools TS and X-Form, TimeFactory 2 Clear Scale, and UVIWorkstation “wobble” more or less. When we slow down even more to 133%, there aren’t too many contenders left: Amazing X, Pitch’n Time Pro (with less transients just the same), TimeFactory 2 DIRAC, and Radius are at their limits …

At 200%, one can appreciate the efforts the programs make just to keep up continuous audio, but most of them take their toll on transients. The others just accentuate the defects they already had.

Access 2 GB of audio examples about time stretching/pitch shifting algorithms.

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