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electronic MUSICIAN

Sony Creative Software Sound Forge Pro 10 (Bonus Material)

By Dennis Miller | November 25, 2009

More In-Depth With élastique Pro

I use time-stretching in a vast number of my projects, and I was curious how zplane élastique Pro would compare with some of the dedicated time-stretching tools I use most often. So I did a quick comparison of its output with that of both SPEAR (Michael Klingbeil''s free program for Mac and Windows at www.klingbeil.com/spear) and Paul''s Extreme Sound Stretch (also free; available at hypermammut.sourceforge.net/paulstretch). Elastique compared very favorably with both of these, and for material where you want to preserve a transient—such as percussion samples—it did the best job of all.

In Web Clip A, you''ll hear a percussive gamelan sample played in its original version, followed by the result of a 2.5x time stretch in élastique Pro, Paul''s Stretch and SPEAR. Both Paul''s Stretch and SPEAR let you adjust the window size, which is a part of the analysis-resynthesis process that many time-stretch programs use. A large window size gives best results in the frequency domain because a larger segment of the original file is analyzed, so the program does a better job at recognizing the cyclic repetition of individual (especially lower) frequencies. A small window size provides better timing resolution as the program looks at smaller chunks of samples and has a better sense of when things are happening. So for Web Clip B, I tweaked the window size from 65,536 samples (which is what I used in Web Clip A for both SPEAR and Paul''s Stretch) to 512 samples; you''ll hear the new versions played in the same order as before. Though the sharp attack of the sound is clearer in Web Clip B, the last two examples are full of artifacts.

Web Clip C has a female vocal recording, where the transient is not a major factor. In this case, I found that élastique again produced excellent results, but that both Paul''s Stretch and SPEAR produced very acceptable output. I also tried Sound Forge''s built-in time-stretch process for comparison using its Speech 07 preset. You''ll hear the results in the following order: original sample, stretched with élastique, Paul''s Stretch, SPEAR and the built-in process.

Note that both of the free programs have a vast range of creative uses; for example, SPEAR lets you edit (frequency shift or time-stretch) or mix and match individual frequencies, and Paul''s Stretch includes its own pitch-shift, filtering and other effects. It''s also optimized for stretching many thousands of time the original length of a sample—up to 10,000x, in fact. Paul''s Stretch also has a time-varying time-stretch option so you can change how much stretching occurs as a sound evolves. But élastique is a great tool for more traditional effects, and, of course, being built directly into Sound Forge it''s much more efficient in your workflow.

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