Vocal Time Stretching: The Good, Bad and Ugly

Discussion in 'Production' started by lostnthesound, Jun 9, 2014.

  1. lostnthesound

    lostnthesound Burns Easily in the Sun

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    For those who wish to avoid the omnipresent "chipmunk" vocal caused via sacrificing pitch for time, we are often left finding new means and methods to effectively time stretch a vocal withou destroying the audio data it contains to a point where it simply sounds like rubbish. Whether you're using a third party app/plugin, an Apple Loop, a time stretching tool/algorithm in your DAW or a transient detecting/editing function, there are many ways to go about getting the plethora of available royalty-free (or bootlegged white label) vocals to stretch to a DnB tempo. However, in your production journey you've probably come across a phenomenon where some vocals simply lend themselves better to the stretching process than others in terms of the final product.

    The vocal for Drumsound & Bassline Smith's "Close" is actually a vocal from a Vengeance pack that was recorded at 135 BPM I believe (I don't have it in front of me at the moment, will follow up later). Yet when it's stretched (or adjusted via Flex Time or similar transient based timing tool) to DnB tempo, it sounds almost as good as the original. Take a different vocal with the same BPM and stretch it, chances are it may sound hollow like someone whacked 100 compressors on it–or it may contain stretching artifacts that can really kill the quality and transient info.

    I've stretched a ton of vocal samples using various tools–everything from Logic's Flex Time/Time Stretching plugin to Melodyne Editor, Elastique Pitch (also used under the hood with Ableton and Reaper) and Waves SoundShaper. I have found the following factors (besides original tempo) play the most significant role(s) when it comes to how well a vocal will maintain when stretched dramatically (i.e. contain less harsh artifacts/hollowness):

    • The timbre of the vocal. I've never been able to pin point a particular key. For some reason, there are some timbres that work much better than others.

    • Single voice, mono recorded. Vocal samples that have double tracking tend to sound very hollow and weak when stretched. A straight mono recording of a single voice works best. If your vocal pack contains stems and you have the choice between using the separate stems of a harmony or a single file with all parts of the harmony together, stick with the individual pieces. You will end up with a much cleaner, brighter sound vocal. Also, be sure to utilize a Monophonic setting for time stretching if your DAW offers the option.

    • Whether it's Dry or Wet. Dry vocals tend to work better since there it is a single, dry monophonic source. Vocals that have reverb, delay, etc. tend to get a bit muddied up when stretched. If you don't have access to Dry vocals but your DAW offers a Polyphonic algorithm for time stretching, use it in this case.

    • If Wet, the type of FX used. Vocals that have a bit of "dirt" to them (ex: distortion, bitcrushing, a single echo tail at the end of the phrase) can work ok. Also, you can sometimes get away with adding distortion/overdrive post time-stretching to slightly mask any artifacts.

    • The strength and amount of vibrato. This is a big one. Vibratos tend to sound either cartoon like or like an artifact injected mess. If your DAW or plugin allows you to analyze and edit the transients of the vocal (ex. Logic, Cubase, Melodyne), use the vibrato tool to dial it back down a little bit. Increments of 5% are a good starting point (examples: 100%, 95%, 90%, etc.). Be careful not to over do it!
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    • The quality of recording. If a top shelf mic was used in a wonderfully treated room and the file was rendered to lossless format, you're off to a good start. As these previously mentioned elements (mic type, room treatment, file resolution) are reduced, so will the quality of the stretched vocal.

    To conclude, in cases where you just can't seem to get a stretched vocal sounding proper enough, despite timing adjustments, transient point editing/deleting/shifting, FX processing and alternate stretching algorithms, it's best to just move on. I speak from experience and many wasted hours–there's nothing worst then spending several hours on a vocal only to find out that no matter what, it's going to sound like shit and not hold its weight within a tune.

    Remember: shit in, shit out.

    Just my .02. Cheers

    P.S. Apologies for being a bit of a ghost lately, between two kids, DJing, day job, and production, only a DeLorean could give me more time. I'll be posting an in-depth tutorial on Logic X's Time Stretching, Flex Time and Flex Pitch functions in the near future.
     
    Last edited: Jun 9, 2014
    Fluff, xiris, Sulihin and 3 others like this.
  2. Optimal Prime

    Optimal Prime Specialising in the arts and crafts of Drum & Bass

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    A few years back, I was working on a track that was to be released by a label and incidentally also got put out with a video, however they wanted this track sped up slightly by a few BPM right at the end of the project. You can imagine how much of a headache this would have been, so I had to resort to software, and decided to research into the predominantly better software options to use. This may not be actual true and it's pretty much based on the one time only result, but I noticed a lot of praise from an algorythm used both in a Protools plugin(I think it is) and Sonar's main timestretch tool.

    I just did a search now and it actually turns out to be Logic not Protools so you might have already tried it. Radius by Izotope is the algorythm and we did end up using the Sonar one just to alter the whole track, something I'd never dream of doing normally, however this was a label decision and they paid for the track anyway. Amazingly it survived several bpm's of change way better than I was expecting. I also remember it taking ages to process as well as this was all offline processing.
     
  3. lostnthesound

    lostnthesound Burns Easily in the Sun

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    Admittedly, Radius is the only one I haven't tried. I have read that it implements itself directly into logics time machine interface which has my interest peaked. I may have to contact isotope to see if they'll provide me with a demo for comparison. Thanks for sharing!
     
  4. RUSSLA

    RUSSLA DNBF Monarch

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    Looking at Radius it sounds the bollocks for audio. Would love to try it so let us know Lost if they sort a demo and I'll be on that for sure.