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Old 03-11-2010, 10:29 PM
bryanatt bryanatt is offline
Join Date: Jan 2009
Posts: 14
Default Xform causing random pase shifts in audio (drum tracks) in PT8

I am experiencing a weird problem with using Xform on drums. I use the Rhythmic setting while placing the drums in time, and everything turns out great (everything is in phase) As soon as I try to put the tracks to xform the resulting tracks come out with random phase problems (mostly with the 2 kick tracks). There doesn't seem to be a consistent change in the phase, it seems random from hit to hit. Is this a common problem with xform, or am I doing something wrong?
iMac 3.06 Ghz 4 Gig
MBox 2 Pro Factory
Pro Tools 9.0.1
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Old 03-12-2010, 06:18 PM
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ryanavery ryanavery is offline
Join Date: Sep 2009
Posts: 27
Default Re: Xform causing random pase shifts in audio (drum tracks) in PT8

This may be a silly question, but if you're happy with the sound you get from Rhythmic, why do you want to render the audio with XForm?

The tech answer is that the way XForm performs time-stretching will naturally introduce *some* phase shift into the signal, and the amount of phase shift you hear is of course signal-dependent. In general, XForm is really good with most source materials, but it isn't the be-all and end-all of time-stretching (I often run into situations where I prefer rhythmic or polyphonic, just because of their sonic properties).

A few workarounds:
1. Try grouping the audio you want to time-stretch across the tracks - IIRC the time-stretching algorithms try to maintain phase-coherence when they operate on grouped audio (though I can't remember if XForm is this way).

2. If you're happy with your drum mix, you can always bounce-down the un-stretched drums and perform time-stretching on the stereo mix. I know that kind've defeats the purpose of having the ability to time-stretch the individual parts, tho!

Hope that helps!
Ryan Avery
Audio DSP Software Engineer, Avid Technology, Inc.
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Old 10-10-2010, 12:03 PM
Dinsane Dinsane is offline
Join Date: Oct 2010
Location: Los Angeles
Posts: 12
Default Re: Xform causing random pase shifts in audio (drum tracks) in PT8

Did you ever find the answer to this problem? I am experiencing the exact same thing.
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Old 09-21-2011, 01:51 PM
studiozero studiozero is offline
Join Date: Sep 2011
Location: Minneapolis
Posts: 4
Angry Re: Xform causing random pase shifts in audio (drum tracks) in PT8

I recently started editing in 8.0.5 and am unable to use the XFORM algorithm due to phase and transient problems.

I've been searching for an update with a fix, or information on if upgrading to 9 has a usable XFORM, but have found nothing.

It seems I will be downgrading to 7.4 since its elastic rendering seems to be the most advanced.

Any feedback is much appreciated.
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