Topic: Tools for fixing the sync drifting recordings?

[dklein]

Hey - been a while since I was on the board but I had this thread set to notify and it's just come back to life!  Here's a little tool that I've been using for a few years now.  It's pretty self-explanatory and will help you do the math behind the resampling required to bring things back into alignment.  I've found that once you know the relationship between two devices it's pretty consistent.  I used to do multitrack on separate devices.  Now the only time I use it is to match up separate audio and video (synch to the camera's crappy audio and your good audio will match the picture).

Here's my experience with some different approaches.
Stretching - I have not found stretching to sound very good, although Wavelab was much better than CEP/Audition.  Neither allow the precision required.  I seem to recall wavelab ignores everything after the first decimal point, or maybe didn't even use the first decimal point.
Cutting / matching - your always drifting off and then realigning so you're never really on the mark.  Weird phase artifacts are introduced.
Deleting samples - similar to above
Resampling - the way to go.  If you think about it, the original event occurred over the same duration to both machines.  If one is shorter, it's being played back faster and the pitch will be slightly up.  Resampling to an adjusted rate but then playing back at the 44.1/48k playback rate should bring the pitch back on while addressing the time drift issue. 

R8Brain is free and really good at it.  Always max out the quality settings...there shouldn't be any rush for this kind of work!  Let me know if you find the worksheet useful.

david

[joemango]

Cool... I didn't know r8brain could do fractional sample rates.  I'll have to use that next time.

[kbergend]

Hey - been a while since I was on the board but I had this thread set to notify and it's just come back to life!  Here's a little tool that I've been using for a few years now.  It's pretty self-explanatory and will help you do the math behind the resampling required to bring things back into alignment.  I've found that once you know the relationship between two devices it's pretty consistent.  I used to do multitrack on separate devices.  Now the only time I use it is to match up separate audio and video (synch to the camera's crappy audio and your good audio will match the picture).

Here's my experience with some different approaches.
Stretching - I have not found stretching to sound very good, although Wavelab was much better than CEP/Audition.  Neither allow the precision required.  I seem to recall wavelab ignores everything after the first decimal point, or maybe didn't even use the first decimal point.
Cutting / matching - your always drifting off and then realigning so you're never really on the mark.  Weird phase artifacts are introduced.
Deleting samples - similar to above
Resampling - the way to go.  If you think about it, the original event occurred over the same duration to both machines.  If one is shorter, it's being played back faster and the pitch will be slightly up.  Resampling to an adjusted rate but then playing back at the 44.1/48k playback rate should bring the pitch back on while addressing the time drift issue. 

R8Brain is free and really good at it.  Always max out the quality settings...there shouldn't be any rush for this kind of work!  Let me know if you find the worksheet useful.

david

I just want to thank you for posting this!  I had to align mic and sbd sources from two different recorders (R-44 and PMD620) last night in Audition and wasn't having much success with the stretch function.  I found this post, downloaded the free version of r8brain, followed the instructions in the spreadsheet, and it worked perfectly!  No noticeable degradation in the slightly faster soundboard resampled to 44,100.33 using Highest Quality, and it saved me hours of tedious work correcting for the drift piecemeal.

+t! (if I live to 500)

[boojum]

What a board!     

[jaz]

  Tap the "R" key in Wave Lab and it brings up the Wave Restore Tool. It only works for a small sections but a digi pop from sync issue usually fits into it's range. BUT through the global analysis of errors it seldom finds digi pops as slight as the ones that occur do to sync issues. 


Or if you got the cash a lynx L22 and you wont have sync issue's.

[kirk97132]

Hey - been a while since I was on the board but I had this thread set to notify and it's just come back to life!  Here's a little tool that I've been using for a few years now.  It's pretty self-explanatory and will help you do the math behind the resampling required to bring things back into alignment.  I've found that once you know the relationship between two devices it's pretty consistent.  I used to do multitrack on separate devices.  Now the only time I use it is to match up separate audio and video (synch to the camera's crappy audio and your good audio will match the picture).

Here's my experience with some different approaches.
Stretching - I have not found stretching to sound very good, although Wavelab was much better than CEP/Audition.  Neither allow the precision required.  I seem to recall wavelab ignores everything after the first decimal point, or maybe didn't even use the first decimal point.
Cutting / matching - your always drifting off and then realigning so you're never really on the mark.  Weird phase artifacts are introduced.
Deleting samples - similar to above
Resampling - the way to go.  If you think about it, the original event occurred over the same duration to both machines.  If one is shorter, it's being played back faster and the pitch will be slightly up.  Resampling to an adjusted rate but then playing back at the 44.1/48k playback rate should bring the pitch back on while addressing the time drift issue. 

R8Brain is free and really good at it.  Always max out the quality settings...there shouldn't be any rush for this kind of work!  Let me know if you find the worksheet useful.

david

Bumping this for dklein's great step by step process.  Thanks and I'm looking forward to using it to fix a very problematic mix of sources.  It's 3.5 hours of recording and even though it is one two of exactly same decks there is a drift issue.  At the end of the show it's pretty significant Even if I tried splitting it into tracks the size difference is audible by the end of the song.  This looks like the perfect solution to my problem.  I've tried stretching in Adobe Audition and just can't seem to get it right.  And I'm not real sure of work flow in WL or Samplitude.  Thanks again!  Kirk