OK…2 vocal tracks…recorded on 2 different laptops…imported … synced…started cleaning up any mic bleed using control +L …about 9 minutes into a 1 hour recording they’ve started to become un synced …haven’t removed anything … the beginning is still perfect…but at around the 9 minute mark they start to separate …only used control +L to muted bleed over…why would this be happening
2 different laptops
Each computer has it’s own clock (oscillator) that generates the 44,100kHz sample rate (or whatever sample rate you’re using). No clock is perfect* and after some time they will drift apart. Sometimes people get the same issue if they record with a USB microphone (which has it’s own clock) and then play-back with their regular soundcard.
Usually, a good-quality USB audio interface has a more accurate & more stable clock than a “consumer soundcard” so you’d probably get more than 9 minutes before it becomes noticeable but you might still get drift over an hour…
You can try the Change Speed effect if you can figure-out the timing difference and if you can get enough precision and/or you can split the files(s) into shorter sections and re-synchronize each song, etc.
BTW - This isn’t latency. Latency is the recording & playback delay that causes a delay in your headphones while you’re recording. There is always some latency, but it’s constant and related to buffer size. (You always need a buffer with a multitasking operating system.) Since it’s constant it can be more-easily compensated for.
\
- Pros use a super-accurate master clock (and interfaces with a master clock input) so the everything is locked-in to the exact sample.
The good news is Effect > Change Speed doesn’t damage the sound like the others, and once you figure out the difference between the two systems, it should be the same multiplier or percentage no matter how long the performance is.
Both parties can look at the long form time (hours, minutes, seconds) on their phones and record a ten minute piece with only a clap at the beginning and then another clap exactly ten minutes later.
Line up the beginning clap and then measure the one at the end.
That’s your standard correction until you change either recorder.
Koz