Need to sync 2 sources that run at different speeds

Source 1 (SBD) was recorded in 24 bit at 44.1 kHz

Source 2 (AUD) was recorded in 24 bit at 48 kHz

Source 1 begins its sync perfectly at 2 minutes 26.8 seconds into Source 2’s recording

By 51 minutes 3.2 seconds of play, Source 1 is running .057 seconds faster.

Can someone please help me find a way to keep them in sync?

The different kHz recording rate was a blooper on my part. After this trouble, I will NOT be screwing that up again.

What was producing the two tracks? Exactly which hardware?


Edirol R-09 = Source 1
Edirol R-09HR = Source 2

Some high end/professional equipment have a “word clock” input/output that allows them to be synchronised with other devices. It doesn’t look like either of your devices have that feature so the closest that you will be able to achieve is to manually cut little bits out of one or other recording to bring them back in sync. It would probably be worth recording a metronome (or similar) and testing the devices at different sample rates to find which combination gives the closest sync.

This is a sister to the poster who wants to plug multiple USB microphones into his computer. Unless they’re locked to each other, the show will have resync clicks or pops on occasion as the two signals drift from each other.


So there’s no formula to use to figure out the drift amount and there’s also no feature in Audacity to counter that drift in order to precisely speed up or slow down a recording?

Of course there is.


Hey Koz-

These are two separate tracks. They were recorded independently, but of the same show. I have both sources separate, my whole problem is getting them to sync.

Thanks for your responses. I really want this to work.


Sorry caffeine deprivation. Count the seconds in both shows and use the formulas we posted in that thread.


Near as I can tell, in 48 minutes and 36.4 seconds Source 1 ends up .057 seconds ahead of Source 2.

This is damn confusing.

The problem with that other thread compared to this one is that both of my media captures are audio and are different lengths. I don’t have any point of reference speed wise (ie. no video to see guitar strums/vocals to match with mouths).

Okay, so Source 1 is 2916.4 seconds and Source 2 is 2916.343 seconds. Which is the difference of .057 seconds.

I am doing the other math right now.


Well, it came out to a 0.00001954464408174462 difference, which is .001954464408174462% speed difference.

Audacity rounded that up to 0.002%, so I will see how this works.

How are you hearing that difference?


Thanks for the help, Koz!

It sounds good to my ears.

I’ll post a sample within a day or so. I have to get the volume right and split it into tracks.

To calculate the required speed change:

(“original length” - “target length”)/“target length”

<<<(“original length” - “target length”)/“target length”>>>

So the number required is a percentage of the target length, not the original length?

Who designed this thing?


A computer programmer :wink:


Without adult supervision.