I’m running Audacity 3.1.3 on Xubuntu 20.04, although I don’t think this question is platform-specific.
I frequently have audio recordings of the same event from two or three different recorders that I need to sync up in Audacity. Right now, I have to do it manually. Is there a way to do it automatically, such as by having Audacity analyze the waveforms of each track and then time-shifting each track appropriately? If not, is there another audio editor that can do this?
I would appreciate any insights the community can provide. Thanks!
The traditional way is to record a clapper board at the start and end of the recording. This provides two clear marks for easier aligning.
Clapping your hands a couple of times is nearly as good.
If the mark at the end does not line up exactly when the start is lined up, then the recorders were running at slightly different speeds. In this case, use Audacity’s “Change Speed” effect to match tracks to your “master” recording.
I’m familiar with clapper boards, but it still requires manually aligning the tracks with the first clap. I’m looking for a way for Audacity to sense the clap on each track and align the tracks automatically.
It would be possible to write a Nyquist plug-in to do that, provided that the tracks have clear marks (such as a clapperboard) to align. I’m not aware of any such tool currently existing.
I prefer to do the alignment manually so that I know for certain that it is aligned correctly. Even if I had an automatic alignment tool, I’d still zoom in to check that it was right, and manually adjust if it was slightly off.
None that I know of, but I’ll see if I can put together a plug-in next week.
That would be fantastic Steve, I suspect that it would help quite a number of people, myself included.
An idea, would it be possible to also add a selectable option to compare the length (to a “master” track) and it will adjust accordingly,
using speed change?
Of course, all the tracks would need to be at the same sample rate.
Ideally, such a tool wouldn’t even need to look for a clap specifically. My dream tool would be one that could simply analyze the frequency patterns of each track and then align them based on its “best guess”.
That would be much harder to do than simply looking for the first peak. There was a proposal added to the Audacity wiki: https://wiki.audacityteam.org/wiki/Proposal_Audio_Diff but though the proposal was added 14 years ago (21st March 2008) there has been little (if any) progress made.
I had some time today so I’ve written a plug-in and uploaded it, along with instructions, to my blog: https://audionyq.com/align-tracks/
Ideally yes, but the plug-in can handle mixed sample rates.
I prefer to write plug-ins that are flexible rather than specialised. Combining multiple effects into one plug-in often makes the effect more complicated and less flexible.
Also, accurately finding synchronisation sounds at the start and end with a Nyquist plug-in would be slow, as it would have to loop through every sample in the track. For long tracks this could be very slow. Better to just use the “Change Speed” effect.
For the first track, select from the initial clap to the end clap, and make a note of the length (hh:mm:ss + samples).
For the second track, select from the initial clap to the end clap, and use Change Speed to change the length to the length measured in the first track.
