Why are these two recordings of the same event slightly different in length and how do I synchronize them?

Question

I played a gig recently and I have two audio sources: one 192 kbps MP3 file from an H2N Zoom sitting near me (I'm the drummer), and another from the sound engineer at the venue which is a mix of the board mix plus a room mic (I have a WAV version and a 320 kbps MP3 version).

I synchronized them based on four drum stick clicks at the start of the first song, and that song sounds well-synchronized. However, there is a drift - if I go to the end of the now-supposedly-synchronized tracks, the track I got from the sound engineer is 160 ms too late compared to my H2N track (drifted over the course of about 47 minutes).

1. Why is there this drift between the two audio sources?
2. How do I fix it?

So far my only option seems to be to re-synchronize each song separately and hope the ~17 ms drift per song won't be too noticeable.

Answer 1

Unless the recording devices are locked to each other or a common masterclock like a blackburst generator the devices will drift over time. The best thing to do is probably slice and readjust as needed, whether thats by song or a really tiny adjustment part way through each song. You could try a slight time stretch but that will probably introduce more phase drift. Whats the purpose of synching the recordings?

Answer 2

The two devices drift slightly out of sync like the other person said, I frequently record concerts where I have cameras and separate recorders and have up to 8 tracks all out of sync. If you don't have access to a program like plural eyes which can sync it for you, the best thing to do is line all of them up at one spot where there's an easily identifiable spot (like a loud transient) then go along every 5-10 minutes and cut the track and move it along until it's out of sync and you'll be left with a few millisecond drop in audio every 10 minutes or so.