Hey Mads,
Thanks for the explanation. I don’t think the Long-GOP issue is what’s causing it in my case though. The recordings are H.264, but I’ve tested the same thing with an intra-frame codec and I’m still getting the sync drift.
I’m also slowing down/speeding up both the video and audio together, so it’s not simply the audio being left at normal speed. I think the issue might be somewhere else in how VEGAS handles the velocity changes.