I import multiple camera videos of a church service. I combine them switching from one view to another, adding pre video images and post video images. When I finish, I produce an MPG 1920X1230 30fps and take it into another project where I add subtitles for readings and hymns. (I use to do this in one project, but that was more complicated than I care for).

When I preview, everything is ok, video and audio are in sync. When I produce the final MPG file, the audio and video are in sync at the beginning and get more and more out of sync towards the end.

I have had this happen in the original project, when I brought in a short MPG file and inserted it in the middle between 2 camera clips (MP4). After producing the final video, from the end of the inserted file to the end of the video, it was out of sync by 3 or 4 frames.

At one time (maybe a one off) I even had the linked audio and video showing as starting at different times in the preview. The audio started about 3 or 4 seconds before the video and ended 3 or 4 seconds before the video. At that point, I tried to unlink them to align them. Could not do that. The only thing that I could do was to delete that clip, bring it back in and re-trim it. However when I cut the MPG, it was off by a few frames.

To get around that problem, I have started cutting MP4 files (smaller) and have not had a problem yet. Paul C