Keep in mind that two digital devices, in this case a camera and an H4N recorder, do not record at exactly the same sample rate and will drift apart after some period of time. However, you say that the audio was recorded in the camera using the analog audio from an H4N so the audio should be absolutely in sync. You wouldn't happen to be using Quicktime to play the rendered AVC files? If so, then that's your problem and you don't need to look any further.

How far out of sync is the audio? If you place the rendered file back on the timeline in Vegas, is it still out of sync?

"of sync with my video clips (Showing The Pink Audio Files)"

I still can't help but think that fixing the out of sync on the timeline would have to be a good thing.

I have noticed that some players do seem to lose sync or make it drift. As has been suggested your first step should be to verify that the rendered file really is out of sync and the best way to do that is to bring it back into the original project and compare the rendered video with what's on the timeline.

Bob.

Two or more cameras will drift out of sync as if not 'gen locked' as well.
Even if the camera's and audio have time code, they will still drift over time. For perfect sync, they ALL need to driven by a master clock source.

Two things would be helpful.

1. Post for download some of the media (that's falling out of sync) in question that used the H4N for audio.
2. Tell us which template or settings you used to render to HD AVC.

This way some one can seek to reproduce the problem.

When you render out to another video format is the audio out of sync?

Do you have multiple audio tracks? If so are they at the same bit rate. If not you may want to re-mix the tracks to the same bit-rate, and/or use different audio bit-rate.

Reason I say this is because since I don't have a master sync clock for my multi cam videos, I've had issues w/ some multi-cam audio tracks going out of sync because the audio bit-rate on different cameras and recording devices was set differently. I now try to get all the cameras, and recording devices set to the same audio bit-rate. This has helped to get the audio tracks to line up and render out pretty well.

I've had very rare issues (2 times) where an audio track just would not sync or play right in Vegas and remixing the track to anther bitrate in Vegas just would not work.. I extracted the audio track out of the video using another audio software (Cubase), remix to the same bitrate as the main audio track and re-import the new audio into Vegas and it worked fine.

Byron K, for Audio, to be pedantic, I'm thinking you mean "samplerate" when you say "bitrate" surely?

e.g.

There will not be an iota of "speed" difference in a 48Khz file that is 16bit or 24bit (or any other bitrate for that matter) = the "speed" is still the same, locked to the same samplerate, which is the only determinant of speed.

However potentially there can be "speed" differences between files recorded at differing samplerates, say 44.1kHz and 48kHz, when the files are subsequently converted to same samplerate; the difference can be explained by how devices derive their Clocks. e.g. I have 2 identical devices here, both have internal clocks which are within 0.001% @ 48kHz, but (unfortunately) are only within 0.1% @ 44.1kHz. Therefore simultaneously recording same material at different samplerates, then converting one, can result in a significant speed difference.....

If it's in sync when rendered to an MPEG2, but out of sync rendered to MP4, it can't surely be anything timeline related? Have you tried rendering a separate WAV or MP3 file and using that instead? By that I mean replace the original audio with it on the TL, then render to MP4. Or can you change the audio setting in the render dialogue? (Make a customised template).

I've used MP4 for 1hr + projects without sync issues, so 15min is not a long project.