I have a few VHS tapes that I have previously transferred to my PC via a capture card. Recorded audio is 1 channel. So I've been importing to Vegas Pro 12 to duplicate the audio channel. I also have a plugin that cleans a bit of the noise from that old, rusty VHS footage.
I've rendered a few a while ago, on my old computer. Recently got a new PC and resumed rendering. I'm noticing however that the audio and video are out of sync. I even rendered a small, 2-minute part of the video, and the output is still out of sync.
I made sure that the project frame rate is the same as the rendered template. Tried audio at 48,000 Hz and at 44,100 Hz (read somewhere it might make a difference). Same thing.
I tried saving as MP4, Avi, and mpeg...out of sync with all.
The entire captured footage is in mpeg format, and, needless to say, plays well without any sync issues.
I even tried importing it into vegas and directly rendering a portion (without noise cleaning/audio channel duplication). Same thing. Audio and video out of sync.
And audio and video are 2 separate tracks. Source recording is 1 channel, so I'm duplicating the audio channel to get stereo output. (I did try rendering without duplicating, rendered vid is also out of sync)
there are many things that could go wrong with your technique.
My main guess is that you may have cut a small section of the audio off when you took it into the timeline.
In saying that if it is synced in the timeline's preview player, then it could also be the player itself, have you tried it in VLC and quicktime, etc?
apart from that without seeing what you are doing there are many variables that could cause this.
The plug in could cause it, i would try and render without using this also try another program say premiere pro or even live movie maker (I am just saying to see if it renders synced) and see if you end up with the same result.
I doubt I did, as I repeated the process a few times just to eliminate the possibility of an error on my part. And to eliminiate it being the plugin/my method of duplicating audio channel, I simply imported source audio and rendered directly, without duplicating audio channel or applying plugin. Result? Out of sync audio.
I tried playing in VLC and Windows Media Player, also tried on my Mac with VLC and QuickTime. Same thing.