Audio Sync Help

Hi guys, i keep looking for this online, but i cant seem to define a definitive answer.

I am trying to edit a super-basic vlog video in FCP7. I record video on my DSLR and record sound via my mac (the sound quality is marginally better). All i need to do is sync the audio to the video, and then go through and crop both down as needed.

Even though i converted my original M4A audio into AIFF with a bitrate matching that of the original video (16-bit integer) it still slowly drifts out of place after about 15-20 seconds. Its driving me absolutely nuts, because what should be a simple 2 hour job is taking so much more time and work because 70% of my time is being taken up by trying to shift the audio back or forward by a few frames - but obviously that doesnt always work out, cos after a while it just gets confusing.

Is there any way of correcting this thing for good? I still have another 20 minutes to edit, and its taken me about 3 hours just to do the first 10-15 minutes.

Really appreciate it if you guys can help. Thanks.

Hi Pete
Welcome to the forums.
Unfortunately, legacy FCP has some real audio issues and keeping in sync is one of them, IMHO.
If doing external recording, make sure to match sample rates, video typically is 48K. Check both the camera settings and audio recorder settings.
I think this is most likely your problem.
Did you by chance also do audio recording on the DSLR? Always a good idea to record audio on the camera even if you use external recorder. This way you can use it as reference and for sync.
If you did, one trick is to export the two audio files out and into a Digital Audio Workstation (DAW) like Logic Pro X or even Garageband (I think, don't use much). You can create 2 tracks and then align/stretch the tracks to match the wave forms. If you are really lucky, you will be able to simply stretch the audio track to the proper length and everything will align. Most likely tho, you will need to work on regions separately.
Make sure the pitch remains the same.
You can then export back to FCP and add the audio track.
If you don't have a reference track, you may be able to still align via timecode in a DAW. You need to make sure your audio and video start time is the same. Set the end time to length of video, then make audio end at that time.
In a similar vane, inside FCP you can detach the audio track and then attempt to align the audio to video. You will need to especially watch the pitch however, as I don't think FCP legacy does maintain pitch.
If you have lots of clips instead of a single take, you will most likely need to do this for each clip.
Finally you can look into 3rd party apps.

Hope this helps, Greg

I never had audio issues in legacy FCP, aside from mismatched sample rates. All audio source sample rates must match, or you get this drifting out of sync. Same thing happens in FCPX today. Unfortunately, simply converting won't always help.