Synch audio and video in iMovie

[Rockbassman-yo]

I recorded a bass track onto a bass-removed mp3; I used my iPhone to video record as i played my bass on the recording. Even though I succeeded in putting the audio and video files into iMovie, I can't seem to synch them together accurately enough so that the audio doesn't lag or out-race the action in the video (like those old movies where it looks like the guy started talking 2 seconds before any words came out). For the first couple of minutes of the song, it looks like the audio is lined up with the video, but after a few minutes it looks like I need to re-synch. I thought about throwing in the towel and just recording the entire audio and video using my iPhone but I imagine it wouldn't record my computer speakers and bass cab very well. I certainly don't want to end up posting a video with lousy sound quality.

Any suggestions/remedies you have would be greatly appreciated.

 

[FunkHead]

Did you see this yet?

 

[DirtDog]

I recorded a bass track onto a bass-removed mp3; I used my iPhone to video record as i played my bass on the recording. Even though I succeeded in putting the audio and video files into iMovie, I can't seem to synch them together accurately enough so that the audio doesn't lag or out-race the action in the video (like those old movies where it looks like the guy started talking 2 seconds before any words came out). For the first couple of minutes of the song, it looks like the audio is lined up with the video, but after a few minutes it looks like I need to re-synch. I thought about throwing in the towel and just recording the entire audio and video using my iPhone but I imagine it wouldn't record my computer speakers and bass cab very well. I certainly don't want to end up posting a video with lousy sound quality.

Any suggestions/remedies you have would be greatly appreciated.

You need a visual cue on video and an audible cue on audio. With a room mic, a single loud clap is a good way to sync. Filmmakers use those clap boards to generate the "transient". Same principle.

If you just have your bass plugged in (no mics involved), just give your strings an obvious slap (muting with your left hand) to generate the transient. Syncing with that on audio and video is a piece of cake after that.

 

[DirkP]

Did you record your bass track at 48 khz? Never happened to me in iMovie that video and audio where in sync and later were out of sync. The reason that your audio is at sync when you start, but is getting recognizable out of sync after some minutes is highly likely that your audio (bass) was recorded at 44.1 khz.
If possible you should record your bass again at 48 khz or change it to 48 khz, when exporting the wave file.
The technical background is a bit hard to explain, but search for it on the internet, if you are interested.

The postings above mine just try to explain how to sync audio and video in general, but they don't consider that your video and audio is synced at the start, but goes out of sync after some time.

 

[GreatRandini]

Google “how to fix audio drift” …
you may find some guidance.
I was having an issue like this in Premiere and I had to convert my video file to a different kind of file. (I think it was a sony video file I was working with).
I bet there is something like that for iMovie as well