Sync 29.970 FPS audio to 23.976 FPS video?

[LCO1971]

I need to sync an audio track extracted from a 29.970 video (AUDIO 1), to a 23.976 video (AUDIO 2). They start in sync and progressively loose it throughout the movie.

I used a small test sample and an editor to shrink AUDIO 1 (5min:08s) to the same lenght of AUDIO 2 (5min:00s). Now they start and end in sync but desynchronize in the middle.

I want to adjust ony the audio, don't want to mess with the 23.976 video.

Any ideas will be welcome.

Thanks.

[jagabo]

There should be no difference in running time between a 23.976 fps and 29.97 fps version of a video. Something is wrong with one or both of your sources or how they were treated.

[lordsmurf]

I'd see if the sync loss is really progressive, or if it loses frames or frame groups in various locations int he clip.

Indeed, something went wrong somewhere, but such a realization may not be of any benefit. I deal with projects like this a lot, fixing people's mistakes.

[Loomis]

This is just a wild guess:

Is it a 0.1% drift?

Something somewhere is ‘pulling down’ your audio sample rate from 48000Hz to 48048Hz.

Please don’t ask me to explain. I’m probably wrong anyhow.