How do I sync audio with a specific frame rate

[Darby Edelen]

When converting frame rates the duration of your video should not change, so neither should the duration of your audio.

If the duration of your video is changing then you are either speeding or slowing the footage and that is not desirable unless it is a stylistic decision.

Hypothetically if you have 2 seconds of footage at 30fps, then that totals 60 frames.

If you want to play that at 24fps then you want to reduce the number of frames to 48 so that the footage will still play back in real time (2 seconds).

You should not need to apply a conversion to the original 2 seconds of audio at all, but instead bypass any conversion and use the original audio with the converted video. Since you should still have 2 seconds of footage.

The exception might be 24fps -> 25fps where the old standard was to simply play back the 24fps at 25fps (so the audio would be sped up by the same factor, resulting in a subtle increase in pitch).

I may be misunderstanding some part of your question, please clarify if I am.

Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA

[Scott Roberts]

Audio is based on time. Think of it as separate from video which is based on frames. Audio works for any frame rate . . . be it 24fps or 29.97 or 30 or 59.94 . . . as long as the length of your clip in time matches the length of your audio you’re good to go. So, if you have 2 minutes of video, two minutes of audio will match regardless of frames per second. It’s a waveform. Make sense?

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[Sean Harper]

Well I’m using Andrew kramer’s frame Rate conversion downloa but when I modify the sources frame rate to 23.976 fps it does increase the videos duration… Waht am I doing wrong with that?

I’ll make some great things with this

[Darby Edelen]

I’m not familiar with that tutorial. If I had to guess, then perhaps it’s a problem with the frame rate of the composition you are working in?

If it works in the tutorial, then there may be some step that you missed. Still, you probably should not use the audio on the layer that you are affecting (since I’m assuming there are some time-based effects involved). Place another copy of your source footage in the composition and turn the video off. Then just be sure that everything syncs up.

Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA