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Audio playback out of sync
I have a PAL timeline set at 25fps. The production audio is PCM aiff file 48k, 16 bit. The soundtrack was remixed at 48k, 24 bit. I lined up the waveforms of the production audio and new mix. They are exact. Checked it all throughout the picture. However, the audio starts out in sync but starts to drift over the course of an almost two hour show. By the end, the audio is almost 5 seconds ahead of the picture. If I turn off the new mix, and switch to the production track, its perfectly in sync.
Is this some type of playback issue or is it really out of sync?
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18 Replies
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it is probably a recording issue. Some external recorders tends to drift of on longer takes. I don’t think there is much you can do about it, except cut the clips up and resync them.
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FCP can get itself in a pickle by assigning a frame rate to an audio clip. Wav files are usually the problem, which is why I advise people to use aif for final mixes.
Often the problem relates to how the file was imported. If you just drag and drop the file from the finder it can get things wrong. Correctly importing when your Easy Setup is on a different frame rate will also cause the file to have the wrong frame rate stamped. Check your Easy Setup is on 25 fps and try to reimport the file again (from another source with a different name). Don’t involve other software like iTunes.
Personally I have never had this issue with PAL and aif files so the problem may well be with the mix.
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Somehow I don’t think that’s the problem. The show was originally shot on PAL, then converted to NTSC. The NTSC version had no audio problems and used the exact same mixed audio tracks.
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Ah new information. How was the PAL to NTSC conversion done. The drift you describe is close to .1% which is the real time difference between drop and non drop timecode.
Try slowing the audio down to 99.9% and see if it syncs.
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I’m not sure how the PAL to NTSC conversion was done because it was handled by a facility outside the country. I will attempt to find out.
But, just to be clear, the original footage was shot in PAL. The new soundtrack was mixed to the PAL picture. Shouldn’t that audio be in sync?
(The NTSC video conversion was done “after” the new audio mix although, due to delivery deadlines, I did the post edit of the NTSC first, without any audio issues.)
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I double checked and the Easy Setup was set at 25fps and only aiff files were used. When I reimported to a new timeline, the problem did not get fixed.
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Did you have your FCP set to NTSC when you imported the audio file? If so reimport the file (change the name first) with the Easy Setup on 25 fps and see if the problem remains.
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I’m not exactly sure what you mean by having “FCP set to NTSC”: the timeline was DV PAL Timebase 25. For good measure, I set up a new timeline, changed the name of the mixed audio aiff file, then imported the new aiff, and the problem remained the same.
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I just tried this fix recommended by Apple (https://support.apple.com/kb/TS1256), but it also did not work:
Delete audio files from Timeline and Browser; change Easy Setup to PAL; quit project and reopen; re-import audio file.
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Did you try changing the speed to 99.9%?
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