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dumb ass question – audio going out of sync from h264…
yes i know h.264 isnt an editing codec but..
i have large amounts of video (getting on for 22 hrs) captured by someone else from handycams as h.264 AVI files (29.97 fps) with the built in mic picking up the conference room audio.
Also recorded at the same time were mp3 files of the conference – sound feed from mixer so clean and much nicer quality!.
i have to stich the two together, now normal workflow would be recode the .AVI to a Prores .mov, recode .mp3 to AIFF and combine the two in FCP to sync up , then export the finished article.
as i’m not really ‘editing’ i have tried sticking the source avi and mp3 on FCP timeline and syncing up the first words of the speech. however it wanders off out of sync as you get further through the timeline.
I have made sure my FCP timeline is set to 1280×720@29.97 (what QT7 shows in inspector on the h.264 video) Ive also tried recoding the video from .264 to prores (same pixel and timebase settings) and still get the same issue.
tried joining the clips in soundtrack as theres no video editing and i still get the same issue.
should i recode (mpeg streamclip) to prores@30fps -(just set one rendering but theyre long renders)
what simple thing have i missed!! aarghnot looking forward to having a long workflow for this amount of video!
ron
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4 Replies
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What sample rate is the audio?
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mp3s are often 44.1khz. They play badly in FCP anyway, but at the wrong sample rate, sync cannot be trusted. So you are basically wasting time wondering if a compressed audio format with the wrong sample rate drifting sync is an issue. Yes it will almost always drift, click pop and sputter.
When you convert the audio to 48khz aif, also make sure that your default FCP project has exactly the same frame rate and timecode type as the sequence you are going to be editing, otherwise when you import the aif, it might then be stamped with the wrong timecode/ frame rate and it will drift.
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i thought of the audio sample rate once i’d gone to bed….
a) not posting it and
b) whether that was the problemowill look into that now 🙂
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As well as sample rate miss-match it may be worth checking that the sequence set up for the whole project is the same as the actual sequence that you are working on. When you import audio I think that FCP gives it the frame rate set in the project settings. (Search this forum as this has been covered before). You may also want to look at Pluraleyes which is a plug-in which might make your job a lot easier.
Matt.
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