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Audio Sync issues with imported audio from a CD (FCP 6)
I have been taping and editing a radio talk show on my panasonic dvx100A camera (at 24p) for about a year now. Because the radio station records all the shows onto an audio CD (AIFF audio file), I always use THAT audio instead of the audio I record with my camera’s microphone because the quality is so much better.
When I was working on FCP 4.5, all I would have to do was align the two audio files ontop of each other in my timeline, then I’d just delete my camera’s audio – leaving only the studio-quality audio tack that would match perfectly with the video I captured.
This is the first project I’ve tried to do since updating to FCP 6, and when I follow this same procedure, now the video/audio from my camera seems to be moving at a slightly faster frame rate than the AIFF audio from the CD (NOTE: the video/audio from my imported footage stays in sync).
It looks as though I’ll have to re-align the audio from the cd with the video from my camera about every 5 minutes or so… unless I figure out what I’m doing differently than before. My guess is that I captured the footage in 24p this time, whereas I have no clue how it was captured when I was working with FCP 4.5 (probably just the factory presets, I’m guessing)
Please help! Thanks.
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5 Replies
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Sean,
This kind of problems come up way too much.For you, and for the records:
NTSC BASED VIDEO CAMERAS CANNOT RECORD 24P !!!!
Video in NTSC has a frame rate of 29.97
To be more correct, 30 * 1000 / 1001 = 29.970027
If pulldown is added, you’ll loose 6 out of 30 frames.
Thus, instead of 24, the video runs at 23.976FCP calls that 23.98. THIS IS INCORRECT FOR THE FRAMERATE
Again, 23.98 is a NAME that is often mistaken for the actual framerate. Does not seem a big difference, but doing math on large numbers will cause sync errors.Pal on the other hand ‘should’ be able to do ‘true’ 24 in video.
(a field doubled every 12/13 frames), but i’ve never seen that in a camera.So for you, switch to a 23.98 setup and you’ll be fine.
Bouke
https://www.videotoolshed.com/
smart tools for video pro’s -
Bourke, your explanation is correct. However, one second at 23.98 = 1 sec at 29.97 so I question whether 23.98 vs 29.97 is the issue. Perhaps there’s drift since the audio recorder and videocam were not resolved to ref. Also, the camera probably records audio at a different sample rate from a CD. Depending how the audio was captured, this, too, could have an effect. What do you think?
John
MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.5 QT7.5.5 Kona 3 Dual Cinema 23 ATI Radeon HD 3870
ATTO ExpressSAS R380 RAID Adapter, PDE Enclosure with 8-drive 6TB RAID 5
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John,
Since all was fine when the OP used plain NTSC, i really suspect something else.
If the sample rate correction is done wrong, the problems are way bigger. He said he had to re-align every 5 minutes.
That is 60 * 5 * 30 = 9000 frames – 60 * 5 * 29.97 = 9 frames.
(I would think that offset would be more obvious earlier, but well…)
Sync drift normally isn’t that big…
But yes, if the audio was captured from a player instead of ripped from CD, and it is a fancy player that has playback speed control, that could be an issue…(Oh plesase, there is no ‘r’ in my name. It’s my first name, and totally different from the Amerian lookalikes..)
Bouke
https://www.videotoolshed.com/
smart tools for video pro’s -
I just tried capturing the footage in the 23.98 setup – still having the same problem. 🙁
Any other suggestions?
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Also just tried the 29.97 set-up. Same thing. 🙁
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