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24 fps timeline, 24 fps 5D, 24 fps F5 footage, but the 5D falls out of sync
I am having a mysterious problem that I hope is something simple I’m missing. I am working in Final Cut Pro in a sequence that is 24 fps, with two cameras both transcoded to 24 fps: a Sony F5 and a 5D. (The 5D serves as the second camera angle for an interview) The F5 was shot in 24 fps and syncs to the 4800 khz audio fine, but the 5D was filmed in 23.98 and even after I transcode it to 24, and fcp 7 tells me the footage is 24, it falls out of sync with the audio and F5 in the sequence. I tried using mpeg streamclip to transcode, Compressor, and Cinema Tools. I am so confused! Has anyone experienced this issue before?
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4 Replies
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The 23.98 footage is running .1% fast if it has been changed to 24 so it must drift. This is normal when you speed up a shot compared to real time which is what the other camera and sound are referencing.
Frame rates need to match on two camera shoots.
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Unless your cameras have GenLock and they shared a common external clock, they will always drift out of sync because the clock crystals just aren’t that accurate nor are they synchronized with each other in any way. I don’t think framerate alone is the problem. You would have the same problem syncing camera audio with an external audio recorder. They just drift because they have separate clocks and you need to compensate in the edit.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
My experience is that professional equipment crystal clocks are in the order of +- 1 frame over 24 hours. Hardly an issue. Some cheap gear may have drift but I have only encountered significant crystal drift using a cheap zoom multitrack recorder against three RED cameras in a concert. Meanwhile my 788t Sound Devices did not drift even sub frame over the two hour concert.
I can tell because we were unclocked to each other but they jammed to my timecode. To notice drift with most equipment suggests a frame rate problem and the OP has indicated that there is a .1% frame rate discrepancy between cameras.
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Thank you! Wow, I thought transcoding would do the trick to match frame rates! I’m just relieved of a headache that the blame doesn’t fall on me as an AE. 😀
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