Problems with Sound Recorder and Video

C

cityvideographer

Member
I'm shooting with the 7D and I used the Sony ICD-UX200 to record sound. I plugged a lav microphone into it and then placed it on the actor.

Here is the link to the recorder http://www.bhphotovideo.com

When I went to edit the footage, I synced the audio from the Sony recorder to the footage at a point at the beginning of the timeline. A couple minutes into the video, it begins going out of sync even though at the beginning it sounds perfectly matched.

Does anyone know how to fix the problem?
 
The clock in any two devices aren't going to be perfectly matched, so sync will drift over time. Coupling that with recording to a compressed format that requires a bunch of processing to take place before the file is written just exacerbates the problem.

You'll have to resync the audio as you go. Cut the audio and line it up again as you go through the footage.
 
seeing that its an mp3 only recorder there's where your problem is. and what rate does the recorder record at? usually you want to recorder 24 bit/48 khz .wav files. a lot of consumer recorders will record at 44.1 khz and your video's audio will be at 48 khz, so thats going to cause some drift.
 
Probably your problem is connected in part to what the others have said. Sample rate conversion will generally not throw you out of sync and MP3 will also not nec. loose sync, though your chance of loosing sync certainly will go up. Also the clocks don't nec need to be in sync though they do need to be the same speed.

Anyway all are "risk factors" for loosing sync so all together they are probably your problem. The solution is generally what has been described, resync as you go.

You could try to time stretch the whole file but that will be kind of hit or miss and IF the MP3 encoding time is a factor then the drift will probably vary so time stretching will not work.

There is one other possibility IF you are using FCP and shooting at a x.0 frame rate. But I don't think the 7D has a X.0 frame rate other than PAL so that is probably not the problem.
 
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