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Gear / Technical Help => Photo / Video Recording => Topic started by: willndmb on November 08, 2013, 02:59:25 PM
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Any ideas here, first time I have had it happen or at least I noticed it...
I have this recording(s)
Mics > lb > m10 (24/48) > camcorder (whatever the camcorder captures at)
The m10 file was resampled/dithered in audacity and tracked out
The camcorder file was captured in Final Cut Pro
I used the track times from audacity to place chapter makers on the video
HOWEVER
The audio on the video was much shorter in time. The first track/chapter was off by about 10 seconds and I just thought it was because I didn't start everything at the same time but by the 1.5 hr mark the difference was almost 7 minutes
For example audacity track 1 started at :45 and in fcp it was at :35 then in audacity track 15 was at 1:15:00 and in fcp it was at 1:08:30
Everything sounds and looks fine ???
Tia
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Different clock signals. Same problem as if you use two recorders that aren't clocked together via wordclock/spdif.
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Different clock signals. Same problem as if you use two recorders that aren't clocked together via wordclock/spdif.
That would be first thought - but that seems like A LOT of drift...
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Are you sure you don't have any 44.1Khz vs. 48Khz issues?
Because that difference, as a percentage, is pretty close to the time difference you describe.
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Are you sure you don't have any 44.1Khz vs. 48Khz issues?
Because that difference, as a percentage, is pretty close to the time difference you describe.
thats what I was leaning towards
Or
This time I went from the m10 to the camcorder and most of the time I go from the lb to the camcorder and never had an issue.
I suppose it could have need rift but I too thought that was a huge amount of drift
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7 minutes is slightly odd, but not outside of what I'd expect for that problem in particular. I've seen 5 minutes over slightly less then that (a 722 and a R-4 unit in my case).
If it was in the range of 15% drift, then yeah, I wouldn't expect it to be the clocks.
That's my best guess.
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I would run about a hour and half test by making a video with the camera recording the M10 counter. I use a dog clicker at the beginning and at 15 minute intervals so I have something to line up for comparison in my video software or DAW.
Been several months ago, but the amount of drift between the M10 and my canon camcorder was just about enough to create an echo effect about 75 minutes into the recording. About 95 minutes, it became slightly more noticeable. It was enough to require some adjusting, but 7 minutes???? :o
Something seems really odd here.
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Are you sure you don't have any 44.1Khz vs. 48Khz issues?
Because that difference, as a percentage, is pretty close to the time difference you describe.
^^^
Has this very plausible explaination been explored yet? I bet that's it.
The m10 file was resampled/dithered in audacity and tracked out
The camcorder file was captured in Final Cut Pro
I used the track times from audacity to place chapter makers on the video
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I agree with it-goes-to-eleven and Gutbucket, a sample-rate mismatch is a likely explanation. It may have been recorded at different sample rates on the two devices in the first place, or when you did your editing in Audacity and Final Cut you may have inadvertently exported to a file with a different sample rate. You said:
The m10 file was resampled/dithered in audacity and tracked out
^ If the M10 file was 24/48 and you resampled, then I'm guessing you resampled to 44.1. Try putting the original M10 file into Audacity again, do your edits, but don't downsample or decimate (i.e. keep your tracks all 24/48). See if things line up then.
The first track/chapter was off by about 10 seconds and I just thought it was because I didn't start everything at the same time but by the 1.5 hr mark the difference was almost 7 minutes
For example audacity track 1 started at :45 and in fcp it was at :35 then in audacity track 15 was at 1:15:00 and in fcp it was at 1:08:30
^ Sorry to be Captain Obvious, but make sure you are also compensating for the different start time of the tracks in FCP. You can't just drag Track 2 10 seconds to the right - you will have to visually and aurally line up some claps or other nice clear peaks in the recording. I do this by level-matching the two tracks, then hard panning them to each side and listening through headphones until they line up. Once you've done that at the beginning of the recording, check the alignment at various places throughout. Just make sure you are absolutely dealing with two tracks of the same sample-rate first, otherwise it's going to drift and you're just going to be chasing your tail.
Even professional rock bands sometimes set the wrong sample rate: https://www.youtube.com/watch?v=Mjx_GjyXCs4 (https://www.youtube.com/watch?v=Mjx_GjyXCs4)
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To be more clear, I am NOT putting the audio files into FCP
The audio was recorded directly onto the m10 and at the same time recorded directly to the camcorder/video
My littlebox has two outs and one was used for each source
I'm guessing the sample rate is the answer more then "normal" drift because I have done this many times and never had an issue
Although it has been a while since I used the lb outs,typically I use the m10 out into the camcorder but for some reason this night I didn't