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High-pitched audio glitch on export
Hi everyone,
I’m working on a mini documentary shot on the Canon 5D and have had no trouble in the edit or during playback, but when trying to export a rough cut for the web, found a shrill buzz running through certain parts of the audio. It’s not throughout the entire video, just certain moments. It is very consistent over all the interview footage, and also exists over some of the broll, but I can’t pinpoint why it’s on some clips but not others. I tried exporting it out as different quicktime formats and exporting out just the audio as an aiff, but the buzz still occurs. When exporting out just the clip by itself it’s fine, but somehow putting it in the cut makes it react weirdly. There are no audio filters on the clips and I’ve tried trashing preferences, restarting my computer, exporting to my local drive, to external drives, everything I could think of. I’ve uploaded a reference so you can hear what I’m talking about. Any help would be greatly appreciated.
Sample of what it sounds like: https://soundcloud.com/mandymbrown/audiosample-1-2
Sample of what it should sound like: https://soundcloud.com/mandymbrown/audiosample-solo-1-2I’m working in Final Cut 7.0.2 on a Mac Book Pro
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7 Replies
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Some detail is needed. Is the sound from the camera or a separate recorder. What format is the sound. What sample rate and bit depth is the sound and the sequence settings. Does the sound that has the problem have a different setting to the other clips and the sequence setting.
The problem sound seems to be playing with the wrong bit depth setting. FCP loves the audio to be 16 or 24 bit, 48khz and uncompressed (either wav, aif or quicktime). mp3 or aac is a problem and must be first converted before editing.
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Hi Michael, thanks so much for responding. The sound is from the camera and is the same for all clips – 48 khz and 16 bit. My sequence settings are 48 khz and 32 bit floating point, though when I pull up the window to change the sequence settings, it says 16 bit. I don’t know as much about audio as I probably should, so please bear with me. Could it have to do with my sequence being 32 bit?
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No 32 bit is OK for the sequence settings. With the clip and sequence settings, it is definitely weird.
What settings are you exporting to?
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I tried exporting to my sequence settings and also as an aiff – 48 khz, 16 bit
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Definitely weird if you were exporting with those settings.
Left field time. Try sending the sequence to Sound Track Pro and see if it plays OK from there. If it does, then make you 16 bit 48khz wav or aif mix file from there and bring that back into a copy of your sequence to make the final QT delivery file.
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Thanks Michael! I think it may be the audio levels were peaking. I brought it into Soundtrack Pro and could see that the levels were going up to 6db on the problem clips, whereas in Final Cut I could only see them max out at 0. (The audio wasn’t too great, so I guess I was trying to compensate by making it louder.) Anyway, after bringing the levels down, the noise went away. Does that seem to make sense? Thanks so much for all your help!
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Yes that makes sense. Reducing would make a difference. It must have been coping with the clipping because the sequence was using 32 bit floating point. When that came down to 16 bit in the final it had to clip the peaks.
In digital audio there is zero head room in the final digital scale.
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