Not sure what a helicoptory distortion sounds like. Would love to hear a sample.
If the audio is in sync, you'll want to select the Sync clip in the Brower, go to the Inspector, the Audio section, down towards the bottom to Channel Configuration. Turn off the D800 audio channels, and whatever configuration tweeks will be needed. The goal is to only hear the DR40 channels that are necessary.
Also be sure in the Audio Enhancements section that Background Noise Removal is off, or adjusted properly.
Hi Benb, I have done those things. At first I thought it was a problem with the enhancements but they are all off.'
Only the Tascam channels are playing.
Here is a bizzare example of the sound:
By syncing I mean when I choose the audio file and video file in the events browser and select "Synchronize Clips"
I think I've found out what causes it but still don't have a fix. A lot of what I'm doing involves retiming sections of two clips so that two voices recorded separately flow together like a conversation. The helicopter sound happens in parts of audio clips that aren't retimed if there is another section of the same clip that is retimed.
I hope that makes sense because it's confusing to explain it.
I'm going to try razor blading the clip in the timline before retiming it instead of just using the range selection tool. I'll check back.
Retiming sections of a clip is what causes the oscillating. I've worked around it by chopping the clips before I retime them instead of selecting a portion with the range selection tool. Feels like a bug to me. I'm not sure if it's just with synced audio or if it does that with the audio out of camera.
Not exactly sure whether its a bug when audio sounds weird after being stretched. Even the best audio software has "problems: dealing with pitch when slowing down & speeding up...
The best plug-in in the biz (In my opinion) is waves' SoundShifter
Generally, one can slow down a video clip by a certain percentage and get away with it, quality wise... But as soon as one tries that with audio the quality WILL suffer greatly.
Best results without quality loss is to take use of the chipmunk principle... Make the audio a tiny bit slower/faster... Caveat of this technique is that one cannot go very far before it sounds like a devil or chipmunk
Another technique is to use a Strip-Silence function which will "solo" the words of a phrase. Thus enabling the editor to "move" closer, the words making up the sentence... This technique WILL "mess" with the tone of the phrase and caution should be used.
IF one lacks the know how of doing what is described above Waves' soundshifter is an amazing tool for such. Amazing because its sound algorhithm is grand. Melodyne would be another editor (superior interface) which is capable of doing such, ONLY caveat is that its pitch engine is inferior to that of Waves'
That's good advice but I think what I am talking about is different than just the problems of stretching audio. I actually welcome the kind of metallic effect that comes with timestretching. What's happening in this bug is that if I use the range selection tool to select a portion of a clip and stretch or speed it up, the parts of the clip that didn't have the retiming appilied exhibit an irritating, thumpy distortion. Not the sound of stretched audio.
Furthermore, when this problem has occured. FCP X crashes if I try and reset the timing to normal. It happens like clockwork. I've since learned to not retime portions of clips but I have a bunch of compositing that needs to be done all over again because I can't undo the problem that is causing the bug. It's like the clip's audio becomes corrupted and can't be reset. Lame. Thanks for the help though.
Just some langiappe information:
Slowing down and speeding up audio and maintaining pitch is old hat these days. Super easy to do. Up until FCP X 10.0.5 we could slow down and speed up audio by very large amounts and it was pristine quality. Just like in Logic Pro or SoundTrack Pro. But something broke in 10.0.5 and FCP X has a major bug now. Even the slightest speed changes distort the audio incredibly bad.
As for a "chipmunk effect", maybe in days of tape, but today's DAWs like ProTools and Logic Pro can change audio speed to great amounts and have no issues at all. Again, our editors are doing it daily.
As for crashes during retimeing, that is not a bug, there's something else going on. Many of my editors do it daily with no issues (outside of the audio distortion problem). Maybe get Preference Manager, try trashing preferences. Not sure that will do it, but that's not a poputlar bug of any sort..