This is topic Is there anybody here with knowledge of handling audio in iMovie? in forum Film-Yak at Film-Tech Forum ARCHIVE.


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Posted by Stephen Furley (Member # 1277) on 08-30-2015, 02:48 PM:
 
I own a Macbook Pro, on which is installed a copy of iMovie 10.0.6. I've never used it until a couple of days ago, and it's completely different to a much older version which I did use a few times, long ago.

On Thursday evening we had two screenings of the film 'The Forgotten Kingdom, the evening one of which was followed by a live interview and Q&A, via Skype, with the director, Andrew Mudge. With permission, this interview was recorded.

So far, so good. The original recording was a single MOV container, with a single video stream with two 16:9 images side by side, and two audio streams, one for each end of the conversation. The recording software came with a utility to divide the video into two separate files, each with just it's own audio. Due to some technical problems at our end there were some problems with the audio of the interviewer.

I took the video of the director, with it's attached audio into iMovie. I then took the interviewer footage into Quicktime 7 Pro, exported just the audio from it as a WAV file, and brought this into iMovie as a second audio stream. I increased the level of the interviewer audio by about 5 dB, to bring it close to the level of the director audio, removed a few odd noises here and there, applied a bit of noise reduction, and then reduced the level where the interviewer wasn't speaking to get rid of most of some noise, similar to running water, that we had somehow picked up in places. At the end of the exercise I've got reasonable audio, in two separate streams. I now need to export just the interviewer audio, preferably to a WAV file, so I can send it to the person who is going to edit the video. She already has both ends of the video, and the audio of the director. I thought this would be a simple matter, but it seems not. There is no Save or export option in the menus; there is a 'share' from where you can select 'file', and then 'audio only', but this exports a mix of both audio streams. I can select the whole of the audio stream which I want and then do 'Copy' I thought I would be able to paste this into Quicktime 7 Pro, and then save it, but no. Can't delete the other audio stream, then share|file|audio only as above because I cannot save the project first, and would therefore have lost the complete version.

Any suggestions? I need to somehow export this audio by Tuesday morning.
 

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Posted by Scott Norwood (Member # 30) on 08-30-2015, 05:13 PM:
 
Can you get a copy of a recent version of ffmpeg installed somewhere? If so, then it should be just a matter of doing this:

ffmpeg -i file.mov file.wav

This will take file.mov as input and give you file.wav as output. There are all kinds of options for changing the sample rate and bit depth and such, but the defaults should be fine in most cases.
 

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Posted by Bobby Henderson (Member # 840) on 08-30-2015, 06:02 PM:
 
tsMuxeR is a pretty good open source application that's good about replacing the audio track in a movie clip with a new audio track without re-encoding the video.

Just make whatever audio edits you need to make (and make sure you don't shift around anything in terms of placement in the time line).
 

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Posted by Stephen Furley (Member # 1277) on 08-31-2015, 03:59 AM:
 
Thanks for the suggestions, but I'm not sure if either of these will do what I need. Scott, I do not have a MOV file including all of the edits which I've made, I can't even find where iMovie stores the files, or how it stores them; there's no obvious sign of them anywhere on the laptop. Even if I had a MOV file, containing both of the audio streams, would it allow me to export just one of them? Quicktime 7 Pro could do this, if I had a MOV file still containing the two audio streams separately, but I don't. The two streams still exist separately in iMovie since I can make changes to just one of them.

Bobby, I don't think tsMuxeR will do what I need either, I don't want to replace the audio but export it to a WAV file. This does sound like it might be useful for something else though; I'll have to take a look at it.

I wish I could work out how iMovie is storing the project, and its media content. Remind me never to use iMovie again, it's terrible. There's not even an option to close a project, or open an existing one. If you close iMovie, and then re-open it, any project that you had open is still there, so it looks like once you create a new project it's there forever.
 

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Posted by Bobby Henderson (Member # 840) on 08-31-2015, 08:36 AM:
 
Some audio editing applications can open video files, allowing editing of the track and exporting of individual channels or the whole thing in different formats. I've done this with Adobe Audition.
 

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Posted by Mike Blakesley (Member # 26) on 08-31-2015, 06:35 PM:
 
I think Sony Vegas can do that too.
 

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Posted by Scott Norwood (Member # 30) on 08-31-2015, 07:23 PM:
 
If you can get a multichannel WAV file, "sox" (also freeware) can extract the individual channels, for example

sox file.wav left.wav remix 1
sox file.wav right.wav remix 2

will take a stereo "file.wav" and give you "left.wav" and "right.wav" mono files.

But if you can't get to the point of a multichannel WAV file (which appears to be your problem), none of this will help. What sort of output does Imovie provide?
 

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Posted by Stephen Furley (Member # 1277) on 09-01-2015, 07:32 AM:
 

quote: Scott Norwood

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But if you can't get to the point of a multichannel WAV file (which appears to be your problem), none of this will help. What sort of output does Imovie provide?

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