Converting ADPCM audio track for editing videos in iMovie

Thanks for the link. I actually read that before posting this one and it did not do the trick. I don't have QTPro and couldn't get GarageBand to do what I wanted.

Any thoughts on another program on my computer that may be interfering with the audio playback? I read somewhere that Roxio's CD burner might be causing trouble but I don't have that or any other burning software (other than Disk Util) on my Mac.

Just to clarify what I meant by GarageBand not doing what I want it to and maybe help someone who is in a similar situation:
Following this post http://discussions.apple.com/thread.jspa?threadID=1232251

2) Since H.264 video is already good, you can simply "Pass through" the unchanged video while converting the DVI ADPCM audio to MPEG-4 audio (i.e., AAC). This can be accomplished most easily with QT Po if you have it. If you don't, then create a GarageBand project and import/drop the file to the iPod/Move track and confirm "replacement." Once loaded to GarageBand project window, it can then be exported using QuickTime. In this case use the "Expert" option to select the "Movie to MPEG-4" pop-up menu and select "Options" to open the main options window. Once there, select the basic MP4 file format with "Pass Through" video tab option, "AAC-LC (Music" with a mono data rate of 64 Kbps at a 44.1 KHz sampling rate audio tab option, and deselect the streaming tab option. New file will have your original video plus editable AAC audio which can be imported to iMovie '08.

I tried the above steps as follows:
1. Open GarageBand
--a. New Project --> Choose --> named whatever / saved wherever
2. Actually drag the original .avi from Finder window to GB "Tracks" frame (or wherever). This loads fine with video and audio both playing.
3. Share --> Export Movie to Disk...
4. Video Setting: Expert Setting --> Export
5. Name whatever, save wherever using Export: Movie to MPEG-4
6. Click Options...
7. File Format: MP4
(This is where I can't continue as the above quote recommends. For "Video Format" the "Pass through" option is grayed out.)
8. Video tab
--a.Video Format: H.264 (the original format)
--b. Data Rate: 8500 kbits/sec (around original rate from QT stats)
--c.Image Size: 1280 x 720 HD
9. Audio tab
--a. Audio Format: AAC-LC (Music)
--b. Data Rate: 192 kbps (original was 177 from MPEGSC)
--c. Channels: Mono
--d. Output Sample Rate: 44.100 kHz
Anything not mentioned was kept as default values.
--> OK --> Save

This takes a little over a minute for a 17 second clip. Output is a .mp4 with following format:
AAC, Mono, 44.100 kHz, H.264, 1280 x 720, Millions

This can now be dragged into iMovie with audio and video playing fine. So, in the end, this process does work.

The problem is the time it takes (4 times the playback time, not counting the setup in GB menus, since I can't pass through the video and am essentially converting the original video format to itself) and the lack of the ability to automate.

I guess the last question to be answered: Why would QT play an .avi video and audio without problems, but then MPEGSC not get the audio playing?

I will try good ol' FFmpeg(X) to get this automated and I will post results if a single-lined command gets the job done.

FFmpeg worked. I installed it on my Mac using this page
http://stephenjungels.com/jungels.net/articles/ffmpeg-howto.html
and everything went OK except installing the AAC encoder/decoder (related to original issue?), but I didn't try too hard to figure out why and the processes below worked without that step.

The command-line code to do what I wanted is

ffmpeg -i OriginalVid.avi -sameq -acodec aac OutputVid.mov

This worked perfectly.

"-sameq" keeps the original quality of the video format
"-acodec aac" changed the audio codec to AAC as desired.

Obviously you name OriginalVid.avi whatever your original file is called and OutputVid.mov whatever you want to call your new movie. The resulting file worked in iMovie and after exporting the project the quality was preserved. I'll post again if I figure out a nice Automator work flow that converts several vids with two clicks.

Karsten Schlüter wrote:
arrghgh.. command-lines! are way above my head (=me Mac user since 1986) .. 😀

I know that FFmpegX is a GUI version of FFmpeg. Haven't tried it out but I'm sure there are some good tuts to get it working for those more graphically inclined.