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Re: Using the audio extraction API

I have been experimenting with the new audio extraction API in QT.
I have some questions:

- What is the min version of OSX this works on. It does not seem to compile on 10.2.8.

QT 7.0.

Not exactly what I asked. Setting the target OS in XCode to 10.2.8 causes my code to NOT compile.
I know what you are saying, but its not working.

- Given the above, can I make a NEW movie referencing each audio track I want data out of, and then start a new session on that movie?

Yes.

I assume this means for EACH movie, I can have ONE session open, thus making new movies allows me to have, effectively, many open. This is what I need. I may be extracting data out of the SAME audio track, but for each reference movie, at different times in the movie.


- I want to extract and convert the audio from a single track. How do I specify this? I can see how to specify left or right etc, but that mixes all left and rights together, but I want say the left of a single track only. 

There are two ways.

1) iterate through the tracks in the source movie, get the track layout, and set the channel labels you want to exclude to kAudioChannelLabel_Unused. Note that if you leave, say, multiple "Left's" labelled as "Left", they will still all mix into a single "Left", unless you specify:

2) kQTMovieAudioExtractionMoviePropertyID_AllChannelsDiscrete on the MovieAudioExtractionSession. This causes QuickTime to do _no_ mixing. You get all the source channels in all the audio tracks in the movie (in order) if you set this property.

So, if the track in question is stereo, and all others are set to "unused", then I just pick out the left or right track as needed.
Is there any other track layouts, like say 5.1 where I have more options than just left and right PER TRACK?

I'll try making the ref movie and will get back to you if there are oddities.

Thanks again.

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References: 
 >Using the audio extraction API (From: Steve Israelson <email@hidden>)
 >Re: Using the audio extraction API (From: Brad Ford <email@hidden>)



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