Re: Deinterleave using ExtendedAudioFile

Subject: Re: Deinterleave using ExtendedAudioFile

From: David Paterson <email@hidden>

Date: Mon, 19 Mar 2007 18:37:03 -0400

Delivered-to: email@hidden

Thanks. I had thought of that approach, but correct me if I am wrong, won't that run through the whole process twice and take twice as long?

It seemed to me that the most efficient approach is to create 3 AudioBufferLists, that share 2 AudioBuffers. I list that is deinterleaved with 2 channels and 2 lists that are each mono. 1 for the left and 1 for the right. And to get the 2 AudioBuffers in the mono list to simply point to each of the buffers in the 2 channel list.

Then I can read into the Stereo list and write from each of the mono lists. As long as I set the clientformat of the reader to be canonical, deinterleaved.

I think I am correct in all of this - but I simply can not figure out the way to set up the AudiBufferLists correctly. That is the only part that eludes me, and I am sure it is quite simple.

I have been able to find a number of examples on setting up the buffer lists - but none that do this, They seem to do this in the afInterleave example, but in a way that is fairly convoluted and I have not been able to duplicate it.

Any advice would be appreciated.

David Paterson

On Mar 19, 2007, at 6:27 PM, William Stewart wrote:

You can use the ExtendedAudioFile API (see the ConvertFile code in /Developer/Examples/CoreAudio/SimpleSDK/)

The only bit not covered in this is using the channel map property (to say which channel you do/don't want). So in the case of the mono file, this would be 1 UInt32 int, with either 0 (the first channel) or 1 (the second channel) to come from the file for your mono file

Bill

On 16/03/2007, at 4:18 PM, David Paterson wrote:

I know I am going to feel stupid. Everywhere I search it implies that this is easy but I can not figure out how to do it. I simply want to take an interleaved stereo file and convert it to 2 mono files. I tried looking at afInterleave to see if I could reverse the process - but I couldn't figure it out. If anyone can point me in the right direction I would greatly appreciate it.

David Paterson

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References:
	>Deinterleave using ExtendedAudioFile (From: David Paterson <email@hidden>)
	>Re: Deinterleave using ExtendedAudioFile (From: William Stewart <email@hidden>)