Re: Playing 2 or more audio data simultaneously
Re: Playing 2 or more audio data simultaneously
- Subject: Re: Playing 2 or more audio data simultaneously
- From: Bill Stewart <email@hidden>
- Date: Wed, 18 Sep 2002 11:18:05 -0700
on 18/9/02 10:01 AM, Kurt Revis wrote:
>
On Wednesday, September 18, 2002, at 08:28 AM, Robert Goulet wrote:
>
>
> It is possible to mix sound with core audio? I'm currently able to
>
> play a single audio file because I don't understand how am I suppose
>
> to have more than one buffer in my output audio buffer list that I
>
> receive in my AudioIOProc.
>
>
This is not difficult at all; here's an overview. Use a mixer AudioUnit
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to mix multiple audio streams into one stream. You set up an input
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callback on the mixer, so it will ask you for data for each stream when
>
it needs it. On the output side, you can do two things:
>
>
1. Use one of the default audio output AudioUnits (see
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AudioToolbox/DefaultAudioOutput.h). You can connect the mixer directly
>
to this, and your application won't need to implement an IO proc
>
anymore. This is definitely the easiest route.
Then....
The PlayAudioFile code has a path which plays the same file multiple times
(this uses a mixer unit and a separate bus for each version of the file to
play)
This would be easily modified to play a different file to each bus
Bill
>
2. Keep using the same IO proc that you're using now, but in it, ask
>
the mixer AU for data using AudioUnitRender() (or
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AudioUnitRenderSlice() if the mixer AU is still a version-1 AU).
>
>
Despite what the other poster said, it's definitely not recommended to
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set up more than one IO proc on the same output in the same
>
application. I think it works, but it will cost you CPU time and
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increase the total load on the system, and will be confusing too.
>
>
Hope this helps.
>
>
--
>
Kurt Revis
>
email@hidden
>
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