Re: iOS - Play streaming(mp3) audio with effects
Re: iOS - Play streaming(mp3) audio with effects
- Subject: Re: iOS - Play streaming(mp3) audio with effects
- From: "Hank Heijink (Mailinglists)" <email@hidden>
- Date: Thu, 31 Mar 2011 09:27:57 -0400
On Mar 30, 2011, at 11:14 PM, Sasikumar JP wrote:
> I am new to iOS Audio Technology.
> I am developing an application which will play streaming audio(mp3), planning to add some effects like iPod Equalizer,Pan Control.
>
> I have tried to use Matt Gallagher's AudioStreamer API (http://cocoawithlove.com/2008/09/streaming-and-playing-live-mp3-stream.html).
> I was able to play the streaming audio. but i was not sure how to add the effects using AudioQueue .
>
> From Apple Documentation, i understood that AudioUnit can be used to add Effects. But streaming format should be in Linear PCM.
Audio Units are hosted in an Audio Graph, and they use a different API than AudioQueue. To get linear PCM into your audio units, you'll have to use an instance of AudioConverter to convert between mp3 and linear PCM. Apple's Audio Unit Hosting Guide has a pretty good example of how to set this up:
http://developer.apple.com/library/ios/#documentation/MusicAudio/Conceptual/AudioUnitHostingGuide_iOS/Introduction/Introduction.html
In the callback function that provides the audio to the graph, you call AudioConverterFillComplexBuffer and associate a callback there to provide the audio converter with the mp3 data.
Keep in mind that the number of out-of-the-box effects available to iOS is limited.
Good luck,
Hank
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