Re: AudioConverter.h

Subject: Re: AudioConverter.h
From: Gavin Burke <email@hidden>
Date: Mon, 04 Aug 2008 21:17:11 +0100
Delivered-to: email@hidden
Delivered-to: email@hidden

Hi Khamba,

Looking at AudioFramework in the sdk for the mobile version of 10.5, it seems to be missing ExtAudioFile.h and also AudioConverter.h AudioConverter.h would have made life very easy.

Correct me where I am wrong, I think the main problem is that on the platform that this version of 10.5 is for, mp3 decoding is done in hardware and thus its tied to the AudioQueue and not something that can be done offline as you would expect. Due to this hardware decoding its missing all mp3 decoding functions other than those in AudioFile.h, with no offline mp3 decode functions available.

The main idea is that we want to play two mp3 files at the same time. One way was to decode both mp3 files offline, not tied to the audio callback, save back as .wav and then play them back simultaneously with out any restrictions. But as it looks like this version of 10.5 is lacking a software mp3 decoder, with the ability to decode only one mp3 file at a time and that decoding tied into the audio clock. I'm starting to think it is not possible to achieve what we want without using a 3rd party software mp3 decoder lib.

I could be way off though!

Message: 7
Date: Mon, 4 Aug 2008 13:42:11 +0200 (CEST)
From: "Khamba Staring" <email@hidden>
Subject: Re: AudioConverter.h
To: email@hidden
Message-ID:
	<email@hidden>
Content-Type: text/plain;charset=iso-8859-1
Hello Gavin,
On OSX, you can use ExtAudioFile to open a file and have it converted into another format. What do you mean by only having AudioFile.h ? ExtAudioFile should be on every OSX install.

Alternatively you can use AudioFile & AudioQueue (Leopard, iP) to render audio using AudioQueueOfflineRender(); this call can convert compressed audio into a PCM format. If you have it working, please tell me how you did it! ;)
Regards,
Khamba Staring

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