Re: How can I use a WAV based DSP library with AudioQueue?
Re: How can I use a WAV based DSP library with AudioQueue?
- Subject: Re: How can I use a WAV based DSP library with AudioQueue?
- From: "tahome izwah" <email@hidden>
- Date: Tue, 9 Dec 2008 21:01:11 +0100
I think you are confusing different terms here: "WAV" (MS-WAVE) is a
file format for storing PCM (and compressed formats like IMA ADPCM) in
a file that has a specific format.
Is your "WAV based DSP library" really using MS-WAVE files to apply
some kind of DSP processing to them?
Or are you in fact talking about using DSP algorithms on a linear PCM
representation of an audio signal? If so, what data format does that
library expect? IEEE754 float? 16bit signed ints? You can convert MP3
content to these data types using the CoreAudio API.
--th
2008/12/9 Andrew E. Davidson <email@hidden>:
> Hi
>
>
>
> I want to modify the iPhone "Speak Hear" sample application to use a WAV
> based DSP library.
>
>
>
> I figured out how to play audio files in just about any format using
> AudioFileReadPackets() AudioQueueEnqueueBuffer(). How ever I am not sure
> what format the buffer returned by AudioFileReadPackets will be in or what
> format the buffer needs to be in before I can call
> AudioQueueEnqueueBuffer().
>
>
>
> At a high level I want do something like
>
>
>
> 1) read buffer from mp3
>
> 2) convert to wav format
>
> 3) process buffer using WAV based DSP library
>
> 4) play buffer
>
>
>
> I think WAV is a linear PCM format. Will AudioFileReadPackets() returns the
> buffer in a format I can use with my WAV library or do I need to run some
> sort of conversation / codec? Can some one point me at the library for
> conversions?
>
>
>
> I assume that if I need to convert the format between step 2) & 3) I will
> need to perform another conversation from wav to ??? between step 3) and 4)
> Is this correct?
>
>
>
> I expect my application will get more complicated in the future. Should I be
> using AudioQueues or something else? The Audio documentation talks about
> audio graphs, how ever its not clear to me if they are available on iPhone
> or if they will make my job easier or not.
>
>
>
> Thanks
>
>
>
> Andy
>
>
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