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Re: Audio data in float format for iOS?
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Re: Audio data in float format for iOS?


  • Subject: Re: Audio data in float format for iOS?
  • From: tahome izwah <email@hidden>
  • Date: Tue, 18 Jan 2011 13:20:20 +0100

Ah well, I get it now. Like Brian said you don't, at least not on iOS.

--th

2011/1/18 Steve gfx <email@hidden>:
> Thanks Tahome.
> Sorry to labour the point, but what I'm trying to get at is how do you make
> Core Audio play nicely with these floats?
> You seem to be saying that Core Audio is allowing you to pass floats up the
> chain until the output stage?
> I'm being forced to convert back & forth at every stage, e.g. between a
> mixer and master AU.
> If you try to create an ASBD with floats you'll get an unsupported error on
> iOS.
> i.e. I know how to read a file as floats, and how to process as floats, and
> how to convert back to SInt16. The problem seems that Core Audio disallows
> floats  anywhere in its chain.
> Apologies if my original post wasn't clear on this, I only want to know how
> to make Core Audio accept floats.
>
>
> On 18 Jan 2011, at 09:06, tahome izwah wrote:
>
> In our particular case we use the EAFReader class from the Dirac
> project to convert chunks of audio coming from a file to float32,
> process the data entirely in float32 domain using our own DSP and
> convert it back to SInt16 for playback at the very end of our
> processing chain.
>
> Not sure if this answers your questions, but as I read it this sounded
> like it's what you wanted to do in your application so I recommended
> it.
>
> --th
>
>
> 2011/1/18 Steve gfx <email@hidden>:
>
> Well that sounds like the OP's original question then (See below) : How do
>
> you do remain in float32 land given the constraints of iOS & Core Audio?
>
> (Or were you originally implying that some Dirac code handles this for you?
>
> Or, do you only have ONE stage of processing anyway?)
>
> "1)Load some audio data as 32-bit floats (2-ch stereo) in to buffers.
>
> 2) Keep it in this format so that in the mixer and master callbacks no
>
> conversion is necessary to perform per-channel, or global DSP.
>
> 3) Finally convert it to whatever necessary for output."
>
> On 18 Jan 2011, at 06:07, tahome izwah wrote:
>
> No. We convert on input (and output) and stay entirely in float32 land
>
> for all computations.
>
>
>
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References: 
 >Audio data in float format for iOS? (From: Steve gfx <email@hidden>)
 >Re: Audio data in float format for iOS? (From: tahome izwah <email@hidden>)
 >Re: Audio data in float format for iOS? (From: Steve gfx <email@hidden>)
 >Re: Audio data in float format for iOS? (From: Aran Mulholland <email@hidden>)
 >Re: Audio data in float format for iOS? (From: morgan packard <email@hidden>)
 >Re: Audio data in float format for iOS? (From: Gregory Wieber <email@hidden>)
 >Re: Audio data in float format for iOS? (From: tahome izwah <email@hidden>)
 >Re: Audio data in float format for iOS? (From: Gregory Wieber <email@hidden>)
 >Re: Audio data in float format for iOS? (From: tahome izwah <email@hidden>)
 >Re: Audio data in float format for iOS? (From: Gregory Wieber <email@hidden>)
 >Re: Audio data in float format for iOS? (From: tahome izwah <email@hidden>)
 >Re: Audio data in float format for iOS? (From: tahome izwah <email@hidden>)
 >Re: Audio data in float format for iOS? (From: Steve gfx <email@hidden>)

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