Re: Audio data in float format for iOS?

Subject: Re: Audio data in float format for iOS?
From: Gregory Wieber <email@hidden>
Date: Mon, 17 Jan 2011 12:34:04 -0800

Morgan,

Depending on the processor you are using, you may be taking a HUGE hit for those conversions between integers and floats. I noticed a giant speed-up in my app when I removed any floating point operations and converted everything to integer calculations (which means you'll most likely have to read up on bit shifting, etc).

Again, as I just mentioned though, this was for an app compiled without Thumb enabled. On newer processors, thumb 2 supports floating point calculations, so I would also be curious to hear other's recommendations.

Specifically, to your question: from my limited knowledge on the subject, whether you use integers or floats really depends on the processor. I would look at whether your app needs to work on older devices where thumb is not recommended, and if so, avoid floats. Otherwise, let's see what some of the more experienced folks here recommend for the newer processors that support floats with thumb 2.

On Mon, Jan 17, 2011 at 12:25 PM, morgan packard <email@hidden> wrote:

I'm currently doing all of my synthesis in floating point land (0-1
values) and converting to ints only at the final step, when writing to
the remote io callback. Any guesses as to how much of a performance
hit I'm taking because of this? I'm using the STK library for
envelopes and oscillators, which is float-based.

Sent from my iPhone

On Jan 17, 2011, at 1:17 PM, Aran Mulholland <email@hidden> wrote:

> Im pretty sure (but don't mindbeing corrected) that on the iOS platform the only core audio data type that is supported is just integer. The most efficient format to use is going to be a pure integer one and the next candidate will be a fixed point implementation. Until we get a floating point processor on board.....
>
>
> On Jan 18, 2011, at 1:32 AM, Steve gfx <email@hidden> wrote:
>
>> Thanks, I'll take a look at that.
>>
>>
>> On 17 Jan 2011, at 14:26, tahome izwah wrote:
>>
>>> Stephan Bernsee's Dirac iPhone example comes with an EAFRead class
>>> that converts CA ABLs into float arrays. I found it quite useful and
>>> am (mis)using it frequently ever since I discovered it:
>>>
>>> http://dirac.dspdimension.com
>>>
>>> HTH
>>> --th
>>
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Follow-Ups:
- Re: Audio data in float format for iOS?
  - From: tahome izwah <email@hidden>

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>)

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