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Re: using integer audio data
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Re: using integer audio data


  • Subject: Re: using integer audio data
  • From: Bill Stewart <email@hidden>
  • Date: Fri, 24 Aug 2001 14:57:30 -0700

I think you have some misunderstanding here.

Firstly int->float is pretty cheap in the scheme of things (say like playing DVD)

Secondly, latency is determined by how big your buffer is when you're asked to provide data to a device and then the time it takes once the hardware has that buffer to actually put it out speakers. Neither of these things are effected by int->float overhead, except if you do so much work when given a buffer of audio to provide data for that you over-step the time constraints of your app. Still, this is not really a question about latency - though if you have to do alot of work (like decode MP3, then you typically deal with larger buffers to ease the load of the system - thus introduce some "latency", but this can be accounted for quite easily... if synchronization is a concern CoreAUdio publishes an abundance of timing information so you can work out how long it will take before your sample actually hits the speaker.

Bill

On Friday, August 24, 2001, at 02:10 PM, James Farwell wrote:


AudioConverter sounds nice, but the thing that worries me is since
it is yet another layer on top of the hardware it means increased
latency. Would you still consider it the best solution for
streaming audio apps?

This does not introduce latency.

The AudioConverter will deal with PCM formats only (at least
initially) - I'm not sure what you're asking though...


Bill,

I meant as a function of how long it takes between when you write the audio data and when it actually gets played. It sounded like AudioConverter was designed to sit on top of CoreAudio and convert the integer audio data, so I was assuming that it probably had a buffer of its own to store the data, which is one more buffer the data has to pass through before it gets to the hardware and is actually played. However, from other replies it sounds like the latency is really quite low already and getting better, so it's not a big deal.

- James

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