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Re: remoteio glitches - minimum workable buffer size? maximum available cpu time?
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Re: remoteio glitches - minimum workable buffer size? maximum available cpu time?


  • Subject: Re: remoteio glitches - minimum workable buffer size? maximum available cpu time?
  • From: Aran Mulholland <email@hidden>
  • Date: Sat, 29 May 2010 21:45:19 +1000

I can answer some of this...
 
I'm trying to get some low-latency network audio streaming code up on a current-generation ipod touch/latest 3.x iphone os. Using remoteio I'm getting glitches which seem like remoteio deadlines getting missed -- they happen when there's on screen animation (like the keyboard sliding out) or often when a 2 line text label is updated every 10 seconds from an NSTimer callback. My remoteio callback is completely lock and blocking-api free, but it does use some CPU... I've included some info about why I'm using remoteio later.

Are you getting these in release mode, or even when not running from the debugger. I have had this issue when pushing a view when running in the debugger but not when the run is initiated from the device (not xcode)
 
My questions are:

- I'm currently using a 256 sample callback buffer size at 44.1k (set using kAudioSessionProperty_PreferredHardwareSampleRate  , kAudioSessionProperty_PreferredHardwareIOBufferDuration). Should I expect this setting to deliver stable audio? Can I use even smaller buffers?

 im using this code and it gives me a buffer size of 64 samples.

    Float32 preferredBufferSize = 0.0025;
    status = AudioSessionSetProperty(kAudioSessionProperty_PreferredHardwareIOBufferDuration, sizeof(preferredBufferSize), &preferredBufferSize);
   
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 >remoteio glitches - minimum workable buffer size? maximum available cpu time? (From: "Ross Bencina" <email@hidden>)

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