Apple

  if (iOS_8) {
  bytesPerSample = sizeof (float);
  //     NSLog (@"size of AudioUnitSampleType: %lu", bytesPerSample);
  stereoStreamFormat.mFormatFlags     = kAudioFormatFlagsNativeFloatPacked | kAudioFormatFlagIsNonInterleaved;
  }
  else {
  bytesPerSample = sizeof (int32_t);

  stereoStreamFormat.mFormatFlags     = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked | kAudioFormatFlagIsNonInterleaved | (kAudioUnitSampleFractionBits << kLinearPCMFormatFlagsSampleFractionShift);
  }

This leads to a lot of unfortunate branched code. ie. separate audio callbacks for pre iOS 8 vs iOS 8 etc. If there is a cleaner solution, I would love to know it.

Hope this is helpful.

Robert Carroll

RSM Records

Toronto

http://www.rsmrecords.com

On Mar 3, 2015, at 3:00 PM, email@hidden wrote:

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Today's Topics:

  1. rendered sound is crackly under iOS8 (Bob Sabiston)

----------------------------------------------------------------------

Message: 1
Date: Mon, 02 Mar 2015 19:21:39 -0600
From: Bob Sabiston <email@hidden>
To: email@hidden
Subject: rendered sound is crackly under iOS8
Message-ID: <email@hidden>
Content-Type: text/plain; charset="windows-1252"

Hello,

I wrote about this a few weeks ago but I don’t think anyone had a response. I am trying to update my game from iOS7 to 8.   My rendered sounds are full of noise on iOS8 and I haven’t been able to figure out the problem.

The AudioUnitSampleType is deprecated, for one thing. I’ve tried setting it to float, and to SInt32, as that seems to be the two possible old values. But it doesn’t fix the problem. Also when setting up the AudioStreamBasicDescription stream format, the mFormatFlags used to be kAudioFormatFlagsAudioUnitCanonical.   I’ve read that it should now be kAudioFormatFlagIsFloat | kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked | kAudioFormatFlagIsNonInterleaved.

I’ve tried that and also changing ‘IsFloat’ to ‘IsSInt32’ to match whatever I had AudioUnitSampleType defined as. Nope, didn’t work.

Does anyone use the AUGraph stuff, with AUGraphSetNodeInputCallback for example to set the callback to render a buffer full of sound samples? I use that and a bunch of AudioUnit stuff like result = AudioUnitSetProperty (
                                              mixerUnit,
                                              kAudioUnitProperty_StreamFormat,
                                              kAudioUnitScope_Input,
                                              busNumber,
                                              &monoStreamFormat,
                                              sizeof (monoStreamFormat)
                                              );

It’s a couple of years since I looked at this stuff and I remember it being a pain to get working in the first place.   Anyone else had to port code using these functions to iOS8? Any ideas about why it isn’t working right?

Thanks!
Bob

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