Re: Stuttering in audio with VPIO

Subject: Re: Stuttering in audio with VPIO
From: Lucas Ives <email@hidden>
Date: Mon, 14 Jan 2013 13:59:47 -0800

I believe there are (well, were) only two algorithms for echo cancellation quality -- 0-63 was the first, and 64-127 was the more expensive 2nd. It sounds like you have enough other stuff going on in your app and audio callback to bring the processing to its knees.

But ... that setting is deprecated going forward .. meaning in a future version of iOS your app will *always* stutter on the iPhone 4. That being the case, I'd leave it set to >64 and bring down your processing load by looking for low-hanging fruit in the audio callback.

-l

On Mon, Jan 14, 2013 at 9:44 AM, Pier <email@hidden> wrote:

Hi,

I'm recording several audio tracks with the VPIO input.
I've been experimenting and realised that the sound is significantly better when I set the kAUVoiceIOProperty_VoiceProcessingQuality above 63. On the iPhone4 it also resolves my issue of the volume not being loud enough. However, when I set the quality above 63, I hear stutters in my playback. I'm running using AUGraph :

Source : VPIO in
MultiChannelMixer (4 inputs) -> VPIO out

  // Quality

  UInt32 flagnvaw = 65; // 63 is the best it will go without stutter

  status = AudioUnitSetProperty(_remoteIOUnit,

  kAUVoiceIOProperty_VoiceProcessingQuality,

  kAudioUnitScope_Output,
  0,

  &flagnvaw,
  sizeof(flagnvaw));

With one track it's ok, however when I record the 2nd track it stutters and the playback is distorted.

Anyone here has experience with this? How did you resolve the issue?

Thank you.

Pier.

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References:
	>Stuttering in audio with VPIO (From: Pier <email@hidden>)

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