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Re: VoiceProcessingIO - echo cancellation issues
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Re: VoiceProcessingIO - echo cancellation issues


  • Subject: Re: VoiceProcessingIO - echo cancellation issues
  • From: Raphaël - Mancing Dolecules <email@hidden>
  • Date: Wed, 23 Jun 2010 22:52:10 +0200

Hi Zachary,

I've done some tests today on the VoiceProcessingIO too.

I've also noticed that when using external speakers the echo cancellation is not that good, if there is any at all (tested on an iPod Touch 2G OS 3.1.3). On an iPhone Edge Os 3.1.3 using built-in mic/speaker, the AU simply don't work (no callback called) whereas the standard RemoteIO is fine, but works when headset is plugged. And on the iPad using built-in mic/speaker, here it works quite well !

I suppose that on OS 3.X the echo cancellation is calibrated for "hand free" use of the phone alone. Haven't tested on iOS4.

Is the VoiceProcessingIO simply not supported on the iPhone Edge using built-in mic ? Would not be too surprised as the audio device seems to be particular in this configuration (hardware sample rate limited to 8000Hz for example).

Thanks :) !

Raphaël

2010/6/23 Zachary Kulis <email@hidden>
Hi all,

I am trying to use the VoiceProcessingIO audio unit to perform acoustic
echo suppression for a VoIP chat client. I've noticed that the echo
cancellation in iPhone OS 3.X does not perform very well when the output
audio is connected to external speakers. I can hear that the VPIO unit
is performing *some* echo cancellation, but the suppression is not very
good.

I was wondering if anyone else has tried using the VPIO to perform echo
cancellation (using external speakers), and whether the results were
satisfactory. Also, iOS4 introduces a new quality parameter for the
VPIO; could anyone shed some light onto what this parameter actually does?

Thanks,

Zach
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