Re: Disabling dual-mic noise suppression in iPhone 4?
Re: Disabling dual-mic noise suppression in iPhone 4?
- Subject: Re: Disabling dual-mic noise suppression in iPhone 4?
- From: William Stewart <email@hidden>
- Date: Fri, 2 Jul 2010 18:13:52 -0700
On Jul 2, 2010, at 1:31 PM, Paul Nettle wrote:
> Hi Bill,
>
> I’m really stuck at the moment on this issue, because I’m unable to find any documentation that covers how to control the noise-cancelling mic.
Paul
I know you are frustrated, but you really need to read my responses. This is NOT engaged in any use case you can run at the moment.
> I understand that you don’t believe that noise cancellation is the cause of the problem, but at the same time, the results I’m seeing are very convincing that this is actually cancelling the audio.
>
> If the problem is not related to noise cancellation, can you suggest what it might be, and where I can look for a solution?
So, you stated to me in a separate email that you are using the VoiceProcessing audio unit. That does indeed do echo cancellation and the like. If you don't want this, then you should be using the AURemoteIO. There are also some bypass properties of the VP AU that you can use to turn processing on and off, but the best way to ensure that you don't have anything like this going on is to run with the AURemoteIO.
I would also run one of the sample apps that does recording (SpeakHere for example). That way you can verify that you can actually record sound ok. You could also try AVAudioRecorder to verify this yourself, it is pretty straight forward to run.
I would also look carefully at the formats you are getting from the audio units you are using. If you are expecting say 16it, but are actually getting 8.24, then that could be quite weird.
If you are still stuck, then please file a bug report and include some code we can run and we will see what we can figure out.
Thanks
Bill
>
> Paul Nettle
> Creator of Break Speed
> MyBreakSpeed.com
>
> From: coreaudio-api-bounces+pnettle=email@hidden [mailto:coreaudio-api-bounces+pnettle=email@hidden] On Behalf Of Paul Nettle
> Sent: Thursday, July 01, 2010 4:18 PM
> To: William Stewart
> Cc: email@hidden
> Subject: Re: Disabling dual-mic noise suppression in iPhone 4?
>
> Hi again Bill,
>
> I suppose then that I am confused as to why the same app would receive such different audio results from the iPhone 4 device, when compared to all other devices (iPod 2nd & 3rd gen, all iPhones.)
>
> Paul Nettle
> Creator of Break Speed
>
> ----- Reply message -----
> From: "William Stewart" <email@hidden>
> Date: Thu, Jul 1, 2010 3:54 pm
> Subject: Disabling dual-mic noise suppression in iPhone 4?
> To: "Paul Nettle" <email@hidden>
> Cc: <email@hidden>
>
>
> On Jul 1, 2010, at 11:51 AM, Paul Nettle wrote:
>
>
> Bill,
>
> You are correct that it is using the bottom mic. However, it is also using the noise suppression mic to reduce ambient nose.
>
> No Paul, it is not. That is not engaged at all times but only in limited use cases (for instance, a phone call is one case where this is engaged), and not in any use case that is available to an application at this stage.
>
> Bill
>
>
> My app (Break Speed) allows the user to view/pan/zoom into the recorded waveform. You can see a clear difference. In fact, I compared the difference between an iphone 4 and a 3gs in a noisy environment and the iphone 4 did a very impressive job of supressing the ambient noise to nearly a flat line.
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