Re: kAudioSessionProperty_InputGainScalar default value?
Re: kAudioSessionProperty_InputGainScalar default value?
- Subject: Re: kAudioSessionProperty_InputGainScalar default value?
- From: Zachary Kulis <email@hidden>
- Date: Sat, 29 Oct 2011 11:45:25 -0400
Yes, I did try -1.0, but it returned an error. Guess I'll have to file a
bug report.
Thanks,
Zach
> This may be a long shot but did you try -1?
>
> --th
>
> 2011/10/27 Zachary Kulis <email@hidden>:
>> iOS5 introduced a new audio session property called
>> 'kAudioSessionProperty_InputGainScalar' that allows setting the gain of the
>> input device.
>>
>> This property seems to work as expected - setting to 0 turns the gain off,
>> while setting to 1.0 sets the gain to its max value. The thing that I can't
>> figure out is how to set the input gain to its default value after setting
>> it to some other value.
>>
>> For example, setting the input gain to any valid value seems to permanently
>> disable the automatic gain control. This would be fine in 'measurement'
>> mode, but per Apple's documentation, the 'default' audio session mode should
>> enable automatic gain adjustment of the input signal. However, setting the
>> mode to 'measurement', setting the input gain to 1.0, and then setting the
>> mode back to 'default' does not reset/re-enable the AGC. In fact, the
>> microphone signal becomes completely saturated if the input gain is set to
>> 1.0 and 'default' mode is enabled.
>>
>> The documentation states:
>>
>> "If no app with an active audio session is using this property for a given
>> input source, the system restores the default input gain setting for the
>> input source."
>>
>> Either I'm missing something, or Apple did not provide a way to disable
>> manual gain control (via the property) and re-enable the AGC (via setting
>> the audio session mode).
>>
>> If anyone has any ideas of how to "reset" the input gain controller, I'd be
>> most grateful.
>>
>> -Zach
>>
>>
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