CODEWITHSUNDEEP
xcodeaudioaudio-recordingavaudiosession
Mikail Lo
Mikail Lo

Reputation: 31

How to change the input gain for AVAudioSession? xcode

I've been having some problems trying to adjust the input gain when recording using the AVAudioSession and AVAudioRecorder from the AVFoundations framework. I've found the method setInputGain which accepts a float [0.0, 1.0], So far, it kinda looks like this:

In my viewDidLoad:

    //Initialise the AVAudioSession, and share between different functions
    AVAudioSession *audioSession = [AVAudioSession sharedInstance];
    [audioSession setCategory:AVAudioSessionCategoryPlayAndRecord error:nil];
    [audioSession setActive:YES error:nil];
    [audioSession setInputGain:1.0 error:nil];

However, the setInputGain method only gives you additional gain on top of what is currently being recorded, so setting it at 0.0 is not going to mute it but setting it at 1.0 is going to make the input louder. There is a property that I've found in the AudioSession class called kAudioSessionProperty_InputGainScalar but can't seem to write a value into it. I need a little help, please.

This is the recording function, which follows another tutorial:

    //Creating a temporary place to record
    tempRecFile = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent:@"sound.caf"]];
    recorder = [[AVAudioRecorder alloc] initWithURL:tempRecFile
                                           settings:nil
                                              error:nil];
    [recorder setDelegate:self];
    //Setting the input gain for the recording, then proceed to record
    //[audioSession setInputGain:inputGainSlider.value error:nil];
    [recorder prepareToRecord];
    [recorder record];
    [self.inputGainSlider setEnabled:NO];

Upvotes: 3

Views: 2880

Answers (2)

Manuel Alejandro Arredondo
Manuel Alejandro Arredondo

Reputation: 11

none of the devices I've tested this on allows for setting input gain. I haven't found an official list of devices from apple yet... Here are the devices I tried: iphone 4s iphone 6s ipad pro

Upvotes: 1

LetBulletFlies
LetBulletFlies

Reputation: 285

From official document, I see following lines,

Discussion

Before calling this method, you should check the value in the inputGainSettable property to make sure the input gain level is settable for the current inputs.

so is there any possibility that device doesn't support change it?

Upvotes: 0

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