How to get Mac audio level?

Question

Currently, I have code that successfully returns the value of the users system audio value that they can set with the volume keys.

However, what I want is a value of the audio the speakers are playing. So if the user is watching Netflix and a character starts screaming, the value would return higher than if the character was whispering.

Code I have now:

+ (AudioDeviceID)defaultOutputDeviceID {
    OSStatus status = noErr;

    AudioDeviceID outputDeviceID = kAudioObjectUnknown;

    AudioObjectPropertyAddress propertyAOPA;
    propertyAOPA.mElement = kAudioObjectPropertyElementMaster;
    propertyAOPA.mScope = kAudioObjectPropertyScopeGlobal;
    propertyAOPA.mSelector = kAudioHardwarePropertyDefaultSystemOutputDevice;

    UInt32 propertySize = sizeof(outputDeviceID);

    if (!AudioHardwareServiceHasProperty(kAudioObjectSystemObject, &propertyAOPA)) {
        NSLog(@"Cannot find default output device!");
        return outputDeviceID;
    }

    status = AudioHardwareServiceGetPropertyData(kAudioObjectSystemObject, &propertyAOPA, 0, NULL, &propertySize, &outputDeviceID);

    if(status) {
        NSLog(@"Cannot find default output device!");
    }

    return outputDeviceID;
}

+ (float)volume {
    OSStatus status = noErr;

    AudioDeviceID outputDeviceID = [[self class] defaultOutputDeviceID];

    if (outputDeviceID == kAudioObjectUnknown) {
        NSLog(@"Unknown device");
        return 0.0;
    }

    AudioObjectPropertyAddress propertyAOPA;
    propertyAOPA.mElement = kAudioObjectPropertyElementMaster;
    propertyAOPA.mScope = kAudioDevicePropertyScopeOutput;
    propertyAOPA.mSelector = kAudioHardwareServiceDeviceProperty_VirtualMasterVolume;

    Float32 outputVolume;
    UInt32 propertySize = sizeof(outputVolume);

    if (!AudioHardwareServiceHasProperty(outputDeviceID, &propertyAOPA)) {
        NSLog(@"No volume returned for device 0x%0x", outputDeviceID);
        return 0.0;
    }

    status = AudioHardwareServiceGetPropertyData(outputDeviceID, &propertyAOPA, 0, NULL, &propertySize, &outputVolume);

    if (status) {
        NSLog(@"No volume returned for device 0x%0x", outputDeviceID);
        return 0.0;
    }

    if (outputVolume < 0.0 || outputVolume > 1.0)
        return 0.0;

    return outputVolume;
}

possible duplicate of [How can I get the current sound level of the current audio output device?](http://stackoverflow.com/questions/11893555/how-can-i-get-the-current-sound-level-of-the-current-audio-output-device), [this tutorial may also help.](http://www.raywenderlich.com/36475/how-to-make-a-music-visualizer-in-ios) — davidcondrey, Dec 14 '14 at 08:05
Not exactly the same question. I'm looking for the audio level itself. Not the system audio level. The code in that answer honestly didn't help me much. — , Dec 14 '14 at 18:55

score -1 · Answer 1 · edited May 23 '17 at 12:06

-1

Get the volume level and set it as you want (as max. volume) and then revert it back again to users original volume level. For more details you can see the below link; https://stackoverflow.com/a/27743599/1351327
Hope it will help. (Be careful that Apple will reject your app)

edited May 23 '17 at 12:06

Community

1
1

answered Apr 27 '15 at 07:31

ondermerol

524
1
11
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I have only test and use it for i-phone so I am not sure that it will work for Mac or not. – ondermerol May 13 '15 at 07:00

How to get Mac audio level?

1 Answers1