Example.cpp

#include <stdio.h>
#include <windows.h>
#include <mmdeviceapi.h>
#include <endpointvolume.h>

void Usage()
{
	printf("Usage: \n");
	printf(" SetVolume [Reports the current volume]\n");
	printf(" SetVolume -d <new volume in decibels> [Sets the current default render device volume to the new volume]\n");
	printf(" SetVolume -f <new volume as an amplitude scalar> [Sets the current default render device volume to the new volume]\n");
}

int _tmain(int argc, _TCHAR* argv[])
{
	HRESULT hr;

	bool decibels = false;
	bool scalar = false;
	double newVolume;
	
	if (argc != 3 && argc != 1)
	{
		Usage();
		return -1;
	}
	
	if (argc == 3)
	{
		if (argv[1][0] == '-')
		{
			if (argv[1][1] == 'f')
			{
				scalar = true;
			}
			else if (argv[1][1] == 'd')
			{
				decibels = true;
			}
		}
		else
		{
			Usage();
			return -1;
		}
		
		newVolume = _tstof(argv[2]);
	}
	
	// -------------------------
	
	CoInitialize(NULL);

	IMMDeviceEnumerator *deviceEnumerator = NULL;
	hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_INPROC_SERVER, __uuidof(IMMDeviceEnumerator), (LPVOID *)&deviceEnumerator);
	
	IMMDevice *defaultDevice = NULL;
	hr = deviceEnumerator->GetDefaultAudioEndpoint(eRender, eConsole, &defaultDevice);
	deviceEnumerator->Release();
	deviceEnumerator = NULL;
	
	IAudioEndpointVolume *endpointVolume = NULL;
	hr = defaultDevice->Activate(__uuidof(IAudioEndpointVolume), CLSCTX_INPROC_SERVER, NULL, (LPVOID *)&endpointVolume);
	defaultDevice->Release();
	defaultDevice = NULL;
	
	// -------------------------
	
	float currentVolume = 0;
	endpointVolume->GetMasterVolumeLevel(&currentVolume);
	
	printf("Current volume in dB is: %f\n", currentVolume);
	
	hr = endpointVolume->GetMasterVolumeLevelScalar(&currentVolume);
	
	printf("Current volume as a scalar is: %f\n", currentVolume);
	
	if (decibels)
	{
		hr = endpointVolume->SetMasterVolumeLevel((float)newVolume, NULL);
	}
	else if (scalar)
	{
		hr = endpointVolume->SetMasterVolumeLevelScalar((float)newVolume, NULL);
	}
	
	endpointVolume->Release();
	CoUninitialize();
	return 0;
}