private static ISimpleAudioVolume GetVolumeObject(int pid)
{
// get the speakers (1st render + multimedia) device
IMmDeviceEnumerator deviceEnumerator = (IMmDeviceEnumerator)(new MMDeviceEnumerator());
IMmDevice speakers;
deviceEnumerator.GetDefaultAudioEndpoint(EDataFlow.ERender, ERole.EMultimedia, out speakers);
string defaultDeviceId;
speakers.GetId(out defaultDeviceId);
ISimpleAudioVolume volumeControl = GetVolumeObject(pid, speakers);
Marshal.ReleaseComObject(speakers);
if (volumeControl == null)
{
// If volumeControl is null, then the process's volume object might be on a different device.
// This happens if the process doesn't use the default device.
//
// As far as Spotify is concerned, if using the "--enable-audio-graph" command line argument,
// a new option becomes available in the Settings that makes it possible to change the playback device.
IMmDeviceCollection deviceCollection;
deviceEnumerator.EnumAudioEndpoints(EDataFlow.ERender, EDeviceState.Active, out deviceCollection);
int count;
deviceCollection.GetCount(out count);
for (int i = 0; i < count; i++)
{
IMmDevice device;
deviceCollection.Item(i, out device);
string deviceId;
device.GetId(out deviceId);
try
{
if (deviceId == defaultDeviceId)
{
continue;
}
volumeControl = GetVolumeObject(pid, device);
if (volumeControl != null)
{
break;
}
}
finally
{
Marshal.ReleaseComObject(device);
}
}
}
Marshal.ReleaseComObject(deviceEnumerator);
return(volumeControl);
}
private static ISimpleAudioVolume GetVolumeObject(int pid)
{
// get the speakers (1st render + multimedia) device
IMmDeviceEnumerator deviceEnumerator = (IMmDeviceEnumerator)(new MMDeviceEnumerator());
IMmDevice speakers;
deviceEnumerator.GetDefaultAudioEndpoint(EDataFlow.ERender, ERole.EMultimedia, out speakers);
// activate the session manager. we need the enumerator
Guid iidIAudioSessionManager2 = typeof(IAudioSessionManager2).GUID;
object o;
speakers.Activate(ref iidIAudioSessionManager2, 0, IntPtr.Zero, out o);
IAudioSessionManager2 mgr = (IAudioSessionManager2)o;
// enumerate sessions for on this device
IAudioSessionEnumerator sessionEnumerator;
mgr.GetSessionEnumerator(out sessionEnumerator);
int count;
sessionEnumerator.GetCount(out count);
// search for an audio session with the required name
// NOTE: we could also use the process id instead of the app name (with IAudioSessionControl2)
ISimpleAudioVolume volumeControl = null;
for (int i = 0; i < count; i++)
{
IAudioSessionControl2 ctl;
sessionEnumerator.GetSession(i, out ctl);
int cpid;
ctl.GetProcessId(out cpid);
if (cpid == pid)
{
volumeControl = (ISimpleAudioVolume)ctl;
break;
}
Marshal.ReleaseComObject(ctl);
}
Marshal.ReleaseComObject(sessionEnumerator);
Marshal.ReleaseComObject(mgr);
Marshal.ReleaseComObject(speakers);
Marshal.ReleaseComObject(deviceEnumerator);
return(volumeControl);
}
