windows - Change audio level from powershell?

Question

How can I use powershell to set the speaker volume? Ive dug around on here and elsewhere online can cant really find an answer.

I think I will have to write something in C# that wraps a Win32 API and THEN call it from my powershell script. The Win32 API's would be one of these

[DllImport("winmm.dll")]
public static extern int waveOutGetVolume(IntPtr hwo, out uint dwVolume);

[DllImport("winmm.dll")]
public static extern int waveOutSetVolume(IntPtr hwo, uint dwVolume);

Answer 1

SendKeys stopped working for me in Windows 10 (it literally types digits where my caret is). I found this blog post with a very convenient way of doing it.

First, run this to get access to the audio API:

Add-Type -TypeDefinition @'
using System.Runtime.InteropServices;
[Guid("5CDF2C82-841E-4546-9722-0CF74078229A"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
interface IAudioEndpointVolume
{
    // f(), g(), ... are unused COM method slots. Define these if you care
    int f(); int g(); int h(); int i();
    int SetMasterVolumeLevelScalar(float fLevel, System.Guid pguidEventContext);
    int j();
    int GetMasterVolumeLevelScalar(out float pfLevel);
    int k(); int l(); int m(); int n();
    int SetMute([MarshalAs(UnmanagedType.Bool)] bool bMute, System.Guid pguidEventContext);
    int GetMute(out bool pbMute);
}
[Guid("D666063F-1587-4E43-81F1-B948E807363F"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
interface IMMDevice
{
    int Activate(ref System.Guid id, int clsCtx, int activationParams, out IAudioEndpointVolume aev);
}
[Guid("A95664D2-9614-4F35-A746-DE8DB63617E6"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
interface IMMDeviceEnumerator
{
    int f(); // Unused
    int GetDefaultAudioEndpoint(int dataFlow, int role, out IMMDevice endpoint);
}
[ComImport, Guid("BCDE0395-E52F-467C-8E3D-C4579291692E")] class MMDeviceEnumeratorComObject { }
public class Audio
{
    static IAudioEndpointVolume Vol()
    {
        var enumerator = new MMDeviceEnumeratorComObject() as IMMDeviceEnumerator;
        IMMDevice dev = null;
        Marshal.ThrowExceptionForHR(enumerator.GetDefaultAudioEndpoint(/*eRender*/ 0, /*eMultimedia*/ 1, out dev));
        IAudioEndpointVolume epv = null;
        var epvid = typeof(IAudioEndpointVolume).GUID;
        Marshal.ThrowExceptionForHR(dev.Activate(ref epvid, /*CLSCTX_ALL*/ 23, 0, out epv));
        return epv;
    }
    public static float Volume
    {
        get { float v = -1; Marshal.ThrowExceptionForHR(Vol().GetMasterVolumeLevelScalar(out v)); return v; }
        set { Marshal.ThrowExceptionForHR(Vol().SetMasterVolumeLevelScalar(value, System.Guid.Empty)); }
    }
    public static bool Mute
    {
        get { bool mute; Marshal.ThrowExceptionForHR(Vol().GetMute(out mute)); return mute; }
        set { Marshal.ThrowExceptionForHR(Vol().SetMute(value, System.Guid.Empty)); }
    }
}
'@

Then control the volume like this:

[audio]::Volume  = 0.2 # 0.2 = 20%, etc.

And mute/unmute like this:

[audio]::Mute = $true  # Set to $false to un-mute