#2782

Switching Audio Input and Output With PowerShell

Switching between different audio input and output devices on Windows XP is pretty straightforward. You can do this using the Control Panel > Sounds, Speech, and Audio Devices > Sounds and Audio Devices tab (see right). It means opening this up and changing the appropriate dropdowns.

I wanted to implement be able to quickly switch between the onboard Realtek HD Audio sound and a Bluetooth handsfree audio device – in this case a Jawbone earpiece – on my Samsung NC10. There are a couple of tools that will switch sound devices. But it seemed like a good excuse to play around some more with PowerShell…

Switching devices in PowerShell

All the control panel dialog is doing under the hood is changing a few registry settings. What I wanted a script that would let me change from one profile to another.

$r = [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
$regRoot = "HKCU:\Software\Microsoft\"


$profiles = @{"Netbook" = @("Realtek HD Audio output",      
                            "Realtek HD Audio input");
            "Bluetooth" = @("Bluetooth Hands-free Audio", 
                            "Bluetooth Hands-free Audio") }

function Write-Message ( [string]$message )
{
    echo $message
    # Uncomment this line to show dialog outputs from -set 
    # $r = [System.Windows.Forms.MessageBox]::Show($message)
}

function Set-Mapping ( [string]$devOut, [string]$devIn )
{
    echo "Profile audio:`n  in  = $devIn`n  out = $devOut"

    $regKey = $regRoot + "\Multimedia\Sound Mapper\"
    Set-ItemProperty $regKey -name Playback -value $devOut
    Set-ItemProperty $regKey -name Record -value $devIn
}

function List-Devices
{
    $regKey = $regRoot + "\Windows\CurrentVersion\Applets\Volume Control\"
    echo "Sound devices:"
    ls $regKey | where { ! $_.Name.EndsWith("Options") } | 
        Foreach-Object { 
            echo ("  " + $_.Name.Substring($_.Name.LastIndexOf("\")+1)) 
        }
}

$cmd = $args[0]
switch ($cmd)
{
    "-profiles" 
    {
        echo "Sound profiles:"
        echo $profiles
    }
    "-devices"
    {
        List-Devices
    }
    "-set" 
    {
        $p = $args[1]
        if (!$profiles.ContainsKey($p)) {
            echo "No such profile: $p"
            echo $profiles
            exit
        }
        Set-Mapping $profiles.Get_Item($p)[0] $profiles.Get_Item($p)[1]
        Write-Message "Profile set to: $p"
    }
    default 
    { 
        Write-Message "No such option: $cmd" 
    }
}

As you can see it has three options:

• -profiles – List the available sound profiles.
• -devices – List the sound devices.
• -set [profile] – Set the audio profile.

You can add more profiles by updating the $profiles hash at the top of the script. You can setup one click switching by creating shortcuts on the desktop that run set commands:

%WINDIR%\system32\windowspowershell\v1.0\powershell.exe -command ".\SwitchAudio.ps1 -set Bluetooth"

I just have two shortcuts on my desktop to switch between the netbook speakers and bluetooth audio inputs and outputs. The only other thing to not is that many applications don’t detect that the default audio settings have changed after they start up so you may have to restart the application you’re using.