right alt + F1 - headphones // right alt + F2 - speakers (you can add more devices)

playback_device_switcher.ahk

; PURPOSE: Use hotkeys to switch between audio devices

; source: https://www.autohotkey.com/boards/viewtopic.php?t=49980

Devices := {}
IMMDeviceEnumerator := ComObjCreate("{BCDE0395-E52F-467C-8E3D-C4579291692E}", "{A95664D2-9614-4F35-A746-DE8DB63617E6}")

; IMMDeviceEnumerator::EnumAudioEndpoints
; eRender = 0, eCapture, eAll
; 0x1 = DEVICE_STATE_ACTIVE
DllCall(NumGet(NumGet(IMMDeviceEnumerator+0)+3*A_PtrSize), "UPtr", IMMDeviceEnumerator, "UInt", 0, "UInt", 0x1, "UPtrP", IMMDeviceCollection, "UInt")
ObjRelease(IMMDeviceEnumerator)

; IMMDeviceCollection::GetCount
DllCall(NumGet(NumGet(IMMDeviceCollection+0)+3*A_PtrSize), "UPtr", IMMDeviceCollection, "UIntP", Count, "UInt")
Loop % (Count)
{
    ; IMMDeviceCollection::Item
    DllCall(NumGet(NumGet(IMMDeviceCollection+0)+4*A_PtrSize), "UPtr", IMMDeviceCollection, "UInt", A_Index-1, "UPtrP", IMMDevice, "UInt")

    ; IMMDevice::GetId
    DllCall(NumGet(NumGet(IMMDevice+0)+5*A_PtrSize), "UPtr", IMMDevice, "UPtrP", pBuffer, "UInt")
    DeviceID := StrGet(pBuffer, "UTF-16"), DllCall("Ole32.dll\CoTaskMemFree", "UPtr", pBuffer)

    ; IMMDevice::OpenPropertyStore
    ; 0x0 = STGM_READ
    DllCall(NumGet(NumGet(IMMDevice+0)+4*A_PtrSize), "UPtr", IMMDevice, "UInt", 0x0, "UPtrP", IPropertyStore, "UInt")
    ObjRelease(IMMDevice)

    ; IPropertyStore::GetValue
    VarSetCapacity(PROPVARIANT, A_PtrSize == 4 ? 16 : 24)
    VarSetCapacity(PROPERTYKEY, 20)
    DllCall("Ole32.dll\CLSIDFromString", "Str", "{A45C254E-DF1C-4EFD-8020-67D146A850E0}", "UPtr", &PROPERTYKEY)
    NumPut(14, &PROPERTYKEY + 16, "UInt")
    DllCall(NumGet(NumGet(IPropertyStore+0)+5*A_PtrSize), "UPtr", IPropertyStore, "UPtr", &PROPERTYKEY, "UPtr", &PROPVARIANT, "UInt")
    DeviceName := StrGet(NumGet(&PROPVARIANT + 8), "UTF-16")    ; LPWSTR PROPVARIANT.pwszVal
    DllCall("Ole32.dll\CoTaskMemFree", "UPtr", NumGet(&PROPVARIANT + 8))    ; LPWSTR PROPVARIANT.pwszVal
    ObjRelease(IPropertyStore)

    ObjRawSet(Devices, DeviceName, DeviceID)
}
ObjRelease(IMMDeviceCollection)
Return

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; CHANGE HOTKEYS FOR SWITCHING HERE;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>!F1:: SetDefaultEndpoint( GetDeviceID(Devices, "Headphones") )
>!F2:: SetDefaultEndpoint( GetDeviceID(Devices, "Speakers") )


SetDefaultEndpoint(DeviceID)
{
    IPolicyConfig := ComObjCreate("{870af99c-171d-4f9e-af0d-e63df40c2bc9}", "{F8679F50-850A-41CF-9C72-430F290290C8}")
    DllCall(NumGet(NumGet(IPolicyConfig+0)+13*A_PtrSize), "UPtr", IPolicyConfig, "UPtr", &DeviceID, "UInt", 0, "UInt")
    ObjRelease(IPolicyConfig)
}

GetDeviceID(Devices, Name)
{
    For DeviceName, DeviceID in Devices
        If (InStr(DeviceName, Name))
            Return DeviceID
}