waveOutGetDevCaps, Win7 and long device names - windows-7

Question

I'm maintaining an old code base that's using waveOutGetDevCaps to get the names of the audio devices on the system. On Windows 7 machines this results in truncated names, as WAVEOUTCAPS.szPname is limited by MAXPNAMELEN (31 chars).
What's the Win7 way of doing this?

Answer 1

You could use one of the Core Audio APIs:
// get the device enumerator
IMMDeviceEnumerator* pEnumerator = NULL;
HRESULT hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL,
CLSCTX_ALL,__uuidof(IMMDeviceEnumerator),
(void**)&pEnumerator);
// get the endpoint collection
IMMDeviceCollection* pCollection = NULL;
DWORD mask = DEVICE_STATE_ACTIVE || DEVICE_STATE_UNPLUGGED;
hr = pEnumerator->EnumAudioEndpoints(eRender, mask, &pCollection);
// get the size of the collection
UINT count = 0;
hr = pCollection->GetCount(&count);
for (int i = 0; i < (int)count; i++)
{
// get the endpoint
IMMDevice* pEndPoint = NULL;
hr = pCollection->Item(i, &pEndPoint);
// get the human readable name
String^ friendlyName;
IPropertyStore* pProps = NULL;
HRESULT hr = pEndPoint->OpenPropertyStore(STGM_READ, &pProps);
PROPVARIANT varName;
PropVariantInit(&varName);
hr = pProps->GetValue(PKEY_Device_FriendlyName, &varName);
friendlyName = gcnew String(varName.pwszVal);
PropVariantClear(&varName);
}
Error handling was removed in the above code to make it more readable. (I happen to love using C++/CLI to move between C# and the Windows APIs.)
Now the harder part will be to relate the endpoint names to the MME devices in your old code base.

Answer 2

I have found another way using the registry to find audio devices' full name, both Input and Output.
Works on Windows 7 and Windows 10.
procedure TForm_Config.FormCreate(Sender: TObject);
type
tagWAVEOUTCAPS2A = packed record
wMid: WORD;
wPid: WORD;
vDriverVersion: MMVERSION;
szPname: array[0..MAXPNAMELEN-1] of AnsiChar;
dwFormats: DWORD;
wChannels: WORD;
wReserved1: WORD;
dwSupport: DWORD;
ManufacturerGuid: System.TGUID;
ProductGuid: System.TGUID;
NameGuid: System.TGUID;
end;
var
i,outdevs: Integer;
woCaps: tagWAVEOUTCAPS2A;
RegistryService: TRegistry;
iClasses, iSubClasses, iNames: Integer;
audioDeviceClasses, audioDeviceSubClasses, audioDeviceNames: TStringList;
initialDeviceName, partialDeviceName, fullDeviceName: string;
begin
audioDeviceClasses := TStringList.Create;
audioDeviceSubClasses := TStringList.Create;
audioDeviceNames := TStringList.Create;
try
RegistryService := TRegistry.Create;
try
RegistryService.RootKey := HKEY_LOCAL_MACHINE;
if RegistryService.OpenKeyReadOnly('\SYSTEM\CurrentControlSet\Enum\HDAUDIO\') then begin
RegistryService.GetKeyNames(audioDeviceClasses);
RegistryService.CloseKey();
for iClasses := 0 to audioDeviceClasses.Count - 1 do begin
if RegistryService.OpenKeyReadOnly('\SYSTEM\CurrentControlSet\Enum\HDAUDIO\'+audioDeviceClasses[iClasses]) then begin
RegistryService.GetKeyNames(audioDeviceSubClasses);
RegistryService.CloseKey();
for iSubClasses := 0 to audioDeviceSubClasses.Count - 1 do begin
if RegistryService.OpenKeyReadOnly('\SYSTEM\CurrentControlSet\Enum\HDAUDIO\'+audioDeviceClasses[iClasses]+'\'+audioDeviceSubClasses[iSubClasses]) then begin
if RegistryService.ValueExists('DeviceDesc') then begin
fullDeviceName := Trim(RegistryService.ReadString('DeviceDesc'));
if AnsiPos(';',fullDeviceName) > 0 then begin
fullDeviceName := Trim(AnsiMidStr(fullDeviceName, AnsiPos(';',fullDeviceName)+1, Length(fullDeviceName)));
end;
audioDeviceNames.Add(fullDeviceName);
end;
RegistryService.CloseKey();
end;
end;
end;
end;
end;
finally
FreeAndNil(RegistryService);
end;
// WaveOutDevComboBox is a selection box (combo) placed in the form and will receive the list of output audio devices
WaveOutDevComboBox.Clear;
try
outdevs := waveOutGetNumDevs;
for i := 0 to outdevs - 1 do begin
ZeroMemory(#woCaps, sizeof(woCaps));
if waveOutGetDevCaps(i, #woCaps, sizeof(woCaps)) = MMSYSERR_NOERROR then begin
RegistryService := TRegistry.Create;
try
RegistryService.RootKey := HKEY_LOCAL_MACHINE;
if RegistryService.OpenKeyReadOnly('\System\CurrentControlSet\Control\MediaCategories\' + GUIDToString(woCaps.NameGuid)) then begin
WaveOutDevComboBox.Items.Add(RegistryService.ReadString('Name'));
RegistryService.CloseKey();
end
else begin
initialDeviceName := '';
partialDeviceName := Trim(woCaps.szPname);
if AnsiPos('(',partialDeviceName) > 0 then begin
initialDeviceName := Trim(AnsiLeftStr(partialDeviceName,AnsiPos('(',partialDeviceName)-1));
partialDeviceName := Trim(AnsiMidStr(partialDeviceName,AnsiPos('(',partialDeviceName)+1,Length(partialDeviceName)));
if AnsiPos(')',partialDeviceName) > 0 then begin
partialDeviceName := Trim(AnsiLeftStr(partialDeviceName,AnsiPos(')',partialDeviceName)-1));
end;
end;
for iNames := 0 to audioDeviceNames.Count - 1 do begin
fullDeviceName := audioDeviceNames[iNames];
if AnsiStartsText(partialDeviceName,fullDeviceName) then begin
break;
end
else begin
fullDeviceName := partialDeviceName;
end;
end;
WaveOutDevComboBox.Items.Add(initialDeviceName + IfThen(initialDeviceName<>EmptyStr,' (','') + fullDeviceName + IfThen(initialDeviceName<>EmptyStr,')',''));
end;
finally
FreeAndNil(RegistryService);
end;
end;
end;
except
WaveOutDevComboBox.Enabled := False;
end;
finally
FreeAndNil(audioDeviceClasses);
FreeAndNil(audioDeviceSubClasses);
FreeAndNil(audioDeviceNames);
end;
end;