Windows not sending 'KSCATEGORY_AUDIO' notification for audio devices

[siradam7th]

I noticed that KSCATEGORY_AUDIO isn't being sent by Windows to WndProc in WM_DEVICECHANGE, but instead DEVINTERFACE_AUDIO_RENDER is received when a playback device is inserted.

Test setup
Platform: Windows 10
Windows SDK version: 10.0.22000
Tested using both a Headset & Earbuds (front and back panel).

Solution:
Assuming this is the actual behaviour on other systems, I suggest this wiki page to be updated to filter for DEVINTERFACE_AUDIO_RENDER and handle receiving it, maybe even alongside KSCATEGORY_AUDIO (just in case)
the Wiki page in question: "Adding audio to your project"

Changes:

// for DEVINTERFACE_AUDIO_RENDER 
#include <Mmdeviceapi.h>

DEV_BROADCAST_DEVICEINTERFACE filter = {};
        filter.dbcc_size = sizeof( filter );
        filter.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;
        filter.dbcc_classguid = DEVINTERFACE_AUDIO_RENDER ;

        hNewAudio = RegisterDeviceNotification( hwnd, &filter,
            DEVICE_NOTIFY_WINDOW_HANDLE );

and

case WM_DEVICECHANGE:
    if ( wParam == DBT_DEVICEARRIVAL )
    {
        auto pDev = reinterpret_cast<PDEV_BROADCAST_HDR>( lParam );
        if( pDev )
        {
            if ( pDev->dbch_devicetype == DBT_DEVTYP_DEVICEINTERFACE )
            {
                auto pInter = reinterpret_cast<
                    const PDEV_BROADCAST_DEVICEINTERFACE>( pDev );
                if ( pInter->dbcc_classguid == DEVINTERFACE_AUDIO_RENDER)
                {
                    if (game)
                        game->OnNewAudioDevice();
                }
            }
        }
    }
    return 0;

Sidenote:
In order to get KSCATEGORY_AUDIO definition you must also include ks.h before ksmedia.h for it to compile.

// for KSCATEGORY_AUDIO
#include <Dbt.h>
#include <ks.h>
#include <ksmedia.h>

[walbourn]

Thanks for the follow-up. All audio devices are supposed to use KSCATEGORY_AUDIO as well, so maybe it's a driver bug?

What driver is it?

[siradam7th]

Realtek High Definition Audio, version 6.0.8945.1

[walbourn]

Are you using the default audio device when creating the XAudio2 mastering graph, or are you enumerating a specific device?

[siradam7th]

I have confirmed that this is a driver bug.
Since uninstalling the Realtek HD Audio Driver and reverting back to the standard Windows 10 driver solves this problem (still a realtek driver, but the one that ships with Windows), it sends an KSCATEGORY_AUDIO as expected.
But once the Realtek HD Audio Driver (tested versions: 6.0.9225.1, 6.0.8945.1) is installed, it no longer receives it, and instead starts receiving DEVINTERFACE_AUDIO_RENDER.

Proposition:
Since this bug might affect other systems causing inconsistent behaviour based on the audio driver, I suggest to also register notifications for DEVINTERFACE_AUDIO_RENDER so that even systems with an audio driver with this behaviour can get notifications as expected.

[walbourn]

Thanks for the follow-up.

If you use the default device for XAudio2 instead of enumerate a specific device, on Windows 10+ you won't actually get a graph error for changing end-points as OnCriticalError. This relies on WASAPI virtualized client. In that case, you don't really need this notification.

[siradam7th]

Yes, it is best to handle this using Audio apis rather than rely on WM_DEVICECHANGE.
Anyways, I hope this issue will be helpful to anyone that runs into this bug as I couldn't find anything about it.