mpv/audio/out/ao_wasapi_changenotify.c

/*
 * This file is part of mpv.
 *
 * Original author: Jonathan Yong <10walls@gmail.com>
 *
 * mpv is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * mpv is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <wchar.h>

#include "ao_wasapi.h"

static HRESULT STDMETHODCALLTYPE sIMMNotificationClient_QueryInterface(
    IMMNotificationClient* This, REFIID riid, void **ppvObject)
{
    // Compatible with IMMNotificationClient and IUnknown
    if (IsEqualGUID(&IID_IMMNotificationClient, riid) ||
        IsEqualGUID(&IID_IUnknown, riid))
    {
        *ppvObject = (void *)This;
        return S_OK;
    } else {
        *ppvObject = NULL;
        return E_NOINTERFACE;
    }
}

// these are required, but not actually used
static ULONG STDMETHODCALLTYPE sIMMNotificationClient_AddRef(
    IMMNotificationClient *This)
{
    return 1;
}

// MSDN says it should free itself, but we're static
static ULONG STDMETHODCALLTYPE sIMMNotificationClient_Release(
    IMMNotificationClient *This)
{
    return 1;
}

static HRESULT STDMETHODCALLTYPE sIMMNotificationClient_OnDeviceStateChanged(
    IMMNotificationClient *This,
    LPCWSTR pwstrDeviceId,
    DWORD dwNewState)
{
    change_notify *change = (change_notify *)This;
    struct ao *ao = change->ao;

    if (change->is_hotplug) {
        MP_VERBOSE(ao,
                   "OnDeviceStateChanged triggered: sending hotplug event\n");
        ao_hotplug_event(ao);
    } else if (pwstrDeviceId && !wcscmp(pwstrDeviceId, change->monitored)) {
        switch (dwNewState) {
        case DEVICE_STATE_DISABLED:
        case DEVICE_STATE_NOTPRESENT:
        case DEVICE_STATE_UNPLUGGED:
            MP_VERBOSE(ao, "OnDeviceStateChanged triggered on device %ls: "
                       "requesting ao reload\n", pwstrDeviceId);
            ao_request_reload(ao);
            break;
        case DEVICE_STATE_ACTIVE:
            break;
        }
    }

    return S_OK;
}

static HRESULT STDMETHODCALLTYPE sIMMNotificationClient_OnDeviceAdded(
    IMMNotificationClient *This,
    LPCWSTR pwstrDeviceId)
{
    change_notify *change = (change_notify *)This;
    struct ao *ao = change->ao;

    if (change->is_hotplug) {
        MP_VERBOSE(ao, "OnDeviceAdded triggered: sending hotplug event\n");
        ao_hotplug_event(ao);
    }

    return S_OK;
}

// maybe MPV can go over to the preferred device once it is plugged in?
static HRESULT STDMETHODCALLTYPE sIMMNotificationClient_OnDeviceRemoved(
    IMMNotificationClient *This,
    LPCWSTR pwstrDeviceId)
{
    change_notify *change = (change_notify *)This;
    struct ao *ao = change->ao;

    if (change->is_hotplug) {
        MP_VERBOSE(ao, "OnDeviceRemoved triggered: sending hotplug event\n");
        ao_hotplug_event(ao);
    } else if (pwstrDeviceId && !wcscmp(pwstrDeviceId, change->monitored)) {
        MP_VERBOSE(ao, "OnDeviceRemoved triggered for device %ls: "
                   "requesting ao reload\n", pwstrDeviceId);
        ao_request_reload(ao);
    }

    return S_OK;
}

static HRESULT STDMETHODCALLTYPE sIMMNotificationClient_OnDefaultDeviceChanged(
    IMMNotificationClient *This,
    EDataFlow flow,
    ERole role,
    LPCWSTR pwstrDeviceId)
{
    change_notify *change = (change_notify *)This;
    struct ao *ao = change->ao;

    // don't care about "eCapture" or non-"eMultimedia" roles
    if (flow == eCapture || role != eMultimedia) return S_OK;

    if (change->is_hotplug) {
        MP_VERBOSE(ao,
                   "OnDefaultDeviceChanged triggered: sending hotplug event\n");
        ao_hotplug_event(ao);
    } else {
        // stay on the device the user specified
        bstr device = wasapi_get_specified_device_string(ao);
        if (device.len) {
            MP_VERBOSE(ao, "OnDefaultDeviceChanged triggered: "
                       "staying on specified device %.*s\n", BSTR_P(device));
            return S_OK;
        }

        // don't reload if already on the new default
        if (pwstrDeviceId && !wcscmp(pwstrDeviceId, change->monitored)) {
            MP_VERBOSE(ao, "OnDefaultDeviceChanged triggered: "
                       "already using default device, no reload required\n");
            return S_OK;
        }

        // if we got here, we need to reload
        MP_VERBOSE(ao,
                   "OnDefaultDeviceChanged triggered: requesting ao reload\n");
        ao_request_reload(ao);
    }

    return S_OK;
}

static HRESULT STDMETHODCALLTYPE sIMMNotificationClient_OnPropertyValueChanged(
    IMMNotificationClient *This,
    LPCWSTR pwstrDeviceId,
    const PROPERTYKEY key)
{
    change_notify *change = (change_notify *)This;
    struct ao *ao = change->ao;

    if (!change->is_hotplug && pwstrDeviceId &&
        !wcscmp(pwstrDeviceId, change->monitored))
    {
        MP_VERBOSE(ao, "OnPropertyValueChanged triggered on device %ls\n",
                   pwstrDeviceId);
        if (IsEqualPropertyKey(PKEY_AudioEngine_DeviceFormat, key)) {
            MP_VERBOSE(change->ao,
                       "Changed property: PKEY_AudioEngine_DeviceFormat "
                       "- requesting ao reload\n");
            ao_request_reload(change->ao);
        } else {
            MP_VERBOSE(ao, "Changed property: %s\n", mp_PKEY_to_str(&key));
        }
    }

    return S_OK;
}

static CONST_VTBL IMMNotificationClientVtbl sIMMNotificationClientVtbl = {
    .QueryInterface = sIMMNotificationClient_QueryInterface,
    .AddRef = sIMMNotificationClient_AddRef,
    .Release = sIMMNotificationClient_Release,
    .OnDeviceStateChanged = sIMMNotificationClient_OnDeviceStateChanged,
    .OnDeviceAdded = sIMMNotificationClient_OnDeviceAdded,
    .OnDeviceRemoved = sIMMNotificationClient_OnDeviceRemoved,
    .OnDefaultDeviceChanged = sIMMNotificationClient_OnDefaultDeviceChanged,
    .OnPropertyValueChanged = sIMMNotificationClient_OnPropertyValueChanged,
};


HRESULT wasapi_change_init(struct ao *ao, bool is_hotplug)
{
    struct wasapi_state *state = ao->priv;
    struct change_notify *change = &state->change;
    HRESULT hr = CoCreateInstance(&CLSID_MMDeviceEnumerator, NULL, CLSCTX_ALL,
                                  &IID_IMMDeviceEnumerator,
                                  (void **)&change->pEnumerator);
    EXIT_ON_ERROR(hr);

    // so the callbacks can access the ao
    change->ao = ao;

    // whether or not this is the hotplug instance
    change->is_hotplug = is_hotplug;

    if (is_hotplug) {
        MP_DBG(ao, "Monitoring for hotplug events\n");
    } else {
        // Get the device string to compare with the pwstrDeviceId
        change->monitored = state->deviceID;
        MP_VERBOSE(ao, "Monitoring changes in device %ls\n", change->monitored);
    }

    // COM voodoo to emulate c++ class
    change->client.lpVtbl = &sIMMNotificationClientVtbl;

    // register the change notification client
    hr = IMMDeviceEnumerator_RegisterEndpointNotificationCallback(
        change->pEnumerator, (IMMNotificationClient *)change);
    EXIT_ON_ERROR(hr);

    return hr;
exit_label:
    MP_ERR(state, "Error setting up device change monitoring: %s\n",
           mp_HRESULT_to_str(hr));
    wasapi_change_uninit(ao);
    return hr;
}

void wasapi_change_uninit(struct ao *ao)
{
    struct wasapi_state *state = ao->priv;
    struct change_notify *change = &state->change;

    if (change->pEnumerator && change->client.lpVtbl) {
        IMMDeviceEnumerator_UnregisterEndpointNotificationCallback(
            change->pEnumerator, (IMMNotificationClient *)change);
    }

    SAFE_RELEASE(change->pEnumerator);
}