ao/wasapi: new wasapi device monitoring interface

Implement skeleton IMMNotificationClient to watch for changes in the
sound device.  This will make recovery possible from changes shared
mode sample rate, bit depth, "enhancements"/effects and even graceful
device removal.

http://msdn.microsoft.com/en-us/library/windows/desktop/dd371417%28v=vs.85%29.aspx

Signed-off-by: Kevin Mitchell <kevmitch@gmail.com>

audio/out/ao_wasapi.h

@@ -30,6 +30,14 @@
 
 #include "osdep/atomics.h"
 
+typedef struct change_notify {
+    IMMNotificationClient client;
+    LPWSTR monitored; /* Monitored device */
+} change_notify;
+
+HRESULT wasapi_change_init(struct change_notify *change, IMMDevice *monitor);
+void wasapi_change_free(struct change_notify *change);
+
 typedef struct wasapi_state {
     struct mp_log *log;
     HANDLE threadLoop;

audio/out/ao_wasapi_changenotify.c

@@ -0,0 +1,171 @@
+/*
+ * 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 General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define COBJMACROS 1
+#define _WIN32_WINNT 0x600
+
+#include <initguid.h>
+#include <audioclient.h>
+#include <endpointvolume.h>
+#include <mmdeviceapi.h>
+#include <wchar.h>
+#include <stdlib.h>
+
+#include "ao_wasapi.h"
+#include "ao_wasapi_utils.h"
+
+static int GUID_compare(const GUID *l, const GUID *r)
+{
+    unsigned int i;
+    if (l->Data1 != r->Data1) return 1;
+    if (l->Data2 != r->Data2) return 1;
+    if (l->Data3 != r->Data3) return 1;
+    for (i = 0; i < 8; i++) {
+        if (l->Data4[i] != r->Data4[i]) return 1;
+    }
+    return 0;
+}
+
+static HRESULT STDMETHODCALLTYPE sIMMNotificationClient_QueryInterface(
+    IMMNotificationClient* This, REFIID riid, void **ppvObject)
+{
+    /* Compatible with IMMNotificationClient and IUnknown */
+    if (!GUID_compare(&IID_IMMNotificationClient, riid) ||
+        !GUID_compare(&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;
+
+    if (!wcscmp(change->monitored, pwstrDeviceId)){
+        switch (dwNewState) {
+        case DEVICE_STATE_DISABLED:
+        case DEVICE_STATE_NOTPRESENT:
+        case DEVICE_STATE_UNPLUGGED:
+
+        case DEVICE_STATE_ACTIVE:
+        default:
+            return S_OK;
+        }
+    }
+    return S_OK;
+}
+
+static HRESULT STDMETHODCALLTYPE sIMMNotificationClient_OnDeviceAdded(
+    IMMNotificationClient *This,
+    LPCWSTR pwstrDeviceId)
+{
+    change_notify *change = (change_notify *)This;
+
+    return S_OK;
+}
+
+/* maybe MPV can go over to the prefered device once it is plugged in? */
+static HRESULT STDMETHODCALLTYPE sIMMNotificationClient_OnDeviceRemoved(
+    IMMNotificationClient *This,
+    LPCWSTR pwstrDeviceId)
+{
+    change_notify *change = (change_notify *)This;
+
+    if (!wcscmp(change->monitored, pwstrDeviceId)) {
+
+    }
+    return S_OK;
+}
+
+static HRESULT STDMETHODCALLTYPE sIMMNotificationClient_OnDefaultDeviceChanged(
+    IMMNotificationClient *This,
+    EDataFlow flow,
+    ERole role,
+    LPCWSTR pwstrDeviceId)
+{
+    change_notify *change = (change_notify *)This;
+
+    if (!wcscmp(change->monitored, pwstrDeviceId)) {
+
+    }
+    return S_OK;
+}
+
+static HRESULT STDMETHODCALLTYPE sIMMNotificationClient_OnPropertyValueChanged(
+    IMMNotificationClient *This,
+    LPCWSTR pwstrDeviceId,
+    const PROPERTYKEY key)
+{
+    change_notify *change = (change_notify *)This;
+
+    if (!wcscmp(change->monitored, pwstrDeviceId)) {
+
+    }
+    return S_OK;
+}
+
+static CONST_VTBL IMMNotificationClientVtbl sIMMDeviceEnumeratorVtbl_vtbl = {
+    .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 change_notify *change, IMMDevice *monitor)
+{
+    HRESULT ret;
+
+    if ( ((ret = IMMDevice_GetId(monitor, &change->monitored)) != S_OK) ) {
+        wasapi_change_free(change);
+        return ret;
+    }
+
+    ret = S_OK;
+    change->client.lpVtbl = &sIMMDeviceEnumeratorVtbl_vtbl;
+    return ret;
+}
+
+void wasapi_change_free(struct change_notify *change)
+{
+    if (change->monitored) CoTaskMemFree(change->monitored);
+}

wscript_build.py

@@ -153,6 +153,7 @@ def build(ctx):
         ( "audio/out/ao_sndio.c",                "sndio" ),
         ( "audio/out/ao_wasapi.c",               "wasapi" ),
         ( "audio/out/ao_wasapi_utils.c",         "wasapi" ),
+        ( "audio/out/ao_wasapi_changenotify.c",  "wasapi" ),
         ( "audio/out/pull.c" ),
         ( "audio/out/push.c" ),