Make RAW WASAPI streams opt-in

include/cubeb/cubeb.h

@@ -230,12 +230,14 @@ typedef enum {
   CUBEB_STREAM_PREF_DISABLE_DEVICE_SWITCHING = 0x02, /**< Disable switching
                                                           default device on OS
                                                           changes. */
-  CUBEB_STREAM_PREF_VOICE = 0x04  /**< This stream is going to transport voice data.
+  CUBEB_STREAM_PREF_VOICE = 0x04, /**< This stream is going to transport voice data.
                                        Depending on the backend and platform, this can
                                        change the audio input or output devices
                                        selected, as well as the quality of the stream,
                                        for example to accomodate bluetooth SCO modes on
                                        bluetooth devices. */
+  CUBEB_STREAM_PREF_RAW = 0x08  /**< Windows only. Bypass all signal processing
+                                     except for always on APO, driver and hardware. */
 } cubeb_stream_prefs;
 
 /** Stream format initialization parameters. */

src/cubeb_wasapi.cpp

@@ -2102,9 +2102,12 @@ int setup_wasapi_stream_one_side(cubeb_stream * stm,
     LOG("Could not get cubeb_device_info.");
   }
 
-  if (initialize_iaudioclient2(audio_client) != CUBEB_OK) {
-    LOG("Can't create the reconfigure event, error: %lx", GetLastError());
-    // This is not fatal.
+  if (stm->output_stream_params.prefs & CUBEB_STREAM_PREF_RAW ||
+      stm->input_stream_params.prefs & CUBEB_STREAM_PREF_RAW) {
+    if (initialize_iaudioclient2(audio_client) != CUBEB_OK) {
+      LOG("Can't initialize an IAudioClient2, error: %lx", GetLastError());
+      // This is not fatal.
+    }
   }
 
 #if 0 // See https://bugzilla.mozilla.org/show_bug.cgi?id=1590902