Bug 848954 - Part 22 - Port the osx panning code to live in the AudioCallbackDriver. r=jesup

content/media/GraphDriver.cpp

@@ -6,6 +6,10 @@
 #include <MediaStreamGraphImpl.h>
 #include "CubebUtils.h"
 
+#ifdef XP_MACOSX
+#include <sys/sysctl.h>
+#endif
+
 #ifdef PR_LOGGING
 extern PRLogModuleInfo* gMediaStreamGraphLog;
 #define STREAM_LOG(type, msg) PR_LOG(gMediaStreamGraphLog, type, msg)
@@ -515,6 +519,9 @@ AudioCallbackDriver::Init()
     return;
   }
 
+  cubeb_stream_register_device_changed_callback(mAudioStream,
+                                                AudioCallbackDriver::DeviceChangedCallback_s);
+
   StartStream();
 
   STREAM_LOG(PR_LOG_DEBUG, ("AudioCallbackDriver started."));
@@ -659,6 +666,13 @@ AudioCallbackDriver::StateCallback_s(cubeb_stream* aStream, void * aUser,
   driver->StateCallback(aState);
 }
 
+/* static */ void
+AudioCallbackDriver::DeviceChangedCallback_s(void* aUser)
+{
+  AudioCallbackDriver* driver = reinterpret_cast<AudioCallbackDriver*>(aUser);
+  driver->DeviceChangedCallback();
+}
+
 bool AudioCallbackDriver::InCallback() {
   MonitorAutoLock mon(mGraphImpl->GetMonitor());
   return mInCallback;
@@ -813,6 +827,59 @@ AudioCallbackDriver::MixerCallback(AudioDataValue* aMixedBuffer,
   NS_WARN_IF_FALSE(written == aFrames - toWrite, "Dropping frames.");
 };
 
+void AudioCallbackDriver::PanOutputIfNeeded(bool aMicrophoneActive)
+{
+#ifdef XP_MACOSX
+  cubeb_device* out;
+  int rv;
+  char name[128];
+  size_t length = sizeof(name);
+
+  rv = sysctlbyname("hw.model", name, &length, NULL, 0);
+  if (rv) {
+    return;
+  }
+
+  if (!strncmp(name, "MacBookPro", 10)) {
+    if (cubeb_stream_get_current_device(mAudioStream, &out) == CUBEB_OK) {
+      // Check if we are currently outputing sound on external speakers.
+      if (!strcmp(out->output_name, "ispk")) {
+        // Pan everything to the right speaker.
+        if (aMicrophoneActive) {
+          if (cubeb_stream_set_panning(mAudioStream, 1.0) != CUBEB_OK) {
+            NS_WARNING("Could not pan audio output to the right.");
+          }
+        } else {
+          if (cubeb_stream_set_panning(mAudioStream, 0.0) != CUBEB_OK) {
+            NS_WARNING("Could not pan audio output to the center.");
+          }
+        }
+      } else {
+        if (cubeb_stream_set_panning(mAudioStream, 0.0) != CUBEB_OK) {
+          NS_WARNING("Could not pan audio output to the center.");
+        }
+      }
+      cubeb_stream_device_destroy(mAudioStream, out);
+    }
+  }
+#endif
+}
+
+void
+AudioCallbackDriver::DeviceChangedCallback() {
+  MonitorAutoLock mon(mGraphImpl->GetMonitor());
+  PanOutputIfNeeded(mMicrophoneActive);
+}
+
+void
+AudioCallbackDriver::SetMicrophoneActive(bool aActive)
+{
+  MonitorAutoLock mon(mGraphImpl->GetMonitor());
+
+  mMicrophoneActive = aActive;
+
+  PanOutputIfNeeded(mMicrophoneActive);
+}
 
 uint32_t
 AudioCallbackDriver::IterationDuration()

content/media/GraphDriver.h

@@ -342,6 +342,7 @@ public:
                              long aFrames);
   static void StateCallback_s(cubeb_stream* aStream, void * aUser,
                               cubeb_state aState);
+  static void DeviceChangedCallback_s(void * aUser);
   /* This function is called by the underlying audio backend when a refill is
    * needed. This is what drives the whole graph when it is used to output
    * audio. If the return value is exactly aFrames, this function will get
@@ -370,7 +371,19 @@ public:
   bool InCallback();
 
   bool IsStarted();
+
+  /* Tell the driver whether this process is using a microphone or not. This is
+   * thread safe. */
+  void SetMicrophoneActive(bool aActive);
 private:
+  /**
+   * On certain MacBookPro, the microphone is located near the left speaker.
+   * We need to pan the sound output to the right speaker if we are using the
+   * mic and the built-in speaker, or we will have terrible echo.  */
+  void PanOutputIfNeeded(bool aMicrophoneActive);
+  /**
+   * This is called when the output device used by the cubeb stream changes. */
+  void DeviceChangedCallback();
   /* Start the cubeb stream */
   void StartStream();
   friend class AsyncCubebTask;
@@ -426,6 +439,10 @@ private:
    * but has not done so yet. This indicates tha the callback should return
    * early */
   bool mPauseRequested;
+  /**
+   * True if microphone is being used by this process. This is synchronized by
+   * the graph's monitor. */
+  bool mMicrophoneActive;
 };
 
 class AsyncCubebTask : public nsRunnable