Bug 1481152 - Restrict to a single input stream per process on Linux, when using PulseAudio and audio remoting is enabled. r=pehrsons

Differential Revision: https://phabricator.services.mozilla.com/D5543

--HG--
extra : moz-landing-system : lando

dom/media/CubebUtils.cpp

@@ -38,6 +38,8 @@
 #define PREF_CUBEB_OUTPUT_DEVICE "media.cubeb.output_device"
 #define PREF_CUBEB_LATENCY_PLAYBACK "media.cubeb_latency_playback_ms"
 #define PREF_CUBEB_LATENCY_MSG "media.cubeb_latency_msg_frames"
+// This only works when audio remoting is active, and pulseaudio is the backend.
+#define PREF_CUBEB_MAX_INPUT_STREAMS "media.cubeb_max_input_streams"
 // Allows to get something non-default for the preferred sample-rate, to allow
 // troubleshooting in the field and testing.
 #define PREF_CUBEB_FORCE_SAMPLE_RATE "media.cubeb.force_sample_rate"
@@ -127,6 +129,9 @@ cubeb* sCubebContext;
 double sVolumeScale = 1.0;
 uint32_t sCubebPlaybackLatencyInMilliseconds = 100;
 uint32_t sCubebMSGLatencyInFrames = 512;
+// Maximum number of audio input streams that can be open at once. This pref is
+// only used when remoting is on, and we're using PulseAudio as a backend.
+uint32_t sCubebMaxInputStreams = 1;
 // If sCubebForcedSampleRate is zero, PreferredSampleRate will return the
 // preferred sample-rate for the audio backend in use. Otherwise, it will be
 // used as the preferred sample-rate.
@@ -231,6 +236,9 @@ void PrefChanged(const char* aPref, void* aClosure)
     // We don't want to limit the upper limit too much, so that people can
     // experiment.
     sCubebMSGLatencyInFrames = std::min<uint32_t>(std::max<uint32_t>(value, 128), 1e6);
+  } else if (strcmp(aPref, PREF_CUBEB_MAX_INPUT_STREAMS) == 0) {
+    StaticMutexAutoLock lock(sMutex);
+    sCubebMaxInputStreams = Preferences::GetUint(aPref);
   } else if (strcmp(aPref, PREF_CUBEB_FORCE_SAMPLE_RATE) == 0) {
     StaticMutexAutoLock lock(sMutex);
     sCubebForcedSampleRate = Preferences::GetUint(aPref);
@@ -551,12 +559,19 @@ uint32_t GetCubebMSGLatencyInFrames(cubeb_stream_params * params)
 #endif
 }
 
+uint32_t GetMaxInputStreams()
+{
+  StaticMutexAutoLock lock(sMutex);
+  return sCubebMaxInputStreams;
+}
+
 static const char* gInitCallbackPrefs[] = {
   PREF_VOLUME_SCALE,           PREF_CUBEB_OUTPUT_DEVICE,
   PREF_CUBEB_LATENCY_PLAYBACK, PREF_CUBEB_LATENCY_MSG,
   PREF_CUBEB_BACKEND,          PREF_CUBEB_FORCE_NULL_CONTEXT,
   PREF_CUBEB_SANDBOX,          PREF_AUDIOIPC_POOL_SIZE,
-  PREF_AUDIOIPC_STACK_SIZE,    nullptr,
+  PREF_CUBEB_MAX_INPUT_STREAMS, PREF_AUDIOIPC_STACK_SIZE,
+  nullptr,
 };
 static const char* gCallbackPrefs[] = {
   PREF_CUBEB_FORCE_SAMPLE_RATE,

dom/media/CubebUtils.h

@@ -50,6 +50,7 @@ void GetDeviceCollection(nsTArray<RefPtr<AudioDeviceInfo>>& aDeviceInfos,
                          Side aSide);
 cubeb_stream_prefs GetDefaultStreamPrefs();
 char* GetForcedOutputDevice();
+uint32_t GetMaxInputStreams();
 
 #ifdef MOZ_WIDGET_ANDROID
 uint32_t AndroidGetAudioOutputSampleRate();

dom/media/tests/mochitest/head.js

@@ -422,7 +422,8 @@ function setupEnvironment() {
       ['media.getusermedia.screensharing.enabled', true],
       ['media.getusermedia.window.focus_source.enabled', false],
       ['media.recorder.audio_node.enabled', true],
-      ['media.webaudio.audiocontextoptions-samplerate.enabled', true]
+      ['media.webaudio.audiocontextoptions-samplerate.enabled', true],
+      ['media.cubeb_max_input_streams', 10000]
     ]
   };
 

dom/media/webrtc/MediaEngineWebRTCAudio.cpp

@@ -36,6 +36,10 @@ using namespace webrtc;
 #define MAX_AEC_FIFO_DEPTH 200 // ms - multiple of 10
 static_assert(!(MAX_AEC_FIFO_DEPTH % 10), "Invalid MAX_AEC_FIFO_DEPTH");
 
+#ifdef MOZ_PULSEAUDIO
+static uint32_t sInputStreamsOpen = 0;
+#endif
+
 namespace mozilla {
 
 #ifdef LOG
@@ -761,6 +765,22 @@ MediaEngineWebRTCMicrophoneSource::Start(const RefPtr<const AllocationHandle>& a
     return NS_ERROR_FAILURE;
   }
 
+  // On Linux with PulseAudio, we still only allow a certain number of audio
+  // input stream in each content process, because of issues related to audio
+  // remoting and PulseAudio.
+#ifdef MOZ_PULSEAUDIO
+  // When remoting, cubeb reports it's using the "remote" backend instead of the
+  // backend on the other side of the IPC.
+  const char* backend = cubeb_get_backend_id(CubebUtils::GetCubebContext());
+  if (strstr(backend, "remote") &&
+      sInputStreamsOpen == CubebUtils::GetMaxInputStreams()) {
+    LOG(("%p Already capturing audio in this process, aborting", this));
+    return NS_ERROR_FAILURE;
+  }
+
+  sInputStreamsOpen++;
+#endif
+
   MOZ_ASSERT(!allocation.mEnabled, "Source already started");
   {
     // This spans setting both the enabled state and mState.
@@ -820,6 +840,10 @@ MediaEngineWebRTCMicrophoneSource::Stop(const RefPtr<const AllocationHandle>& aH
     Maybe<CubebUtils::AudioDeviceID> id = Some(deviceID);
     allocation.mStream->CloseAudioInput(id, mListener);
     mListener = nullptr;
+#ifdef MOZ_PULSEAUDIO
+    MOZ_ASSERT(sInputStreamsOpen > 0);
+    sInputStreamsOpen--;
+#endif
 
     if (HasEnabledTrack()) {
       // Another track is keeping us from stopping

modules/libpref/init/all.js

@@ -622,6 +622,11 @@ pref("media.audioipc.stack_size", 262144);
 pref("media.cubeb.sandbox", false);
 #endif
 
+#ifdef XP_LINUX
+// Bug 1481152
+pref("media.cubeb_max_input_streams", 1);
+#endif
+
 #ifdef MOZ_AV1
 pref("media.av1.enabled", false);
 #endif