Query native channel count in preferred parameters.

w/o this, WebAudio will always think there are only two channels
available. Untested since I don't have a 5.1 setup on Linux.

BUG=646435
TEST=verified that 2 channels are reported locally.

Review-Url: https://codereview.chromium.org/2345813002
Cr-Commit-Position: refs/heads/master@{#419052}

media/audio/pulse/audio_manager_pulse.cc

@@ -58,7 +58,8 @@ AudioManagerPulse::AudioManagerPulse(
       input_mainloop_(NULL),
       input_context_(NULL),
       devices_(NULL),
-      native_input_sample_rate_(0) {
+      native_input_sample_rate_(0),
+      native_channel_count_(0) {
   SetMaxOutputStreamsAllowed(kMaxOutputStreams);
 }
 
@@ -136,8 +137,9 @@ AudioParameters AudioManagerPulse::GetInputStreamParameters(
       user_buffer_size : kDefaultInputBufferSize;
 
   // TODO(xians): add support for querying native channel layout for pulse.
+  UpdateNativeAudioHardwareInfo();
   return AudioParameters(AudioParameters::AUDIO_PCM_LOW_LATENCY,
-                         CHANNEL_LAYOUT_STEREO, GetNativeSampleRate(), 16,
+                         CHANNEL_LAYOUT_STEREO, native_input_sample_rate_, 16,
                          buffer_size);
 }
 
@@ -180,10 +182,15 @@ AudioParameters AudioManagerPulse::GetPreferredOutputStreamParameters(
   // TODO(tommi): Support |output_device_id|.
   VLOG_IF(0, !output_device_id.empty()) << "Not implemented!";
 
-  ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
   int buffer_size = kMinimumOutputBufferSize;
   int bits_per_sample = 16;
-  int sample_rate = GetNativeSampleRate();
+
+  // Query native parameters where applicable; Pulse does not require these to
+  // be respected though, so prefer the input parameters for channel count.
+  UpdateNativeAudioHardwareInfo();
+  int sample_rate = native_input_sample_rate_;
+  ChannelLayout channel_layout = GuessChannelLayout(native_channel_count_);
+
   if (input_params.IsValid()) {
     bits_per_sample = input_params.bits_per_sample();
     channel_layout = input_params.channel_layout();
@@ -213,15 +220,13 @@ AudioInputStream* AudioManagerPulse::MakeInputStream(
                                    input_mainloop_, input_context_);
 }
 
-int AudioManagerPulse::GetNativeSampleRate() {
+void AudioManagerPulse::UpdateNativeAudioHardwareInfo() {
   DCHECK(input_mainloop_);
   DCHECK(input_context_);
   AutoPulseLock auto_lock(input_mainloop_);
   pa_operation* operation = pa_context_get_server_info(
-      input_context_, SampleRateInfoCallback, this);
+      input_context_, AudioHardwareInfoCallback, this);
   WaitForOperationCompletion(input_mainloop_, operation);
-
-  return native_input_sample_rate_;
 }
 
 bool AudioManagerPulse::InitPulse() {
@@ -336,12 +341,13 @@ void AudioManagerPulse::OutputDevicesInfoCallback(pa_context* context,
                                                info->name));
 }
 
-void AudioManagerPulse::SampleRateInfoCallback(pa_context* context,
-                                               const pa_server_info* info,
-                                               void* user_data) {
+void AudioManagerPulse::AudioHardwareInfoCallback(pa_context* context,
+                                                  const pa_server_info* info,
+                                                  void* user_data) {
   AudioManagerPulse* manager = reinterpret_cast<AudioManagerPulse*>(user_data);
 
   manager->native_input_sample_rate_ = info->sample_spec.rate;
+  manager->native_channel_count_ = info->sample_spec.channels;
   pa_threaded_mainloop_signal(manager->input_mainloop_, 0);
 }
 

media/audio/pulse/audio_manager_pulse.h

@@ -72,10 +72,10 @@ class MEDIA_EXPORT AudioManagerPulse : public AudioManagerBase {
                                         int error, void* user_data);
 
   // Callback to get the native sample rate of PulseAudio, used by
-  // GetNativeSampleRate().
-  static void SampleRateInfoCallback(pa_context* context,
-                                     const pa_server_info* info,
-                                     void* user_data);
+  // UpdateNativeAudioHardwareInfo().
+  static void AudioHardwareInfoCallback(pa_context* context,
+                                        const pa_server_info* info,
+                                        void* user_data);
 
   // Called by MakeLinearOutputStream and MakeLowLatencyOutputStream.
   AudioOutputStream* MakeOutputStream(const AudioParameters& params,
@@ -85,13 +85,14 @@ class MEDIA_EXPORT AudioManagerPulse : public AudioManagerBase {
   AudioInputStream* MakeInputStream(const AudioParameters& params,
                                     const std::string& device_id);
 
-  // Gets the native sample rate of Pulse.
-  int GetNativeSampleRate();
+  // Updates |native_input_sample_rate_| and |native_channel_count_|.
+  void UpdateNativeAudioHardwareInfo();
 
   pa_threaded_mainloop* input_mainloop_;
   pa_context* input_context_;
   AudioDeviceNames* devices_;
   int native_input_sample_rate_;
+  int native_channel_count_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerPulse);
 };