[Chromecast] Process streams with different post-processing.

chromecast/media/cma/backend/alsa/stream_mixer_alsa.h

Index: chromecast/media/cma/backend/alsa/stream_mixer_alsa.h
diff --git a/chromecast/media/cma/backend/alsa/stream_mixer_alsa.h b/chromecast/media/cma/backend/alsa/stream_mixer_alsa.h
index 53a48911f72ae92fe6fed42b1db7703d52aab2fd..44525f9ab3dfcbecf29598cdc3a7f1a53b2b676a 100644
--- a/chromecast/media/cma/backend/alsa/stream_mixer_alsa.h
+++ b/chromecast/media/cma/backend/alsa/stream_mixer_alsa.h
@@ -29,6 +29,8 @@ namespace chromecast {
 namespace media {
 class AlsaWrapper;
 
+const int kNumFilterGroups = 2;
+
 // Mixer implementation. The mixer has one or more input queues; these can be
 // added/removed at any time. When an input source pushes frames to an input
 // queue, the queue should call StreamMixerAlsa::WriteFrames(); this causes
@@ -67,6 +69,11 @@ class StreamMixerAlsa {
     // precedence for sample rates and will dictate when data is polled.
     virtual bool primary() const = 0;
 
+    // Returns a string describing the content type class.
+    // Should be from chromecast/public/media/audio_device_ids.h
+    // or media/audio/audio_device_description.h
+    virtual std::string name() const = 0;
+
     // Returns true if PrepareToDelete() has been called.
     virtual bool IsDeleting() const = 0;
 
@@ -195,10 +202,20 @@ class StreamMixerAlsa {
 
   void WriteFrames();
   bool TryWriteFrames();
-  void WriteMixedPcm(const ::media::AudioBus& mixed, int frames,
-      bool is_silence);
+
+  // Mixes |acitve_inputs| and processes the resulting buffer

[kmackay, 2017/02/17 06:11:25]

active_inputs

[bshaya, 2017/02/17 18:26:54]

Done.

+  // with pre_loopback_filter_[|filter|].
+  // If |accumulate| is false, |interleaved_| will be overwritten
+  //  (rather than summed).
+  // Returns |true| if non-zero data was written to |interleaved_|.
+  bool MixAndFilterGroup(const std::vector<InputQueue*>& active_inputs,
+                         int filter,
+                         int frames,
+                         bool accumulate);
+  void WriteMixedPcm(int frames, bool filter_frames);
   void UpdateRenderingDelay(int newly_pushed_frames);
   ssize_t BytesPerOutputFormatSample();
+  void ResizeBuffersIfNecessary(int chunk_size);
 
   static bool single_threaded_for_test_;
 
@@ -229,6 +246,9 @@ class StreamMixerAlsa {
   std::vector<std::unique_ptr<InputQueue>> inputs_;
   std::vector<std::unique_ptr<InputQueue>> ignored_inputs_;
   MediaPipelineBackendAlsa::RenderingDelay rendering_delay_;
+  // Buffer to write interleaved data for each stream type before
+  // writing to |interleaved_|.

[kmackay, 2017/02/17 06:11:25]

Could you clarify the comment a bit? Something about how we mix data for each
stream type, apply appropriate filters, and then mix into |interleaved_|

[bshaya, 2017/02/17 18:26:54]

Done.

+  std::vector<uint8_t> interleaved_intermediate_;
   // Buffer to write final interleaved data before sending to snd_pcm_writei().
   std::vector<uint8_t> interleaved_;
 
@@ -245,9 +265,9 @@ class StreamMixerAlsa {
 
   std::vector<CastMediaShlib::LoopbackAudioObserver*> loopback_observers_;
 
-  std::unique_ptr<AudioFilterInterface> pre_loopback_filter_;
+  std::unique_ptr<AudioFilterInterface> pre_loopback_filter_[kNumFilterGroups];
   std::unique_ptr<AudioFilterInterface> post_loopback_filter_;
-  int silence_frames_filtered_ = 0;
+  int silence_frames_filtered_[kNumFilterGroups];
 
   DISALLOW_COPY_AND_ASSIGN(StreamMixerAlsa);
 };