Integrate Intelligibility with APM

webrtc/modules/audio_processing/include/audio_processing.h

Index: webrtc/modules/audio_processing/include/audio_processing.h
diff --git a/webrtc/modules/audio_processing/include/audio_processing.h b/webrtc/modules/audio_processing/include/audio_processing.h
index 6fa1c96c0771c14d141836dc0c88bf69ec9f5aea..befea252a204fe84e6139aa93acfe7568ec1c9aa 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -122,6 +122,18 @@ struct AudioProcessing48kHzSupport {
   bool enabled;
 };
 
+// Use to enable intelligibility enhancer in audio processing. Must be provided
+// though the constructor. It will have no impact if used with
+// AudioProcessing::SetExtraOptions().
+//
+// Note: If enabled and the reverse stream has more than one output channel,
+// the reverse stream will become an upmixed mono signal.
+struct Intelligibility {
+  Intelligibility() : enabled(false) {}
+  explicit Intelligibility(bool enabled) : enabled(enabled) {}
+  bool enabled;
+};
+
 static const int kAudioProcMaxNativeSampleRateHz = 32000;
 
 // The Audio Processing Module (APM) provides a collection of voice processing
@@ -321,9 +333,19 @@ class AudioProcessing {
 
   // Accepts deinterleaved float audio with the range [-1, 1]. Each element
   // of |data| points to a channel buffer, arranged according to |layout|.
+  //
+  // DEPRECATED: Use |ProcessReverseStream| instead.
+  // TODO(ekm): Remove once all users have updated to |ProcessReverseStream|.
   virtual int AnalyzeReverseStream(const float* const* data,
                                    int samples_per_channel,
-                                   int sample_rate_hz,
+                                   int rev_sample_rate_hz,
+                                   ChannelLayout layout) = 0;
+
+  // Same as |AnalyzeReverseStream|, but may modify |data| if intelligibility
+  // is enabled.
+  virtual int ProcessReverseStream(float* const* data,
+                                   int samples_per_channel,
+                                   int rev_sample_rate_hz,
                                    ChannelLayout layout) = 0;
 
   // This must be called if and only if echo processing is enabled.