Integrate Intelligibility with APM

webrtc/common_audio/include/audio_util.h

Index: webrtc/common_audio/include/audio_util.h
diff --git a/webrtc/common_audio/include/audio_util.h b/webrtc/common_audio/include/audio_util.h
index b217c683fd05815a7f10f95b000371f03e2db393..6a9699357149346a5b5140512c293030f5e57d73 100644
--- a/webrtc/common_audio/include/audio_util.h
+++ b/webrtc/common_audio/include/audio_util.h
@@ -65,6 +65,21 @@ void FloatS16ToS16(const float* src, size_t size, int16_t* dest);
 void FloatToFloatS16(const float* src, size_t size, float* dest);
 void FloatS16ToFloat(const float* src, size_t size, float* dest);
 
+// Copy audio from |src| channels to |dest| channels. |src| and |dest| must
+// have the same number of channels, and there must be sufficient space
+// allocated in the |dest| channels.

[aluebs-webrtc, 2015/08/10 19:14:18]

Comment something about that there is no copy done when they are the same
pointer.

[Andrew MacDonald, 2015/08/10 19:24:05]

Add a comment here about what "needed" means.
"Skips the copy when a |src| and |dest| channel point to the same address."

[ekm, 2015/08/11 23:59:36]

Done.

+template <typename T>
+void CopyAudioIfNeeded(const T* const* src,
+                       int num_frames,
+                       int num_channels,
+                       T* const* dest) {
+  for (int i = 0; i < num_channels; ++i) {
+    if (src[i] != dest[i]) {
+      std::copy(src[i], src[i] + num_frames, dest[i]);
+    }
+  }
+}
+
 // Deinterleave audio from |interleaved| to the channel buffers pointed to
 // by |deinterleaved|. There must be sufficient space allocated in the
 // |deinterleaved| buffers (|num_channel| buffers with |samples_per_channel|
@@ -102,6 +117,22 @@ void Interleave(const T* const* deinterleaved,
   }
 }
 
+// Copies audio from a single channel buffer pointed to by |mono| to each
+// channel of |interleaved|. There must be sufficient space allocated in
+// |interleaved| (|samples_per_channel| * |num_channels|).
+template <typename T>
+void UpmixMonoToInterleaved(const T* mono,
+                            int num_frames,
+                            int num_channels,
+                            T* interleaved) {
+  int interleaved_idx = 0;
+  for (int i = 0; i < num_frames; ++i) {
+    for (int j = 0; j < num_channels; ++j) {
+      interleaved[interleaved_idx++] = mono[i];
+    }
+  }
+}
+
 template <typename T, typename Intermediate>
 void DownmixToMono(const T* const* input_channels,
                    int num_frames,