Integrate Intelligibility with APM

webrtc/common_audio/include/audio_util.h

 /*
  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 79 matching lines @@
   for (int i = 0; i < num_channels; ++i) {
     const T* channel = deinterleaved[i];
     int interleaved_idx = i;
     for (int j = 0; j < samples_per_channel; ++j) {
       interleaved[interleaved_idx] = channel[j];
       interleaved_idx += num_channels;
     }
   }
 }
 
+// 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 samples_per_channel,

[Andrew MacDonald, 2015/07/29 03:52:27]

Go with num_frames for new code rather than samples_per_channel.

[ekm, 2015/07/29 23:35:06]

Done.

+                            int num_channels, T* interleaved) {
+  int interleaved_idx = 0;
+  for (int i = 0; i < samples_per_channel; ++i) {
+    for (int j = 0; j < num_channels; ++j) {
+      interleaved[interleaved_idx] = mono[i];

[aluebs-webrtc, 2015/07/29 22:17:10]

How about:

interleaved[i * num_channels + j] = mono[i];

And drop interleaved_idx completely?

[ekm, 2015/07/29 23:35:06]

I'd like to avoid the inner multiplication, though not of the tradeoff in
practice vs declaring the int every call.

[aluebs-webrtc, 2015/07/30 15:28:07]

Agreed.

+      interleaved_idx++;

[Andrew MacDonald, 2015/07/29 03:52:27]

nit: could put the post-increment in the above line.

[ekm, 2015/07/29 23:35:06]

Done.

+    }
+  }
+}
+
 }  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_