Move functionality out from AudioFrame and into AudioFrameOperations.

webrtc/modules/audio_conference_mixer/source/audio_conference_mixer_impl.cc

 /*
  *  Copyright (c) 2012 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 22 matching lines @@
 // These effects are applied to |frame| itself prior to mixing. Assumes that
 // |mixed_frame| always has at least as many channels as |frame|. Supports
 // stereo at most.
 //
 // TODO(andrew): consider not modifying |frame| here.
 void MixFrames(AudioFrame* mixed_frame, AudioFrame* frame, bool use_limiter) {
   assert(mixed_frame->num_channels_ >= frame->num_channels_);
   if (use_limiter) {
     // Divide by two to avoid saturation in the mixing.
     // This is only meaningful if the limiter will be used.
-    *frame >>= 1;
+    AudioFrameOperations::ShiftDown(frame);

[the sun, 2016/10/19 09:23:16]

Note, if this function was called DivideBy2(), ApplyHalfGain() or similar, the
comment could be removed.

[aleloi, 2016/10/20 08:27:05]

Done.

   }
   if (mixed_frame->num_channels_ > frame->num_channels_) {
     // We only support mono-to-stereo.
     assert(mixed_frame->num_channels_ == 2 &&
            frame->num_channels_ == 1);
     AudioFrameOperations::MonoToStereo(frame);
   }
 
-  *mixed_frame += *frame;
+  AudioFrameOperations::AddFrames(*frame, mixed_frame);
 }
 
 // Return the max number of channels from a |list| composed of AudioFrames.
 size_t MaxNumChannels(const AudioFrameList* list) {
   size_t max_num_channels = 1;
   for (AudioFrameList::const_iterator iter = list->begin();
        iter != list->end();
        ++iter) {
     max_num_channels = std::max(max_num_channels, (*iter).frame->num_channels_);
   }
@@ skipping 214 matching lines @@
         CriticalSectionScoped cs(_crit.get());
 
         // TODO(henrike): it might be better to decide the number of channels
         //                with an API instead of dynamically.
 
         // Find the max channels over all mixing lists.
         const size_t num_mixed_channels = std::max(MaxNumChannels(&mixList),
             std::max(MaxNumChannels(&additionalFramesList),
                      MaxNumChannels(&rampOutList)));
 
-        mixedAudio->UpdateFrame(-1, _timeStamp, NULL, 0, _outputFrequency,
-                                AudioFrame::kNormalSpeech,
-                                AudioFrame::kVadPassive, num_mixed_channels);
+        AudioFrameOperations::UpdateFrame(
+            -1, _timeStamp, NULL, 0, _outputFrequency,
+            AudioFrame::kNormalSpeech, AudioFrame::kVadPassive,
+            num_mixed_channels, mixedAudio);
 
         _timeStamp += static_cast<uint32_t>(_sampleSize);
 
         // We only use the limiter if it supports the output sample rate and
         // we're actually mixing multiple streams.
         use_limiter_ =
             _numMixedParticipants > 1 &&
             _outputFrequency <= AudioProcessing::kMaxNativeSampleRateHz;
 
         MixFromList(mixedAudio, mixList);
         MixAnonomouslyFromList(mixedAudio, additionalFramesList);
         MixAnonomouslyFromList(mixedAudio, rampOutList);
 
         if(mixedAudio->samples_per_channel_ == 0) {
             // Nothing was mixed, set the audio samples to silence.
             mixedAudio->samples_per_channel_ = _sampleSize;
-            mixedAudio->Mute();
+            AudioFrameOperations::Mute(mixedAudio);
         } else {
             // Only call the limiter if we have something to mix.
             LimitMixedAudio(mixedAudio);
         }
     }
 
     {
         CriticalSectionScoped cs(_cbCrit.get());
         if(_mixReceiver != NULL) {
             const AudioFrame** dummy = NULL;
@@ skipping 598 matching lines @@
     // And now we can safely restore the level. This procedure results in
     // some loss of resolution, deemed acceptable.
     //
     // It's possible to apply the gain in the AGC (with a target level of 0 dbFS
     // and compression gain of 6 dB). However, in the transition frame when this
     // is enabled (moving from one to two participants) it has the potential to
     // create discontinuities in the mixed frame.
     //
     // Instead we double the frame (with addition since left-shifting a
     // negative value is undefined).
-    *mixedAudio += *mixedAudio;
+    AudioFrameOperations::AddFrames(*mixedAudio, mixedAudio);
 
     if(error != _limiter->kNoError) {
         WEBRTC_TRACE(kTraceError, kTraceAudioMixerServer, _id,
                      "Error from AudioProcessing: %d", error);
         assert(false);
         return false;
     }
     return true;
 }
 }  // namespace webrtc