commit 228c268065bd74d8fc8bd92681d8f375a9f5781a
author jens.nielsen <jens.nielsen@berotec.se> Wed Mar 01 13:11:22 2017
committer Commit bot <commit-bot@chromium.org> Wed Mar 01 13:11:22 2017
tree 01e05104a3791ce11a72683b9debbcde865a664e
parent c5726c1579358260a7587ed05943f01dba506fa6

Support 4 channel mic in Windows Core Audio

BUG=webrtc:7220

Review-Url: https://codereview.webrtc.org/2712743004
Cr-Commit-Position: refs/heads/master@{#16940}

webrtc/voice_engine/utility.cc

diff --git a/webrtc/voice_engine/utility.cc b/webrtc/voice_engine/utility.cc
index 595c711..720817f 100644
--- a/webrtc/voice_engine/utility.cc
+++ b/webrtc/voice_engine/utility.cc
@@ -41,14 +41,20 @@
                       AudioFrame* dst_frame) {
   const int16_t* audio_ptr = src_data;
   size_t audio_ptr_num_channels = num_channels;
-  int16_t mono_audio[AudioFrame::kMaxDataSizeSamples];
+  int16_t downsampled_audio[AudioFrame::kMaxDataSizeSamples];
 
   // Downmix before resampling.
-  if (num_channels == 2 && dst_frame->num_channels_ == 1) {
-    AudioFrameOperations::StereoToMono(src_data, samples_per_channel,
-                                       mono_audio);
-    audio_ptr = mono_audio;
-    audio_ptr_num_channels = 1;
+  if (num_channels > dst_frame->num_channels_) {
+    RTC_DCHECK(num_channels == 2 || num_channels == 4)
+        << "num_channels: " << num_channels;
+    RTC_DCHECK(dst_frame->num_channels_ == 1 || dst_frame->num_channels_ == 2)
+        << "dst_frame->num_channels_: " << dst_frame->num_channels_;
+
+    AudioFrameOperations::DownmixChannels(
+        src_data, num_channels, samples_per_channel, dst_frame->num_channels_,
+        downsampled_audio);
+    audio_ptr = downsampled_audio;
+    audio_ptr_num_channels = dst_frame->num_channels_;
   }
 
   if (resampler->InitializeIfNeeded(sample_rate_hz, dst_frame->sample_rate_hz_,