Support Opus Ambisonics playback

content/renderer/media/audio_renderer_mixer_manager.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/audio_renderer_mixer_manager.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 52 matching lines @@
           output_sample_rate, preferred_high_latency_output_buffer_size);
       break;
     case media::AudioLatency::LATENCY_EXACT_MS:
     // TODO(olka): add support when WebAudio requires it.
     default:
       NOTREACHED();
   }
 
   DCHECK_NE(output_buffer_size, 0);
 
+  // If the input has discrete channel layout, the hardware channel mapping is
+  // unknown. Default to the hardware channel layout instead. Any input
+  // channels beyond the hardware channel count will not be played out.
+  media::ChannelLayout channel_layout =
+      input_params.channel_layout() == media::CHANNEL_LAYOUT_DISCRETE
+          ? hardware_params.channel_layout()
+          : input_params.channel_layout();
+

[DaleCurtis, 2017/03/31 19:06:53]

Needs set_channels.

[flim-chromium, 2017/04/05 18:19:34]

I ended up removing this. 

   // Force to 16-bit output for now since we know that works everywhere;
   // ChromeOS does not support other bit depths.
-  media::AudioParameters params(input_params.format(),
-                                input_params.channel_layout(),
+  media::AudioParameters params(input_params.format(), channel_layout,
                                 output_sample_rate, 16, output_buffer_size);
 
   // Specify the latency info to be passed to the browser side.
   params.set_latency_tag(latency);
   return params;
 }
 
 void LogMixerUmaHistogram(media::AudioLatency::LatencyType latency, int value) {
   switch (latency) {
     case media::AudioLatency::LATENCY_EXACT_MS:
@@ skipping 160 matching lines @@
     const url::Origin& security_origin)
     : source_render_frame_id(source_render_frame_id),
       params(params),
       latency(latency),
       device_id(device_id),
       security_origin(security_origin) {}
 
 AudioRendererMixerManager::MixerKey::MixerKey(const MixerKey& other) = default;
 
 }  // namespace content