Support Opus Ambisonics playback

media/formats/webm/webm_audio_client.cc

 // Copyright 2014 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 "media/formats/webm/webm_audio_client.h"
 
 #include "media/base/audio_decoder_config.h"
 #include "media/base/channel_layout.h"
 #include "media/formats/webm/webm_constants.h"
 
@@ skipping 32 matching lines @@
     return false;
   }
 
   if (samples_per_second_ <= 0)
     return false;
 
   // Set channel layout default if a Channels element was not present.
   if (channels_ == -1)
     channels_ = 1;
 
-  ChannelLayout channel_layout =  GuessChannelLayout(channels_);
+  bool is_opus_discrete = false;
+  if (audio_codec == kCodecOpus && codec_private.size() >= 19) {
+    int mapping_family = codec_private[18];
+    is_opus_discrete = mapping_family == 2;
+  }
+  ChannelLayout channel_layout = is_opus_discrete && channels_ > 8
+                                     ? CHANNEL_LAYOUT_DISCRETE
+                                     : GuessChannelLayout(channels_);
 
   if (channel_layout == CHANNEL_LAYOUT_UNSUPPORTED) {
     MEDIA_LOG(ERROR, media_log_) << "Unsupported channel count " << channels_;
     return false;
   }
 
   int samples_per_second = samples_per_second_;
   if (output_samples_per_second_ > 0)
     samples_per_second = output_samples_per_second_;
 
@@ skipping 11 matching lines @@
         0.5 +
         samples_per_second * (static_cast<double>(codec_delay) /
                               base::Time::kNanosecondsPerSecond);
   }
 
   config->Initialize(audio_codec, sample_format, channel_layout,
                      samples_per_second, codec_private, encryption_scheme,
                      base::TimeDelta::FromMicroseconds(
                          (seek_preroll != -1 ? seek_preroll : 0) / 1000),
                      codec_delay_in_frames);
+  config->SetChannelsForDiscrete(channels_);
   return config->IsValidConfig();
 }
 
 bool WebMAudioClient::OnUInt(int id, int64_t val) {
   if (id == kWebMIdChannels) {
     if (channels_ != -1) {
       MEDIA_LOG(ERROR, media_log_) << "Multiple values for id " << std::hex
                                    << id << " specified. (" << channels_
                                    << " and " << val << ")";
       return false;
@@ skipping 26 matching lines @@
                                  << " specified (" << *dst << " and " << val
                                  << ")";
     return false;
   }
 
   *dst = val;
   return true;
 }
 
 }  // namespace media