Opus implementation of the AudioDecoderFactoryTemplate API

webrtc/api/audio_codecs/opus/audio_decoder_opus.cc

+/*
+ *  Copyright (c) 2017 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.
+ */
+
+#include "webrtc/api/audio_codecs/opus/audio_decoder_opus.h"
+
+#include <memory>
+#include <utility>
+#include <vector>
+
+#include "webrtc/base/ptr_util.h"
+#include "webrtc/common_types.h"
+#include "webrtc/modules/audio_coding/codecs/opus/audio_decoder_opus.h"
+
+namespace webrtc {
+
+rtc::Optional<AudioDecoderOpus::Config> AudioDecoderOpus::SdpToConfig(
+    const SdpAudioFormat& format) {
+  const rtc::Optional<int> num_channels = [&] {
+    auto stereo = format.parameters.find("stereo");
+    if (stereo != format.parameters.end()) {
+      if (stereo->second == "0") {
+        return rtc::Optional<int>(1);
+      } else if (stereo->second == "1") {
+        return rtc::Optional<int>(2);
+      } else {
+        return rtc::Optional<int>();  // Bad stereo parameter.
+      }
+    }
+    return rtc::Optional<int>(1);  // Default to mono.
+  }();
+  if (STR_CASE_CMP(format.name.c_str(), "opus") == 0 &&
+      format.clockrate_hz == 48000 && format.num_channels == 2 &&
+      num_channels) {
+    return rtc::Optional<Config>(Config{*num_channels});
+  } else {
+    return rtc::Optional<Config>();
+  }
+}
+
+void AudioDecoderOpus::AppendSupportedDecoders(
+    std::vector<AudioCodecSpec>* specs) {
+  AudioCodecInfo opus_info{48000, 1, 64000, 6000, 510000};
+  opus_info.allow_comfort_noise = false;
+  opus_info.supports_network_adaption = true;
+  SdpAudioFormat opus_format(
+      {"opus", 48000, 2, {{"minptime", "10"}, {"useinbandfec", "1"}}});
+  specs->push_back({std::move(opus_format), std::move(opus_info)});
+}
+
+std::unique_ptr<AudioDecoder> AudioDecoderOpus::MakeAudioDecoder(
+    Config config) {
+  return rtc::MakeUnique<AudioDecoderOpusImpl>(config.num_channels);
+}
+
+}  // namespace webrtc