Initial asymmetric codec support in MediaSessionDescription

webrtc/pc/mediasession.cc

 /*
  *  Copyright 2004 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 1216 matching lines @@
       add_legacy_(true),
       transport_desc_factory_(transport_desc_factory) {
 }
 
 MediaSessionDescriptionFactory::MediaSessionDescriptionFactory(
     ChannelManager* channel_manager,
     const TransportDescriptionFactory* transport_desc_factory)
     : secure_(SEC_DISABLED),
       add_legacy_(true),
       transport_desc_factory_(transport_desc_factory) {
-  channel_manager->GetSupportedAudioCodecs(&audio_codecs_);
+  channel_manager->GetSupportedAudioCodecs(&audio_sendrecv_codecs_);
   channel_manager->GetSupportedAudioRtpHeaderExtensions(&audio_rtp_extensions_);
   channel_manager->GetSupportedVideoCodecs(&video_codecs_);
   channel_manager->GetSupportedVideoRtpHeaderExtensions(&video_rtp_extensions_);
   channel_manager->GetSupportedDataCodecs(&data_codecs_);
+  audio_send_codecs_ = audio_sendrecv_codecs_;
+  audio_recv_codecs_ = audio_sendrecv_codecs_;
+}
+
+const AudioCodecs& MediaSessionDescriptionFactory::audio_codecs() const {
+  return audio_sendrecv_codecs_;
+}
+
+void MediaSessionDescriptionFactory::set_audio_codecs(
+    const AudioCodecs& send_and_recv_codecs) {
+  audio_send_codecs_ = send_and_recv_codecs;
+  audio_recv_codecs_ = send_and_recv_codecs;
+  audio_sendrecv_codecs_ = send_and_recv_codecs;
+}
+
+void MediaSessionDescriptionFactory::set_audio_codecs(
+    const AudioCodecs& send_codecs, const AudioCodecs& recv_codecs) {
+  audio_send_codecs_ = send_codecs;
+  audio_recv_codecs_ = recv_codecs;
+  audio_sendrecv_codecs_.clear();
+
+  // Intersect the two lists of codecs, preserving the order of the send codecs.
+  // If there's any difference in priorities, chances are encoding is more
+  // expensive than decoding, and high-priority send codecs are likely handled
+  // better (e.g. through hardware encoder support) than low-priority ones.
+  // TODO(ossu): Deal with channels == 0 also meaning channels = 1.
+  // TODO(ossu): This is O(n^2). Normalizing and putting in a set could handle
+  //             both issues.
+  for (const auto& sc : audio_send_codecs_) {

[ossu, 2016/05/09 10:57:06]

This clearly needs testing and should probably be placed somewhere else.

+    for (const auto& rc : audio_recv_codecs_) {
+      if (sc.clockrate == rc.clockrate &&
+          sc.bitrate == rc.bitrate &&
+          sc.channels == rc.channels &&
+          sc.name == rc.name &&
+          sc.params == rc.params &&
+          sc.feedback_params == rc.feedback_params) {
+        audio_sendrecv_codecs_.push_back(sc);
+        break;
+      }
+    }
+  }
 }
 
 SessionDescription* MediaSessionDescriptionFactory::CreateOffer(
     const MediaSessionOptions& options,
     const SessionDescription* current_description) const {
   std::unique_ptr<SessionDescription> offer(new SessionDescription());
 
   StreamParamsVec current_streams;
   GetCurrentStreamParams(current_description, &current_streams);
 
+  const AudioCodecs *supported_audio_codecs = nullptr;

[kwiberg-webrtc, 2016/05/17 12:22:36]

You set this in all branches below, so the default value is unnecessary.

[ossu, 2016/05/23 14:18:04]

Acknowledged.

+  if (options.HasSendMediaStream(MEDIA_TYPE_AUDIO)) {
+    if (options.recv_audio) {
+      // sendrecv
+      supported_audio_codecs = &audio_sendrecv_codecs_;
+    } else {
+      // sendonly
+      supported_audio_codecs = &audio_send_codecs_;
+    }
+  } else if (options.recv_audio) {
+    // recvonly
+    supported_audio_codecs = &audio_recv_codecs_;
+  } else {
+    // Stream is inactive - generate list as if sendrecv.
+    // See RFC 3264 Section 6.1.
+    supported_audio_codecs = &audio_sendrecv_codecs_;
+  }
+
   AudioCodecs audio_codecs;
   VideoCodecs video_codecs;
   DataCodecs data_codecs;
-  GetCodecsToOffer(current_description, &audio_codecs, &video_codecs,
-                   &data_codecs);
+  GetCodecsToOffer(current_description, *supported_audio_codecs,
+                   video_codecs_, data_codecs_,
+                   &audio_codecs, &video_codecs, &data_codecs);
 
   if (!options.vad_enabled) {
     // If application doesn't want CN codecs in offer.
     StripCNCodecs(&audio_codecs);
   }
 
   RtpHeaderExtensions audio_rtp_extensions;
   RtpHeaderExtensions video_rtp_extensions;
   GetRtpHdrExtsToOffer(current_description, &audio_rtp_extensions,
                        &video_rtp_extensions);
@@ skipping 140 matching lines @@
         return NULL;
       }
     }
   }
 
   return answer.release();
 }
 
 void MediaSessionDescriptionFactory::GetCodecsToOffer(
     const SessionDescription* current_description,
+    const AudioCodecs& supported_audio_codecs,
+    const VideoCodecs& supported_video_codecs,
+    const DataCodecs& supported_data_codecs,
     AudioCodecs* audio_codecs,
     VideoCodecs* video_codecs,
     DataCodecs* data_codecs) const {
   UsedPayloadTypes used_pltypes;
   audio_codecs->clear();
   video_codecs->clear();
   data_codecs->clear();
 
 
   // First - get all codecs from the current description if the media type
@@ skipping 15 matching lines @@
     }
     const DataContentDescription* data =
         GetFirstDataContentDescription(current_description);
     if (data) {
       *data_codecs = data->codecs();
       used_pltypes.FindAndSetIdUsed<DataCodec>(data_codecs);
     }
   }
 
   // Add our codecs that are not in |current_description|.
-  FindCodecsToOffer<AudioCodec>(audio_codecs_, audio_codecs, &used_pltypes);
-  FindCodecsToOffer<VideoCodec>(video_codecs_, video_codecs, &used_pltypes);
-  FindCodecsToOffer<DataCodec>(data_codecs_, data_codecs, &used_pltypes);
+  FindCodecsToOffer<AudioCodec>(supported_audio_codecs, audio_codecs,
+                                &used_pltypes);
+  FindCodecsToOffer<VideoCodec>(supported_video_codecs, video_codecs,
+                                &used_pltypes);
+  FindCodecsToOffer<DataCodec>(supported_data_codecs, data_codecs,
+                               &used_pltypes);
 }
 
 void MediaSessionDescriptionFactory::GetRtpHdrExtsToOffer(
     const SessionDescription* current_description,
     RtpHeaderExtensions* audio_extensions,
     RtpHeaderExtensions* video_extensions) const {
   // All header extensions allocated from the same range to avoid potential
   // issues when using BUNDLE.
   UsedRtpHeaderExtensionIds used_ids;
   RtpHeaderExtensions all_extensions;
@@ skipping 261 matching lines @@
   return true;
 }
 
 bool MediaSessionDescriptionFactory::AddAudioContentForAnswer(
     const SessionDescription* offer,
     const MediaSessionOptions& options,
     const SessionDescription* current_description,
     StreamParamsVec* current_streams,
     SessionDescription* answer) const {
   const ContentInfo* audio_content = GetFirstAudioContent(offer);
+  const AudioContentDescription* audio_content_description =
+      static_cast<const AudioContentDescription*>(audio_content->description);
 
   std::unique_ptr<TransportDescription> audio_transport(CreateTransportAnswer(
       audio_content->name, offer,
       GetTransportOptions(options, audio_content->name), current_description));
   if (!audio_transport) {
     return false;
   }
 
-  AudioCodecs audio_codecs = audio_codecs_;
+  // Pick codecs based on the requested communications direction in the offer.
+  // According to RFC 3264 Section 6.1, inactive is to be treated as sendrecv
+  // when constructing the list of supported formats.
+  AudioCodecs audio_codecs;
+  switch (audio_content_description->direction()) {
+    case MD_INACTIVE:
+      audio_codecs = audio_sendrecv_codecs_;
+        break;
+    case MD_SENDRECV:
+      if (options.HasSendMediaStream(MEDIA_TYPE_AUDIO))
+        audio_codecs = audio_sendrecv_codecs_;
+      else
+        audio_codecs = audio_recv_codecs_;
+      break;
+    case MD_RECVONLY:
+      if (options.HasSendMediaStream(MEDIA_TYPE_AUDIO))
+        audio_codecs = audio_send_codecs_;
+      else
+        audio_codecs = audio_sendrecv_codecs_;  // inactive
+      break;
+    case MD_SENDONLY:
+      audio_codecs = audio_recv_codecs_;
+      break;
+  }
+
   if (!options.vad_enabled) {
     StripCNCodecs(&audio_codecs);
   }
 
   bool bundle_enabled =
       offer->HasGroup(GROUP_TYPE_BUNDLE) && options.bundle_enabled;
   std::unique_ptr<AudioContentDescription> audio_answer(
       new AudioContentDescription());
   // Do not require or create SDES cryptos if DTLS is used.
   cricket::SecurePolicy sdes_policy =
       audio_transport->secure() ? cricket::SEC_DISABLED : secure();
   if (!CreateMediaContentAnswer(
-          static_cast<const AudioContentDescription*>(
-              audio_content->description),
+          audio_content_description,
           options,
           audio_codecs,
           sdes_policy,
           GetCryptos(GetFirstAudioContentDescription(current_description)),
           audio_rtp_extensions_,
           current_streams,
           add_legacy_,
           bundle_enabled,
           audio_answer.get())) {
     return false;  // Fails the session setup.
@@ skipping 211 matching lines @@
       GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_VIDEO));
 }
 
 const DataContentDescription* GetFirstDataContentDescription(
     const SessionDescription* sdesc) {
   return static_cast<const DataContentDescription*>(
       GetFirstMediaContentDescription(sdesc, MEDIA_TYPE_DATA));
 }
 
 }  // namespace cricket