Creating Simulcast offer and answer in Peer Connection.
CreateOffer and CreateAnswer will now examine the layers on the
transceiver to determine if multiple layers are requested (Simulcast).
In this scenario RIDs will be used in the layers (instead of SSRCs).
When the offer is created, only RIDs are signalled in the offer.
When the offer is set locally SetLocalDescription() SSRCs will be
generated for each layer by the Channel and sent downstream to the
MediaChannel.
The MediaChannel receives configuration that looks identical to that of
legacy simulcast, and should be able to integrate the streams correctly
regardless of how they were signalled.
Setting multiple layers on the transciever is still not supported
through the API.
Bug: webrtc:10075
Change-Id: Id4ad3637b87b68ef6ca7eec69166fee2d9dfa36f
Reviewed-on: https://webrtc-review.googlesource.com/c/119780
Reviewed-by: Seth Hampson <shampson@webrtc.org>
Reviewed-by: Steve Anton <steveanton@webrtc.org>
Commit-Queue: Amit Hilbuch <amithi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26428}diff --git a/pc/peer_connection.cc b/pc/peer_connection.cc
index 3be5ca3..33f4ce1 100644
--- a/pc/peer_connection.cc
+++ b/pc/peer_connection.cc
@@ -59,8 +59,13 @@
using cricket::ContentInfos;
using cricket::MediaContentDescription;
using cricket::MediaProtocolType;
+using cricket::RidDescription;
+using cricket::RidDirection;
using cricket::SessionDescription;
+using cricket::SimulcastDescription;
+using cricket::SimulcastLayer;
using cricket::SimulcastLayerList;
+using cricket::StreamParams;
using cricket::TransportInfo;
using cricket::LOCAL_PORT_TYPE;
@@ -1092,7 +1097,7 @@
webrtc_session_desc_factory_.reset(new WebRtcSessionDescriptionFactory(
signaling_thread(), channel_manager(), this, session_id(),
- std::move(dependencies.cert_generator), certificate));
+ std::move(dependencies.cert_generator), certificate, &ssrc_generator_));
webrtc_session_desc_factory_->SignalCertificateReady.connect(
this, &PeerConnection::OnCertificateReady);
@@ -2198,18 +2203,20 @@
if (!content) {
continue;
}
- const auto& streams = content->media_description()->streams();
- if (!content->rejected && !streams.empty()) {
- transceiver->internal()->sender_internal()->set_stream_ids(
- streams[0].stream_ids());
- transceiver->internal()->sender_internal()->SetSsrc(
- streams[0].first_ssrc());
- } else {
+ cricket::ChannelInterface* channel = transceiver->internal()->channel();
+ if (content->rejected || !channel || channel->local_streams().empty()) {
// 0 is a special value meaning "this sender has no associated send
// stream". Need to call this so the sender won't attempt to configure
// a no longer existing stream and run into DCHECKs in the lower
// layers.
transceiver->internal()->sender_internal()->SetSsrc(0);
+ } else {
+ // Get the StreamParams from the channel which could generate SSRCs.
+ const std::vector<StreamParams>& streams = channel->local_streams();
+ transceiver->internal()->sender_internal()->set_stream_ids(
+ streams[0].stream_ids());
+ transceiver->internal()->sender_internal()->SetSsrc(
+ streams[0].first_ssrc());
}
}
} else {
@@ -2911,6 +2918,72 @@
return RTCError::OK();
}
+// This method will extract any send encodings that were sent by the remote
+// connection. This is currently only relevant for Simulcast scenario (where
+// the number of layers may be communicated by the server).
+static std::vector<RtpEncodingParameters> GetSendEncodingsFromRemoteDescription(
+ const MediaContentDescription& desc) {
+ if (!desc.HasSimulcast()) {
+ return {};
+ }
+ std::vector<RtpEncodingParameters> result;
+ const SimulcastDescription& simulcast = desc.simulcast_description();
+
+ // This is a remote description, the parameters we are after should appear
+ // as receive streams.
+ for (const auto& alternatives : simulcast.receive_layers()) {
+ RTC_DCHECK(!alternatives.empty());
+ // There is currently no way to specify or choose from alternatives.
+ // We will always use the first alternative, which is the most preferred.
+ const SimulcastLayer& layer = alternatives[0];
+ RtpEncodingParameters parameters;
+ parameters.rid = layer.rid;
+ parameters.active = !layer.is_paused;
+ result.push_back(parameters);
+ }
+
+ return result;
+}
+
+static RTCError UpdateSimulcastLayerStatusInSender(
+ const std::vector<SimulcastLayer>& layers,
+ RtpSenderInterface* sender) {
+ RTC_DCHECK(sender);
+ RtpParameters parameters = sender->GetParameters();
+
+ // The simulcast envelope cannot be changed, only the status of the streams.
+ // So we will iterate over the send encodings rather than the layers.
+ for (RtpEncodingParameters& encoding : parameters.encodings) {
+ auto iter = std::find_if(layers.begin(), layers.end(),
+ [&encoding](const SimulcastLayer& layer) {
+ return layer.rid == encoding.rid;
+ });
+ // A layer that cannot be found may have been removed by the remote party.
+ encoding.active = iter != layers.end() && !iter->is_paused;
+ }
+
+ return sender->SetParameters(parameters);
+}
+
+static RTCError DisableSimulcastInSender(RtpSenderInterface* sender) {
+ RTC_DCHECK(sender);
+ RtpParameters parameters = sender->GetParameters();
+ if (parameters.encodings.empty()) {
+ return RTCError::OK();
+ }
+
+ bool first_layer_status = parameters.encodings[0].active;
+ for (RtpEncodingParameters& encoding : parameters.encodings) {
+ // TODO(bugs.webrtc.org/10251): Active does not really disable the layer.
+ // The user might enable it at a later point in time even though it was
+ // rejected.
+ encoding.active = false;
+ }
+ parameters.encodings[0].active = first_layer_status;
+
+ return sender->SetParameters(parameters);
+}
+
RTCErrorOr<rtc::scoped_refptr<RtpTransceiverProxyWithInternal<RtpTransceiver>>>
PeerConnection::AssociateTransceiver(cricket::ContentSource source,
SdpType type,
@@ -2969,8 +3042,10 @@
<< " at i=" << mline_index
<< " in response to the remote description.";
std::string sender_id = rtc::CreateRandomUuid();
- auto sender =
- CreateSender(media_desc->type(), sender_id, nullptr, {}, {});
+ std::vector<RtpEncodingParameters> send_encodings =
+ GetSendEncodingsFromRemoteDescription(*media_desc);
+ auto sender = CreateSender(media_desc->type(), sender_id, nullptr, {},
+ send_encodings);
std::string receiver_id;
if (!media_desc->streams().empty()) {
receiver_id = media_desc->streams()[0].id;
@@ -2982,6 +3057,22 @@
transceiver->internal()->set_direction(
RtpTransceiverDirection::kRecvOnly);
}
+
+ // Check if the offer indicated simulcast but the answer rejected it.
+ // This can happen when simulcast is not supported on the remote party.
+ // This check can be simplified to comparing the number of send encodings,
+ // but that might break legacy implementation in which simulcast is not
+ // signaled in the remote description.
+ if (old_local_content && old_local_content->media_description() &&
+ old_local_content->media_description()->HasSimulcast() &&
+ !media_desc->HasSimulcast()) {
+ RTCError error =
+ DisableSimulcastInSender(transceiver->internal()->sender());
+ if (!error.ok()) {
+ RTC_LOG(LS_ERROR) << "Failed to remove rejected simulcast.";
+ return std::move(error);
+ }
+ }
}
RTC_DCHECK(transceiver);
if (transceiver->media_type() != media_desc->type()) {
@@ -2989,6 +3080,20 @@
RTCErrorType::INVALID_PARAMETER,
"Transceiver type does not match media description type.");
}
+ if (media_desc->HasSimulcast()) {
+ std::vector<SimulcastLayer> layers =
+ source == cricket::CS_LOCAL
+ ? media_desc->simulcast_description().send_layers().GetAllLayers()
+ : media_desc->simulcast_description()
+ .receive_layers()
+ .GetAllLayers();
+ RTCError error = UpdateSimulcastLayerStatusInSender(
+ layers, transceiver->internal()->sender());
+ if (!error.ok()) {
+ RTC_LOG(LS_ERROR) << "Failed updating status for simulcast layers.";
+ return std::move(error);
+ }
+ }
// Associate the found or created RtpTransceiver with the m= section by
// setting the value of the RtpTransceiver's mid property to the MID of the m=
// section, and establish a mapping between the transceiver and the index of
@@ -4035,6 +4140,20 @@
offer_answer_options.num_simulcast_layers);
}
+static void GetSimulcastInformationFromRtpParameters(
+ const RtpParameters& parameters,
+ RidDirection direction,
+ std::vector<RidDescription>* rids,
+ SimulcastLayerList* layers) {
+ for (const RtpEncodingParameters& encoding : parameters.encodings) {
+ if (encoding.rid.empty()) {
+ continue;
+ }
+ rids->push_back(RidDescription(encoding.rid, direction));
+ layers->AddLayer(SimulcastLayer(encoding.rid, !encoding.active));
+ }
+}
+
static cricket::MediaDescriptionOptions
GetMediaDescriptionOptionsForTransceiver(
rtc::scoped_refptr<RtpTransceiverProxyWithInternal<RtpTransceiver>>
@@ -4048,18 +4167,46 @@
// sendrecv.
// 2. If the MSID is included, then it must be included in any subsequent
// offer/answer exactly the same until the RtpTransceiver is stopped.
- if (!transceiver->stopped() &&
- (RtpTransceiverDirectionHasSend(transceiver->direction()) ||
- transceiver->internal()->has_ever_been_used_to_send())) {
- cricket::SenderOptions sender_options;
- sender_options.track_id = transceiver->sender()->id();
- sender_options.stream_ids = transceiver->sender()->stream_ids();
- int num_send_encoding_layers =
- transceiver->sender()->init_send_encodings().size();
- sender_options.num_sim_layers =
- !num_send_encoding_layers ? 1 : num_send_encoding_layers;
- media_description_options.sender_options.push_back(sender_options);
+ if (transceiver->stopped() ||
+ (!RtpTransceiverDirectionHasSend(transceiver->direction()) &&
+ !transceiver->internal()->has_ever_been_used_to_send())) {
+ return media_description_options;
}
+
+ cricket::SenderOptions sender_options;
+ sender_options.track_id = transceiver->sender()->id();
+ sender_options.stream_ids = transceiver->sender()->stream_ids();
+
+ // The following sets up RIDs and Simulcast.
+ // RIDs are included if Simulcast is requested or if any RID was specified.
+ RtpParameters send_parameters = transceiver->sender()->GetParameters();
+ RtpParameters receive_parameters = transceiver->receiver()->GetParameters();
+ bool has_rids = std::any_of(send_parameters.encodings.begin(),
+ send_parameters.encodings.end(),
+ [](const RtpEncodingParameters& encoding) {
+ return !encoding.rid.empty();
+ });
+
+ std::vector<RidDescription> send_rids, receive_rids;
+ SimulcastLayerList send_layers, receive_layers;
+ GetSimulcastInformationFromRtpParameters(send_parameters, RidDirection::kSend,
+ &send_rids, &send_layers);
+ GetSimulcastInformationFromRtpParameters(receive_parameters,
+ RidDirection::kReceive,
+ &receive_rids, &receive_layers);
+ if (has_rids) {
+ sender_options.rids = send_rids;
+ }
+
+ sender_options.simulcast_layers = send_layers;
+ media_description_options.receive_simulcast_layers = receive_layers;
+ media_description_options.receive_rids = receive_rids;
+ // When RIDs are configured, we must set num_sim_layers to 0 to.
+ // Otherwise, num_sim_layers must be 1 because either there is no
+ // simulcast, or simulcast is acheived by munging the SDP.
+ sender_options.num_sim_layers = has_rids ? 0 : 1;
+ media_description_options.sender_options.push_back(sender_options);
+
return media_description_options;
}
@@ -5930,7 +6077,7 @@
cricket::VoiceChannel* voice_channel = channel_manager()->CreateVoiceChannel(
call_.get(), configuration_.media_config, rtp_transport, media_transport,
signaling_thread(), mid, SrtpRequired(), GetCryptoOptions(),
- audio_options_);
+ &ssrc_generator_, audio_options_);
if (!voice_channel) {
return nullptr;
}
@@ -5955,7 +6102,7 @@
cricket::VideoChannel* video_channel = channel_manager()->CreateVideoChannel(
call_.get(), configuration_.media_config, rtp_transport, media_transport,
signaling_thread(), mid, SrtpRequired(), GetCryptoOptions(),
- video_options_);
+ &ssrc_generator_, video_options_);
if (!video_channel) {
return nullptr;
}
@@ -6002,7 +6149,7 @@
RtpTransportInternal* rtp_transport = GetRtpTransport(mid);
rtp_data_channel_ = channel_manager()->CreateRtpDataChannel(
configuration_.media_config, rtp_transport, signaling_thread(), mid,
- SrtpRequired(), GetCryptoOptions());
+ SrtpRequired(), GetCryptoOptions(), &ssrc_generator_);
if (!rtp_data_channel_) {
return false;
}