Send side Simulcast/Track encodings (webrtc-rs#578)

* track_local: Add ability to set RTP stream ID

This change makes it possible to set the RTP stream ID to
allow forwarding and production of simulcast streams.

* peer_connection: Bolt on send side simulcast

Introduces add_encoding method in RTP sender to add simulcast encodings.

* rtp_sender: Add some missing tests

Ported over from pion

* peer_connection: Add Simulcast send test

This is a port from a pion test

* track_local: Insert mid and rid RTP header extension

When MID and RTP stream ID header extension are enabled all RTP packets
get corresponding MID and RID added as extension headers.

* peer_connection: Handle Simulcast Offer with one Media Section

This is ported from Pion

webrtc/src/api/mod.rs

@@ -157,9 +157,11 @@ impl API {
         transport: Arc<RTCDtlsTransport>,
         interceptor: Arc<dyn Interceptor + Send + Sync>,
     ) -> RTCRtpSender {
+        let kind = track.as_ref().map(|t| t.kind()).unwrap_or_default();
         RTCRtpSender::new(
             self.setting_engine.get_receive_mtu(),
             track,
+            kind,
             transport,
             Arc::clone(&self.media_engine),
             interceptor,

webrtc/src/error.rs

@@ -199,6 +199,10 @@ pub enum Error {
     #[error("new track must be of the same kind as previous")]
     ErrRTPSenderNewTrackHasIncorrectKind,
 
+    /// ErrRTPSenderNewTrackHasIncorrectEnvelope indicates that the new track has a different envelope than the previous/original
+    #[error("new track must have the same envelope as previous")]
+    ErrRTPSenderNewTrackHasIncorrectEnvelope,
+
     /// ErrRTPSenderDataSent indicates that the sequence number transformer tries to be enabled after the data sending began
     #[error("Sequence number transformer must be enabled before sending data")]
     ErrRTPSenderDataSent,
@@ -328,6 +332,20 @@ pub enum Error {
     },
     #[error("Track must not be nil")]
     ErrRTPSenderTrackNil,
+    #[error("Sender has already been stopped")]
+    ErrRTPSenderStopped,
+    #[error("Sender Track has been removed or replaced to nil")]
+    ErrRTPSenderTrackRemoved,
+    #[error("Sender cannot add encoding as rid is empty")]
+    ErrRTPSenderRidNil,
+    #[error("Sender cannot add encoding as there is no base track")]
+    ErrRTPSenderNoBaseEncoding,
+    #[error("Sender cannot add encoding as provided track does not match base track")]
+    ErrRTPSenderBaseEncodingMismatch,
+    #[error("Sender cannot encoding due to RID collision")]
+    ErrRTPSenderRIDCollision,
+    #[error("Sender does not have track for RID")]
+    ErrRTPSenderNoTrackForRID,
     #[error("RTPSender must not be nil")]
     ErrRTPSenderNil,
     #[error("RTPReceiver must not be nil")]

webrtc/src/peer_connection/mod.rs

@@ -1410,6 +1410,7 @@ impl RTCPeerConnection {
                                 RTCRtpSender::new(
                                     receive_mtu,
                                     None,
+                                    kind,
                                     Arc::clone(&self.internal.dtls_transport),
                                     Arc::clone(&self.internal.media_engine),
                                     Arc::clone(&self.interceptor),
@@ -1608,7 +1609,10 @@ impl RTCPeerConnection {
         let current_transceivers = self.internal.rtp_transceivers.lock().await;
         for transceiver in &*current_transceivers {
             let sender = transceiver.sender().await;
-            if sender.is_negotiated() && !sender.has_sent() {
+            if !sender.track_encodings.lock().await.is_empty()
+                && sender.is_negotiated()
+                && !sender.has_sent()
+            {
                 sender.send(&sender.get_parameters().await).await?;
             }
         }

webrtc/src/peer_connection/peer_connection_internal.rs

@@ -14,6 +14,7 @@ use crate::stats::{
     InboundRTPStats, OutboundRTPStats, RTCStatsType, RemoteInboundRTPStats, RemoteOutboundRTPStats,
     StatsReportType,
 };
+use crate::track::track_local::track_local_static_sample::TrackLocalStaticSample;
 use crate::track::TrackStream;
 use crate::SDP_ATTRIBUTE_RID;
 
@@ -442,44 +443,60 @@ impl PeerConnectionInternal {
             .map(|value| value.direction)
             .unwrap_or(RTCRtpTransceiverDirection::Sendrecv);
 
-        if direction == RTCRtpTransceiverDirection::Unspecified {
-            return Err(Error::ErrPeerConnAddTransceiverFromKindSupport);
-        }
-
-        let interceptor = self
-            .interceptor
-            .upgrade()
-            .ok_or(Error::ErrInterceptorNotBind)?;
-        let receiver = Arc::new(RTCRtpReceiver::new(
-            self.setting_engine.get_receive_mtu(),
-            kind,
-            Arc::clone(&self.dtls_transport),
-            Arc::clone(&self.media_engine),
-            Arc::clone(&interceptor),
-        ));
+        let t = match direction {
+            RTCRtpTransceiverDirection::Sendonly | RTCRtpTransceiverDirection::Sendrecv => {
+                let codec = self
+                    .media_engine
+                    .get_codecs_by_kind(kind)
+                    .first()
+                    .map(|c| c.capability.clone())
+                    .ok_or(Error::ErrNoCodecsAvailable)?;
+                let track = Arc::new(TrackLocalStaticSample::new(
+                    codec,
+                    math_rand_alpha(16),
+                    math_rand_alpha(16),
+                ));
+                self.new_transceiver_from_track(direction, track).await?
+            }
+            RTCRtpTransceiverDirection::Recvonly => {
+                let interceptor = self
+                    .interceptor
+                    .upgrade()
+                    .ok_or(Error::ErrInterceptorNotBind)?;
+                let receiver = Arc::new(RTCRtpReceiver::new(
+                    self.setting_engine.get_receive_mtu(),
+                    kind,
+                    Arc::clone(&self.dtls_transport),
+                    Arc::clone(&self.media_engine),
+                    Arc::clone(&interceptor),
+                ));
 
-        let sender = Arc::new(
-            RTCRtpSender::new(
-                self.setting_engine.get_receive_mtu(),
-                None,
-                Arc::clone(&self.dtls_transport),
-                Arc::clone(&self.media_engine),
-                interceptor,
-                false,
-            )
-            .await,
-        );
+                let sender = Arc::new(
+                    RTCRtpSender::new(
+                        self.setting_engine.get_receive_mtu(),
+                        None,
+                        kind,
+                        Arc::clone(&self.dtls_transport),
+                        Arc::clone(&self.media_engine),
+                        interceptor,
+                        false,
+                    )
+                    .await,
+                );
 
-        let t = RTCRtpTransceiver::new(
-            receiver,
-            sender,
-            direction,
-            kind,
-            vec![],
-            Arc::clone(&self.media_engine),
-            Some(Box::new(self.make_negotiation_needed_trigger())),
-        )
-        .await;
+                RTCRtpTransceiver::new(
+                    receiver,
+                    sender,
+                    direction,
+                    kind,
+                    vec![],
+                    Arc::clone(&self.media_engine),
+                    Some(Box::new(self.make_negotiation_needed_trigger())),
+                )
+                .await
+            }
+            _ => return Err(Error::ErrPeerConnAddTransceiverFromKindSupport),
+        };
 
         self.add_rtp_transceiver(Arc::clone(&t)).await;
 
@@ -512,6 +529,7 @@ impl PeerConnectionInternal {
             RTCRtpSender::new(
                 self.setting_engine.get_receive_mtu(),
                 Some(Arc::clone(&track)),
+                track.kind(),
                 Arc::clone(&self.dtls_transport),
                 Arc::clone(&self.media_engine),
                 Arc::clone(&interceptor),
@@ -858,6 +876,8 @@ impl PeerConnectionInternal {
         let only_media_section = &remote_description.media_descriptions[0];
         let mut stream_id = "";
         let mut id = "";
+        let mut has_rid = false;
+        let mut has_ssrc = false;
 
         for a in &only_media_section.attributes {
             match a.key.as_str() {
@@ -870,12 +890,18 @@ impl PeerConnectionInternal {
                         }
                     }
                 }
-                ATTR_KEY_SSRC => return Err(Error::ErrPeerConnSingleMediaSectionHasExplicitSSRC),
-                SDP_ATTRIBUTE_RID => return Ok(false),
+                ATTR_KEY_SSRC => has_ssrc = true,
+                SDP_ATTRIBUTE_RID => has_rid = true,
                 _ => {}
             };
         }
 
+        if has_rid {
+            return Ok(false);
+        } else if has_ssrc {
+            return Err(Error::ErrPeerConnSingleMediaSectionHasExplicitSSRC);
+        }
+
         let mut incoming = TrackDetails {
             ssrcs: vec![ssrc],
             kind: RTPCodecType::Video,
@@ -1343,32 +1369,29 @@ impl PeerConnectionInternal {
         }
         let mut track_infos = vec![];
         for transceiver in transceivers {
-            let sender = transceiver.sender().await;
-
             let mid = match transceiver.mid() {
                 Some(mid) => mid,
                 None => continue,
             };
 
-            let track = match sender.track().await {
-                Some(track) => track,
-                None => continue,
-            };
-
-            let track_id = track.id().to_string();
-            let kind = match track.kind() {
-                RTPCodecType::Unspecified => continue,
-                RTPCodecType::Audio => "audio",
-                RTPCodecType::Video => "video",
-            };
+            let sender = transceiver.sender().await;
+            let track_encodings = sender.track_encodings.lock().await;
+            for encoding in track_encodings.iter() {
+                let track_id = encoding.track.id().to_string();
+                let kind = match encoding.track.kind() {
+                    RTPCodecType::Unspecified => continue,
+                    RTPCodecType::Audio => "audio",
+                    RTPCodecType::Video => "video",
+                };
 
-            track_infos.push(TrackInfo {
-                track_id,
-                ssrc: sender.ssrc,
-                mid,
-                rid: None,
-                kind,
-            });
+                track_infos.push(TrackInfo {
+                    track_id,
+                    ssrc: encoding.ssrc,
+                    mid: mid.to_owned(),
+                    rid: encoding.track.rid().map(Into::into),
+                    kind,
+                });
+            }
         }
 
         let stream_stats = self

webrtc/src/peer_connection/peer_connection_test.rs

@@ -19,6 +19,7 @@ use crate::ice_transport::ice_server::RTCIceServer;
 use crate::peer_connection::configuration::RTCConfiguration;
 use crate::rtp_transceiver::rtp_codec::RTCRtpCodecCapability;
 use crate::stats::StatsReportType;
+use crate::track::track_local::track_local_static_rtp::TrackLocalStaticRTP;
 use crate::track::track_local::track_local_static_sample::TrackLocalStaticSample;
 use crate::Error;
 
@@ -513,3 +514,127 @@ async fn peer() -> Result<()> {
 
     Ok(())
 }
+
+pub(crate) fn on_connected() -> (OnPeerConnectionStateChangeHdlrFn, mpsc::Receiver<()>) {
+    let (done_tx, done_rx) = mpsc::channel::<()>(1);
+    let done_tx = Arc::new(Mutex::new(Some(done_tx)));
+    let hdlr_fn: OnPeerConnectionStateChangeHdlrFn =
+        Box::new(move |state: RTCPeerConnectionState| {
+            let done_tx_clone = Arc::clone(&done_tx);
+            Box::pin(async move {
+                if state == RTCPeerConnectionState::Connected {
+                    let mut tx = done_tx_clone.lock().await;
+                    tx.take();
+                }
+            })
+        });
+    (hdlr_fn, done_rx)
+}
+
+// Everytime we receive a new SSRC we probe it and try to determine the proper way to handle it.
+// In most cases a Track explicitly declares a SSRC and a OnTrack is fired. In two cases we don't
+// know the SSRC ahead of time
+// * Undeclared SSRC in a single media section
+// * Simulcast
+//
+// The Undeclared SSRC processing code would run before Simulcast. If a Simulcast Offer/Answer only
+// contained one Media Section we would never fire the OnTrack. We would assume it was a failed
+// Undeclared SSRC processing. This test asserts that we properly handled this.
+#[tokio::test]
+async fn test_peer_connection_simulcast_no_data_channel() -> Result<()> {
+    let mut m = MediaEngine::default();
+    for ext in [
+        ::sdp::extmap::SDES_MID_URI,
+        ::sdp::extmap::SDES_RTP_STREAM_ID_URI,
+    ] {
+        m.register_header_extension(
+            RTCRtpHeaderExtensionCapability {
+                uri: ext.to_owned(),
+            },
+            RTPCodecType::Video,
+            None,
+        )?;
+    }
+    m.register_default_codecs()?;
+    let api = APIBuilder::new().with_media_engine(m).build();
+
+    let (mut pc_send, mut pc_recv) = new_pair(&api).await?;
+    let (send_notifier, mut send_connected) = on_connected();
+    let (recv_notifier, mut recv_connected) = on_connected();
+    pc_send.on_peer_connection_state_change(send_notifier);
+    pc_recv.on_peer_connection_state_change(recv_notifier);
+    let (track_tx, mut track_rx) = mpsc::unbounded_channel();
+    pc_recv.on_track(Box::new(move |t, _, _| {
+        let rid = t.rid().to_owned();
+        let _ = track_tx.send(rid);
+        Box::pin(async move {})
+    }));
+
+    let id = "video";
+    let stream_id = "webrtc-rs";
+    let track = Arc::new(TrackLocalStaticRTP::new_with_rid(
+        RTCRtpCodecCapability {
+            mime_type: MIME_TYPE_VP8.to_owned(),
+            ..Default::default()
+        },
+        id.to_owned(),
+        "a".to_owned(),
+        stream_id.to_owned(),
+    ));
+    let track_a = Arc::clone(&track);
+    let transceiver = pc_send.add_transceiver_from_track(track, None).await?;
+    let sender = transceiver.sender().await;
+
+    let track = Arc::new(TrackLocalStaticRTP::new_with_rid(
+        RTCRtpCodecCapability {
+            mime_type: MIME_TYPE_VP8.to_owned(),
+            ..Default::default()
+        },
+        id.to_owned(),
+        "b".to_owned(),
+        stream_id.to_owned(),
+    ));
+    let track_b = Arc::clone(&track);
+    sender.add_encoding(track).await?;
+
+    let track = Arc::new(TrackLocalStaticRTP::new_with_rid(
+        RTCRtpCodecCapability {
+            mime_type: MIME_TYPE_VP8.to_owned(),
+            ..Default::default()
+        },
+        id.to_owned(),
+        "c".to_owned(),
+        stream_id.to_owned(),
+    ));
+    let track_c = Arc::clone(&track);
+    sender.add_encoding(track).await?;
+
+    // signaling
+    signal_pair(&mut pc_send, &mut pc_recv).await?;
+    let _ = send_connected.recv().await;
+    let _ = recv_connected.recv().await;
+
+    for sequence_number in [0; 100] {
+        let pkt = rtp::packet::Packet {
+            header: rtp::header::Header {
+                version: 2,
+                sequence_number,
+                payload_type: 96,
+                ..Default::default()
+            },
+            payload: Bytes::from_static(&[0; 2]),
+        };
+
+        track_a.write_rtp_with_extensions(&pkt, &[]).await?;
+        track_b.write_rtp_with_extensions(&pkt, &[]).await?;
+        track_c.write_rtp_with_extensions(&pkt, &[]).await?;
+    }
+
+    assert_eq!(track_rx.recv().await.unwrap(), "a".to_owned());
+    assert_eq!(track_rx.recv().await.unwrap(), "b".to_owned());
+    assert_eq!(track_rx.recv().await.unwrap(), "c".to_owned());
+
+    close_pair_now(&pc_send, &pc_recv).await;
+
+    Ok(())
+}