interceptor: Add AssociatedStreamInfo and populate for rtx streams

anders-avos · Aug 26, 2024 · caeaa88 · caeaa88
1 parent 23bbc1f
commit caeaa88
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Showing 6 changed files with 60 additions and 9 deletions.
diff --git a/interceptor/src/stream_info.rs b/interceptor/src/stream_info.rs
@@ -20,6 +20,15 @@ pub struct StreamInfo {
     pub channels: u16,
     pub sdp_fmtp_line: String,
     pub rtcp_feedback: Vec<RTCPFeedback>,
+    pub associated_stream: Option<AssociatedStreamInfo>,
+}
+
+/// AssociatedStreamInfo provides a mapping from an auxiliary stream (RTX, FEC,
+/// etc.) back to the original stream.
+#[derive(Default, Debug, Clone)]
+pub struct AssociatedStreamInfo {
+    pub ssrc: u32,
+    pub payload_type: u8,
 }
 
 /// RTCPFeedback signals the connection to use additional RTCP packet types.

diff --git a/webrtc/src/peer_connection/peer_connection_internal.rs b/webrtc/src/peer_connection/peer_connection_internal.rs
@@ -1080,6 +1080,7 @@ impl PeerConnectionInternal {
             params.codecs[0].payload_type,
             params.codecs[0].capability.clone(),
             &params.header_extensions,
+            None,
         );
         let (rtp_read_stream, rtp_interceptor, rtcp_read_stream, rtcp_interceptor) = self
             .dtls_transport

diff --git a/webrtc/src/rtp_transceiver/mod.rs b/webrtc/src/rtp_transceiver/mod.rs
@@ -7,7 +7,7 @@ use std::pin::Pin;
 use std::sync::atomic::Ordering;
 use std::sync::Arc;
 
-use interceptor::stream_info::{RTPHeaderExtension, StreamInfo};
+use interceptor::stream_info::{AssociatedStreamInfo, RTPHeaderExtension, StreamInfo};
 use interceptor::Attributes;
 use log::trace;
 use portable_atomic::{AtomicBool, AtomicU8};
@@ -136,6 +136,7 @@ pub(crate) fn create_stream_info(
     payload_type: PayloadType,
     codec: RTCRtpCodecCapability,
     webrtc_header_extensions: &[RTCRtpHeaderExtensionParameters],
+    associated_stream: Option<AssociatedStreamInfo>,
 ) -> StreamInfo {
     let header_extensions: Vec<RTPHeaderExtension> = webrtc_header_extensions
         .iter()
@@ -165,6 +166,7 @@ pub(crate) fn create_stream_info(
         channels: codec.channels,
         sdp_fmtp_line: codec.sdp_fmtp_line,
         rtcp_feedback: feedbacks,
+        associated_stream,
     }
 }
 

diff --git a/webrtc/src/rtp_transceiver/rtp_codec.rs b/webrtc/src/rtp_transceiver/rtp_codec.rs
@@ -168,3 +168,31 @@ pub(crate) fn codec_parameters_fuzzy_search(
 
     (RTCRtpCodecParameters::default(), CodecMatch::None)
 }
+
+pub(crate) fn codec_rtx_search(
+    original_codec: &RTCRtpCodecParameters,
+    available_codecs: &[RTCRtpCodecParameters],
+) -> Option<RTCRtpCodecParameters> {
+    // find the rtx codec as defined in RFC4588
+
+    let (mime_kind, _) = original_codec.capability.mime_type.split_once("/")?;
+    let rtx_mime = format!("{mime_kind}/rtx");
+
+    for codec in available_codecs {
+        if codec.capability.mime_type != rtx_mime {
+            continue;
+        }
+
+        let params = fmtp::parse(&codec.capability.mime_type, &codec.capability.sdp_fmtp_line);
+
+        if params
+            .parameter("apt")
+            .and_then(|v| v.parse::<u8>().ok())
+            .is_some_and(|apt| apt == original_codec.payload_type)
+        {
+            return Some(codec.clone());
+        }
+    }
+
+    None
+}
diff --git a/webrtc/src/rtp_transceiver/rtp_receiver/mod.rs b/webrtc/src/rtp_transceiver/rtp_receiver/mod.rs
@@ -5,7 +5,7 @@ use std::fmt;
 use std::sync::Arc;
 
 use arc_swap::ArcSwapOption;
-use interceptor::stream_info::RTPHeaderExtension;
+use interceptor::stream_info::{AssociatedStreamInfo, RTPHeaderExtension};
 use interceptor::{Attributes, Interceptor};
 use log::trace;
 use smol_str::SmolStr;
@@ -16,12 +16,12 @@ use crate::dtls_transport::RTCDtlsTransport;
 use crate::error::{flatten_errs, Error, Result};
 use crate::peer_connection::sdp::TrackDetails;
 use crate::rtp_transceiver::rtp_codec::{
-    codec_parameters_fuzzy_search, CodecMatch, RTCRtpCodecCapability, RTCRtpCodecParameters,
-    RTCRtpParameters, RTPCodecType,
+    codec_parameters_fuzzy_search, CodecMatch, RTCRtpCodecParameters, RTCRtpParameters,
+    RTPCodecType,
 };
 use crate::rtp_transceiver::rtp_transceiver_direction::RTCRtpTransceiverDirection;
 use crate::rtp_transceiver::{
-    create_stream_info, RTCRtpDecodingParameters, RTCRtpReceiveParameters, SSRC,
+    codec_rtx_search, create_stream_info, RTCRtpDecodingParameters, RTCRtpReceiveParameters, SSRC,
 };
 use crate::track::track_remote::TrackRemote;
 use crate::track::{TrackStream, TrackStreams};
@@ -519,9 +519,9 @@ impl RTCRtpReceiver {
         };
 
         let codec = if let Some(codec) = global_params.codecs.first() {
-            codec.capability.clone()
+            codec.clone()
         } else {
-            RTCRtpCodecCapability::default()
+            RTCRtpCodecParameters::default()
         };
 
         for encoding in &parameters.encodings {
@@ -531,8 +531,9 @@ impl RTCRtpReceiver {
                         "".to_owned(),
                         encoding.ssrc,
                         0,
-                        codec.clone(),
+                        codec.capability.clone(),
                         &global_params.header_extensions,
+                        None,
                     );
                     let (rtp_read_stream, rtp_interceptor, rtcp_read_stream, rtcp_interceptor) =
                         self.internal
@@ -585,12 +586,21 @@ impl RTCRtpReceiver {
 
             let rtx_ssrc = encoding.rtx.ssrc;
             if rtx_ssrc != 0 {
+                let rtx_info = AssociatedStreamInfo {
+                    ssrc: encoding.ssrc,
+                    payload_type: 0,
+                };
+
+                let rtx_codec =
+                    codec_rtx_search(&codec, &global_params.codecs).unwrap_or(codec.clone());
+
                 let stream_info = create_stream_info(
                     "".to_owned(),
                     rtx_ssrc,
                     0,
-                    codec.clone(),
+                    rtx_codec.capability,
                     &global_params.header_extensions,
+                    Some(rtx_info),
                 );
                 let (rtp_read_stream, rtp_interceptor, rtcp_read_stream, rtcp_interceptor) = self
                     .internal

diff --git a/webrtc/src/rtp_transceiver/rtp_sender/mod.rs b/webrtc/src/rtp_transceiver/rtp_sender/mod.rs
@@ -427,6 +427,7 @@ impl RTCRtpSender {
                 codec.payload_type,
                 codec.capability.clone(),
                 &parameters.rtp_parameters.header_extensions,
+                None,
             );
             context.params.codecs = vec![codec];