rtpbin2: Implement support for reduced size RTCP (RFC 5506)

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1426>

docs/plugins/gst_plugins_cache.json

@@ -7263,6 +7263,18 @@
                         "type": "guint",
                         "writable": true
                     },
+                    "reduced-size-rtcp": {
+                        "blurb": "Use reduced size RTCP. Only has an effect if rtp-profile=avpf",
+                        "conditionally-available": false,
+                        "construct": false,
+                        "construct-only": false,
+                        "controllable": false,
+                        "default": "false",
+                        "mutable": "ready",
+                        "readable": true,
+                        "type": "gboolean",
+                        "writable": true
+                    },
                     "rtp-profile": {
                         "blurb": "RTP Profile to use",
                         "conditionally-available": false,

net/rtp/src/rtpbin2/imp.rs

@@ -22,6 +22,7 @@ use crate::rtpbin2::RUNTIME;
 
 const DEFAULT_LATENCY: gst::ClockTime = gst::ClockTime::from_mseconds(0);
 const DEFAULT_MIN_RTCP_INTERVAL: Duration = RTCP_MIN_REPORT_INTERVAL;
+const DEFAULT_REDUCED_SIZE_RTCP: bool = false;
 
 static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
     gst::DebugCategory::new(
@@ -65,6 +66,7 @@ struct Settings {
     latency: gst::ClockTime,
     min_rtcp_interval: Duration,
     profile: Profile,
+    reduced_size_rtcp: bool,
 }
 
 impl Default for Settings {
@@ -73,6 +75,7 @@ impl Default for Settings {
             latency: DEFAULT_LATENCY,
             min_rtcp_interval: DEFAULT_MIN_RTCP_INTERVAL,
             profile: Profile::default(),
+            reduced_size_rtcp: DEFAULT_REDUCED_SIZE_RTCP,
         }
     }
 }
@@ -161,6 +164,9 @@ impl BinSession {
             .session
             .set_min_rtcp_interval(settings.min_rtcp_interval);
         inner.session.set_profile(settings.profile.into());
+        inner
+            .session
+            .set_reduced_size_rtcp(settings.reduced_size_rtcp);
         Self {
             id,
             inner: Arc::new(Mutex::new(inner)),
@@ -1066,6 +1072,12 @@ impl ObjectImpl for RtpBin2 {
                     .default_value(Profile::default())
                     .mutable_ready()
                     .build(),
+                glib::ParamSpecBoolean::builder("reduced-size-rtcp")
+                    .nick("Reduced Size RTCP")
+                    .blurb("Use reduced size RTCP. Only has an effect if rtp-profile=avpf")
+                    .default_value(DEFAULT_REDUCED_SIZE_RTCP)
+                    .mutable_ready()
+                    .build(),
             ]
         });
 
@@ -1097,6 +1109,10 @@ impl ObjectImpl for RtpBin2 {
                 let mut settings = self.settings.lock().unwrap();
                 settings.profile = value.get::<Profile>().expect("Type checked upstream");
             }
+            "reduced-size-rtcp" => {
+                let mut settings = self.settings.lock().unwrap();
+                settings.reduced_size_rtcp = value.get::<bool>().expect("Type checked upstream");
+            }
             _ => unimplemented!(),
         }
     }
@@ -1119,6 +1135,10 @@ impl ObjectImpl for RtpBin2 {
                 let settings = self.settings.lock().unwrap();
                 settings.profile.to_value()
             }
+            "reduced-size-rtcp" => {
+                let settings = self.settings.lock().unwrap();
+                settings.reduced_size_rtcp.to_value()
+            }
             _ => unimplemented!(),
         }
     }

net/rtp/src/rtpbin2/session.rs

@@ -72,6 +72,7 @@ pub struct Session {
     // settings
     min_rtcp_interval: Duration,
     profile: RtpProfile,
+    reduced_size_rtcp: bool,
     // state
     local_senders: HashMap<u32, LocalSendSource>,
     local_receivers: HashMap<u32, LocalReceiveSource>,
@@ -162,6 +163,7 @@ impl Session {
         Self {
             min_rtcp_interval: RTCP_MIN_REPORT_INTERVAL,
             profile: RtpProfile::default(),
+            reduced_size_rtcp: false,
             local_senders: HashMap::new(),
             // also known as remote_senders
             local_receivers: HashMap::new(),
@@ -197,6 +199,11 @@ impl Session {
         self.profile = profile;
     }
 
+    /// Set usage of reduced size RTCP
+    pub fn set_reduced_size_rtcp(&mut self, reduced_size_rtcp: bool) {
+        self.reduced_size_rtcp = reduced_size_rtcp;
+    }
+
     fn n_members(&self) -> usize {
         self.bye_state
             .as_ref()
@@ -759,6 +766,11 @@ impl Session {
         minimum: bool, // RFC 4585
         ssrcs_reported: &mut Vec<u32>,
     ) -> CompoundBuilder<'a> {
+        // Don't include in an early reduced-size RTCP packet
+        if minimum && self.reduced_size_rtcp_allowed() {
+            return rtcp;
+        }
+
         let ntp_time = system_time_to_ntp_time_u64(ntp_now);
         if self
             .local_senders
@@ -844,6 +856,10 @@ impl Session {
         rtcp
     }
 
+    fn reduced_size_rtcp_allowed(&self) -> bool {
+        self.reduced_size_rtcp && matches!(self.profile, RtpProfile::Avpf)
+    }
+
     fn have_ssrc(&self, ssrc: u32) -> bool {
         self.local_senders.contains_key(&ssrc)
             || self.local_receivers.contains_key(&ssrc)
@@ -882,6 +898,11 @@ impl Session {
         minimum: bool, // RFC 4585
         ssrcs_reported: &mut Vec<u32>,
     ) -> CompoundBuilder<'a> {
+        // Don't include in an early reduced-size RTCP packet
+        if minimum && self.reduced_size_rtcp_allowed() {
+            return rtcp;
+        }
+
         if self
             .local_senders
             .values()
@@ -924,6 +945,11 @@ impl Session {
         rtcp: CompoundBuilder<'a>,
         minimum: bool, // RFC 4585
     ) -> CompoundBuilder<'a> {
+        // Don't include in an early reduced-size RTCP packet
+        if minimum && self.reduced_size_rtcp_allowed() {
+            return rtcp;
+        }
+
         let mut sdes = Sdes::builder();
         let mut have_chunk = false;
         for sender in self.local_senders.values() {