From 8d02c52f770e5626a67dfdc47214fc23b744ac47 Mon Sep 17 00:00:00 2001
From: metamuffin <metamuffin@disroot.org>
Date: Tue, 19 Nov 2024 15:28:29 +0100
Subject: more rtcp

---
 rtp/src/lib.rs | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 77 insertions(+), 1 deletion(-)

(limited to 'rtp/src/lib.rs')

diff --git a/rtp/src/lib.rs b/rtp/src/lib.rs
index 8c87af8..0c80412 100644
--- a/rtp/src/lib.rs
+++ b/rtp/src/lib.rs
@@ -1,2 +1,78 @@
-pub mod rtp;
+#![feature(random)]
+use std::{
+    collections::HashSet,
+    random::random,
+    time::{Duration, Instant},
+};
+
+use rtcp::RtcpPacket;
+use rtp::SSRC;
+
 pub mod rtcp;
+pub mod rtp;
+
+pub struct Session {
+    tp: Instant,
+    tc: Instant,
+    tn: Instant,
+    pmembers: usize,
+    members: usize,
+    senders: usize,
+    rtcp_bw: f32,
+    we_sent: bool,
+    avg_rtcp_size: f32,
+    initial: bool,
+
+    member_table: HashSet<SSRC>,
+}
+
+impl Session {
+    /// RFC 3550, Section 6.3.1
+    pub fn compute_rtcp_transmission_interval(&self) -> Duration {
+        let n;
+        let c;
+        if self.senders * 4 < self.members {
+            if self.we_sent {
+                // Senders use a quarter of the bandwidth
+                c = self.avg_rtcp_size / (self.rtcp_bw * 0.25);
+                n = self.senders;
+            } else {
+                // Receivers use the remaining three quarters
+                c = self.avg_rtcp_size / (self.rtcp_bw * 0.75);
+                n = self.members - self.senders
+            }
+        } else {
+            // Equally split between members
+            c = self.avg_rtcp_size / self.rtcp_bw;
+            n = self.members;
+        }
+
+        let tmin = if self.initial { 2.5f32 } else { 5. };
+        let td = tmin.max(n as f32 * c);
+        let t = td * ((random::<u16>() as f32) / (u16::MAX as f32) + 0.5);
+        let t = t / 1.5f32.exp();
+        Duration::from_secs_f32(t)
+    }
+
+    /// RFC 3550, Section 6.3.2
+    pub fn new() -> Self {
+        let mut se = Self {
+            tp: Instant::now(),
+            tc: Instant::now(),
+            tn: Instant::now(),
+            senders: 0,
+            pmembers: 1,
+            members: 1,
+            we_sent: false,
+            initial: true,
+            member_table: HashSet::new(), // TODO add own ssrc to members
+            rtcp_bw: 1000.,               // TODO set rtcp bandwidth from params
+            avg_rtcp_size: 1000.,         // TODO set to next likely rtcp packet size
+        };
+        se.tn += se.compute_rtcp_transmission_interval();
+        se
+    }
+
+    /// RFC 3550, Section 6.3.3
+    pub fn on_receive(&mut self, packet: RtcpPacket) {}
+}
-- 
cgit v1.2.3-70-g09d2