rtc_interceptor/rtpfb/
acknowledgement.rs

1//! What a feedback report says happened to one packet.
2
3use rtcp::transport_feedbacks::cc_feedback_report::Ecn;
4use std::time::{Duration, Instant};
5
6/// One packet's fate, as reported by the receiver.
7///
8/// `arrival` is a [`Duration`] rather than an [`Instant`] because it is measured on the
9/// **receiver's** clock, which this endpoint has no way to align with its own. Only differences
10/// between arrivals are meaningful, and those are what congestion control actually reads: the
11/// spread between send spacing and arrival spacing is the delay the path is imposing.
12///
13/// Each feedback format supplies its own epoch — TWCC's 24-bit reference time, RFC 8888's report
14/// timestamp — and both advance monotonically, so arrivals stay comparable across successive
15/// reports of the same format. They are *not* comparable between formats.
16#[derive(Debug, Clone, Copy, PartialEq, Eq)]
17pub struct Acknowledgement {
18    /// The sequence number this refers to. TWCC numbers packets itself; RFC 8888 uses the RTP
19    /// sequence number of the stream it names.
20    pub sequence_number: u16,
21    /// Whether the receiver got it.
22    pub arrived: bool,
23    /// When it arrived, on the receiver's clock. `None` for a packet that did not arrive, or one
24    /// reported as received without a usable arrival time.
25    pub arrival: Option<Duration>,
26    /// The ECN marking the receiver observed. TWCC cannot carry this and always reports `NotEct`.
27    pub ecn: Ecn,
28}
29
30impl Acknowledgement {
31    /// A packet the receiver did not get.
32    pub fn lost(sequence_number: u16) -> Self {
33        Self {
34            sequence_number,
35            arrived: false,
36            arrival: None,
37            ecn: Ecn::NotEct,
38        }
39    }
40
41    /// A packet the receiver got at `arrival` on its own clock.
42    pub fn received(sequence_number: u16, arrival: Option<Duration>, ecn: Ecn) -> Self {
43        Self {
44            sequence_number,
45            arrived: true,
46            arrival,
47            ecn,
48        }
49    }
50}
51
52/// One outgoing packet, joined with whatever the receiver later said about it.
53///
54/// This is the record congestion control consumes: what was sent, when it left here, and when it
55/// turned up there.
56#[derive(Debug, Clone, PartialEq, Eq)]
57pub struct PacketReport {
58    /// SSRC of the stream the packet belongs to.
59    pub ssrc: u32,
60    /// Monotonic identifier assigned when the packet was recorded, so reports stay in send order
61    /// however the sequence numbers wrap.
62    pub id: u64,
63    /// The RTP sequence number the packet carried.
64    pub rtp_sequence_number: u16,
65    /// Whether this packet is tracked by its transport-wide sequence number rather than its RTP
66    /// one — the two feedback formats identify packets differently.
67    pub is_twcc: bool,
68    /// The transport-wide sequence number, when `is_twcc`.
69    pub twcc_sequence_number: u16,
70    /// Size on the wire, in bytes.
71    pub size: usize,
72    /// Whether the receiver reported it as arrived.
73    pub arrived: bool,
74    /// When it left this endpoint. **The release instant**, not the instant the application
75    /// enqueued it — see the chain contract's rule 3, since a pacer's queueing delay counted as
76    /// network delay is exactly what corrupts a bandwidth estimate.
77    pub departure: Instant,
78    /// When it arrived, on the receiver's clock. See [`Acknowledgement::arrival`].
79    pub arrival: Option<Duration>,
80    /// The ECN marking the receiver observed.
81    pub ecn: Ecn,
82}
83
84/// A batch of packet reports, with the round trip time they imply.
85#[derive(Debug, Clone, PartialEq, Eq)]
86pub struct Report {
87    /// When the feedback that produced this batch was received here.
88    pub arrival: Instant,
89    /// Round trip time derived from the newest packet this feedback acknowledged.
90    pub rtt: Option<Duration>,
91    /// The packets being reported on, in send order.
92    pub packet_reports: Vec<PacketReport>,
93}
rtc_interceptor/rtpfb/acknowledgement.rs

rtc_interceptor/rtpfb/
acknowledgement.rs
