Crate oxpulse_sfu_kit 

A reusable multi-client SFU (Selective Forwarding Unit) kit built on top of str0m.

str0m is a sans-I/O Rust WebRTC library — you plug in your own networking. This crate adds the multi-client glue: per-peer state machines, UDP packet routing, event fanout, and simulcast layer forwarding. It does not replace str0m; it connects multiple str0m Rtc instances together into a functioning room.

What this gives you

• Client — per-peer state wrapping a str0m Rtc instance. Handles poll_output, incoming datagrams, keyframe requests, and simulcast layer filtering.
• Registry — room-level packet router. Routes UDP datagrams to the correct peer via rtc.accepts(), drives poll_all, and fans out events to every non-origin peer.
• Propagated — the event enum flowing between the registry and clients.
• SfuConfig — runtime configuration (UDP port, bind address).
• run_udp_loop — a ready-to-use async UDP receive loop for the simple single-room case.

Quick start

use std::sync::Arc;
use oxpulse_sfu_kit::{Client, Registry, SfuConfig, SfuRtcBuilder, udp_loop};

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let config = SfuConfig {
        udp_port: 3478,
        ..SfuConfig::default()
    };

    // Shutdown on Ctrl-C.
    let shutdown = async { tokio::signal::ctrl_c().await.unwrap() };
    udp_loop::run_udp_loop(config, shutdown).await
}

Clients are inserted into the registry via Registry::insert after completing ICE/DTLS signaling (your responsibility — bring your own WebSocket/HTTP signaling layer).

Feature flags

Feature	What it enables
active-speaker	Dominant speaker detection via rust-dominant-speaker. Adds Propagated::ActiveSpeakerChanged and Registry::tick_active_speaker / Registry::record_audio_level.
metrics-prometheus	Prometheus counters exposed via SfuMetrics. The library carries the handles; you choose how to expose them (e.g. via axum).
test-utils	Exposes test seam helpers (test_seed module, Registry::*_for_tests methods). Gate your own tests on this.

Not included (by design)

• Signaling (bring your own — WebSocket, HTTP, gRPC)
• TURN server (run coturn or similar alongside)
• End-to-end encryption payload processing (use SFrame; see sframe::KeyEpoch)
• Server-side audio/video mixing (MCU mode)
• WHIP / WHEP ingestion endpoints

Examples

• examples/basic-sfu.rs — a complete single-node SFU that binds a UDP port and handles signaling stubs. Run with cargo run --example basic-sfu --features active-speaker,metrics-prometheus.

Relationship to str0m

We build on str0m’s Rtc state machine. We do not replace it — we connect multiple instances together for multi-party rooms. All credit for the underlying protocol work goes to Martin Algesten and the str0m contributors.

Extracted from

Originally built as part of OxPulse Chat. Published standalone for the broader Rust WebRTC ecosystem.

Re-exports

pub use av1::Av1DdInfo;av1-dd

pub use bandwidth::BandwidthEstimate;

pub use bwe::feedback::TwccFeedback;kalman-bwe

pub use bwe::feedback::TwccSample;kalman-bwe

pub use bwe::kalman::DelayEstimator;kalman-bwe

pub use bwe::loss::LossEstimator;kalman-bwe

pub use bwe::subscriber::ClientHint;kalman-bwe

pub use bwe::subscriber::PerSubscriber;kalman-bwe

pub use bwe::BandwidthEstimator;kalman-bwe

pub use bwe::GoogCcEstimator;googcc-bwe

pub use bwe::PacerAction;pacer

pub use bwe::SubscriberPacer;pacer

pub use bwe::PacerConfig;pacer

pub use bwe::PacerConfigError;pacer

pub use cc::CongestionControl;

pub use cc::DefaultGoogCC;

pub use client::Client;

pub use client::TrackIn;

pub use config::SfuConfig;

pub use dc::ChannelConfig;

pub use ids::InvalidRid;

pub use ids::SfuMid;

pub use ids::SfuPt;

pub use ids::SfuRid;

pub use keyframe::SfuKeyframeKind;

pub use keyframe::SfuKeyframeRequest;

pub use layer_selector::BestFitSelector;

pub use layer_selector::LayerSelector;

pub use media::SfuMediaKind;

pub use media::SfuMediaPayload;

pub use metrics::SfuMetrics;

pub use net::IncomingDatagram;

pub use net::OutgoingDatagram;

pub use net::SfuProtocol;

pub use origin::ClientOrigin;

pub use propagate::ClientId;

pub use propagate::Propagated;

pub use raw::rtc_config;

pub use registry::Registry;

pub use rtc::SfuRtc;

pub use rtc::SfuRtcBuilder;

pub use rtcp_stats::PeerRtcpStats;

pub use sframe::KeyEpoch;

pub use udp_loop::bind;

pub use udp_loop::run_udp_loop;

pub use udp_loop::serve;

pub use udp_loop::serve_socket;

pub use vfm::FrameMarkingInfo;vfm

Modules

av1av1-dd

AV1 codec support (feature = "av1-dd").

bandwidth

Bandwidth estimation types for the kit.

bwepacer or kalman-bwe or googcc-bwe

Bandwidth-adaptive layer selection ().

cc

Congestion control plugin seam.

client

Per-peer state machine wrapping a str0m Rtc instance.

config

SFU runtime configuration.

dc

DataChannel configuration wrappers.

fanout

Cross-client event fanout.

ids

Opaque newtype wrappers for str0m identifier types.

keyframe

Keyframe request wrapper.

layer_selector

Trait for per-subscriber simulcast layer selection.

media

Media payload wrapper over str0m::media::MediaData.

metrics

Prometheus metrics for the SFU.

net

UDP datagram wrappers over str0m::net::{Protocol, Transmit}.

origin

Publisher origin — local client or upstream SFU relay connection.

propagate

Cross-client propagated events.

raw

Escape hatch for advanced str0m access.

registry

Multi-client registry — routes UDP datagrams to the owning client and fans out propagated events. Single-task ownership model (no Arc<RwLock>).

rtc

Opaque SFU-owned handle over a str0m Rtc state machine.

rtcp_stats

Per-peer RTCP-derived stats.

sframe

SFrame (RFC 9605) key-epoch forwarding seam.

udp_loop

Async UDP socket loop.

vfmvfm

Video Frame Marking RTP header extension (feature = "vfm").

Structs

RawRtc

The underlying str0m Rtc. Semver-exempt. Instance that does WebRTC. Main struct of the entire library.

RawRtcConfig

The underlying str0m RtcConfig builder. Semver-exempt. Customized config for creating an Rtc instance.