OAAT — Open Advanced Audio Transport

An open-source, bit-perfect, multi-room audio streaming protocol.

OAAT is a network audio transport protocol designed as an open alternative to Roon's proprietary RAAT. It provides:

Bit-perfect audio — PCM up to 768 kHz / 32-bit, native DSD up to DSD512
Multi-room sync — sub-millisecond synchronization via PTP-inspired clock sync
Format negotiation — automatic accept/counter/reject based on endpoint capabilities
Gapless playback — seamless track transitions with format change detection
Zero-config discovery — mDNS/DNS-SD _oaat._tcp, no manual setup
Rust-first — zero-copy wire format, async I/O, ~1500 LOC for a conforming endpoint

Status

v0.1.0 — Protocol specification complete. Phases 1-2 fully implemented, Phase 3-4 in progress.

Crates

Crate	Description
`oaat-core`	Core types, wire format, protocol messages, clock sync, codec
`oaat-endpoint`	Endpoint SDK: transport, mDNS, HAL trait, cpal audio output
`oaat-controller`	Controller: transport, mDNS browsing, zone manager
`oaat-cli`	CLI: `oaat endpoint`, `oaat controller`, `oaat multiroom`, `oaat discover`
`oaat-test`	Protocol conformance test tool (20 automated tests)

Architecture

┌─────────────┐         TCP (control)          ┌──────────────┐
│             │◄──────────────────────────────►│              │
│  Controller │         UDP (audio)            │   Endpoint   │
│   (server)  │──────────────────────────────►│  (renderer)  │
│             │         UDP (clock sync)       │              │
│             │◄──────────────────────────────►│              │
└─────────────┘                                └──────────────┘
     :9740 TCP control        :9741 UDP audio        :9742 UDP clock

Quick Start

cargo build --workspace
cargo test --workspace    # 28 tests

Stream audio to an endpoint

# Terminal 1: start an endpoint with audio output
oaat endpoint --name "Living Room DAC"

# Terminal 2: stream a 440Hz sine wave
oaat controller --target 127.0.0.1:9740 --freq 440 --duration 5

# Or use mDNS auto-discovery
oaat controller --duration 10

Multi-room synchronized streaming

# Stream to multiple endpoints in sync (sub-millisecond)
oaat multiroom 192.168.1.10:9740 192.168.1.11:9740 --freq 440 --duration 10

Discover endpoints on the network

oaat discover --timeout 5

Test endpoint conformance

oaat-test 192.168.1.50:9740

# OAAT Conformance Test — 192.168.1.50:9740
# [Handshake]       4 PASS
# [Capabilities]    4 PASS
# [Format Nego]     3 PASS  (accept, counter, reject)
# [Clock Sync]      1 PASS  (offset < 10ms)
# [Audio]           1 PASS
# [Gapless]         2 PASS  (same format, diff format)
# [Volume]          3 PASS
# [Reconnect]       2 PASS
# 20 tests: 20 passed — Endpoint is CONFORMANT

Features

Feature	Status
TCP control + UDP audio transport	Done
mDNS zero-config discovery	Done
Format negotiation (accept/counter/reject)	Done
Gapless playback (same format + reformat)	Done
Multi-room zones with sync	Done
PTP-inspired clock sync (bootstrap + steady-state)	Done
Volume control + mute	Done
cpal audio output	Done
Reconnection (endpoint loops on disconnect)	Done
Conformance test tool (20 tests)	Done
CI (GitHub Actions, Linux + macOS)	Done
Tune server integration	Done
DSD native transport	Planned
FLAC compressed transport	Planned
TLS / PSK auth	Planned

Comparison

Feature	OAAT	RAAT	DLNA	AirPlay 2	OpenHome
License	Apache 2.0	Proprietary	UPnP Forum	Apple	BSD
Bit-perfect	Yes	Yes	Depends	No	Yes
DSD native	Yes	Yes	DoP only	No	DoP
Multi-room sync	< 1 ms	< 1 ms	None	Apple	Limited
Gapless	Yes	Yes	Unreliable	Yes	Yes
Format negotiation	Auto	Auto	Manual	Fixed	Limited
Open source	Yes	No	Yes	Reverse-eng	Yes
Endpoint LOC	~1500	N/A	~5000+	N/A	~3000+
Conformance tool	Yes	No	No	No	No

License

Apache 2.0 — see LICENSE.

Author

Bertrand Clech / MozAIk Labs

oaat-core 0.2.0