aiomoqt 0.5.8

Python asyncio implementation of the MoQT protocol

aiomoqt - Media over QUIC Transport (MoQT)

aiomoqt is an implementation of the MoQT protocol, based on asyncio and qh3.

Overview

This package implements the MoQT Specification with dual draft-14 and draft-16 support. It is designed for general use as an MoQT client and server library, supporting both 'publish' and 'subscribe' roles.

The architecture follows the asyncio.Protocol design pattern, extending the qh3 QuicConnectionProtocol. It supports both H3/WebTransport and raw QUIC transports, with ALPN-based draft version negotiation, and has been interop tested against 6 relay implementations across draft-14 and draft-16.

The package includes publisher and subscriber example clients, a benchmark suite for throughput/latency measurement, a relay version probe tool, and an interop test client compatible with the moq-interop-runner framework.

Features

• H3/WebTransport and raw QUIC transports
• Async context manager for session lifecycle
• High-level control message API with sync/async response handling
• Low-level message serialization/deserialization
• Version-independent API: MOQTRequestError exception across drafts
• Pluggable message handlers via register_handler()
• Data publishing via SubgroupHeader streams or ObjectDatagrams
• Data reception via on_object_received callback
• Draft-14/16: ALPN negotiation (moq-00 / moqt-16)
• Draft-16: delta-encoded parameter keys, track extensions, unified REQUEST_OK/REQUEST_ERROR
• Wire format: SubgroupHeader/ObjectDatagram flag encoding, delta-encoded object IDs

Installation

Requires Python 3.12+ (tested on 3.12, 3.13, and 3.14).

pip install aiomoqt
# or
uv pip install aiomoqt

Quick Start

Subscriber

import asyncio
from aiomoqt.client import MOQTClient

def on_object(msg, size, recv_time_ms, group_id=None, subgroup_id=None):
    print(f"g={group_id} obj={msg.object_id} {size}B payload={msg.payload}")

async def main():
    client = MOQTClient(
        'relay.example.com', 4433, endpoint='moq',
        use_quic=True, draft_version=16, debug=True,
    )
    async with client.connect() as session:
        await session.client_session_init()
        session.on_object_received = on_object
        await session.subscribe('ns', 'track', wait_response=True)
        await session.async_closed()

asyncio.run(main())

Publisher

import asyncio
from aiomoqt.client import MOQTClient
from aiomoqt.types import MOQTMessageType
from aiomoqt.messages import SubgroupHeader

async def main():
    client = MOQTClient(
        'relay.example.com', 4433,
        endpoint='moq', use_quic=True, draft_version=16,
    )
    client.register_handler(MOQTMessageType.SUBSCRIBE, on_subscribe)

    async with client.connect() as session:
        await session.client_session_init()
        await session.publish_namespace('ns', wait_response=True)
        await session.async_closed()  # serve until closed

async def on_subscribe(session, msg):
    """Called when a subscriber requests a track."""
    ok = session.subscribe_ok(request_msg=msg)
    stream_id = session.open_uni_stream()
    hdr = SubgroupHeader(
        track_alias=ok.track_alias,
        group_id=0, subgroup_id=0, publisher_priority=0,
    )
    session.stream_write(stream_id, hdr.serialize().data)
    session.stream_write(stream_id, hdr.next_object(payload=b"hello").data)
    session.transmit()

asyncio.run(main())

The on_subscribe handler above — stream setup, header serialization, object writing — is the pattern that track data modules will encapsulate into a higher-level TrackWriter / TrackReader API.

Control Message API

Control messages support both sync and async patterns via wait_response:

# Blocking — awaits and returns the response message
resp = await session.subscribe('ns', 'track', wait_response=True)

# Non-blocking — returns request, response arrives via handler
req = await session.subscribe('ns', 'track')

Relay URL Formats

Examples and benchmarks accept relay URLs in several forms:

moqt://host:port            Raw QUIC (default port 4443)
https://host:port/endpoint  H3/WebTransport (default port 4433)
host:port                   H3/WebTransport
host                        H3/WebTransport, port 4433, endpoint /moq

Examples

Publisher / Subscriber

# Publish (SubgroupHeader streams)
python -m aiomoqt.examples.pub_example --host relay.ex.com --port 4433 --use-quic

# Publish (ObjectDatagrams)
python -m aiomoqt.examples.pub_example --host relay.ex.com --port 4433 --use-quic --datagram

# Subscribe
python -m aiomoqt.examples.sub_example --host relay.ex.com --port 4433 --use-quic

# Subscribe + FETCH (join mid-stream)
python -m aiomoqt.examples.join_example --host relay.ex.com --port 4433 --use-quic

Common options: --namespace, --trackname, --endpoint, --debug, --keylogfile

Benchmarks

# Publisher — configurable size, rate, parallelism
python -m aiomoqt.examples.bench_pub moqt://relay.ex.com:4443 -s 4096 -P 4 -r 120 -t 60

# Subscriber — latency/jitter/loss stats
python -m aiomoqt.examples.bench_sub moqt://relay.ex.com:4443 -t 60

# Combined pub/sub
python -m aiomoqt.examples.bench_relay moqt://relay.ex.com:4443 -s 1024 -g 10000 -t 30

# Local loopback (no relay needed)
python -m aiomoqt.examples.bench_loopback -s 4096 -P 4 -t 20

Option	Description	Default
-s, --object-size	Payload size (bytes)	1024
-g, --group-size	Objects per group	10000
-P, --streams	Parallel subgroup streams	1
-r, --rate	Objects/sec per stream (0=max)	0
-t, --duration	Duration (seconds)	30
-i, --interval	Report interval (seconds)	5.0
-D, --datagram	Use datagrams instead of streams	off
-Q, --force-quic	Force raw QUIC for https:// URLs	off

Interop Testing

# All tests (draft-14, auto-detected)
python -m aiomoqt.examples.moq_interop_client -r "moqt://moqx-000.ci.openmoq.org:4433"

# All tests (draft-16)
python -m aiomoqt.examples.moq_interop_client -r "moqt://moqx-000.ci.openmoq.org:4433" --draft 16

# Single test case
python -m aiomoqt.examples.moq_interop_client -r "moqt://relay:4433" -t subscribe-error

# List test cases
python -m aiomoqt.examples.moq_interop_client -l

Relay Probe

python -m aiomoqt.examples.relay_probe

Environment variables: RELAYS_FILE, OUTPUT_FILE, PROBE_TIMEOUT, PROBE_INTERVAL, PROBE_ONCE

WebTransport Server

python -m aiomoqt.examples.server_example \
    --certificate cert.pem --private-key key.pem --port 4433

Example Reference

Example	Description
pub_example.py	Publisher — SubgroupHeader streams or ObjectDatagrams
sub_example.py	Subscriber — receives data from a relay
join_example.py	SUBSCRIBE + FETCH (join mid-stream)
bench_pub.py	Publisher benchmark, configurable parameters
bench_sub.py	Subscriber with latency/jitter/loss stats
bench_relay.py	Combined pub/sub benchmark
bench_loopback.py	Local loopback benchmark (no relay)
server_example.py	WebTransport server (origin)
relay_probe.py	Relay version probe (draft-14/16)
moq_interop_client.py	Interop test client (6 test cases, TAP14)

Interop Test Results

All 6 moq-interop-runner test cases pass against multiple relays on draft-14 and draft-16:

Relay	Draft	Transport	Tests	Result
OpenMoQ moqx	draft-16	Raw QUIC	6/6	PASS
OpenMoQ moqx	draft-14	Raw QUIC	6/6	PASS
Meta moxygen	draft-16	Raw QUIC	6/6	PASS
Meta moxygen	draft-14	Raw QUIC	6/6	PASS
Cloudflare moq-rs	draft-14	Raw QUIC	6/6	PASS
Red5 Pro	draft-14	Raw QUIC	6/6	PASS
Red5 Pro	draft-14	WebTransport	6/6	PASS
Quicr libquicr	draft-14	Raw QUIC	5/6	PASS

Test cases: setup-only, announce-only, publish-namespace-done, subscribe-error, announce-subscribe, subscribe-before-announce

Development

git clone https://github.com/gmarzot/aiomoqt.git
cd aiomoqt
python3 -m venv .venv && source .venv/bin/activate
pip install -e ".[test]"
pytest aiomoqt/tests/

Optionally, ./bootstrap_python.sh sets up a full uv-managed environment with a specific Python version and Cython.

TODO

• Transition from qh3 to aiopquic transport for performance
• Track data modules:
  • File transfer (or MOQT File Format?)
  • Interactive chat
  • MSF/LOC media packaging
  • CMSF media packaging
• Dockerize interop test client for moq-interop-runner registration
• Simple relay implementation

Contributing

Contributions are welcome! Please fork the repository, create a branch, and submit a pull request. For major changes, open an issue first.

Resources

• MoQT Specification
• Media Over QUIC Working Group
• MoQ Interop Runner
• aiomoqt GitHub Repository

---

Author

Giovanni Marzot — [e-mail] | moqarean.marzresearch.net

Acknowledgements

This project takes inspiration from, and has benefited from the great work done by the OpenMoQ/moxygen team, and the continued efforts of the MOQ IETF WG.