mxl-stack

Open-source broadcast media functions for MXL (Media eXchange Layer), the shared-memory media exchange of the EBU Dynamic Media Facility (DMF). Gateways (SMPTE ST 2110, SRT, SDI), a vision mixer, an audio mixer, replay, graphics, a multiviewer, scopes, monitoring, AV sync measurement and multi-host replication over MXL Fabrics. Every function is a container with AMWA NMOS IS-04/IS-05 (BCP-007-03) control, a web UI and Prometheus metrics.

This repository is the entry point. It holds no media code: it lists the function repositories, explains what a host needs, and gives Docker Compose examples and Kubernetes notes to run them together.

Each function repository stays the source of truth: its README and SPECIFICATION document every setting, port, metric and API. If this page and a function's README disagree, the README wins.

This is an independent community project. It is not part of, or endorsed by, the MXL project, the EBU or the Linux Foundation.

What MXL is

MXL lets media functions on one host exchange uncompressed video, audio and data through shared memory. A writer puts grains (frames) or samples into a ring buffer in a memory-backed file system (a tmpfs); readers map the same files. There is no copy and no network stack between functions on one host. Grain positions are derived from TAI time, so every host needs a disciplined clock. Between hosts, the MXL Fabrics API moves flows over RDMA (or TCP).

The functions here add the parts a facility needs around that: AMWA NMOS IS-04/IS-05 with the MXL transport (BCP-007-03) for discovery and routing, web UIs, Prometheus metrics, and WebRTC previews.

Overview

flowchart LR
  subgraph host-a["host-a"]
    direction LR
    SDI[DeckLink SDI] --> MXLa
    ST[ST 2110 network] <--> GW2110[st2110-gateway] <--> MXLa
    SRT[SRT streams] <--> GWSRT[srt-gateway] <--> MXLa
    TP[test-player] --> MXLa
    BS[browser-source] --> MXLa
    MXLa[(MXL domain<br/>tmpfs /Volumes/mxl)]
    MXLa <--> MV[multiviewer]
    MXLa <--> SC[scopes]
    MXLa <--> AM[audio-mixer]
    MXLa <--> RP[replay]
    MXLa <--> CC[color-corrector]
    MXLa <--> FX[FlowXer vision mixer]
    MXLa --> MON[webrtc-monitor]
    MXLa <--> FA[fabrics-agent]
  end
  FA <-->|RDMA / TCP| FB[fabrics-agent on host-b]
  MON -->|RTSP| MTX[MediaMTX] -->|WebRTC| Browser
  REG[NMOS registry<br/>IS-04] -.registration.- MXLa
  CTRL[NMOS crosspoint<br/>IS-05 controller] -.routing.- REG

Loading

• Every function is one container and one NMOS node. It writes its own MXL domain and reads any other domain on the host.
• A controller connects a receiver to a sender with IS-05 (mxl_domain_id, mxl_flow_id). If that flow lives on another host, the fabrics agent on the receiver's host mirrors it locally.
• Browser previews are low-rate H.264 published to MediaMTX and played over WebRTC (WHEP).

The single-host example running: multiviewer, FlowXer vision mixer and audio mixer. Every function README has a screenshot of its web UI.

What you can build

Examples of chains made from these functions. Each arrow is an IS-05 connection made in an NMOS controller.

Workflow	Chain	Start from
A studio on one host	test-player or DeckLink → FlowXer (vision mixer) and audio-mixer → multiviewer, webrtc-monitor	compose/single-host
ST 2110 facility edge	ST 2110 sources → st2110-gateway → MXL functions → st2110-gateway → ST 2110	mxl-st2110-gateway (needs an Intel E810)
Remote contribution	SRT in → srt-gateway → replay, browser-source graphics, audio-mixer → srt-gateway → SRT out	compose/single-host with --profile extras
Two hosts	functions on host-b read host-a's flows; the fabrics agent mirrors them over RDMA	compose/multi-host-rdma
Measure a chain	avsync generator → chain under test → avsync analyzer (AV offset, latency); scopes for levels	mxl-avsync

Media functions

Images are on GitHub Container Registry (ghcr.io/leeo86/<repo>). Release tags are X.Y.Z, X.Y and X; most repos have no latest, so pin a version. The badges show each repository's latest release. The Compose examples pin a set that was run together; see CHANGELOG.md.

Status. All functions below have tagged releases, a container image and a changelog, are tested on real hardware, and several run continuously on a multi-host Kubernetes test platform. They are proofs of concept for MXL-based production, not certified products. Features a README marks as planned are not in the image yet.

Gateways and I/O

Function	What it does	Needs	License	Release
mxl-st2110-gateway	SMPTE ST 2110 (-20, -30, -40, 2022-7) ↔ MXL with MTL/DPDK; two NMOS nodes	Intel E810, DPDK, hugepages, PTP	MIT
mxl-srt-gateway	SRT (MPEG-TS) ingest and egress to and from MXL	CPU; NVDEC/NVENC optional	MIT (image GPL-2.0+, x264/x265)
mxl-decklink	Blackmagic DeckLink SDI input and output as MXL flows	DeckLink card, Desktop Video driver	MIT

Sources and graphics

Function	What it does	Needs	License	Release
mxl-test-player	TAI-locked test source: video, audio, timecode, fill/key	CPU	MIT
mxl-browser-source	Offscreen Chromium (CEF) web page as MXL video, key and audio, frame-locked to TAI; OGraf graphics	CPU; NVIDIA GPU optional	MIT

Production

Function	What it does	Needs	License	Release
FlowXer	Vision mixer: up to 4 MEs, keyers and DME boxes, clip players, stingers, tally (TSL), WebRTC preview, widgets	NVIDIA GPU	Apache-2.0	tag 19.26.68
mxl-audio-mixer	Broadcast audio engine: routable matrix, channel strips, DSP, loudness, control room, VCAs	CPU	MIT
mxl-replay	Live slow-motion replay, clip player, shotbox and playlists	NVIDIA GPU recommended; records and plays clips without one	GPL-3.0
mxl-color-corrector	Colour correction (gain, pedestal, saturation, gamut clip), AVX2/AVX-512	CPU	MIT

FlowXer is developed in its own GitHub account; see its repository for releases and licensing.

Monitoring and measurement

Function	What it does	Needs	License	Release
mxl-multiviewer	Multiviewer with up to 32 inputs, tally (TSL), as an MXL flow	CPU; CUDA optional	Apache-2.0
mxl-webrtc-monitor	Watch and listen to any MXL flow in a browser (WebRTC/HLS)	CPU; NVENC optional	MIT
mxl-scopes	Video scopes (waveform, parades) as an MXL flow and a WebRTC widget	CPU (AVX2/AVX-512)	MIT
mxl-avsync	AV sync and latency measurement: test signal generator and analyzer; phone apps in testing	CPU	MIT

Infrastructure and libraries

Project	What it does	Needs	License	Release
mxl-fabrics-agent	Per-host agent that mirrors flows between hosts over MXL Fabrics, following NMOS connections	RDMA NIC (or TCP)	MIT
mxl-nmos	Rust crate: NMOS node (IS-04, IS-05, BCP-007-03) for MXL media functions. Early, 0.x	—	Apache-2.0

Infrastructure used by the examples (third party)

Component	Purpose	Image
nmos-cpp registry	NMOS IS-04 registry (registration and query)	docker.io/gemini2350/nmos-cpp-registry (pinned digest in the compose files)
dmf-app-nmos-crosspoint	NMOS controller with a crosspoint view; connects ST 2110 and BCP-007-03 MXL senders and receivers over IS-05. Fork of nmos-crosspoint_v3; see upstream for licensing	ghcr.io/qvest-digital/dmf-app-nmos-crosspoint:4.36
MediaMTX	RTSP/WebRTC/HLS server for the browser previews	bluenviron/mediamtx:1.20.1

Getting started

1. Prepare the host: docs/requirements.md (tmpfs MXL root, TAI time, inotify limit, optional GPU).
2. Run the single-host example: compose/single-host. It needs no special hardware: a Linux x86-64 host with Docker is enough for the test player, multiviewer, scopes, audio mixer, replay, browser source and WebRTC monitor.
3. Two hosts over RDMA: compose/multi-host-rdma.
4. Kubernetes notes: docs/kubernetes.md.

New to MXL itself? Start with the SDK documentation and the CBC/Radio-Canada hands-on workshop (below), then come back here.

Related projects

Complementary open-source work around MXL, maintained by others:

• dmf-mxl/mxl: the MXL SDK, with documentation and the community list awesome-mxl.
• cbcrc/mxl-hands-on: MXL workshop with example media functions; the /Volumes/mxl tmpfs convention comes from there. CBC/Radio-Canada also maintain an FFmpeg with MXL guide and a CSI driver for MXL on Kubernetes.
• EASY MXL: a web UI that creates MXL domains and launches media functions from a catalog on a Docker host.
• qvest-digital/mxl-k8s: a Kubernetes control plane for MXL, including Fabrics across nodes.
• AMWA BCP-007-03: NMOS with MXL, the IS-04/IS-05 transport the functions here implement.
• obs-mxl-plugin: OBS Studio input and output plugins for MXL.
• Media Transport Library: ST 2110 over DPDK, used by the ST 2110 gateway.

Security

The function APIs are unauthenticated by design: run them on a protected network only.

Contributing

See CONTRIBUTING.md. Issues about one function belong in that function's repository.

License

MIT, see LICENSE. Each function repository and image has its own license and third-party notices (see the License column above).