MARÉ

Multi-device Audio Realtime Exchange: an open protocol, and a hub that implements it, for moving audio and MIDI between applications and audio devices with low latency.

Maré is Portuguese for the tide. The mangrove lives by it, filling and emptying in cycles, as audio buffers do.

MARÉ keeps what makes low-latency audio fast (applications write straight into the buffers the device plays, on the device's schedule) and adds what ASIO never had (ASIO is a trademark of Steinberg Media Technologies GmbH; see Trademarks):

• many applications at once on the same device, each with low latency;
• many devices as one, with their clocks' drift corrected;
• hot-plug: devices come and go while the session runs;
• MIDI 2.0 on the same clock as the audio, to the sample;
• latency said exactly, part by part, and measured;
• open: MIT or Apache-2.0, a C layout any language can implement.

It is part of the ecosystem of the Manguebyte Audio Framework, from Recife: every program built on Manguebyte will speak MARÉ.

Status: milestones 3, 4 and 6 under way. The shared-memory layout, the client library (Rust, C and C++), the hub and its drift-corrected aggregate of several devices are built and tested on Windows, Linux and macOS (CI), against fake devices. A WASAPI device (output, and input beside it) has been tried by hand on one real device (docs/HARDWARE.md); the mare program runs a hub on one, and programs built on Manguebyte play through it. docs/DESIGN.md is the specification, including what MARÉ is not (not a kernel driver, and not lower latency than the hardware allows); docs/LAYOUT.md is the shared memory byte by byte, and docs/TECH_DEBT.md what the code still owes.

The pieces

Crate	What it is
mare-protocol	The shared-memory layout: no dependencies, no standard library
mare-sys	Named shared memory, doorbells, process watches, per system
mare-client	Connect to a hub and run a cycle each period
mare-hub	The hub: the cycle engine, the housekeeper, an aggregate of several devices, a fake device
include/mare.h	The layout in C, checked against the Rust one
include/mare_client.h, mare_client.hpp	The client library's interface, for C and C++17
mare-drift	Drift correction: an adaptive resampler, its controller, and a link between two clocks
mare-capi	The client library for C and C++: mareclient.dll / libmareclient.so / libmareclient.dylib
mare-manguebyte	MARÉ as an audio backend of the Manguebyte Audio Framework
mare-wasapi	A WASAPI device, output and duplex input, exclusive or shared (Windows)
mare-cli	The mare program: lists devices, runs a hub on one, shows running hubs

cargo test --workspace

Running a hub

cargo run --release -p mare-cli -- devices
cargo run --release -p mare-cli -- run --device Realtek
cargo run --release -p mare-cli -- run --device UMC404HD --exclusive --period 64
cargo run --release -p mare-cli -- run --null

mare run keeps a hub called main running until Ctrl+C; programs connect to it by that name (--name gives another). --input opens a capture device beside the output, and --follow joins further output devices, each on its own clock, resampled to the first. --null runs a hub on no device, on any system, for trying programs without a sound card. mare help lists every option.

cargo run --release -p mare-client --example sine -- --hub main --level -30

plays a quiet sine through a running hub, to hear that it works.

Trademarks

ASIO is a trademark and software of Steinberg Media Technologies GmbH. MARÉ is not affiliated with, endorsed by or derived from Steinberg or ASIO: it uses no part of the ASIO SDK, and its name and its parts' names do not contain "ASIO". The protocol is named here only to compare it with MARÉ.

Licence

Licensed under either of Apache License, Version 2.0 or MIT license at your option.