Aqueduct

Aqueduct is a high-performance Rust implementation of the Open Media Transport (OMT) protocol. It provides a robust framework for transmitting real-time video, audio, and metadata over local networks with minimal latency.

Similar to NDI but open-source and built with Rust's safety and concurrency features, Aqueduct aims to be the standard for open IP video workflows.

Key Features

• Zero-Copy Architecture: Uses bytes::BytesMut and careful buffer management to minimize memory allocations. Frames are encoded directly into transmission buffers.
• Async Core: Built on top of tokio for efficient, non-blocking network I/O.
• Service Discovery: Automatic sender discovery using DNS-SD (mDNS), compatible with standard OMT tools.
• Multi-Stream: Supports synchronized Video, Audio, and Metadata streams.
• Screen Capture: Integrated screen capture (via xcap) for immediate desktop streaming.
• Cross-Platform: Designed to run on Windows, Linux, and macOS.

Architecture: How It Works

1. The Sender (Sender)

The sender is responsible for capturing content, encoding it, and making it available on the network.

• Capture: Grabs frames from a source (e.g., Screen, Camera, Generated Content).
• Encoding: Compresses raw frames using LZ4 (configurable to other codecs) to reduce bandwidth while maintaining low latency.
• Packetization: Wraps compressed data into OMT-compliant binary packets with headers for Timestamp, Type, and Flags.
• Discovery: Registers itself as a _omt._tcp service via mDNS so receivers can find it automatically.

2. The Receiver (Receiver)

The receiver discovers sources and consumes the stream.

• Discovery: Browses for _omt._tcp services on the local network.
• Connection: Establishes a TCP connection to the selected sender.
• Reassembly: Reads the stream, handles packet boundaries, and extracts complete frames.
• Zero-Copy Decoding: Decompresses frame data into reusable buffers to avoid memory churn.

3. The Protocol

Aqueduct uses a lightweight binary protocol over TCP:

• Header: 4-byte Length + 4-byte Type.
• Payload: The actual Video, Audio, or Metadata content.
• Metadata: XML-based sidecar data for tally lights, source names, and custom events.

Getting Started

Prerequisites

• Rust: Install via rustup.rs.
• Toolchain: On Windows, we recommend the GNU toolchain (MinGW) for broad compatibility, though MSVC works with proper setup.

Running the Examples

1. Start the Sender This will capture your primary monitor and stream it.

cargo run --example sender

2. Start the Receiver In a separate terminal, this will discover the sender and open a preview window.

cargo run --example receiver

Press Esc to close the preview window.

Usage as a Library

To use Aqueduct in your own application, add it to your Cargo.toml (once published, or via git):

[dependencies]
aqueduct = { git = "https://github.com/compiling-org/Aqueduct.git" }

Creating a Sender

use aqueduct::{Sender, Packet, VideoFrame};

let sender = Sender::new(9000).await?;
// ... capture frame ...
sender.send(Packet::Video(frame))?;

Creating a Receiver

use aqueduct::{Discovery, Receiver};

// Discover services
let discovery = Discovery::new()?;
discovery.browse_sources(|event| println!("Found: {:?}", event))?;

// Connect
let mut receiver = Receiver::connect("192.168.1.50:9000").await?;
while let Ok(packet) = receiver.receive().await {
    // handle packet
}

Roadmap & Todo

We are actively working towards a stable 1.0 release.

• Crate Publishing: Clean up public API and publish to crates.io.
• Codec Plugins: Abstract codec interface to support NDI-like speed or H.264/HEVC.
• Hardware Acceleration: Integrate GPU encoding/decoding.
• Resilience: Add automatic reconnection and packet loss handling (FEC/Retransmission).
• Audio Sync: Precise audio/video synchronization using PTP or NTP timestamps.
• Cross-Platform UI: Improve the preview window to be a full featured reference player.

License

MIT License. See LICENSE for details.