Content delivery over broadcast and multicast networks relies on transport protocols that can deliver files and media objects one-way, without a return channel from each receiver. This project covers File Delivery over Unidirectional Transport (FLUTE) and Real-time Object delivery over Unidirectional Transport (ROUTE), which underpin 5G-MAG's broadcast and multicast work.
5G-MAG maintains open-source implementations, including the FLUTE library used in the 5G Broadcast tools, a media origin, and a Coded Multisource Media Format (CMMF) encoder.
The Problem It Solves
A broadcast or multicast bearer has no return channel, so a receiver can never ask for a retransmission: reliability has to come from somewhere else, and Forward Error Correction carried by FLUTE and ROUTE is that mechanism. Keeping the media format (DASH, HLS, CMAF) and the transport (FLUTE for files, ROUTE for real-time objects) strictly separate is what lets the same packaged content run over either one: a broadcaster packages a CMAF asset once, and it can be delivered over FLUTE for a download-style MBMS scenario or over ROUTE for ATSC 3.0-style real-time delivery, without repackaging for each transport.
The project at a glance
What it is, how it works, and where the Reference Tools stand, in one deck you can share.
Download the deck (Content Delivery Protocols and Tools)From idea to running code
Read it, check it against the standard, then run it.
Technical Analysis
How this technology works, and what it is good for.
Specifications
The specifications this technology is built on.
Software Accelerator
The open-source software that implements it.
Latest updates and roadmap
Status on 23 October 2026
early stage
- FLUTE conformanceA validator that tests a FLUTE implementation against the FLUTE profiles, starting with the FLUTE library.
- rt-cmmf-encoderA reference implementation of ETSI TS 103 973: no encoder code on the main branch yet, and no release.
in development
- FLUTE libraryFurther FEC schemes, FLUTE version 2 signalling, congestion control and tunnelled operation, outside the 3GPP profiles.
- Media originRadio channels, real-time push transports and documentation for the media origin server and packager.
- Reference Media ApplicationAn Android app and a test rig that check each delivery method of the media origin on a phone.
released
- rt-libflute 0.12.41 Sep 2026. Finish-sending option, a tunnel mode test, and fixes for FDT growth and compression.
Merged since 0.12.4 7 pull requests in 4 repositories
Open Source, Built Together
Repositories of This Project
The real, running software for this technology: what each repository is, what it implements, its latest release and where to find it.
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