james h
librist

Repository



librist
A library that can be used to easily add the RIST protocol to your application.
This code was written to comply with the Video Services Forum (VSF) Technical Recommendations TR-06-1 and TR-06-2. The protocol goes by the codename "RIST"
The canonical repository URL for this repo is https://code.videolan.org/rist/librist
This project is partially funded by the SipRadius LLC.

Goal and Features
The goal of this project is to provide a rist library for most platforms.
It supports all features from the TR-06-1 and most of the features of TR-06-2.

Dependencies
None. This library has no external runtime dependencies on any OS other than normal core OS libraries.

License
librist is released under a very liberal license, a contrario from the other VideoLAN projects, so that it can be embedded anywhere, including non-open-source software; or even drivers, to allow the creation of hybrid decoders.
The reasoning behind this decision is the same as for libvorbis, see RMS on vorbis.

Library sweet spot (optimal use cases with current defaults)

Buffer sizes from 50 ms to 30 seconds
Networks with round trip times from 0ms to 5000ms
Bitrates from 0 to 1 Gbps
Packet size should be kept under the path's MTU (typically 1500). The library does not support packet fragmentation.
Bi-directional communication available (not one-way systems like satellite)

If you have an application that needs to operate outside the sweet spot described above, you will need to modify some constants in the rist-private.h header and/or use some of the more obscure API calls to fine tune the library for your use case. The library can overcome all the limitations above by fine-tuning with the exception of packet fragmentation which will be addressed as a feature enhancement in the future.

Roadmap
The plan is the following:

Reached

Complete C implementation of the rist protocol,
Provide a usable API,


On-going

Improve C code base with various tweaks,
Port/test on most platforms
Provide wrappers for other languages


Contribute
Currently, we are looking for help from:

C developers,
asm developers,
platform-specific developers,
testers.

Our contributions guidelines are quite strict. We want to build a coherent codebase to simplify maintenance and achieve the highest possible speed.
Notably, the codebase is in pure C and asm.
We are on Telegram, on the rist_users and librist_developers channels.
See the contributions document.

CLA
There is no CLA.
VideoLAN will only have the collective work rights.

CoC
The VideoLAN Code of Conduct applies to this project.

Compile using meson/nija (preferred method)

Install Meson (0.47 or higher), Ninja, and, for x86* targets, nasm (2.14 or higher)
Run mkdir build && cd build to create a build directory and enter it
Run meson .. to configure meson, add --default-library=static if static linking is desired
Run ninja to compile


Compile using cmake/make (alternative method)

Run cmake -DCMAKE_BUILD_TYPE=Debug . or cmake -DCMAKE_BUILD_TYPE=Release .

Run make to compile


Support
This project is partially funded by SipRadius LLC.
This company can provide support and integration help, should you need it.

FAQ

Why do you not improve srt rather than starting a new project?

Although SRT provides a similar solution, it is the result of the vision and design of a single company. librist on the other hand, was the collective design work of a large group of experts (companies) that have been providing packet recovery services for many years. From its conception, rist has been based on clear and open standards.


Is librist a recursive acronym?

Yes, libRIST stands for Library - Reliable Internet Stream Transport


Can I help?

Yes. See the contributions document.


I am not a developer. Can I help?

Yes. We need testers, bug reporters, and documentation writers.


What about the packet recovery patents?

This code was written to comply with the Video Services Forum (VSF) Technical Recommendations TR-06-1 and TR-06-2 and as such is free of any patent royalty payments


Will you care about <my_arch>? <my_os>?

We do, but we don't have either the time or the knowledge. Therefore, patches and contributions welcome.


How can I test it?


You can use the utils project https://code.videolan.org/rist/rist-utils to compile and build statically command line utilities that have everything you need to get up and running quickly.


The Wiki has good information on the use of these utilities https://code.videolan.org/rist/rist-utils/-/wikis/home