liburtc
=======

Real-time communication for microcontrollers

The WebRTC reference implementation was designed for web browsers, namely
Chromium. It requires specialized build tools, over 10GB of disk space for
source code, and produces a binary with a large footprint. liburtc, on the
other hand, is designed with the following goals in mind:

* Small footprint. Under 100KB.
* Portable. Implemented in C (C99) and works on nearly any architecture and
  POSIX.1-2001 compliant operating system.
* Easy to use. Straight-forward to compile and integrate into your code.
* Standards compliant. Adheres to IETF specs to ensure interoperability.
* Minimal. Only implements subset of protocols required for basic functionality
  for common embedded applications, such as smart cameras.
* Minimal dependencies. Only dependency is OpenSSL.


Bootstrapping
-------------

If checking out this code via `git`, run `autoconf` to generate a `configure`
script.


Quickstart
----------

To compile the library and usage example from source, you will need autoconf,
automake, and libtool. Use `autogen.sh` to create a `configure` script for
configuring and making the library:

    ./autogen.sh && ./configure && make

To test the library:

    make check

Next, see `example/README.md` for running a demo.


Features
--------

- Autotools based build process
- POSIX.1-2001 compliant implementation

/ sdp
/ stun client
- ice agent (state machine)
  - aes cbc encipher / decipher (openssl)
- v4l2
- libx264
- libopus
- dtls (openssl?)
- srtp

- ANSI C compliant implementation (C99)
- BSD sockets (winsock not supported)

- Session Description Protocol (SDP)
  - SHA-256 certificate fingerprint

- Interactive Connectivity Establishment (ICE) agent
  - STUN: RFC 5389 compliant client (no server capability)
  - TURN: RFC 5766 compliant client (no server capability)

- DTLS-SRTP transport
  - RFC 5764 compliant implementation (using OpenSSL)

- Video codecs:
  - H.264
    - Profiles: baseline, constrained baseline, main, high
    - Levels: 3.1 and up
  - H.265 not supported (few, if any, browsers support this)
  - VP8/9 not supported (few embedded devices support this)

- Video sources:
  - Video4Linux2
  - USB Video Class

- Audio codecs:
  - G.711
  - Opus

- Audio sources:
  - ALSA
  - PulseAudio


Possible Future Improvements
----------------------------

- seamless handoff between network interfaces (e.g. cellular and wifi)

Notes
-----

- A thread is used per peer connection. Each thread asynchronously handles
  i/o events.


Credits
-------

- Diego Elio Petteno (https://autotools.io) for the wonderful resource on
  autoconf, automake, libtool, and other tools in the autotools suite.