EasyRTMP

Lightweight RTMP client/server library

About RTMP

This is old standard, originally developed in 2003 as a proprietary protocol for streaming between a Flash player and a server. In 2012 Adobe released specification. Protocol is designed to stream low latency realtime data. Today, when Flash is dead, but RTMP is de-facto standard for media streaming for first-mile delivery (from streamer to server). Protocol can be used to transfer any data, but in media world it is used to stream FLV packets, often AAC audio with H264 video. Codec parameters are exchanged via ActionScript messages. Many say that RTMP is old and does not support new formats 4K HDR 10bit video, but actually protocol supports everything. New formats are not supported by agreements and FLV specification. During writing library I found that some software and services violates or work differently with protocol. Facebook violates some AMF serialization. YouTube accepted streams even without codec parameters, but warn about 65k x 65k resolution. Twitch required correct composition_offset parameter in video packets, or video jitters, while YouTube playbacks smoothly. XSplit sends AMF codec data not as numbers defined in FLV specification but as text. All this stuff I commented in code. So, you can easily stream with new formats as long as client and server have an agreement about format exchange.

About library

Library is splitted to 3 parts: transport, protocol, media streaming.

Protocol contains communicating logic between two peers.

Transport contains logic for lower data transport and layering, such as TLS. Library contains TCP client/server Windows/Linux transport and OpenSSL TLS.

Media streaming contains logic of media streaming. Is compatible with the most of streaming services and software. You can use this to build media server or client applications. Actually RTMP is bidirectional protocol so it can be used to stream media in both directions.

Documentation

The most important code is documented with doxygen.

Dependencies

C++11 compiler (tested on MSVCv14.29, gcc 8.3.0)
OpenSSL (optional, to support RTMPS)

Building

Project has CMake build script

Example server

using namespace librtmp;

//start tcp server on port 1935
TCPServer tcp_server(1935);

//accept connection
auto client = tcp_server.accept();

//initialize endpoint and server session
RTMPEndpoint rtmp_endpoint(client.get());
RTMPServerSession server_session(&rtmp_endpoint);

try{
   while(true){
      //receive media message
      auto message = server_session.GetRTMPMessage();
      //get received media codec parameters and streaming key
      auto params = server_session.GetClientParameters();
      switch (message.message_type){			
         case RTMPMessageType::VIDEO:
            HandleVideo(message,params);
            break;
         case RTMPMessageType::AUDIO:
            HandleAudio(message,params);
            break;
      }
   }
}catch(...){
   //connection terminated by peer or network conditions
}

Other examples

Examples are available in next products: RTMP2NDI, RTMP-Restreamer

Acknowledgements

OpenSSL

aloproducao/EasyRTMP