JRTPLIB Examples: Building a Simple RTP Application

JRTPLIB Tutorial: Getting Started with C++ RTP Streaming Real-time transport of audio and video data is a cornerstone of modern networking applications, from video conferencing to IP surveillance. JRTPLIB is a robust, object-oriented C++ library designed specifically to make implementing the Real-time Transport Protocol (RTP) straightforward and efficient.

Developed by Jori Liesenborgs, this library manages the complexities of RTP packets, allowing you to focus on your streaming media content. 1. What is JRTPLIB?

JRTPLIB is a popular open-source library that implements RFC 3550, which defines the RTP protocol. It handles the necessary packaging of data, timestamping, sequence numbering, and RTCP control packets, making it easier to send or receive data streams over IP networks. Key features include: Object-oriented design in C++. Support for RTCP control packets (for monitoring QoS). Flexibility to packetize various media types. 2. Setting Up the Environment

Before writing code, you need to compile and install JRTPLIB. It generally relies on the JThread library for threading support.

Download: Get the latest source from the official repository. Compilation (using CMake):

Use CMake to generate project files (e.g., VS2010 files on Windows or Makefiles on Linux). Compile JThread first, then JRTPLIB. Linking: Link your application against jrtplib and jthread. 3. Getting Started with the RTPSession Class

The heart of JRTPLIB is the RTPSession class, which manages the RTP session initialization, packet sending, and reception. Basic Setup Steps All classes are within the jrtplib namespace.

#include “rtpsession.h” #include “rtpsessionparams.h” #include “rtpudpv4transmitter.h” #include “rtpipv4address.h” #include using namespace jrtplib; int main() { RTPSession session; // 1. Session Parameters RTPSessionParams sessionparams; sessionparams.SetOwnTimestampUnit(1.0/8000.0); // Assuming 8000 Hz audio sessionparams.SetAcceptOwnPackets(true); // 2. Transmitter Parameters RTPUDPv4TransmissionParams transparams; transparams.SetPortbase(8000); // Port to use // 3. Create the Session int status = session.Create(sessionparams, &transparams); if (status < 0) { std::cerr << “Error creating session: ” << RTPGetErrorString(status) << std::endl; return -1; } std::cout << “RTP Session Created Successfully” << std::endl; // … send/receive data here … session.Destroy(); return 0; } Use code with caution. 4. Sending RTP Data

To send data, you create a RTPSession object, add destinations, and then use the SendPacket method.

// Add destination IP and Port RTPIPv4Address dest(ntohl(inet_addr(“127.0.0.1”)), 9000); session.AddDestination(dest); // Send packet char payload[] = “Hello RTP”; session.SendPacket(payload, sizeof(payload), 0, false, 0); Use code with caution.

Note: JRTPLIB handles RTP headers, but you are responsible for preparing the raw payload data (e.g., encoded video frames). 5. Receiving RTP Data For receiving data, you need to call Poll().

session.BeginDataAccess(); if (session.GotoFirstSourceWithData()) { do { RTPPacketpack; while ((pack = session.GetNextPacket()) != NULL) { std::cout << “Received packet!” << std::endl; // Process packet… session.DeletePacket(pack); } } while (session.GotoNextSourceWithData()); } session.EndDataAccess(); Use code with caution. 6. RTCP Control Protocol

RTCP must be used alongside RTP to provide feedback on the quality of data distribution. JRTPLIB manages RTCP automatically, but you should ensure you handle the session polling frequently enough to allow RTCP reports to be processed. Conclusion

JRTPLIB provides a robust foundation for C++ developers entering the world of RTP streaming. By handling the low-level details of packetization and control, it simplifies the creation of real-time applications. To delve deeper, refer to the examples provided with the library source code to understand how to handle specific media formats.

If you are looking for advanced video streaming features, you may want to compare this with the LIVE555 Streaming Media library. If you’d like, I can:

Show you how to integrate a real-time encoder (like FFmpeg) with JRTPLIB.

Provide a complete, runnable example of a receiver in a separate thread.

Explain the differences in RTCP handling between JRTPLIB and LIVE555. Let me know which topic you’d like to explore next! JRTPLIB – Read the Docs