cppSRTWrapper

Simple C++ wrapper of the SRT protocol.

The SRT Protocol is a UDP based protocol. SRT acts as a mix of TCP and UDP where SRT tries to re-send lost data (as TCP would) but only to a deadline in time specified, when the deadline is reached and if the data has not arrived it's marked as lost (as UDP would).

Streaming media solutions benefit from this approach and SRT is adopted widely across the media community. This C++ wrapper is simplifying implementations of SRT in C++ projects and with only a few lines of code you can create a server and/or a client.

The API of SRT has more features than what's exposed in this C++ wrapper, however the base functions exists. If you feel this wrapper is missing any functionalty or features please let me know.

Current auto build status:

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Building

Requires cmake version >= 3.10 and C++17

Linux, MacOS and Windows

(Read below for how to prepare the different systems)

Release:

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
cmake --build . --config Release

Debug:

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Debug ..
cmake --build . --config Debug

##Output (Linux and MacOS):

./libsrtnet.a (The SRT-wrapper lib)

(source_root)/srt/libsrt.a (The SRT-lib)

./cppSRTWrapper (Runs trough the unit tests and returns EXIT_SUCCESS if all unit tests pass.)

./runUnitTests (Runs unit tests using GoogleTest)

##Output (Windows):

./Release/srtnet.lib (The wrapper lib Release build)

./Debug/srtnet.lib (The wrapper lib Debug build)

(source_root)/srt/Release/srt_static.lib (The SRT-lib Release build)

(source_root)/srt/Debug/srt_static.lib (The SRT-lib Release build)

./Release/cppSRTWrapper.exe (Runs trough the unit tests and returns EXIT_SUCCESS if all unit tests pass. Release build)

./Debug/cppSRTWrapper.exe (Runs trough the unit tests and returns EXIT_SUCCESS if all unit tests pass. Debug build)

Preparing Linux

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install tclsh pkg-config cmake libssl-dev build-essential

Preparing MacOS

Prepare your system by installing ->

• Xcode . Then start Xcode and let xcode install Command Line Tools or run xcode-select --install from the terminal.

• Homebrew -> [https://brew.sh)

• Then Install dependencies

brew install cmake
brew install openssl
export OPENSSL_ROOT_DIR=$(brew --prefix openssl)
export OPENSSL_LIB_DIR=$(brew --prefix openssl)"/lib"
export OPENSSL_INCLUDE_DIR=$(brew --prefix openssl)"/include"

Preparing Windows

Prepare your system by installing->

• Visual Studio (Also add the CMake build support if you plan to develop applications)

• chocolatey -> https://chocolatey.org

• Then Install dependencies

choco install openssl
choco install cmake
choco install git

Using the SRT wrapper

Server:

//Create the server
SRTNet mySRTNetServer;

//Register the server callbacks
//The validate connection callback ->
mySRTNetServer.clientConnected=std::bind(&validateConnection, std::placeholders::_1, std::placeholders::_2);
//The got data from client callback
mySRTNetServer.recievedData=std::bind(&handleData, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3, std::placeholders::_4);

//Start the server

//Listen IP
//Listen Port
//Number packet reorder window
//Max re-send window (ms) / also the delay of transmission
//% extra of the BW that will be allowed for re-transmission packets
//MTU
//(Optional) AES-128 key (No key or empty == no encryption)

if (!mySRTNetServer.startServer("0.0.0.0", 8000, 16, 1000, 100, 1456,"Th1$_is_4_0pt10N4L_P$k")) {
   std::cout << "SRT Server failed to start." << std::endl;
   return EXIT_FAILURE;
}

//Send data to a client (you need the client handle)
mySRTNetServer.sendData(content->data(), content->size(), &thisMSGCTRL,clientHandle);

//Get client handles using the lambda 
mySRTNetServer.getActiveClients([](std::map<SRTSOCKET, std::shared_ptr<NetworkConnection>> &clientList)
  {
    std::cout << "The server got " << clientList.size() << " clients." << std::endl;
  }
); 



//When a client connects you can validate the connection and also embedd one of your objects into that SRT connection.

//Return a connection object. (Return nullptr if you don't want to connect to that client)
std::shared_ptr<NetworkConnection> validateConnection(struct sockaddr &sin, SRTSOCKET newSocket) {

//sin contains the connections properties
//newSocket contains the SRT handle for that particular client

//To reject the connection
return nullptr;

//Accepting the connection by returning a 'NetworkConnection'
//A NetworkConnection contains a 'object' where you can put a shared pointer 
//To any of your objects. When the connection drops from that
//Client the destructor is called as long as you do not also keep a 
//handle to that class. 
//In all communication with you the 'NetworkConnection' clas is also provided.
//You can throw generators or parsers in there if wanted (MPEG-TS or anything else)
//See the example for how to retreive the object back.

auto a1 = std::make_shared<NetworkConnection>();
a1->object = std::make_shared<MyClass>();
return a1;

}


/

Client:

//Create the client
SRTNet mySRTNetClient;

//Register the callback (The server sends data to the client)
mySRTNetClient.recievedData=std::bind(&handleDataClient, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3, std::placeholders::_4);

//Connect to a server

//Server IP
//Server Port
//Number packet reorder window
//Max re-send window (ms) / also the delay of transmission
//% extra of the BW that will be allowed for re-transmission packets
//MTU
//(Optional) AES-128 key (No key or empty == no encryption)
if (!mySRTNetClient.startClient("127.0.0.1", 8000, 16, 1000, 100,client1Connection, 1456,"Th1$_is_4_0pt10N4L_P$k")) {
    std::cout << "SRT client failed starting." << std::endl;
    return EXIT_FAILURE;
}

//Send data to the server
SRT_MSGCTRL thisMSGCTRL = srt_msgctrl_default;
mySRTNetClient.sendData(buffer2.data(), buffer2.size(), &thisMSGCTRL);

Credits

The SRT team for all the help and positive feedback

Anders Cedronius for creating the C++ wrapper

anders.cedronius(at)gmail.com

License

MIT

Read LICENCE.md for details