Publisher-Only

Publisher Only

The Publisher Only sample application is a very simple application meant to get a new developer started using the OpenTok Linux SDK.

Upon building and running this sample application, you should be able to have one-way audio and video communication using OpenTok. This sample application is intended to be used in a tiny single-board computer, such as the Raspberry Pi.

You will need a valid Vonage Video API account to build this app. (Note that OpenTok is now the Vonage Video API.)

Building and running the sample app

Let's build this sample for the Raspberry Pi device. For now the SDK build for this device is distributed via a direct download in the TokBox developer center as a tgz package.

Before building the sample application you have to download the OpenTok Linux SDK package and uncompress it to a local folder you create (such as /assets):

$ cd assets; wget https://tokbox.com/downloads/libopentok_linux_llvm_armv7-2.32.1

Uncompress the OpenTok Linux SDK package in the assets folder. Uncompress the version of the SDK for the target host of your sample application. For example, for ARMv7 uncompress the libopentok_linux_llvm_armv7 tgz file:

$ cd assets; unp libopentok_linux_llvm_armv7-2.32.1.tgz

This will create a libopentok_linux_llvm_armv7 folder at assets/libopentok_linux_llvm_armv7. The build system will try find the OpenTok Linux SDK header files and library under the assets folder.

The folder above contains a handy CMakeListz.txt file the developer can use if CMake is used in the application. The developer would need to add it via the ADD_SUBDIRECTORY() command, add $<TARGET_PROPERTY:libopentok,INTERFACE_INCLUDE_DIRECTORIES> to the list of include folders with the INCLUDE_DIRECTORIES() command and finally add libopentok to the list of target link libraries.

  ADD_SUBDIRECTORY(${CMAKE_CURRENT_SOURCE_DIR}/../assets/libopentok_linux_llvm_armv7 ${CMAKE_CURRENT_BINARY_DIR}/libopentok)

  INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR}/../common/src ${LIBSDL2_INCLUDE_DIRS} $<TARGET_PROPERTY:libopentok,INTERFACE_INCLUDE_DIRECTORIES>)
  LINK_DIRECTORIES(${LIBSDL2_LIBRARY_DIRS})

  ADD_EXECUTABLE(${PROJECT_NAME} main.cpp ${CMAKE_CURRENT_SOURCE_DIR}/../common/src/renderer.cpp)
  TARGET_LINK_LIBRARIES(${PROJECT_NAME} ${LIBSDL2_LIBRARIES} libopentok)

This application uses CMake. Before building the sample application, install it and these other dependencies:

• build-essential
• cmake
• clang
• libc++-dev
• libc++abi-dev
• pkg-config
• libasound2
• libpulse-dev
• libsdl2-dev

Next, we will build the sample application. Since it's good practice to create a build folder, let's go ahead and create it in the project directory:

$ mkdir Publisher-Only/build

Copy the config-sample.h file as config.h at Publisher-Only/:

$ cp common/src/config-sample.h  Publisher-Only/config.h

Edit the config.h file and add your OpenTok API key, an OpenTok session ID, and token for that session. For test purposes, you can obtain a session ID and token from the project page in your Vonage Video API account. However, in a production application, you will need to dynamically obtain the session ID and token from a web service that uses one of the Vonage Video API server SDKs.

Next, create the building bits using cmake:

$ cd Publisher-Only/build
$ CC=clang CXX=clang++ cmake ..

Note we are using clang/clang++ compilers.

Use make to build the code:

$ make

When the publisher_only binary is built, run it:

$ ./publisher_only

You can use the OpenTok Playground to connect to the OpenTok session in a web browser and view the stream published by the application.

You can end the sample application by typing Control + C in the console.

Understanding the code

This application uses the same concepts that the Basic Video Chat application uses. See the Understanding the code section of that application's README file (and disregard information about subscribing to streams) to see how the code uses the OpenTok Linux SDK.

Next steps

The Basic Video Chat application sample builds upon the Publisher Only sample, adding an OpenTok stream subscriber in addition to a publisher.

See the Vonage Video API developer center for more information on the OpenTok Linux SDK.