VHAL Client library

libvhal-client is a library written in C++17 for Touch, Joystick, GPS, Camera, Audio and Sensor modules. Currently only Camera is supported. Using this library, a client can interact with Camera Vhal without worrying about socket connection, data structure, command details. Instead, the library exposes simple and powerful API that simplifies the life of VHAL client modules such as CG-Proxy, Streamer, etc. Any internal changes in the Camera VHAL and the library is abstracted and hence it won’t affect client code. New features or improvements can be provided via APIs rather than new socket commands, and other details.

Build steps

shakthi@mypc build (master) mkdir build
shakthi@mypc build (master) cd build
shakthi@mypc build (master) $ cmake ..

-- The CXX compiler identification is GNU 7.5.0
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Project name: vhal-client
-- Looking for C++ include pthread.h
-- Looking for C++ include pthread.h - found
-- Looking for pthread_create
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-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE
-- Configuring done
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-- Build files have been written to: /home/shakthi/gitlab/libvhal-client/build

shakthi@Lenovo-Yoga-C740-14IML build (master) $ cmake --build .

Scanning dependencies of target vhal-client
[ 14%] Building CXX object source/CMakeFiles/vhal-client.dir/unix_stream_socket_client.cc.o
[ 28%] Building CXX object source/CMakeFiles/vhal-client.dir/vhal_video_sink.cc.o
[ 42%] Linking CXX shared library ../../libs/linux/libvhal-client.so
[ 42%] Built target vhal-client
Scanning dependencies of target camera_socket_client
[ 57%] Building CXX object examples/CMakeFiles/camera_socket_client.dir/camera_socket_client.cc.o
[ 71%] Linking CXX executable ../../bins/linux/camera_socket_client
[ 71%] Built target camera_socket_client
Scanning dependencies of target camera_client
[ 85%] Building CXX object examples/CMakeFiles/camera_client.dir/camera_client.cc.o
[100%] Linking CXX executable ../../bins/linux/camera_client
[100%] Built target camera_client

### To install/copy libvhal-clinet.so in to destination directory
cmake -DCMAKE_INSTALL_PREFIX=<Absolute path to install>
      -DCMAKE_INSTALL_LIBDIR=<Relative directory name to install libs>
      -DCMAKE_INSTALL_BINDIR=<Relative directory name to install bins> ..

Example:
libvhal-client$mkdir build
libvhal-client$cd build
cmake -DCMAKE_INSTALL_PREFIX=$(pwd)/..
      -DCMAKE_INSTALL_LIBDIR=lib ..
libvhal-client$make
libvhal-client$make install

Camera

Camera VHal runs socket server (UNIX, VSock are supported). VHAL Client library shall connect to socket server path or address/port endpoint.

Architecture

Steps to interact with libVHAL-Client from Streamer

1. Create an object to libVHAL's vhal::client::VideoSink by passing vhal::client::UnixConnectionInfo. Then libVHAL will prepare and connect to Camera server using UNIX domain sockets.

    UnixConnectionInfo conn_info = { socket_path, instance_id };
    try {
        video_sink = make_shared<VideoSink>(conn_info);
    }

2. Register a callback with vhal::client::VideoSink for Camera open/close commands.

video_sink->RegisterCallback([&](const VideoSink::CtrlMessage& ctrl_msg) {
// Callback Implementation here
}

3. Send the camera frames to libVHAL-client as below.

video_sink->SendDataPacket(inbuf.data(), inbuf_size);

4. For non-encoded data camera frames always of fixed size example I420 in such cases both vhal and libVHAL-client knows the data size exchange in such scenario SendRawPacket will used as below.

video_sink->SendRawPacket(inbuf.data(), inbuf_size);

Example implementation to interact with libVHAL-client is present in examples/camera_client.cc