Cuda motion

A C++20 project inspired by Motion but is GPU-accelerated.

There are two main functions of this program:

1. Detect image change (i.e., "motion") from a video feed and record videos during the periods when a motion event occurs;

2. Provide various inter-process communication methods for downstream programs to consume live images from different types of cameras so that downstream programs don't have to implement their own version of video feed handling repetitively. The following methods are currently supported:

   1. File;
   2. HTTP;
   3. POSIX Shared Memory;
   4. ZeroMQ Pub/Sub mode (with ProtoBuf encoding).

• In Motion, hardware acceleration can only be achieved by piping data to external libraries such as FFmpeg, and some computationally expensive tasks such as motion detection just can't be offloaded to a GPU (as it is beyond the capability of FFmpeg). This greatly limits the practical use of Motion as we won't be able to handle even just a few (say, five) video feeds with an average CPU.

  • In contrast, this project is designed to work only if a CUDA-compatible device (e.g., an Nvidia GPU) is in place, and it offloads all parallelable tasks to GPUs, achieving much better performace.

  • On the con side, Motion works as long as you have a CPU😉, but Cuda motion can only run if you have an Nvidia GPU and its closed source CUDA framework installed.

Dependencies

• Drogon for HTTP service
• nlohmann-json3, JSON support: apt install nlohmann-json3-dev
• spdlog for logging: apt install libspdlog-dev
• v4l-utils: for manually examining and manipulating local video devices.
• cppzmq for message queue, apt install libzmq3-dev
  • cppzmq-dev will be automatically installed with libzmq3-dev
• protobuf for data serialization support: apt install libprotobuf-dev protobuf-compiler
• readerwriterquque for high-performance lock-free queue support: apt install libreaderwriterqueue-dev
• cxxopts for parsing arguments: apt install libcxxopts-dev
• OpenCV: image/video manipulation libraries that do all the heavy lifting.
  • Check build notes here and here.

Build and deployment

mkdir ./build
cmake ../
make -j2

Quality assurance

• Instead of cmake ../, run:

  • cmake -DBUILD_ASAN=ON ../
  • cmake -DBUILD_UBSAN=ON ../

• The repo is also tested with Valgrind from time to time: valgrind --leak-check=yes --log-file=valgrind.rpt ./build/cs.

Profiling

• gprof:

cmake -DCMAKE_CXX_FLAGS=-pg -DCMAKE_EXE_LINKER_FLAGS=-pg -DCMAKE_SHARED_LINKER_FLAGS=-pg  ../
make -j4
./build/cm
gprof ./build/cm gmon.out

• callgrind

valgrind --tool=callgrind ./cm
kcachegrind `ls -tr callgrind.out.* | tail -1`