Add Support for Kinect as Webcam on Linux

CMakeLists.txt

@@ -33,6 +33,7 @@ SET(DEPENDS_DIR "${MY_DIR}/depends" CACHE STRING "dependency directory must be s
 
 OPTION(BUILD_SHARED_LIBS "Build shared (ON) or static (OFF) libraries" ON)
 OPTION(BUILD_EXAMPLES "Build examples" ON)
+OPTION(BUILD_WEBCAM "Build Webcam" ON)
 OPTION(BUILD_OPENNI2_DRIVER "Build OpenNI2 driver" ON)
 OPTION(ENABLE_CXX11 "Enable C++11 support" OFF)
 OPTION(ENABLE_OPENCL "Enable OpenCL support" ON)
@@ -457,6 +458,12 @@ IF(BUILD_EXAMPLES)
   ADD_SUBDIRECTORY(${MY_DIR}/examples)
 ENDIF()
 
+IF(BUILD_WEBCAM)
+  SET(HAVE_WEBCAM yes)
+  MESSAGE(STATUS "Configuration of Kinect as Webcam")
+  ADD_SUBDIRECTORY(${MY_DIR}/examples/kinect_webcam)
+ENDIF()
+
 SET(HAVE_OpenNI2 disabled)
 IF(BUILD_OPENNI2_DRIVER)
   FIND_PACKAGE(OpenNI2)

README.md

@@ -243,6 +243,12 @@ Note: Ubuntu 12.04 is too old to support. Debian jessie may also be too old, and
 * Install OpenNI2 (optional)
     1. (Ubuntu 14.04 only) `sudo apt-add-repository ppa:deb-rob/ros-trusty && sudo apt-get update` (You don't need this if you have ROS repos), then `sudo apt-get install libopenni2-dev`
     2. (Other) `sudo apt-get install libopenni2-dev`
+* Install v4l2loopback-dksm (optional)
+    1. (Ubuntu) `sudo apt-get update && sudo apt-get install v4l2loopback-dkms` 
+    2. (Arch) `sudo pacman -S v4l2loopback-dksm`
+* Install OpenCV (optional)
+    1. (Ubuntu) `sudo apt-get update && sudo apt-get install libopencv-dev` 
+    2. (Arch) `sudo pacman -S opencv`
 * Build (if you have run `cd depends` previously, `cd ..` back to the libfreenect2 root directory first.)
     ```
     mkdir build && cd build
@@ -254,3 +260,4 @@ Note: Ubuntu 12.04 is too old to support. Debian jessie may also be too old, and
 * Set up udev rules for device access: `sudo cp ../platform/linux/udev/90-kinect2.rules /etc/udev/rules.d/`, then replug the Kinect.
 * Run the test program: `./bin/Protonect`
 * Run OpenNI2 test (optional): `sudo apt-get install openni2-utils && sudo make install-openni2 && NiViewer2`. Environment variable `LIBFREENECT2_PIPELINE` can be set to `cl`, `cuda`, etc to specify the pipeline.
+* To use kinect as webcam, you need to run `sudo modprobe v4l2loopback devices=1 video_nr=10 card_label="Kinect Webcam"` and then simply run `Kinect_Webcam`

examples/kinect_webcam/CMakeLists.txt

@@ -0,0 +1,79 @@
+CMAKE_MINIMUM_REQUIRED(VERSION 2.8.12.1)
+
+if(WIN32 AND NOT MINGW)
+  if(NOT DEFINED CMAKE_DEBUG_POSTFIX)
+    set(CMAKE_DEBUG_POSTFIX "d")
+  endif()
+endif()
+
+IF(NOT DEFINED CMAKE_BUILD_TYPE)
+  # No effect for multi-configuration generators (e.g. for Visual Studio)
+  SET(CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "Choose: RelWithDebInfo Release Debug MinSizeRel None")
+ENDIF()
+
+PROJECT(kinect_webcam)
+
+SET(MY_DIR ${libfreenect2_examples_SOURCE_DIR})
+SET(DEPENDS_DIR "${MY_DIR}/../depends" CACHE STRING "Dependency directory")
+
+OPTION(ENABLE_OPENGL "Enable OpenGL support" ON)
+
+# The example build system is standalone and will work out-of-tree with these files copied
+SET(freenect2_ROOT_DIR ${MY_DIR}/../..)
+SET(flextGL_SOURCES ${freenect2_ROOT_DIR}/src/flextGL.cpp)
+SET(flextGL_INCLUDE_DIRS ${freenect2_ROOT_DIR}/src) # for flextGL.h
+
+FIND_PACKAGE(PkgConfig)    # try find PKGConfig as it will be used if found
+LIST(APPEND CMAKE_MODULE_PATH ${freenect2_ROOT_DIR}/cmake_modules) # FindGLFW3.cmake
+
+FIND_PACKAGE(OpenCV REQUIRED)
+SET(RESOURCES_INC_FILE "${PROJECT_BINARY_DIR}/resources.inc.h")
+IF(TARGET freenect2)
+  MESSAGE(STATUS "Using in-tree freenect2 target")
+  SET(freenect2_LIBRARIES freenect2)
+  SET(freenect2_DLLS ${LIBFREENECT2_DLLS})
+ELSE()
+  FIND_PACKAGE(freenect2 REQUIRED)
+  # Out-of-tree build will have to have DLLs manually copied.
+ENDIF()
+
+INCLUDE_DIRECTORIES(
+  "/usr/include/opencv4"
+  ${freenect2_INCLUDE_DIR}
+)
+add_compile_options(-fexceptions)
+SET(Kinect_Webcam_src
+  Kinect_Webcam.cpp
+)
+
+SET(Kinect_Webcam_LIBRARIES
+  ${freenect2_LIBRARIES}
+)
+
+SET(Kinect_Webcam_DLLS
+  ${freenect2_DLLS}
+)
+
+ADD_EXECUTABLE(Kinect_Webcam
+  ${Kinect_Webcam_src}
+)
+
+TARGET_LINK_LIBRARIES(Kinect_Webcam
+  ${Kinect_Webcam_LIBRARIES}
+  opencv_core
+  opencv_highgui
+  ${OpenCV_LIBS}
+)
+
+IF(WIN32)
+  INSTALL(TARGETS Kinect_Webcam DESTINATION bin)
+  LIST(REMOVE_DUPLICATES Kinect_Webcam_DLLS)
+  FOREACH(FILEI ${Kinect_Webcam_DLLS})
+    ADD_CUSTOM_COMMAND(TARGET Kinect_Webcam POST_BUILD
+      COMMAND ${CMAKE_COMMAND} -E copy_if_different ${FILEI} $<TARGET_FILE_DIR:Kinect_Webcam>
+    )
+  ENDFOREACH(FILEI)
+INSTALL(TARGETS Kinect_Webcam DESTINATION bin)
+  INSTALL(FILES ${Kinect_Webcam_DLLS} DESTINATION bin)
+ENDIF()
+INSTALL(TARGETS Kinect_Webcam DESTINATION bin)

examples/kinect_webcam/Kinect_Webcam.cpp

@@ -0,0 +1,124 @@
+#include <iostream>
+#include <cstdlib>
+#include <signal.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/videodev2.h>
+#include <errno.h>
+#include <string.h>
+#include <opencv2/opencv.hpp>
+#include <libfreenect2/libfreenect2.hpp>
+#include <libfreenect2/frame_listener_impl.h>
+#include <libfreenect2/registration.h>
+#include <libfreenect2/packet_pipeline.h>
+#include <libfreenect2/logger.h>
+
+bool protonect_shutdown = false;
+int v4l2_fd = -1;
+
+void sigint_handler(int s)
+{
+  protonect_shutdown = true;
+}
+
+bool init_v4l2_device(const char *device, int width, int height)
+{
+  v4l2_fd = open(device, O_WRONLY);
+  if (v4l2_fd < 0)
+  {
+    std::cerr << "Error opening v4l2loopback device: " << strerror(errno) << std::endl;
+    return false;
+  }
+
+  struct v4l2_format v4l2_fmt;
+  memset(&v4l2_fmt, 0, sizeof(v4l2_fmt));
+  v4l2_fmt.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
+  v4l2_fmt.fmt.pix.width = width;
+  v4l2_fmt.fmt.pix.height = height;
+  v4l2_fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_BGR24;
+  v4l2_fmt.fmt.pix.sizeimage = width * height * 3;
+  v4l2_fmt.fmt.pix.field = V4L2_FIELD_NONE;
+
+  if (ioctl(v4l2_fd, VIDIOC_S_FMT, &v4l2_fmt) < 0)
+  {
+    std::cerr << "Error setting v4l2 format: " << strerror(errno) << std::endl;
+    close(v4l2_fd);
+    v4l2_fd = -1;
+    return false;
+  }
+
+  return true;
+}
+
+void write_frame_to_v4l2(unsigned char *rgb_data, int width, int height)
+{
+  if (v4l2_fd < 0)
+    return;
+
+  cv::Mat frame(height, width, CV_8UC4, rgb_data);
+  cv::Mat bgr_frame;
+  cv::cvtColor(frame, bgr_frame, cv::COLOR_BGRA2BGR);
+
+  write(v4l2_fd, bgr_frame.data, width * height * 3);
+}
+
+int main(int argc, char *argv[])
+{
+  libfreenect2::Freenect2 freenect2;
+  libfreenect2::Freenect2Device *dev = nullptr;
+  libfreenect2::PacketPipeline *pipeline = nullptr;
+
+  if (!init_v4l2_device("/dev/video10", 1920, 1080))
+  {
+    std::cerr << "Failed to initialize v4l2loopback device" << std::endl;
+    return -1;
+  }
+
+  if (freenect2.enumerateDevices() == 0)
+  {
+    std::cout << "No device connected!" << std::endl;
+    return -1;
+  }
+
+  std::string serial = freenect2.getDefaultDeviceSerialNumber();
+
+  dev = freenect2.openDevice(serial);
+
+  if (dev == nullptr)
+  {
+    std::cout << "Failure opening device!" << std::endl;
+    return -1;
+  }
+
+  signal(SIGINT, sigint_handler);
+
+  libfreenect2::SyncMultiFrameListener listener(libfreenect2::Frame::Color);
+  libfreenect2::FrameMap frames;
+
+  dev->setColorFrameListener(&listener);
+
+  if (!dev->start())
+    return -1;
+
+  std::cout << "Device serial: " << dev->getSerialNumber() << std::endl;
+  std::cout << "Device firmware: " << dev->getFirmwareVersion() << std::endl;
+
+  while (!protonect_shutdown)
+  {
+    if (!listener.waitForNewFrame(frames, 10 * 1000)) // 10 seconds
+    {
+      std::cout << "Timeout!" << std::endl;
+      return -1;
+    }
+    libfreenect2::Frame *rgb = frames[libfreenect2::Frame::Color];
+
+    write_frame_to_v4l2(rgb->data, rgb->width, rgb->height);
+
+    listener.release(frames);
+  }
+
+  dev->stop();
+  dev->close();
+  close(v4l2_fd);
+  return 0;
+}