Add v4l2capture to support webcam-based speed index in telemetry

third_party/v4l2capture/v4l2capture.c

+// python-v4l2capture
+// Python extension to capture video with video4linux2
+//
+// 2009, 2010, 2011 Fredrik Portstrom
+//
+// I, the copyright holder of this file, hereby release it into the
+// public domain. This applies worldwide. In case this is not legally
+// possible: I grant anyone the right to use this work for any
+// purpose, without any conditions, unless such conditions are
+// required by law.
+
+#include <Python.h>
+#include <fcntl.h>
+#include <linux/videodev2.h>
+#include <sys/mman.h>
+
+// LIBV4L is not needed for MJPEG capture.
+#undef USE_LIBV4L
+
+#ifdef USE_LIBV4L
+#include <libv4l2.h>
+#else
+#include <sys/ioctl.h>
+#define v4l2_close close
+#define v4l2_ioctl ioctl
+#define v4l2_mmap mmap
+#define v4l2_munmap munmap
+#define v4l2_open open
+#endif
+
+#define ASSERT_OPEN if(self->fd < 0)                                    \
+    {                                                                   \
+      PyErr_SetString(PyExc_ValueError,                                 \
+          "I/O operation on closed file");                              \
+      return NULL;                                                      \
+    }
+
+struct buffer {
+  void *start;
+  size_t length;
+};
+
+typedef struct {
+  PyObject_HEAD
+  int fd;
+  struct buffer *buffers;
+  int buffer_count;
+} Video_device;
+
+struct capability {
+  int id;
+  const char *name;
+};
+
+static struct capability capabilities[] = {
+  { V4L2_CAP_ASYNCIO, "asyncio" },
+  { V4L2_CAP_AUDIO, "audio" },
+  { V4L2_CAP_HW_FREQ_SEEK, "hw_freq_seek" },
+  { V4L2_CAP_RADIO, "radio" },
+  { V4L2_CAP_RDS_CAPTURE, "rds_capture" },
+  { V4L2_CAP_READWRITE, "readwrite" },
+  { V4L2_CAP_SLICED_VBI_CAPTURE, "sliced_vbi_capture" },
+  { V4L2_CAP_SLICED_VBI_OUTPUT, "sliced_vbi_output" },
+  { V4L2_CAP_STREAMING, "streaming" },
+  { V4L2_CAP_TUNER, "tuner" },
+  { V4L2_CAP_VBI_CAPTURE, "vbi_capture" },
+  { V4L2_CAP_VBI_OUTPUT, "vbi_output" },
+  { V4L2_CAP_VIDEO_CAPTURE, "video_capture" },
+  { V4L2_CAP_VIDEO_OUTPUT, "video_output" },
+  { V4L2_CAP_VIDEO_OUTPUT_OVERLAY, "video_output_overlay" },
+  { V4L2_CAP_VIDEO_OVERLAY, "video_overlay" }
+};
+
+static int my_ioctl(int fd, int request, void *arg)
+{
+  // Retry ioctl until it returns without being interrupted.
+
+  for(;;)
+    {
+      int result = v4l2_ioctl(fd, request, arg);
+
+      if(!result)
+        {
+          return 0;
+        }
+
+      if(errno != EINTR)
+        {
+          PyErr_SetFromErrno(PyExc_IOError);
+          return 1;
+        }
+    }
+}
+
+static void Video_device_unmap(Video_device *self)
+{
+  int i;
+
+  for(i = 0; i < self->buffer_count; i++)
+    {
+      v4l2_munmap(self->buffers[i].start, self->buffers[i].length);
+    }
+  free(self->buffers);
+  self->buffers = NULL;
+}
+
+static void Video_device_dealloc(Video_device *self)
+{
+  if(self->fd >= 0)
+    {
+      if(self->buffers)
+        {
+          Video_device_unmap(self);
+        }
+
+      v4l2_close(self->fd);
+    }
+
+  self->ob_type->tp_free((PyObject *)self);
+}
+
+static int Video_device_init(Video_device *self, PyObject *args,
+    PyObject *kwargs)
+{
+  const char *device_path;
+
+  if(!PyArg_ParseTuple(args, "s", &device_path))
+    {
+      return -1;
+    }
+
+  int fd = v4l2_open(device_path, O_RDWR | O_NONBLOCK);
+
+  if(fd < 0)
+    {
+      PyErr_SetFromErrnoWithFilename(PyExc_IOError, (char *)device_path);
+      return -1;
+    }
+
+  self->fd = fd;
+  self->buffers = NULL;
+  self->buffer_count = 0;
+  return 0;
+}
+
+static PyObject *Video_device_close(Video_device *self)
+{
+  if(self->fd >= 0)
+    {
+      if(self->buffers)
+        {
+          Video_device_unmap(self);
+        }
+
+      v4l2_close(self->fd);
+      self->fd = -1;
+    }
+
+  Py_RETURN_NONE;
+}
+
+static PyObject *Video_device_fileno(Video_device *self)
+{
+  ASSERT_OPEN;
+  return PyInt_FromLong(self->fd);
+}
+
+static PyObject *Video_device_get_info(Video_device *self)
+{
+  ASSERT_OPEN;
+  struct v4l2_capability caps;
+
+  if(my_ioctl(self->fd, VIDIOC_QUERYCAP, &caps))
+    {
+      return NULL;
+    }
+
+  PyObject *set = PySet_New(NULL);
+
+  if(!set)
+    {
+      return NULL;
+    }
+
+  struct capability *capability = capabilities;
+
+  while((void *)capability < (void *)capabilities + sizeof(capabilities))
+    {
+      if(caps.capabilities & capability->id)
+        {
+          PyObject *s = PyString_FromString(capability->name);
+
+          if(!s)
+            {
+              Py_DECREF(set);
+              return NULL;
+            }
+
+          PySet_Add(set, s);
+        }
+
+      capability++;
+    }
+
+  return Py_BuildValue("sssO", caps.driver, caps.card, caps.bus_info, set);
+}
+
+static PyObject *Video_device_set_format(Video_device *self, PyObject *args)
+{
+  int size_x;
+  int size_y;
+  if(!PyArg_ParseTuple(args, "ii", &size_x, &size_y))
+    {
+      return NULL;
+    }
+
+  struct v4l2_format format;
+  format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+  format.fmt.pix.width = size_x;
+  format.fmt.pix.height = size_y;
+  format.fmt.pix.pixelformat = V4L2_PIX_FMT_MJPEG;
+  format.fmt.pix.field = V4L2_FIELD_NONE;
+  format.fmt.pix.bytesperline = 0;
+
+  if(my_ioctl(self->fd, VIDIOC_S_FMT, &format))
+    {
+      return NULL;
+    }
+
+  return Py_BuildValue("ii", format.fmt.pix.width, format.fmt.pix.height);
+}
+
+static PyObject *Video_device_set_fps(Video_device *self, PyObject *args)
+{
+  int fps;
+  if(!PyArg_ParseTuple(args, "i", &fps))
+    {
+      return NULL;
+    }
+  struct v4l2_streamparm setfps;
+  memset(&setfps, 0, sizeof(struct v4l2_streamparm));
+  setfps.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+  setfps.parm.capture.timeperframe.numerator = 1;
+  setfps.parm.capture.timeperframe.denominator = fps;
+  if(my_ioctl(self->fd, VIDIOC_S_PARM, &setfps)){
+        return NULL;
+  }
+  return Py_BuildValue("i",setfps.parm.capture.timeperframe.denominator);
+}
+
+static PyObject *Video_device_start(Video_device *self)
+{
+  ASSERT_OPEN;
+  enum v4l2_buf_type type;
+  type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+
+  if(my_ioctl(self->fd, VIDIOC_STREAMON, &type))
+    {
+      return NULL;
+    }
+
+  Py_RETURN_NONE;
+}
+
+static PyObject *Video_device_stop(Video_device *self)
+{
+  ASSERT_OPEN;
+  enum v4l2_buf_type type;
+  type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+
+  if(my_ioctl(self->fd, VIDIOC_STREAMOFF, &type))
+    {
+      return NULL;
+    }
+
+  Py_RETURN_NONE;
+}
+
+static PyObject *Video_device_create_buffers(Video_device *self, PyObject *args)
+{
+  int buffer_count;
+
+  if(!PyArg_ParseTuple(args, "I", &buffer_count))
+    {
+      return NULL;
+    }
+
+  ASSERT_OPEN;
+
+  if(self->buffers)
+    {
+      PyErr_SetString(PyExc_ValueError, "Buffers are already created");
+      return NULL;
+    }
+
+  struct v4l2_requestbuffers reqbuf;
+  reqbuf.count = buffer_count;
+  reqbuf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+  reqbuf.memory = V4L2_MEMORY_MMAP;
+
+  if(my_ioctl(self->fd, VIDIOC_REQBUFS, &reqbuf))
+    {
+      return NULL;
+    }
+
+  if(!reqbuf.count)
+    {
+      PyErr_SetString(PyExc_IOError, "Not enough buffer memory");
+      return NULL;
+    }
+
+  self->buffers = malloc(reqbuf.count * sizeof(struct buffer));
+
+  if(!self->buffers)
+    {
+      PyErr_NoMemory();
+      return NULL;
+    }
+
+  int i;
+
+  for(i = 0; i < reqbuf.count; i++)
+    {
+      struct v4l2_buffer buffer;
+      buffer.index = i;
+      buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+      buffer.memory = V4L2_MEMORY_MMAP;
+
+      if(my_ioctl(self->fd, VIDIOC_QUERYBUF, &buffer))
+        {
+          return NULL;
+        }
+
+      self->buffers[i].length = buffer.length;
+      self->buffers[i].start = v4l2_mmap(NULL, buffer.length,
+          PROT_READ | PROT_WRITE, MAP_SHARED, self->fd, buffer.m.offset);
+
+      if(self->buffers[i].start == MAP_FAILED)
+        {
+          PyErr_SetFromErrno(PyExc_IOError);
+          Video_device_unmap(self);
+          return NULL;
+        }
+      ++self->buffer_count;
+    }
+
+  Py_RETURN_NONE;
+}
+
+static PyObject *Video_device_queue_all_buffers(Video_device *self)
+{
+  if(!self->buffers)
+    {
+      ASSERT_OPEN;
+      PyErr_SetString(PyExc_ValueError, "Buffers have not been created");
+      return NULL;
+    }
+
+  int i;
+  int buffer_count = self->buffer_count;
+
+  for(i = 0; i < buffer_count; i++)
+    {
+      struct v4l2_buffer buffer;
+      buffer.index = i;
+      buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+      buffer.memory = V4L2_MEMORY_MMAP;
+
+      if(my_ioctl(self->fd, VIDIOC_QBUF, &buffer))
+        {
+          return NULL;
+        }
+    }
+
+  Py_RETURN_NONE;
+}
+
+static PyObject *Video_device_read_internal(Video_device *self, int queue)
+{
+  if(!self->buffers)
+    {
+      ASSERT_OPEN;
+      PyErr_SetString(PyExc_ValueError, "Buffers have not been created");
+      return NULL;
+    }
+
+  struct v4l2_buffer buffer;
+  buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+  buffer.memory = V4L2_MEMORY_MMAP;
+
+  if(my_ioctl(self->fd, VIDIOC_DQBUF, &buffer))
+    {
+      return NULL;
+    }
+
+  PyObject *result = PyString_FromStringAndSize(
+      self->buffers[buffer.index].start, buffer.bytesused);
+
+  if(!result)
+    {
+      return NULL;
+    }
+
+  if(queue && my_ioctl(self->fd, VIDIOC_QBUF, &buffer))
+    {
+      return NULL;
+    }
+
+  return result;
+}
+
+static PyObject *Video_device_read(Video_device *self)
+{
+  return Video_device_read_internal(self, 0);
+}
+
+static PyObject *Video_device_read_and_queue(Video_device *self)
+{
+  return Video_device_read_internal(self, 1);
+}
+
+static PyMethodDef Video_device_methods[] = {
+  {"close", (PyCFunction)Video_device_close, METH_NOARGS,
+       "close()\n\n"
+       "Close video device. Subsequent calls to other methods will fail."},
+  {"fileno", (PyCFunction)Video_device_fileno, METH_NOARGS,
+       "fileno() -> integer \"file descriptor\".\n\n"
+       "This enables video devices to be passed select.select for waiting "
+       "until a frame is available for reading."},
+  {"get_info", (PyCFunction)Video_device_get_info, METH_NOARGS,
+       "get_info() -> driver, card, bus_info, capabilities\n\n"
+       "Returns three strings with information about the video device, and one "
+       "set containing strings identifying the capabilities of the video "
+       "device."},
+  {"set_format", (PyCFunction)Video_device_set_format, METH_VARARGS,
+       "set_format(size_x, size_y) -> size_x, size_y\n\n"
+       "Request the video device to set image size and format. The device may "
+       "choose another size than requested and will return its choice. The "
+       "image format will be MJPEG."},
+  {"set_fps", (PyCFunction)Video_device_set_fps, METH_VARARGS,
+       "set_fps(fps) -> fps \n\n"
+       "Request the video device to set frame per seconds.The device may "
+       "choose another frame rate than requested and will return its choice. " },
+  {"start", (PyCFunction)Video_device_start, METH_NOARGS,
+       "start()\n\n"
+       "Start video capture."},
+  {"stop", (PyCFunction)Video_device_stop, METH_NOARGS,
+       "stop()\n\n"
+       "Stop video capture."},
+  {"create_buffers", (PyCFunction)Video_device_create_buffers, METH_VARARGS,
+       "create_buffers(count)\n\n"
+       "Create buffers used for capturing image data. Can only be called once "
+       "for each video device object."},
+  {"queue_all_buffers", (PyCFunction)Video_device_queue_all_buffers,
+       METH_NOARGS,
+       "queue_all_buffers()\n\n"
+       "Let the video device fill all buffers created."},
+  {"read", (PyCFunction)Video_device_read, METH_NOARGS,
+       "read() -> string\n\n"
+       "Reads image data from a buffer that has been filled by the video "
+       "device. The image data is in MJPEG format. "
+       "The buffer is removed from the queue. Fails if no buffer "
+       "is filled. Use select.select to check for filled buffers."},
+  {"read_and_queue", (PyCFunction)Video_device_read_and_queue, METH_NOARGS,
+       "read_and_queue()\n\n"
+       "Same as 'read', but adds the buffer back to the queue so the video "
+       "device can fill it again."},
+  {NULL}
+};
+
+static PyTypeObject Video_device_type = {
+  PyObject_HEAD_INIT(NULL)
+      0, "v4l2capture.Video_device", sizeof(Video_device), 0,
+      (destructor)Video_device_dealloc, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+      0, Py_TPFLAGS_DEFAULT, "Video_device(path)\n\nOpens the video device at "
+      "the given path and returns an object that can capture images. The "
+      "constructor and all methods except close may raise IOError.", 0, 0, 0,
+      0, 0, 0, Video_device_methods, 0, 0, 0, 0, 0, 0, 0,
+      (initproc)Video_device_init
+};
+
+static PyMethodDef module_methods[] = {
+  {NULL}
+};
+
+PyMODINIT_FUNC initv4l2capture(void)
+{
+  Video_device_type.tp_new = PyType_GenericNew;
+
+  if(PyType_Ready(&Video_device_type) < 0)
+    {
+      return;
+    }
+
+  PyObject *module = Py_InitModule3("v4l2capture", module_methods,
+      "Capture video with video4linux2.");
+
+  if(!module)
+    {
+      return;
+    }
+
+  Py_INCREF(&Video_device_type);
+  PyModule_AddObject(module, "Video_device", (PyObject *)&Video_device_type);
+}