static int start_capturing(void) {
unsigned int i;
enum v4l2_buf_type type;
for (i = 0; i < cam_n_buffers; i++) {
struct v4l2_buffer buf;
CLEAR(buf);
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
buf.index = i;
if (xioctl(cam_fd, VIDIOC_QBUF, &buf) == -1) {
return errno_report("VIDIOC_QBUF");
}
}
type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
if (xioctl(cam_fd, VIDIOC_STREAMON, &type)) {
return errno_report("VIDIOC_STREAMON");
}
return 0;
}
static int init_device(void) {
struct v4l2_capability cap;
struct v4l2_cropcap cropcap;
struct v4l2_crop crop;
struct v4l2_format fmt;
unsigned int min;
if (xioctl(cam_fd, VIDIOC_QUERYCAP, &cap)) {
if (EINVAL == errno) {
fprintf(stderr, "%s is no V4L2 device\n", cam_dev_name);
return -1;
} else {
return errno_report("VIDIOC_QUERYCAP");
}
}
if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
fprintf(stderr, "%s is no video capture device\n", cam_dev_name);
return -1;
}
/* Using MMAP */
if (!(cap.capabilities & V4L2_CAP_STREAMING)) {
fprintf(stderr, "%s does not support streaming i/o\n", cam_dev_name);
return -1;
}
CLEAR(cropcap);
cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
if (xioctl(cam_fd, VIDIOC_CROPCAP, &cropcap) == 0) {
/* If cropping is supported, do not crop */
crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
crop.c = cropcap.defrect;
xioctl(cam_fd, VIDIOC_S_CROP, &crop);
}
CLEAR(fmt);
fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
fmt.fmt.pix.width = cam_width;
fmt.fmt.pix.height = cam_height;
fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
fmt.fmt.pix.field = V4L2_FIELD_NONE; /* No interlacing, please */
if (xioctl(cam_fd, VIDIOC_S_FMT, &fmt) == -1) {
return errno_report("VIDIOC_S_FMT");
}
/* Buggy driver paranoia. */
min = fmt.fmt.pix.width * 2;
if (fmt.fmt.pix.bytesperline < min) fmt.fmt.pix.bytesperline = min;
min = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
if (fmt.fmt.pix.sizeimage < min) fmt.fmt.pix.sizeimage = min;
return init_mmap();
}
static int init_mmap(void) {
struct v4l2_requestbuffers req;
CLEAR(req);
req.count = 4;
req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
req.memory = V4L2_MEMORY_MMAP;
if (xioctl(cam_fd, VIDIOC_REQBUFS, &req) == -1) {
if (errno == EINVAL) {
fprintf(stderr, "%s does not support memory mapping\n", cam_dev_name);
return -1;
} else {
return errno_report("VIDIOC_REQBUFS");
}
}
if (req.count < 2) {
fprintf(stderr, "Insufficient buffer memory on %s\n", cam_dev_name);
return -1;
}
cam_buffers = (struct buffer*)calloc (req.count, sizeof(*cam_buffers));
if (!cam_buffers) {
fprintf(stderr, "Out of memory\n");
return -1;
}
/* Stuff buffers with pretty things */
for (cam_n_buffers = 0; cam_n_buffers < req.count; cam_n_buffers++) {
struct v4l2_buffer buf;
CLEAR(buf);
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
buf.index = cam_n_buffers;
if (xioctl(cam_fd, VIDIOC_QUERYBUF, &buf) == -1)
return errno_report("VIDIOC_QUERYBUF");
cam_buffers[cam_n_buffers].len = buf.length;
cam_buffers[cam_n_buffers].start =
mmap(NULL, buf.length, PROT_READ | PROT_WRITE, MAP_SHARED,
cam_fd, buf.m.offset);
if (cam_buffers[cam_n_buffers].start == MAP_FAILED)
return errno_report("mmap");
}
return 0;
}
static int do_capture(void) {
fd_set fds;
struct timeval tv;
int r;
for (;;) {
FD_ZERO(&fds);
FD_SET(cam_fd, &fds);
/* Timeout. */
tv.tv_sec = 2;
tv.tv_usec = 0;
r = select(cam_fd + 1, &fds, NULL, NULL, &tv);
if (r == -1) {
if (errno != EINTR) return errno_report("select");
}
if (r == 0) {
fprintf(stderr, "select timeout\n");
return -1;
}
if (read_frame() == 0) break;
}
return 0;
}
static int close_device(void) {
if (close(cam_fd) == -1) {
return errno_report("close_device()");
}
cam_fd = -1;
return 0;
}
static int stop_capturing(void) {
enum v4l2_buf_type type;
type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
if (xioctl(cam_fd, VIDIOC_STREAMOFF, &type) == -1)
return errno_report("VIDIOC_STREAMOFF");
return 0;
}
static int uninit_device(void) {
unsigned int i;
for (i = 0; i < cam_n_buffers; i++) {
if (munmap(cam_buffers[i].start, cam_buffers[i].len) == -1) {
return errno_report("munmap");
}
}
return 0;
}
static int read_frame(void) {
struct v4l2_buffer buf;
CLEAR(buf);
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
if (xioctl(cam_fd, VIDIOC_DQBUF, &buf)) {
switch (errno) {
case EAGAIN: return -1;
case EIO:
default: return errno_report("VIDIOC_DQBUF");
}
}
process_image(cam_buffers[buf.index].start);
if (xioctl(cam_fd, VIDIOC_QBUF, &buf) == -1) {
return errno_report("VIDIOC_QBUF");
}
return 0;
}
struct buffer*
oss_record(int fd) {
if ((buffers[0].length = read(fd, buffers[0].start, buffers[0].length)) == -1)
errno_report("Audio read");
return buffers;
}
