Small programs that lists supported V4L2 formats.

v4l_check.c

#include <linux/videodev2.h>
#include <fcntl.h>
#include <string.h>
#include <stdio.h>

int main(int argc, char *argv[]) {
  struct v4l2_fmtdesc fmt;
  int i;
  const char *dev;
  int fd;

  dev = "/dev/video0";
  if (argc > 1) {
    dev = argv[1];
  }

  fd = open(dev, O_RDWR);

  if (fd == -1) {
    printf("failed to open %s\n", dev);
    return 1;
  }

  printf("opened %s\n", dev);

  for (i = 0;; i++) {
    memset(&fmt, 0, sizeof fmt);
    fmt.index = i;
    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    if (ioctl(fd, VIDIOC_ENUM_FMT, &fmt) == -1) {
      break;
    }

    char fourcc[5];
    fourcc[0] = fmt.pixelformat & 0xff;
    fourcc[1] = (fmt.pixelformat & 0xff00) >> 8;
    fourcc[2] = (fmt.pixelformat & 0xff0000) >> 16;
    fourcc[3] = (fmt.pixelformat & 0xff000000) >> 24;
    fourcc[4] = 0;

    printf("format %s\n", fourcc);
  }
  close(fd);

  return 0;
}