v4l2grab: Add an userspace application for webcam testing, using libv4l2

From: Mauro Carvalho Chehab <mchehab@redhat.com>

During FISL 10 (Forum Internacional de Software Livre) and the first FudCon Latam
(Fedora Users and Developers Conference), while preparing the V4L panel, I and Douglas
noticed the need of a very simple application to be an example for developers to
test their drivers and to write newer v4l2 applications.

So, we come to the idea of creating a v4l2grab application that takes pictures from the
webcam and saves them with the ppm format, using libv4l to work with all webcam models.

This application uses the absolute minimum of V4L2 calls to take 640x480 pictures, and was tested
with uvcvideo and vivi drivers.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 155 insertions, 0 deletions

diff --git a/v4l2-apps/test/v4l2grab.c b/v4l2-apps/test/v4l2grab.c
new file mode 100644
index 000000000..20692117e
--- /dev/null
+++ b/v4l2-apps/test/v4l2grab.c
@@ -0,0 +1,155 @@
+/* V4L2 video picture grabber
+   Copyright (C) 2006 Mauro Carvalho Chehab <mchehab@infradead.org>
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+#include <linux/videodev2.h>
+#include "../libv4l/include/libv4l2.h"
+
+#define CLEAR(x) memset(&(x), 0, sizeof(x))
+
+struct buffer {
+	void   *start;
+	size_t length;
+};
+
+static void xioctl(int fh, int request, void *arg)
+{
+	int r;
+
+	do {
+		r = v4l2_ioctl(fh, request, arg);
+	} while (r == -1 && ((errno == EINTR) || (errno == EAGAIN)));
+
+	if (r == -1) {
+		fprintf(stderr, "error %d, %s\n", errno, strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+}
+
+int main(int argc, char **argv)
+{
+	struct v4l2_format		fmt;
+	struct v4l2_buffer		buf;
+	struct v4l2_requestbuffers	req;
+	enum v4l2_buf_type		type;
+	fd_set				fds;
+	struct timeval			tv;
+	int				r, fd = -1;
+	unsigned int			i, n_buffers;
+	char				*dev_name = "/dev/video0";
+	char				out_name[256];
+	FILE				*fout;
+	struct buffer			*buffers;
+
+	fd = v4l2_open(dev_name, O_RDWR | O_NONBLOCK, 0);
+	if (fd < 0) {
+		perror("Cannot open device");
+		exit(EXIT_FAILURE);
+	}
+
+	CLEAR(fmt);
+	fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+	fmt.fmt.pix.width       = 640;
+	fmt.fmt.pix.height      = 480;
+	fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB24;
+	fmt.fmt.pix.field       = V4L2_FIELD_INTERLACED;
+	xioctl(fd, VIDIOC_S_FMT, &fmt);
+
+	CLEAR(req);
+	req.count = 2;
+	req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+	req.memory = V4L2_MEMORY_MMAP;
+	xioctl(fd, VIDIOC_REQBUFS, &req);
+
+	buffers = calloc(req.count, sizeof(*buffers));
+	for (n_buffers = 0; n_buffers < req.count; ++n_buffers) {
+		CLEAR(buf);
+
+		buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+		buf.memory      = V4L2_MEMORY_MMAP;
+		buf.index       = n_buffers;
+
+		xioctl(fd, VIDIOC_QUERYBUF, &buf);
+
+		buffers[n_buffers].length = buf.length;
+		buffers[n_buffers].start = v4l2_mmap(NULL, buf.length,
+			      PROT_READ | PROT_WRITE, MAP_SHARED,
+			      fd, buf.m.offset);
+
+		if (MAP_FAILED == buffers[n_buffers].start) {
+			perror("mmap");
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	for (i = 0; i < n_buffers; ++i) {
+		CLEAR(buf);
+		buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+		buf.memory = V4L2_MEMORY_MMAP;
+		buf.index = i;
+		xioctl(fd, VIDIOC_QBUF, &buf);
+	}
+	type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+
+	xioctl(fd, VIDIOC_STREAMON, &type);
+	for (i = 0; i < 20; i++) {
+		do {
+			FD_ZERO(&fds);
+			FD_SET(fd, &fds);
+
+			/* Timeout. */
+			tv.tv_sec = 2;
+			tv.tv_usec = 0;
+
+			r = select(fd + 1, &fds, NULL, NULL, &tv);
+		} while ((r == -1 && (errno = EINTR)));
+		if (r == -1) {
+			perror("select");
+			return errno;
+		}
+
+		CLEAR(buf);
+		buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+		buf.memory = V4L2_MEMORY_MMAP;
+		xioctl(fd, VIDIOC_DQBUF, &buf);
+
+		sprintf(out_name, "out%03d.ppm", i);
+		fout = fopen(out_name, "w");
+		if (!fout) {
+			perror("Cannot open image");
+			exit(EXIT_FAILURE);
+		}
+		fprintf(fout, "P6\n%d %d 255\n",
+			fmt.fmt.pix.width, fmt.fmt.pix.height);
+		fwrite(buffers[buf.index].start, buf.bytesused, 1, fout);
+		fclose(fout);
+
+		xioctl(fd, VIDIOC_QBUF, &buf);
+	}
+
+	type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+	xioctl(fd, VIDIOC_STREAMOFF, &type);
+	for (i = 0; i < n_buffers; ++i)
+		v4l2_munmap(buffers[i].start, buffers[i].length);
+	v4l2_close(fd);
+
+	return 0;
+}