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Diffstat (limited to 'Documentation/DocBook/media/v4l/v4l2grab.c.xml')
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diff --git a/Documentation/DocBook/media/v4l/v4l2grab.c.xml b/Documentation/DocBook/media/v4l/v4l2grab.c.xml
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@@ -0,0 +1,164 @@
+<programlisting>
+/* V4L2 video picture grabber
+ Copyright (C) 2009 Mauro Carvalho Chehab &lt;mchehab@infradead.org&gt;
+
+ 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 &lt;stdio.h&gt;
+#include &lt;stdlib.h&gt;
+#include &lt;string.h&gt;
+#include &lt;fcntl.h&gt;
+#include &lt;errno.h&gt;
+#include &lt;sys/ioctl.h&gt;
+#include &lt;sys/types.h&gt;
+#include &lt;sys/time.h&gt;
+#include &lt;sys/mman.h&gt;
+#include &lt;linux/videodev2.h&gt;
+#include "../libv4l/include/libv4l2.h"
+
+#define CLEAR(x) memset(&amp;(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 &amp;&amp; ((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 <link linkend="v4l2-format">v4l2_format</link> fmt;
+ struct <link linkend="v4l2-buffer">v4l2_buffer</link> buf;
+ struct <link linkend="v4l2-requestbuffers">v4l2_requestbuffers</link> req;
+ enum <link linkend="v4l2-buf-type">v4l2_buf_type</link> 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 &lt; 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, &amp;fmt);
+ if (fmt.fmt.pix.pixelformat != V4L2_PIX_FMT_RGB24) {
+ printf("Libv4l didn't accept RGB24 format. Can't proceed.\n");
+ exit(EXIT_FAILURE);
+ }
+ if ((fmt.fmt.pix.width != 640) || (fmt.fmt.pix.height != 480))
+ printf("Warning: driver is sending image at %dx%d\n",
+ fmt.fmt.pix.width, fmt.fmt.pix.height);
+
+ CLEAR(req);
+ req.count = 2;
+ req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+ req.memory = V4L2_MEMORY_MMAP;
+ xioctl(fd, VIDIOC_REQBUFS, &amp;req);
+
+ buffers = calloc(req.count, sizeof(*buffers));
+ for (n_buffers = 0; n_buffers &lt; 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, &amp;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 &lt; n_buffers; ++i) {
+ CLEAR(buf);
+ buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+ buf.memory = V4L2_MEMORY_MMAP;
+ buf.index = i;
+ xioctl(fd, VIDIOC_QBUF, &amp;buf);
+ }
+ type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+
+ xioctl(fd, VIDIOC_STREAMON, &amp;type);
+ for (i = 0; i &lt; 20; i++) {
+ do {
+ FD_ZERO(&amp;fds);
+ FD_SET(fd, &amp;fds);
+
+ /* Timeout. */
+ tv.tv_sec = 2;
+ tv.tv_usec = 0;
+
+ r = select(fd + 1, &amp;fds, NULL, NULL, &amp;tv);
+ } while ((r == -1 &amp;&amp; (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, &amp;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, &amp;buf);
+ }
+
+ type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+ xioctl(fd, VIDIOC_STREAMOFF, &amp;type);
+ for (i = 0; i &lt; n_buffers; ++i)
+ v4l2_munmap(buffers[i].start, buffers[i].length);
+ v4l2_close(fd);
+
+ return 0;
+}
+</programlisting>