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/Documentation/DocBook/v4l/v4l2grab.c.xml

https://bitbucket.org/sammyz/iscream_thunderc-2.6.35-rebase
XML | 164 lines | 138 code | 26 blank | 0 comment | 0 complexity | daaae9555570f2994ecb8212693c74b0 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  1<programlisting>
  2/* V4L2 video picture grabber
  3   Copyright (C) 2009 Mauro Carvalho Chehab &lt;mchehab@infradead.org&gt;
  4
  5   This program is free software; you can redistribute it and/or modify
  6   it under the terms of the GNU General Public License as published by
  7   the Free Software Foundation version 2 of the License.
  8
  9   This program is distributed in the hope that it will be useful,
 10   but WITHOUT ANY WARRANTY; without even the implied warranty of
 11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12   GNU General Public License for more details.
 13 */
 14
 15#include &lt;stdio.h&gt;
 16#include &lt;stdlib.h&gt;
 17#include &lt;string.h&gt;
 18#include &lt;fcntl.h&gt;
 19#include &lt;errno.h&gt;
 20#include &lt;sys/ioctl.h&gt;
 21#include &lt;sys/types.h&gt;
 22#include &lt;sys/time.h&gt;
 23#include &lt;sys/mman.h&gt;
 24#include &lt;linux/videodev2.h&gt;
 25#include "../libv4l/include/libv4l2.h"
 26
 27#define CLEAR(x) memset(&amp;(x), 0, sizeof(x))
 28
 29struct buffer {
 30        void   *start;
 31        size_t length;
 32};
 33
 34static void xioctl(int fh, int request, void *arg)
 35{
 36        int r;
 37
 38        do {
 39                r = v4l2_ioctl(fh, request, arg);
 40        } while (r == -1 &amp;&amp; ((errno == EINTR) || (errno == EAGAIN)));
 41
 42        if (r == -1) {
 43                fprintf(stderr, "error %d, %s\n", errno, strerror(errno));
 44                exit(EXIT_FAILURE);
 45        }
 46}
 47
 48int main(int argc, char **argv)
 49{
 50        struct <link linkend="v4l2-format">v4l2_format</link>              fmt;
 51        struct <link linkend="v4l2-buffer">v4l2_buffer</link>              buf;
 52        struct <link linkend="v4l2-requestbuffers">v4l2_requestbuffers</link>      req;
 53        enum <link linkend="v4l2-buf-type">v4l2_buf_type</link>              type;
 54        fd_set                          fds;
 55        struct timeval                  tv;
 56        int                             r, fd = -1;
 57        unsigned int                    i, n_buffers;
 58        char                            *dev_name = "/dev/video0";
 59        char                            out_name[256];
 60        FILE                            *fout;
 61        struct buffer                   *buffers;
 62
 63        fd = v4l2_open(dev_name, O_RDWR | O_NONBLOCK, 0);
 64        if (fd &lt; 0) {
 65                perror("Cannot open device");
 66                exit(EXIT_FAILURE);
 67        }
 68
 69        CLEAR(fmt);
 70        fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
 71        fmt.fmt.pix.width       = 640;
 72        fmt.fmt.pix.height      = 480;
 73        fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB24;
 74        fmt.fmt.pix.field       = V4L2_FIELD_INTERLACED;
 75        xioctl(fd, VIDIOC_S_FMT, &amp;fmt);
 76        if (fmt.fmt.pix.pixelformat != V4L2_PIX_FMT_RGB24) {
 77                printf("Libv4l didn't accept RGB24 format. Can't proceed.\n");
 78                exit(EXIT_FAILURE);
 79        }
 80        if ((fmt.fmt.pix.width != 640) || (fmt.fmt.pix.height != 480))
 81                printf("Warning: driver is sending image at %dx%d\n",
 82                        fmt.fmt.pix.width, fmt.fmt.pix.height);
 83
 84        CLEAR(req);
 85        req.count = 2;
 86        req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
 87        req.memory = V4L2_MEMORY_MMAP;
 88        xioctl(fd, VIDIOC_REQBUFS, &amp;req);
 89
 90        buffers = calloc(req.count, sizeof(*buffers));
 91        for (n_buffers = 0; n_buffers &lt; req.count; ++n_buffers) {
 92                CLEAR(buf);
 93
 94                buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
 95                buf.memory      = V4L2_MEMORY_MMAP;
 96                buf.index       = n_buffers;
 97
 98                xioctl(fd, VIDIOC_QUERYBUF, &amp;buf);
 99
100                buffers[n_buffers].length = buf.length;
101                buffers[n_buffers].start = v4l2_mmap(NULL, buf.length,
102                              PROT_READ | PROT_WRITE, MAP_SHARED,
103                              fd, buf.m.offset);
104
105                if (MAP_FAILED == buffers[n_buffers].start) {
106                        perror("mmap");
107                        exit(EXIT_FAILURE);
108                }
109        }
110
111        for (i = 0; i &lt; n_buffers; ++i) {
112                CLEAR(buf);
113                buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
114                buf.memory = V4L2_MEMORY_MMAP;
115                buf.index = i;
116                xioctl(fd, VIDIOC_QBUF, &amp;buf);
117        }
118        type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
119
120        xioctl(fd, VIDIOC_STREAMON, &amp;type);
121        for (i = 0; i &lt; 20; i++) {
122                do {
123                        FD_ZERO(&amp;fds);
124                        FD_SET(fd, &amp;fds);
125
126                        /* Timeout. */
127                        tv.tv_sec = 2;
128                        tv.tv_usec = 0;
129
130                        r = select(fd + 1, &amp;fds, NULL, NULL, &amp;tv);
131                } while ((r == -1 &amp;&amp; (errno = EINTR)));
132                if (r == -1) {
133                        perror("select");
134                        return errno;
135                }
136
137                CLEAR(buf);
138                buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
139                buf.memory = V4L2_MEMORY_MMAP;
140                xioctl(fd, VIDIOC_DQBUF, &amp;buf);
141
142                sprintf(out_name, "out%03d.ppm", i);
143                fout = fopen(out_name, "w");
144                if (!fout) {
145                        perror("Cannot open image");
146                        exit(EXIT_FAILURE);
147                }
148                fprintf(fout, "P6\n%d %d 255\n",
149                        fmt.fmt.pix.width, fmt.fmt.pix.height);
150                fwrite(buffers[buf.index].start, buf.bytesused, 1, fout);
151                fclose(fout);
152
153                xioctl(fd, VIDIOC_QBUF, &amp;buf);
154        }
155
156        type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
157        xioctl(fd, VIDIOC_STREAMOFF, &amp;type);
158        for (i = 0; i &lt; n_buffers; ++i)
159                v4l2_munmap(buffers[i].start, buffers[i].length);
160        v4l2_close(fd);
161
162        return 0;
163}
164</programlisting>