[linux-2.6-block.git] / Documentation / DocBook / media / v4l / capture.c.xml

<programlisting>
/*
 *  V4L2 video capture example
 *
 *  This program can be used and distributed without restrictions.
 *
 *      This program is provided with the V4L2 API
 * see http://linuxtv.org/docs.php for more information
 */

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;string.h&gt;
#include &lt;assert.h&gt;

#include &lt;getopt.h&gt;             /* getopt_long() */

#include &lt;fcntl.h&gt;              /* low-level i/o */
#include &lt;unistd.h&gt;
#include &lt;errno.h&gt;
#include &lt;sys/stat.h&gt;
#include &lt;sys/types.h&gt;
#include &lt;sys/time.h&gt;
#include &lt;sys/mman.h&gt;
#include &lt;sys/ioctl.h&gt;

#include &lt;linux/videodev2.h&gt;

#define CLEAR(x) memset(&amp;(x), 0, sizeof(x))

enum io_method {
        IO_METHOD_READ,
        IO_METHOD_MMAP,
        IO_METHOD_USERPTR,
};

struct buffer {
        void   *start;
        size_t  length;
};

static char            *dev_name;
static enum io_method   io = IO_METHOD_MMAP;
static int              fd = -1;
struct buffer          *buffers;
static unsigned int     n_buffers;
static int              out_buf;
static int              force_format;
static int              frame_count = 70;

static void errno_exit(const char *s)
{
        fprintf(stderr, "%s error %d, %s\n", s, errno, strerror(errno));
        exit(EXIT_FAILURE);
}

static int xioctl(int fh, int request, void *arg)
{
        int r;

        do {
                r = ioctl(fh, request, arg);
        } while (-1 == r &amp;&amp; EINTR == errno);

        return r;
}

static void process_image(const void *p, int size)
{
        if (out_buf)
                fwrite(p, size, 1, stdout);

        fflush(stderr);
        fprintf(stderr, ".");
        fflush(stdout);
}

static int read_frame(void)
{
        struct <link linkend="v4l2-buffer">v4l2_buffer</link> buf;
        unsigned int i;

        switch (io) {
        case IO_METHOD_READ:
                if (-1 == read(fd, buffers[0].start, buffers[0].length)) {
                        switch (errno) {
                        case EAGAIN:
                                return 0;

                        case EIO:
                                /* Could ignore EIO, see spec. */

                                /* fall through */

                        default:
                                errno_exit("read");
                        }
                }

                process_image(buffers[0].start, buffers[0].length);
                break;

        case IO_METHOD_MMAP:
                CLEAR(buf);

                buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                buf.memory = V4L2_MEMORY_MMAP;

                if (-1 == xioctl(fd, VIDIOC_DQBUF, &amp;buf)) {
                        switch (errno) {
                        case EAGAIN:
                                return 0;

                        case EIO:
                                /* Could ignore EIO, see spec. */

                                /* fall through */

                        default:
                                errno_exit("VIDIOC_DQBUF");
                        }
                }

                assert(buf.index &lt; n_buffers);

                process_image(buffers[buf.index].start, buf.bytesused);

                if (-1 == xioctl(fd, VIDIOC_QBUF, &amp;buf))
                        errno_exit("VIDIOC_QBUF");
                break;

        case IO_METHOD_USERPTR:
                CLEAR(buf);

                buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                buf.memory = V4L2_MEMORY_USERPTR;

                if (-1 == xioctl(fd, VIDIOC_DQBUF, &amp;buf)) {
                        switch (errno) {
                        case EAGAIN:
                                return 0;

                        case EIO:
                                /* Could ignore EIO, see spec. */

                                /* fall through */

                        default:
                                errno_exit("VIDIOC_DQBUF");
                        }
                }

                for (i = 0; i &lt; n_buffers; ++i)
                        if (buf.m.userptr == (unsigned long)buffers[i].start
                            &amp;&amp; buf.length == buffers[i].length)
                                break;

                assert(i &lt; n_buffers);

                process_image((void *)buf.m.userptr, buf.bytesused);

                if (-1 == xioctl(fd, VIDIOC_QBUF, &amp;buf))
                        errno_exit("VIDIOC_QBUF");
                break;
        }

        return 1;
}

static void mainloop(void)
{
        unsigned int count;

        count = frame_count;

        while (count-- &gt; 0) {
                for (;;) {
                        fd_set fds;
                        struct timeval tv;
                        int r;

                        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);

                        if (-1 == r) {
                                if (EINTR == errno)
                                        continue;
                                errno_exit("select");
                        }

                        if (0 == r) {
                                fprintf(stderr, "select timeout\n");
                                exit(EXIT_FAILURE);
                        }

                        if (read_frame())
                                break;
                        /* EAGAIN - continue select loop. */
                }
        }
}

static void stop_capturing(void)
{
        enum <link linkend="v4l2-buf-type">v4l2_buf_type</link> type;

        switch (io) {
        case IO_METHOD_READ:
                /* Nothing to do. */
                break;

        case IO_METHOD_MMAP:
        case IO_METHOD_USERPTR:
                type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                if (-1 == xioctl(fd, VIDIOC_STREAMOFF, &amp;type))
                        errno_exit("VIDIOC_STREAMOFF");
                break;
        }
}

static void start_capturing(void)
{
        unsigned int i;
        enum <link linkend="v4l2-buf-type">v4l2_buf_type</link> type;

        switch (io) {
        case IO_METHOD_READ:
                /* Nothing to do. */
                break;

        case IO_METHOD_MMAP:
                for (i = 0; i &lt; n_buffers; ++i) {
                        struct <link linkend="v4l2-buffer">v4l2_buffer</link> buf;

                        CLEAR(buf);
                        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                        buf.memory = V4L2_MEMORY_MMAP;
                        buf.index = i;

                        if (-1 == xioctl(fd, VIDIOC_QBUF, &amp;buf))
                                errno_exit("VIDIOC_QBUF");
                }
                type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                if (-1 == xioctl(fd, VIDIOC_STREAMON, &amp;type))
                        errno_exit("VIDIOC_STREAMON");
                break;

        case IO_METHOD_USERPTR:
                for (i = 0; i &lt; n_buffers; ++i) {
                        struct <link linkend="v4l2-buffer">v4l2_buffer</link> buf;

                        CLEAR(buf);
                        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                        buf.memory = V4L2_MEMORY_USERPTR;
                        buf.index = i;
                        buf.m.userptr = (unsigned long)buffers[i].start;
                        buf.length = buffers[i].length;

                        if (-1 == xioctl(fd, VIDIOC_QBUF, &amp;buf))
                                errno_exit("VIDIOC_QBUF");
                }
                type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                if (-1 == xioctl(fd, VIDIOC_STREAMON, &amp;type))
                        errno_exit("VIDIOC_STREAMON");
                break;
        }
}

static void uninit_device(void)
{
        unsigned int i;

        switch (io) {
        case IO_METHOD_READ:
                free(buffers[0].start);
                break;

        case IO_METHOD_MMAP:
                for (i = 0; i &lt; n_buffers; ++i)
                        if (-1 == munmap(buffers[i].start, buffers[i].length))
                                errno_exit("munmap");
                break;

        case IO_METHOD_USERPTR:
                for (i = 0; i &lt; n_buffers; ++i)
                        free(buffers[i].start);
                break;
        }

        free(buffers);
}

static void init_read(unsigned int buffer_size)
{
        buffers = calloc(1, sizeof(*buffers));

        if (!buffers) {
                fprintf(stderr, "Out of memory\n");
                exit(EXIT_FAILURE);
        }

        buffers[0].length = buffer_size;
        buffers[0].start = malloc(buffer_size);

        if (!buffers[0].start) {
                fprintf(stderr, "Out of memory\n");
                exit(EXIT_FAILURE);
        }
}

static void init_mmap(void)
{
        struct <link linkend="v4l2-requestbuffers">v4l2_requestbuffers</link> req;

        CLEAR(req);

        req.count = 4;
        req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        req.memory = V4L2_MEMORY_MMAP;

        if (-1 == xioctl(fd, VIDIOC_REQBUFS, &amp;req)) {
                if (EINVAL == errno) {
                        fprintf(stderr, "%s does not support "
                                 "memory mapping\n", dev_name);
                        exit(EXIT_FAILURE);
                } else {
                        errno_exit("VIDIOC_REQBUFS");
                }
        }

        if (req.count &lt; 2) {
                fprintf(stderr, "Insufficient buffer memory on %s\n",
                         dev_name);
                exit(EXIT_FAILURE);
        }

        buffers = calloc(req.count, sizeof(*buffers));

        if (!buffers) {
                fprintf(stderr, "Out of memory\n");
                exit(EXIT_FAILURE);
        }

        for (n_buffers = 0; n_buffers &lt; req.count; ++n_buffers) {
                struct <link linkend="v4l2-buffer">v4l2_buffer</link> buf;

                CLEAR(buf);

                buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                buf.memory      = V4L2_MEMORY_MMAP;
                buf.index       = n_buffers;

                if (-1 == xioctl(fd, VIDIOC_QUERYBUF, &amp;buf))
                        errno_exit("VIDIOC_QUERYBUF");

                buffers[n_buffers].length = buf.length;
                buffers[n_buffers].start =
                        mmap(NULL /* start anywhere */,
                              buf.length,
                              PROT_READ | PROT_WRITE /* required */,
                              MAP_SHARED /* recommended */,
                              fd, buf.m.offset);

                if (MAP_FAILED == buffers[n_buffers].start)
                        errno_exit("mmap");
        }
}

static void init_userp(unsigned int buffer_size)
{
        struct <link linkend="v4l2-requestbuffers">v4l2_requestbuffers</link> req;

        CLEAR(req);

        req.count  = 4;
        req.type   = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        req.memory = V4L2_MEMORY_USERPTR;

        if (-1 == xioctl(fd, VIDIOC_REQBUFS, &amp;req)) {
                if (EINVAL == errno) {
                        fprintf(stderr, "%s does not support "
                                 "user pointer i/o\n", dev_name);
                        exit(EXIT_FAILURE);
                } else {
                        errno_exit("VIDIOC_REQBUFS");
                }
        }

        buffers = calloc(4, sizeof(*buffers));

        if (!buffers) {
                fprintf(stderr, "Out of memory\n");
                exit(EXIT_FAILURE);
        }

        for (n_buffers = 0; n_buffers &lt; 4; ++n_buffers) {
                buffers[n_buffers].length = buffer_size;
                buffers[n_buffers].start = malloc(buffer_size);

                if (!buffers[n_buffers].start) {
                        fprintf(stderr, "Out of memory\n");
                        exit(EXIT_FAILURE);
                }
        }
}

static void init_device(void)
{
        struct <link linkend="v4l2-capability">v4l2_capability</link> cap;
        struct <link linkend="v4l2-cropcap">v4l2_cropcap</link> cropcap;
        struct <link linkend="v4l2-crop">v4l2_crop</link> crop;
        struct <link linkend="v4l2-format">v4l2_format</link> fmt;
        unsigned int min;

        if (-1 == xioctl(fd, VIDIOC_QUERYCAP, &amp;cap)) {
                if (EINVAL == errno) {
                        fprintf(stderr, "%s is no V4L2 device\n",
                                 dev_name);
                        exit(EXIT_FAILURE);
                } else {
                        errno_exit("VIDIOC_QUERYCAP");
                }
        }

        if (!(cap.capabilities &amp; V4L2_CAP_VIDEO_CAPTURE)) {
                fprintf(stderr, "%s is no video capture device\n",
                         dev_name);
                exit(EXIT_FAILURE);
        }

        switch (io) {
        case IO_METHOD_READ:
                if (!(cap.capabilities &amp; V4L2_CAP_READWRITE)) {
                        fprintf(stderr, "%s does not support read i/o\n",
                                 dev_name);
                        exit(EXIT_FAILURE);
                }
                break;

        case IO_METHOD_MMAP:
        case IO_METHOD_USERPTR:
                if (!(cap.capabilities &amp; V4L2_CAP_STREAMING)) {
                        fprintf(stderr, "%s does not support streaming i/o\n",
                                 dev_name);
                        exit(EXIT_FAILURE);
                }
                break;
        }


        /* Select video input, video standard and tune here. */


        CLEAR(cropcap);

        cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

        if (0 == xioctl(fd, VIDIOC_CROPCAP, &amp;cropcap)) {
                crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                crop.c = cropcap.defrect; /* reset to default */

                if (-1 == xioctl(fd, VIDIOC_S_CROP, &amp;crop)) {
                        switch (errno) {
                        case EINVAL:
                                /* Cropping not supported. */
                                break;
                        default:
                                /* Errors ignored. */
                                break;
                        }
                }
        } else {
                /* Errors ignored. */
        }


        CLEAR(fmt);

        fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        if (force_format) {
                fmt.fmt.pix.width       = 640;
                fmt.fmt.pix.height      = 480;
                fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
                fmt.fmt.pix.field       = V4L2_FIELD_INTERLACED;

                if (-1 == xioctl(fd, VIDIOC_S_FMT, &amp;fmt))
                        errno_exit("VIDIOC_S_FMT");

                /* Note VIDIOC_S_FMT may change width and height. */
        } else {
                /* Preserve original settings as set by v4l2-ctl for example */
                if (-1 == xioctl(fd, VIDIOC_G_FMT, &amp;fmt))
                        errno_exit("VIDIOC_G_FMT");
        }

        /* Buggy driver paranoia. */
        min = fmt.fmt.pix.width * 2;
        if (fmt.fmt.pix.bytesperline &lt; min)
                fmt.fmt.pix.bytesperline = min;
        min = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
        if (fmt.fmt.pix.sizeimage &lt; min)
                fmt.fmt.pix.sizeimage = min;

        switch (io) {
        case IO_METHOD_READ:
                init_read(fmt.fmt.pix.sizeimage);
                break;

        case IO_METHOD_MMAP:
                init_mmap();
                break;

        case IO_METHOD_USERPTR:
                init_userp(fmt.fmt.pix.sizeimage);
                break;
        }
}

static void close_device(void)
{
        if (-1 == close(fd))
                errno_exit("close");

        fd = -1;
}

static void open_device(void)
{
        struct stat st;

        if (-1 == stat(dev_name, &amp;st)) {
                fprintf(stderr, "Cannot identify '%s': %d, %s\n",
                         dev_name, errno, strerror(errno));
                exit(EXIT_FAILURE);
        }

        if (!S_ISCHR(st.st_mode)) {
                fprintf(stderr, "%s is no device\n", dev_name);
                exit(EXIT_FAILURE);
        }

        fd = open(dev_name, O_RDWR /* required */ | O_NONBLOCK, 0);

        if (-1 == fd) {
                fprintf(stderr, "Cannot open '%s': %d, %s\n",
                         dev_name, errno, strerror(errno));
                exit(EXIT_FAILURE);
        }
}

static void usage(FILE *fp, int argc, char **argv)
{
        fprintf(fp,
                 "Usage: %s [options]\n\n"
                 "Version 1.3\n"
                 "Options:\n"
                 "-d | --device name   Video device name [%s]\n"
                 "-h | --help          Print this message\n"
                 "-m | --mmap          Use memory mapped buffers [default]\n"
                 "-r | --read          Use read() calls\n"
                 "-u | --userp         Use application allocated buffers\n"
                 "-o | --output        Outputs stream to stdout\n"
                 "-f | --format        Force format to 640x480 YUYV\n"
                 "-c | --count         Number of frames to grab [%i]\n"
                 "",
                 argv[0], dev_name, frame_count);
}

static const char short_options[] = "d:hmruofc:";

static const struct option
long_options[] = {
        { "device", required_argument, NULL, 'd' },
        { "help",   no_argument,       NULL, 'h' },
        { "mmap",   no_argument,       NULL, 'm' },
        { "read",   no_argument,       NULL, 'r' },
        { "userp",  no_argument,       NULL, 'u' },
        { "output", no_argument,       NULL, 'o' },
        { "format", no_argument,       NULL, 'f' },
        { "count",  required_argument, NULL, 'c' },
        { 0, 0, 0, 0 }
};

int main(int argc, char **argv)
{
        dev_name = "/dev/video0";

        for (;;) {
                int idx;
                int c;

                c = getopt_long(argc, argv,
                                short_options, long_options, &amp;idx);

                if (-1 == c)
                        break;

                switch (c) {
                case 0: /* getopt_long() flag */
                        break;

                case 'd':
                        dev_name = optarg;
                        break;

                case 'h':
                        usage(stdout, argc, argv);
                        exit(EXIT_SUCCESS);

                case 'm':
                        io = IO_METHOD_MMAP;
                        break;

                case 'r':
                        io = IO_METHOD_READ;
                        break;

                case 'u':
                        io = IO_METHOD_USERPTR;
                        break;

                case 'o':
                        out_buf++;
                        break;

                case 'f':
                        force_format++;
                        break;

                case 'c':
                        errno = 0;
                        frame_count = strtol(optarg, NULL, 0);
                        if (errno)
                                errno_exit(optarg);
                        break;

                default:
                        usage(stderr, argc, argv);
                        exit(EXIT_FAILURE);
                }
        }

        open_device();
        init_device();
        start_capturing();
        mainloop();
        stop_capturing();
        uninit_device();
        close_device();
        fprintf(stderr, "\n");
        return 0;
}
</programlisting>
Commit	Line	Data
8e080c2e MCC	1	<programlisting>
	2	/*
	3	* V4L2 video capture example
	4	*
	5	* This program can be used and distributed without restrictions.
	6	*
9aa08855 MCC	7	* This program is provided with the V4L2 API
9aa08855 MCC	8	* see http://linuxtv.org/docs.php for more information
8e080c2e MCC	9	*/
	10
	11	#include <stdio.h>
	12	#include <stdlib.h>
	13	#include <string.h>
	14	#include <assert.h>
	15
	16	#include <getopt.h> /* getopt_long() */
	17
	18	#include <fcntl.h> /* low-level i/o */
	19	#include <unistd.h>
	20	#include <errno.h>
	21	#include <sys/stat.h>
	22	#include <sys/types.h>
	23	#include <sys/time.h>
	24	#include <sys/mman.h>
	25	#include <sys/ioctl.h>
	26
	27	#include <linux/videodev2.h>
	28
	29	#define CLEAR(x) memset(&(x), 0, sizeof(x))
	30
	31	enum io_method {
	32	IO_METHOD_READ,
	33	IO_METHOD_MMAP,
	34	IO_METHOD_USERPTR,
	35	};
	36
	37	struct buffer {
	38	void *start;
	39	size_t length;
	40	};
	41
	42	static char *dev_name;
	43	static enum io_method io = IO_METHOD_MMAP;
	44	static int fd = -1;
	45	struct buffer *buffers;
	46	static unsigned int n_buffers;
	47	static int out_buf;
	48	static int force_format;
	49	static int frame_count = 70;
	50
	51	static void errno_exit(const char *s)
	52	{
	53	fprintf(stderr, "%s error %d, %s\n", s, errno, strerror(errno));
	54	exit(EXIT_FAILURE);
	55	}
	56
	57	static int xioctl(int fh, int request, void *arg)
	58	{
	59	int r;
	60
	61	do {
	62	r = ioctl(fh, request, arg);
	63	} while (-1 == r && EINTR == errno);
	64
	65	return r;
	66	}
	67
	68	static void process_image(const void *p, int size)
	69	{
	70	if (out_buf)
	71	fwrite(p, size, 1, stdout);
	72
73	fflush(stderr);
74	fprintf(stderr, ".");
75	fflush(stdout);
76	}
77
78	static int read_frame(void)
79	{
80	struct <link linkend="v4l2-buffer">v4l2_buffer</link> buf;
81	unsigned int i;
82
83	switch (io) {
84	case IO_METHOD_READ:
85	if (-1 == read(fd, buffers[0].start, buffers[0].length)) {
86	switch (errno) {
87	case EAGAIN:
88	return 0;
89
90	case EIO:
91	/* Could ignore EIO, see spec. */
92
93	/* fall through */
94
95	default:
96	errno_exit("read");
97	}
98	}
99
100	process_image(buffers[0].start, buffers[0].length);
101	break;
102
103	case IO_METHOD_MMAP:
104	CLEAR(buf);
105
106	buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
107	buf.memory = V4L2_MEMORY_MMAP;
108
109	if (-1 == xioctl(fd, VIDIOC_DQBUF, &buf)) {
110	switch (errno) {
111	case EAGAIN:
112	return 0;
113
114	case EIO:
115	/* Could ignore EIO, see spec. */
116
117	/* fall through */
118
119	default:
120	errno_exit("VIDIOC_DQBUF");
121	}
122	}
123
124	assert(buf.index < n_buffers);
125
126	process_image(buffers[buf.index].start, buf.bytesused);
127
128	if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
129	errno_exit("VIDIOC_QBUF");
130	break;
131
132	case IO_METHOD_USERPTR:
133	CLEAR(buf);
134
135	buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
136	buf.memory = V4L2_MEMORY_USERPTR;
137
138	if (-1 == xioctl(fd, VIDIOC_DQBUF, &buf)) {
139	switch (errno) {
140	case EAGAIN:
141	return 0;
142
143	case EIO:
144	/* Could ignore EIO, see spec. */
145
146	/* fall through */
147
148	default:
149	errno_exit("VIDIOC_DQBUF");
150	}
151	}
152
153	for (i = 0; i < n_buffers; ++i)
154	if (buf.m.userptr == (unsigned long)buffers[i].start
155	&& buf.length == buffers[i].length)
156	break;
157
158	assert(i < n_buffers);
159
160	process_image((void *)buf.m.userptr, buf.bytesused);
161
162	if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
163	errno_exit("VIDIOC_QBUF");
164	break;
165	}
166
167	return 1;
168	}
169
170	static void mainloop(void)
171	{
172	unsigned int count;
173
174	count = frame_count;
175
176	while (count-- > 0) {
177	for (;;) {
178	fd_set fds;
179	struct timeval tv;
180	int r;
181
182	FD_ZERO(&fds);
183	FD_SET(fd, &fds);
184
185	/* Timeout. */
186	tv.tv_sec = 2;
187	tv.tv_usec = 0;
188
189	r = select(fd + 1, &fds, NULL, NULL, &tv);
190
191	if (-1 == r) {
192	if (EINTR == errno)
193	continue;
194	errno_exit("select");
195	}
196
197	if (0 == r) {
198	fprintf(stderr, "select timeout\n");
199	exit(EXIT_FAILURE);
200	}
201
202	if (read_frame())
203	break;
204	/* EAGAIN - continue select loop. */
205	}
206	}
207	}
208
209	static void stop_capturing(void)
210	{
211	enum <link linkend="v4l2-buf-type">v4l2_buf_type</link> type;
212
213	switch (io) {
214	case IO_METHOD_READ:
215	/* Nothing to do. */
216	break;
217
218	case IO_METHOD_MMAP:
219	case IO_METHOD_USERPTR:
220	type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
221	if (-1 == xioctl(fd, VIDIOC_STREAMOFF, &type))
222	errno_exit("VIDIOC_STREAMOFF");
223	break;
224	}
225	}
226
227	static void start_capturing(void)
228	{
229	unsigned int i;
230	enum <link linkend="v4l2-buf-type">v4l2_buf_type</link> type;
231
232	switch (io) {
233	case IO_METHOD_READ:
234	/* Nothing to do. */
235	break;
236
237	case IO_METHOD_MMAP:
238	for (i = 0; i < n_buffers; ++i) {
239	struct <link linkend="v4l2-buffer">v4l2_buffer</link> buf;
240
241	CLEAR(buf);
242	buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
243	buf.memory = V4L2_MEMORY_MMAP;
244	buf.index = i;
245
246	if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
247	errno_exit("VIDIOC_QBUF");
248	}
249	type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
250	if (-1 == xioctl(fd, VIDIOC_STREAMON, &type))
251	errno_exit("VIDIOC_STREAMON");
252	break;
253
254	case IO_METHOD_USERPTR:
255	for (i = 0; i < n_buffers; ++i) {
256	struct <link linkend="v4l2-buffer">v4l2_buffer</link> buf;
257
258	CLEAR(buf);
259	buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
260	buf.memory = V4L2_MEMORY_USERPTR;
261	buf.index = i;
262	buf.m.userptr = (unsigned long)buffers[i].start;
263	buf.length = buffers[i].length;
264
265	if (-1 == xioctl(fd, VIDIOC_QBUF, &buf))
266	errno_exit("VIDIOC_QBUF");
267	}
268	type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
269	if (-1 == xioctl(fd, VIDIOC_STREAMON, &type))
270	errno_exit("VIDIOC_STREAMON");
271	break;
272	}
273	}
274
275	static void uninit_device(void)
276	{
277	unsigned int i;
278
279	switch (io) {
280	case IO_METHOD_READ:
281	free(buffers[0].start);
282	break;
283
284	case IO_METHOD_MMAP:
285	for (i = 0; i < n_buffers; ++i)
286	if (-1 == munmap(buffers[i].start, buffers[i].length))
287	errno_exit("munmap");
288	break;
289
290	case IO_METHOD_USERPTR:
291	for (i = 0; i < n_buffers; ++i)
292	free(buffers[i].start);
293	break;
294	}
295
296	free(buffers);
297	}
298
299	static void init_read(unsigned int buffer_size)
300	{
301	buffers = calloc(1, sizeof(*buffers));
302
303	if (!buffers) {
304	fprintf(stderr, "Out of memory\n");
305	exit(EXIT_FAILURE);
306	}
307
308	buffers[0].length = buffer_size;
309	buffers[0].start = malloc(buffer_size);
310
311	if (!buffers[0].start) {
312	fprintf(stderr, "Out of memory\n");
313	exit(EXIT_FAILURE);
314	}
315	}
316
317	static void init_mmap(void)
318	{
319	struct <link linkend="v4l2-requestbuffers">v4l2_requestbuffers</link> req;
320
321	CLEAR(req);
322
323	req.count = 4;
324	req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
325	req.memory = V4L2_MEMORY_MMAP;
326
327	if (-1 == xioctl(fd, VIDIOC_REQBUFS, &req)) {
328	if (EINVAL == errno) {
329	fprintf(stderr, "%s does not support "
330	"memory mapping\n", dev_name);
331	exit(EXIT_FAILURE);
332	} else {
333	errno_exit("VIDIOC_REQBUFS");
334	}
335	}
336
337	if (req.count < 2) {
338	fprintf(stderr, "Insufficient buffer memory on %s\n",
339	dev_name);
340	exit(EXIT_FAILURE);
341	}
342
343	buffers = calloc(req.count, sizeof(*buffers));
344
345	if (!buffers) {
346	fprintf(stderr, "Out of memory\n");
347	exit(EXIT_FAILURE);
348	}
349
350	for (n_buffers = 0; n_buffers < req.count; ++n_buffers) {
351	struct <link linkend="v4l2-buffer">v4l2_buffer</link> buf;
352
353	CLEAR(buf);
354
355	buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
356	buf.memory = V4L2_MEMORY_MMAP;
357	buf.index = n_buffers;
358
359	if (-1 == xioctl(fd, VIDIOC_QUERYBUF, &buf))
360	errno_exit("VIDIOC_QUERYBUF");
361
362	buffers[n_buffers].length = buf.length;
363	buffers[n_buffers].start =
364	mmap(NULL /* start anywhere */,
365	buf.length,
366	PROT_READ \| PROT_WRITE /* required */,
367	MAP_SHARED /* recommended */,
368	fd, buf.m.offset);
369
370	if (MAP_FAILED == buffers[n_buffers].start)
371	errno_exit("mmap");
372	}
373	}
374
375	static void init_userp(unsigned int buffer_size)
376	{
377	struct <link linkend="v4l2-requestbuffers">v4l2_requestbuffers</link> req;
378
379	CLEAR(req);
380
381	req.count = 4;
382	req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
383	req.memory = V4L2_MEMORY_USERPTR;
384
385	if (-1 == xioctl(fd, VIDIOC_REQBUFS, &req)) {
386	if (EINVAL == errno) {
387	fprintf(stderr, "%s does not support "
388	"user pointer i/o\n", dev_name);
389	exit(EXIT_FAILURE);
390	} else {
391	errno_exit("VIDIOC_REQBUFS");
392	}
393	}
394
395	buffers = calloc(4, sizeof(*buffers));
396
397	if (!buffers) {
398	fprintf(stderr, "Out of memory\n");
399	exit(EXIT_FAILURE);
400	}
401
402	for (n_buffers = 0; n_buffers < 4; ++n_buffers) {
403	buffers[n_buffers].length = buffer_size;
404	buffers[n_buffers].start = malloc(buffer_size);
405
406	if (!buffers[n_buffers].start) {
407	fprintf(stderr, "Out of memory\n");
408	exit(EXIT_FAILURE);
409	}
410	}
411	}
412
413	static void init_device(void)
414	{
415	struct <link linkend="v4l2-capability">v4l2_capability</link> cap;
416	struct <link linkend="v4l2-cropcap">v4l2_cropcap</link> cropcap;
417	struct <link linkend="v4l2-crop">v4l2_crop</link> crop;
418	struct <link linkend="v4l2-format">v4l2_format</link> fmt;
419	unsigned int min;
420
421	if (-1 == xioctl(fd, VIDIOC_QUERYCAP, &cap)) {
422	if (EINVAL == errno) {
423	fprintf(stderr, "%s is no V4L2 device\n",
424	dev_name);
425	exit(EXIT_FAILURE);
426	} else {
427	errno_exit("VIDIOC_QUERYCAP");
428	}
429	}
430
431	if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
432	fprintf(stderr, "%s is no video capture device\n",
433	dev_name);
434	exit(EXIT_FAILURE);
435	}
436
437	switch (io) {
438	case IO_METHOD_READ:
439	if (!(cap.capabilities & V4L2_CAP_READWRITE)) {
440	fprintf(stderr, "%s does not support read i/o\n",
441	dev_name);
442	exit(EXIT_FAILURE);
443	}
444	break;
445
446	case IO_METHOD_MMAP:
447	case IO_METHOD_USERPTR:
448	if (!(cap.capabilities & V4L2_CAP_STREAMING)) {
449	fprintf(stderr, "%s does not support streaming i/o\n",
450	dev_name);
451	exit(EXIT_FAILURE);
452	}
453	break;
454	}
455
456
457	/* Select video input, video standard and tune here. */
458
459
460	CLEAR(cropcap);
461
462	cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
463
464	if (0 == xioctl(fd, VIDIOC_CROPCAP, &cropcap)) {
465	crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
466	crop.c = cropcap.defrect; /* reset to default */
467
468	if (-1 == xioctl(fd, VIDIOC_S_CROP, &crop)) {
469	switch (errno) {
470	case EINVAL:
471	/* Cropping not supported. */
472	break;
473	default:
474	/* Errors ignored. */
475	break;
476	}
477	}
478	} else {
479	/* Errors ignored. */
480	}
481
482
483	CLEAR(fmt);
484
485	fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
486	if (force_format) {
487	fmt.fmt.pix.width = 640;
488	fmt.fmt.pix.height = 480;
489	fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
490	fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
491
492	if (-1 == xioctl(fd, VIDIOC_S_FMT, &fmt))
493	errno_exit("VIDIOC_S_FMT");
494
495	/* Note VIDIOC_S_FMT may change width and height. */
496	} else {
497	/* Preserve original settings as set by v4l2-ctl for example */
498	if (-1 == xioctl(fd, VIDIOC_G_FMT, &fmt))
499	errno_exit("VIDIOC_G_FMT");
500	}
501
502	/* Buggy driver paranoia. */
503	min = fmt.fmt.pix.width * 2;
504	if (fmt.fmt.pix.bytesperline < min)
505	fmt.fmt.pix.bytesperline = min;
506	min = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
507	if (fmt.fmt.pix.sizeimage < min)
508	fmt.fmt.pix.sizeimage = min;
509
510	switch (io) {
511	case IO_METHOD_READ:
512	init_read(fmt.fmt.pix.sizeimage);
513	break;
514
515	case IO_METHOD_MMAP:
516	init_mmap();
517	break;
518
519	case IO_METHOD_USERPTR:
520	init_userp(fmt.fmt.pix.sizeimage);
521	break;
522	}
523	}
524
525	static void close_device(void)
526	{
527	if (-1 == close(fd))
528	errno_exit("close");
529
530	fd = -1;
531	}
532
533	static void open_device(void)
534	{
535	struct stat st;
536
537	if (-1 == stat(dev_name, &st)) {
538	fprintf(stderr, "Cannot identify '%s': %d, %s\n",
539	dev_name, errno, strerror(errno));
540	exit(EXIT_FAILURE);
541	}
542
543	if (!S_ISCHR(st.st_mode)) {
544	fprintf(stderr, "%s is no device\n", dev_name);
545	exit(EXIT_FAILURE);
546	}
547
548	fd = open(dev_name, O_RDWR /* required */ \| O_NONBLOCK, 0);
549
550	if (-1 == fd) {
551	fprintf(stderr, "Cannot open '%s': %d, %s\n",
552	dev_name, errno, strerror(errno));
553	exit(EXIT_FAILURE);
554	}
555	}
556
557	static void usage(FILE fp, int argc, char *argv)
558	{
559	fprintf(fp,
560	"Usage: %s [options]\n\n"
561	"Version 1.3\n"
562	"Options:\n"
563	"-d \| --device name Video device name [%s]\n"
564	"-h \| --help Print this message\n"
565	"-m \| --mmap Use memory mapped buffers [default]\n"
566	"-r \| --read Use read() calls\n"
567	"-u \| --userp Use application allocated buffers\n"
568	"-o \| --output Outputs stream to stdout\n"
569	"-f \| --format Force format to 640x480 YUYV\n"
570	"-c \| --count Number of frames to grab [%i]\n"
571	"",
572	argv[0], dev_name, frame_count);
573	}
574
575	static const char short_options[] = "d:hmruofc:";
576
577	static const struct option
578	long_options[] = {
579	{ "device", required_argument, NULL, 'd' },
580	{ "help", no_argument, NULL, 'h' },
581	{ "mmap", no_argument, NULL, 'm' },
582	{ "read", no_argument, NULL, 'r' },
583	{ "userp", no_argument, NULL, 'u' },
584	{ "output", no_argument, NULL, 'o' },
585	{ "format", no_argument, NULL, 'f' },
586	{ "count", required_argument, NULL, 'c' },
587	{ 0, 0, 0, 0 }
588	};
589
590	int main(int argc, char **argv)
591	{
592	dev_name = "/dev/video0";
593
594	for (;;) {
595	int idx;
596	int c;
597
598	c = getopt_long(argc, argv,
599	short_options, long_options, &idx);
600
601	if (-1 == c)
602	break;
603
604	switch (c) {
605	case 0: /* getopt_long() flag */
606	break;
607
608	case 'd':
609	dev_name = optarg;
610	break;
611
612	case 'h':
613	usage(stdout, argc, argv);
614	exit(EXIT_SUCCESS);
615
616	case 'm':
617	io = IO_METHOD_MMAP;
618	break;
619
620	case 'r':
621	io = IO_METHOD_READ;
622	break;
623
624	case 'u':
625	io = IO_METHOD_USERPTR;
626	break;
627
628	case 'o':
629	out_buf++;
630	break;
631
632	case 'f':
633	force_format++;
634	break;
635
636	case 'c':
637	errno = 0;
638	frame_count = strtol(optarg, NULL, 0);
639	if (errno)
640	errno_exit(optarg);
641	break;
642
643	default:
644	usage(stderr, argc, argv);
645	exit(EXIT_FAILURE);
646	}
647	}
648
649	open_device();
650	init_device();
651	start_capturing();
652	mainloop();
653	stop_capturing();
654	uninit_device();
655	close_device();
656	fprintf(stderr, "\n");
657	return 0;
658	}
659	</programlisting>