another snipper of code / libv4l2

v4l2/v4l2grab.c

@@ -0,0 +1,163 @@
+   /* V4L2 video picture grabber
+       Copyright (C) 2009 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 <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);
+	    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, &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);
+			sleep(30);
+
+		    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;
+    }