Add a framerate control, cargo-culting Corbet's code.

1 files changed, 24 insertions, 1 deletions

diff --git a/capture.c b/capture.c
index 086733f..437cd65 100644
--- a/capture.c
+++ b/capture.c
@@ -66,6 +66,20 @@ xioctl                          (int                    fd,
         return r;
 }
 
+static int
+set_framerate                   (int                    numerator,
+                                 int                    denominator)
+{
+	struct v4l2_streamparm parm;
+	struct v4l2_fract *tpf = &(parm.parm.capture.timeperframe);
+	memset(&parm, 0, sizeof(parm));
+	parm.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+	
+	tpf->numerator = numerator;
+	tpf->denominator = denominator;
+	return xioctl(fd, VIDIOC_S_PARM, &parm);
+}
+
 static void
 process_image                   (const void *           p)
 {
@@ -590,11 +604,12 @@ usage                           (FILE *                 fp,
                  "-r | --read          Use read() calls\n"
                  "-u | --userp         Use application allocated buffers\n"
                  "-n | --numframes     Number of frames to acquire (default=1)\n"
+                 "-f | --framerate     Frame rate at which to acquire (default: use driver's default)\n"
                  "",
 		 argv[0]);
 }
 
-static const char short_options [] = "d:hmrun";
+static const char short_options [] = "d:hmrunf";
 
 static const struct option
 long_options [] = {
@@ -604,6 +619,7 @@ long_options [] = {
         { "read",       no_argument,            NULL,           'r' },
         { "userp",      no_argument,            NULL,           'u' },
         { "numframes",  required_argument,      NULL,           'n' },
+        { "framerate",  required_argument,      NULL,           'f' },
         { 0, 0, 0, 0 }
 };
 
@@ -617,6 +633,7 @@ main                            (int                    argc,
                 int index;
                 int c;
                 unsigned int numframes = 1;
+                unsigned int framerate = 0;
                 
                 c = getopt_long (argc, argv,
                                  short_options, long_options,
@@ -653,6 +670,10 @@ main                            (int                    argc,
                         numframes = atoi(optarg);
 			break;
 
+                case 'f':
+                        framerate = atoi(optarg);
+			break;
+
                 default:
                         usage (stderr, argc, argv);
                         exit (EXIT_FAILURE);
@@ -665,6 +686,8 @@ main                            (int                    argc,
 
         start_capturing ();
 
+        if (framerate > 0) set_framerate(framerate, 1);
+
         mainloop (numframes);
 
         stop_capturing ();