live: Add support for periodical skipping of frames on the display

When the sensor delivers a frame rate higher than what the display can
process, the OMAP3 ISP continuously runs out of buffers. The new --skip
command line option can be used to avoid that situation by skipping
display of n frames out of n+1.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 28 insertions, 8 deletions

diff --git a/live.c b/live.c
index c102893..77587cb 100644
--- a/live.c
+++ b/live.c
@@ -60,6 +60,9 @@ static struct timespec fps_ts = { 0, 0 };
 static unsigned int fps_count = 0;
 static bool show_fps = true;
 
+static unsigned int frame_count = 0;
+static unsigned int frame_skip = 0;
+
 static struct omap3_isp_device *isp = NULL;
 static struct videoout *vo = NULL;
 
@@ -167,6 +170,9 @@ static void viewfinder_process(struct omap3_isp_device *isp __attribute__((__unu
 {
 	struct timespec ts;
 	float interval;
+	int ret;
+
+	frame_count++;
 
 	if (show_fps){
 		fps_count++;
@@ -190,7 +196,18 @@ static void viewfinder_process(struct omap3_isp_device *isp __attribute__((__unu
 		return;
 	}
 
-	vo_queue_buffer(vo, buffer);
+	/* Queue the buffer to the display, or requeue it to the viewfinder if
+	 * it needs to be skipped.
+	 */
+	if ((frame_count % (frame_skip + 1)) == 0) {
+		vo_queue_buffer(vo, buffer);
+		return;
+	}
+
+	ret = omap3_isp_viewfinder_put_buffer(isp, buffer);
+	if (ret < 0)
+		printf("error: unable to requeue buffer: %s (%d)\n",
+		       strerror(-ret), ret);
 }
 
 
@@ -354,11 +371,13 @@ static void usage(const char *argv0)
 {
 	printf("Usage: %s [options]\n", argv0);
 	printf("Supported options:\n");
-	printf("-h, --help			Show this help screen\n");
+	printf("-h, --help		Show this help screen\n");
+	printf("-s, --skip n		Skip display of n frames out of n+1\n");
 }
 
 static struct option opts[] = {
 	{ "help", 0, 0, 'h' },
+	{ "skip", 1, 0, 's' },
 	{ 0, 0, 0, 0 }
 };
 
@@ -367,7 +386,6 @@ int main(int argc __attribute__((__unused__)), char *argv[] __attribute__((__unu
 	struct v4l2_mbus_framefmt view_format;
 	struct v4l2_buffers_pool *pool = NULL;
 	struct timespec start, end;
-	unsigned int count = 0;
 	struct v4l2_rect rect;
 	int exit_code = EXIT_FAILURE;
 	const char *vo_devname;
@@ -375,11 +393,14 @@ int main(int argc __attribute__((__unused__)), char *argv[] __attribute__((__unu
 	int ret;
 	int c;
 
-	while ((c = getopt_long(argc, argv, "h", opts, NULL)) != -1) {
+	while ((c = getopt_long(argc, argv, "hs:", opts, NULL)) != -1) {
 		switch (c) {
 		case 'h':
 			usage(argv[0]);
 			return 0;
+		case 's':
+			frame_skip = atoi(optarg);
+			break;
 		default:
 			printf("Invalid option -%c\n", c);
 			printf("Run %s -h for help.\n", argv[0]);
@@ -492,7 +513,6 @@ int main(int argc __attribute__((__unused__)), char *argv[] __attribute__((__unu
 		}
 
 		events_dispatch(&rfds, &wfds);
-		count++;
 	}
 
 	clock_gettime(CLOCK_MONOTONIC, &end);
@@ -508,10 +528,10 @@ int main(int argc __attribute__((__unused__)), char *argv[] __attribute__((__unu
 		end.tv_nsec += 1000000000;
 	}
 
-	fps = count / (end.tv_sec + end.tv_nsec / 1000000000.0);
+	fps = frame_count / (end.tv_sec + end.tv_nsec / 1000000000.0);
 
-	printf("%u images processed in %lu.%06lu seconds (%f fps)\n", count,
-	       end.tv_sec, end.tv_nsec / 1000, fps);
+	printf("%u images processed in %lu.%06lu seconds (%f fps)\n",
+	       frame_count, end.tv_sec, end.tv_nsec / 1000, fps);
 
 	exit_code = EXIT_SUCCESS;