Prevent activating an already active size

Changing resolution is costly, as we need first to wait
for pending buffers and stop streaming.

So, optimize resolution switch by not trying to
activate the already activated resolution.

1 files changed, 16 insertions, 0 deletions

diff --git a/src/v4l.c b/src/v4l.c
index 47c0fe6..f2eff32 100644
--- a/src/v4l.c
+++ b/src/v4l.c
@@ -258,6 +258,22 @@ void get_win_info(cam * cam)
    }
 }
 
+void try_set_win_info(cam * cam, int *x, int *y)
+{
+   gchar *msg;
+   struct v4l2_format fmt;
+
+   memset(&fmt, 0, sizeof(fmt));
+   fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+   fmt.fmt.pix.pixelformat = cam->pixformat;
+   fmt.fmt.pix.width  = *x;
+   fmt.fmt.pix.height = *y;
+   if (!v4l2_ioctl(cam->dev, VIDIOC_TRY_FMT, &fmt)) {
+      *x = fmt.fmt.pix.width;
+      *y = fmt.fmt.pix.height;
+   }
+}
+
 void set_win_info(cam * cam)
 {
    gchar *msg;