mirror of https://gitee.com/openkylin/linux.git
2e74598d7f
Judging from what drivers do and from my experience temeperframe
fraction is set in seconds - look e.g. here
static int bttv_g_parm(struct file *file, void *f,
struct v4l2_streamparm *parm)
{
struct bttv_fh *fh = f;
struct bttv *btv = fh->btv;
v4l2_video_std_frame_period(bttv_tvnorms[btv->tvnorm].v4l2_id,
&parm->parm.capture.timeperframe);
...
void v4l2_video_std_frame_period(int id, struct v4l2_fract *frameperiod)
{
if (id & V4L2_STD_525_60) {
frameperiod->numerator = 1001;
frameperiod->denominator = 30000;
} else {
frameperiod->numerator = 1;
frameperiod->denominator = 25;
}
and also v4l2-ctl in userspace decodes this as seconds:
if (doioctl(fd, VIDIOC_G_PARM, &parm, "VIDIOC_G_PARM") == 0) {
const struct v4l2_fract &tf = parm.parm.capture.timeperframe;
...
printf("\tFrames per second: %.3f (%d/%d)\n",
(1.0 * tf.denominator) / tf.numerator,
tf.denominator, tf.numerator);
The typo was there from day 1 - added in 2002 in e028b61b ([PATCH]
add v4l2 api)(*)
(*) found in history tree
git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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