On Mon, Oct 22, 2012 at 09:01:39PM +0400, Kirill Smelkov wrote:
> On Mon, Oct 22, 2012 at 04:16:14PM +0200, Hans Verkuil wrote:
> > On Mon October 22 2012 15:54:44 Kirill Smelkov wrote:
> > > I was testing my video-over-ethernet subsystem today, and vivi seemed to
> > > be perfect video source for testing when one don't have lots of capture
> > > boards and cameras. Only its framerate was hardcoded to NTSC's 30fps,
> > > while in my country we usually use PAL (25 fps). That's why the patch.
> > > Thanks.
> >
> > Rather than introducing a module option, it's much nicer if you can
> > implement enum_frameintervals and g/s_parm. This can be made quite flexible
> > allowing you to also support 50/59.94/60 fps.
>
> Thanks for feedback. I've reworked the patch for FPS to be set via
> ->{g,s}_parm(), and yes now it is more flexble, because one can set
By the way, here is what I've found while working on the abovementioned
patch:
---- 8< ----
From: Kirill Smelkov <kirr@xxxxxxxxxx>
Date: Mon, 22 Oct 2012 21:14:01 +0400
Subject: [PATCH] v4l2: Fix typo in struct v4l2_captureparm description
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@xxxxxxxxxx>
---
include/uapi/linux/videodev2.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 57bfa59..2fff7ff 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -726,29 +726,29 @@ struct v4l2_window {
__u32 field; /* enum v4l2_field */
__u32 chromakey;
struct v4l2_clip __user *clips;
__u32 clipcount;
void __user *bitmap;
__u8 global_alpha;
};
/*
* C A P T U R E P A R A M E T E R S
*/
struct v4l2_captureparm {
__u32 capability; /* Supported modes */
__u32 capturemode; /* Current mode */
- struct v4l2_fract timeperframe; /* Time per frame in .1us units */
+ struct v4l2_fract timeperframe; /* Time per frame in seconds */
__u32 extendedmode; /* Driver-specific extensions */
__u32 readbuffers; /* # of buffers for read */
__u32 reserved[4];
};
/* Flags for 'capability' and 'capturemode' fields */
#define V4L2_MODE_HIGHQUALITY 0x0001 /* High quality imaging mode */
#define V4L2_CAP_TIMEPERFRAME 0x1000 /* timeperframe field is supported */
struct v4l2_outputparm {
__u32 capability; /* Supported modes */
__u32 outputmode; /* Current mode */
struct v4l2_fract timeperframe; /* Time per frame in seconds */
__u32 extendedmode; /* Driver-specific extensions */
--
1.8.0.rc3.331.g5b9a629
--
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