[FFmpeg-devel] [PATCH] Set frame rate on v4l2 devices

Luca Abeni lucabe72
Sun Sep 26 12:14:53 CEST 2010

Hi Reimar,

On Thu, 2010-09-23 at 20:55 +0200, Reimar D?ffinger wrote:
> > >I've also used a Logitech webcam (the QuickCam Sphere AF) with uvcvideo
> > >driver, and it works without the VIDIOC_G_PARM call. When I try to set a
> > >rate different from the supported ones, the VIDIOC_S_PARM call already
> > >returns the modified value.
> > >But if the get call is needed for some other devices and/or drivers,
> > >let's put it.
> > Ok, with VIDIOC_G_PARM things are even worse: the time base is changed to
> > 0... :(
> > 
> > This looks like a driver's bug (I am using something called "gspca_zc3xx",
> > I think). So, no need for the VIDIOC_G_PARM thing... I'll run some
> > other tests, and then I'll commit your first patch.
> Please, please add a comment when you commit such "hacks" that contain
> also bug workarounds, otherwise nobody will remember in a few years
> why the code is so strange and probably try to "fix" it.
Well, I do not know if what I committed is a hack (I mean: it is still
not clear if VIDIOC_G_PARM is needed or not - the documentation is not
clear here - In Jos? Miguel tests, it is not needed; in my first tests
it seemed to be needed, but then I realised that the driver I am using
is buggy...).

Anyway, I can add a comment like "VIDIOC_G_PARM could be needed here,
but it breaks with some drivers". Let me know what you think it's


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