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

Luca Abeni lucabe72
Thu Sep 23 08:28:21 CEST 2010

On 09/22/2010 05:11 PM, Jos? Miguel Gon?alves wrote:
>> This patch seems to assume that after calling the VIDIOC_S_PARM
>> ioctl, the v4l2_streamparm structure is updated by the driver with
>> the parameters that have actually been set...
>> However, my tests with a logitech webcam seem to show that this
>> is not the case. I think you should call VIDIOC_G_PARM after
>> VIDIOC_S_PARM, to check which parameters have actually been set.
> 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.


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