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

Luca Abeni lucabe72
Wed Sep 22 16:28:16 CEST 2010


On 09/17/2010 12:06 PM, Jos? Miguel Gon?alves wrote:
> jose.goncalves at inov.pt  writes:
>> Using ffmpeg to stream a webcam MJPEG feed, I found that it can't set
>> the webcam frame rate. For that we must use the VIDIOC_S_PARM
>> ioctl. Please check the attached patch that fixes this.
> Was this patch forgotten? New attempt...

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.


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