Re: [PATCH v5 00/39] i.MX Media Driver

From: Russell King - ARM Linux
Date: Sun Mar 19 2017 - 05:57:22 EST


On Sat, Mar 18, 2017 at 08:41:14PM -0400, Nicolas Dufresne wrote:
> Along with the norm fallback, GStreamer could could also consider the
> currently set framerate as returned by VIDIOC_G_PARM. At the same time,
> implementing that enumeration shall be straightforward, and will make a
> large amount of existing userspace work.

Since, according to v4l2-compliance, providing the enumeration ioctls
appears to be optional:

1) should v4l2-compliance be checking whether other frame sizes/frame
intervals are possible, and failing if the enumeration ioctls are
not supported?

2) would it also make sense to allow gstreamer's v4l2src to try setting
a these parameters, and only fail if it's unable to set it? IOW, if
I use:

gst-launch-1.0 v4l2src device=/dev/video10 ! \
video/x-bayer,format=RGGB,framerate=20/1 ! ...

where G_PARM says its currently configured for 25fps, but a S_PARM
with 20fps would actually succeed.

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