More v4l2 command line options

[meekys]

I think this issue may need to be expanded. I'm using a generic EasyCap, with the Empia chipset and a generic NTSC backup camera. (BTW, there are at least 4 different chipsets, STK1160 being one of the others, used in Easycaps, described here: https://www.linuxtv.org/wiki/index.php/Easycap). My EasyCap defaults to Pal output and S-video input, so I get no picture in Cam_overlay at all unless I go into V4L2 settings after each statup and reset things to NTSC and composite input. There are numerous other settings that could be changed also depending on which capture device is used. Unfortunately, there is no way short of a script to reset things at each restart of the RPi using V4l2-ctl. Even the V4l2 capture utility does not carry settings across restarts. This can be done with a startup script, or udev as outlined here: https://askubuntu.com/questions/295637/v4l2-change-default-setting. Raspbian works the same as Ubuntu in this case.

Obviously, this approach is not user friendly. If cam_overlay (or Crankshaft) could read the device options, and allow them to be set
once as persistent settings, this would simplify things greatly. Cam_overlay already has a number of settable options, so it would appear these could be added.

Originally posted by @jonlowe in #7 (comment)