How do I change the v4l defaults?

spikeygg · 04-06-2014, 02:54 PM

I have a linux machine that runs 24hrs a day and it has zoneminder running on it watching the frames from a camera. I have the camera going into a TV/Video-capture card and everything works great. That is until I reboot the machine. V4L has "default" value which I can't seem to change. I've looked through the documentation and googled all around and I can't find any information on how to change the default. I can issue this command:

Code:

sudo v4lctl -c /dev/video0 setattr input Composite1

Which will set the "current" value to the correct input but as soon as I reboot, it gets reset to "Television".

I know there's a default value but I don't know how to SET it.

Code:

$ sudo v4lctl -c /dev/video0 list
attribute  | type   | current | default | comment
-----------+--------+---------+---------+-------------------------------------
norm       | choice | NTSC-M  | NTSC-M  | NTSC-M NTSC-M-JP NTSC-443 PAL-BG PAL-I PAL-DK PAL-M PAL-N PAL-Nc PAL-60 SECAM-B SECAM-G SECAM-H SECAM-DK SECAM-L
input      | choice | Composi | Televis | Television Composite1 S-Video
audio mode | choice | mono    | mono    | mono stereo lang1 lang2
bright     | int    |     127 |     127 | range is 0 => 255
contrast   | int    |      63 |      63 | range is 0 => 255
color      | int    |     127 |     127 | range is 0 => 255
hue        | int    |     127 |     127 | range is 0 => 255
volume     | int    |      63 |      63 | range is 0 => 63
Balance    | int    |      64 |      64 | range is 0 => 127
mute       | bool   | on      | on      |
Sharpness  | int    |       0 |       0 | range is 0 => 4
Chroma AGC | bool   | on      | on      |
Color kill | bool   | on      | on      |
$

Anyone know how to *set* this "default"?

Thanks,
-Greg

ichrispa · 04-09-2014, 07:52 AM

Hello spikeegg,

since the camera is probably detected by the driver/udev after the v4l module is loaded, you would set a default device that does not exist if you modify the drivers parameters... I havent looked it up, but I suppose you can pass the default values to the v4l-module using the appropriate /etc/modprobe.d config file.

Might I suggest a simple if not so elegant workaround?

Just add the line

Code:

/usr/sbin/v4lctl -c /dev/video0 setattr input Composite1

either to /etc/rc.local or to the startup script of zoneminder (I am guessing /etc/init.d/zoneminder, but it depends on the distro you are using).

Regards,

ichrispa