# uvcvideo and power line frequency [solved]

## costel78

Hello,

I have a Logitech 3500 QuickCam. By default power line frequency is set to 60 Hz. I live in Europe where default power line frequency is 50Hz.

```

v4lctl -c /dev/video1 list

ioctl: VIDIOC_G_STD(std=0x0 []): Invalid argument

attribute  | type   | current | default | comment

-----------+--------+---------+---------+-------------------------------------

norm       | choice | (null)  | (null)  |

input      | choice | Camera  | Camera  | Camera 1

bright     | int    |     128 |     128 | range is 0 => 255

contrast   | int    |      32 |      32 | range is 0 => 255

color      | int    |      32 |      32 | range is 0 => 255

White Bala | bool   | on      | on      |

Gain       | int    |     226 |       0 | range is 0 => 255

Power Line | choice | 60 Hz   | 60 Hz   | Disabled 50 Hz 60 Hz

White Bala | int    |    6771 |    4000 | range is 0 => 10000

Sharpness  | int    |     240 |     240 | range is 0 => 255

Backlight  | int    |       1 |       1 | range is 0 => 2

```

For applications like tvtime or Cheese Webcam Booth (cheese) this is not an issue because they are able to automatically change frequency to 50 Hz.

But, sometimes, in skype frequency remain 60 Hz and this give me an annoying flitcher.

uvcvideo is compiled as module.

v4lctl -c /dev/video1 setattr "Power Line Frequency" "50 Hz" tell me that I can not change "Power Line Frequency" parameter. In case you are wondering, yes, /dev/video1 is the Logitech webcam.

It is possible,and if yes, how, to change default powerline frequency when module is loaded via modprobe ?

Thank you!

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## keyson

Hi,

 *Quote:*   

> 
> 
> It is possible,and if yes, how, to change default powerline frequency when module is loaded via modprobe ? 
> 
> 

 

Yes it should be possible. By using the modinfo command.

```

modinfo <modulename>

```

You get info about parameters that may be sent to the module during loading.

If you can set the 'Power Line' during module loading you may add the parameter to the

/etc/modprobe.d/<module> and it would be set during load.

EDIT: If you use openrc there is a different way of doing this.

See 'Kernel modules' in  page 

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## costel78

modinfo was the trick. Problem solved.

Thank you very much.

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