[pvrusb2] vertical black lines in the video

Mike Isely isely at isely.net
Tue Jan 30 07:44:37 CST 2007

On Mon, 29 Jan 2007, devsk wrote:

> Hi,
> I see vertical black lines in some of the channels, which look more like vertical interlace. e.g.
> http://home.comcast.net/~funtoos/vertical-lines.png
> Do you know if some sysfs setting can get rid of these? They are 
> prominently present on channel 2 (KTVU) but are seen some other 
> channels as well. These are not seen on the normal tv set.
> Is there a filter that I can apply to get rid of these after the fact?
> Thanks a bunch,
> -devsk

I just looked at this.  You are seeing an interference pattern.  I've 
seen this sort of thing all the time on different TV sets over the 
years.  Just because one TV picks it up (be it a TV or a digital tuner) 
while another one does not "see it" could mean many things.  Different 
RF tuner designs can have different abilities to reject interference.  
The interference might also be highly localized.  Another hallmark of 
interference is that it is different on different channels.

I'll bet that the composite or s-video inputs will be perfectly fine - 
which would rule out everything downstream of the demodulator.

Lowering the capture resolution might lessen the effects of this 
interference.  Of course that comes at a large price in picture quality.


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