[mythtv-users] PVR 250 card success, but jumpy video/interlacing problem

Marius Kjeldahl marius at kjeldahl.net
Mon Jul 14 19:08:10 EDT 2003


Following up on my own question, after advice from another member of this 
list, this problem is related to the ivtv driver, PAL and a vertical 
resolution different from 576. The default setting in mythtv is 480, which is 
probably optimized for NTSC. Some part of the ivtv driver that deals with 
vertical scaling currently does not work correctly with linux.

Changing the capture resolution to 576x576 solves the jumping up and down 
issue, but introduces another one; problems with capturing at full speed 
(introducing delays every now and then).

So to follow up on the questions, is anybody having success using the PVR 250 
capturing PAL _without_ jumping issues? And if so, why (one possible answer 
is a faster disk system, but I've read the hints and enabled DMA etc on my 
brand new 160 GB disk, so I am a bit surprised that the disk itself would be 
too slow).

Thanks,

Marius K.

On Monday 14 July 2003 12:09, Marius Kjeldahl wrote:
> I finally got everything working on my new Shuttle XPC with the PVR 250
> card. To be honest, I literally had to hand code tuning frequencies into
> the channel table to find all the channels on my cable feed (UPC in Norway)
> since I could not get XawTV working, but after I found the channels,
> capturing and watching live TV seems to work fine, with one exception:
>
> The screen looks jumpy. I'm outputting this onto a normal computer monitor,
> and the image seems to jump up and down. I am not talking about jerkiness
> or anything, it just seems every second frame seems to be offset by one
> line compared to the next, so the image seems to jump up and down in place.
>
> I also attempted to capture some video (using cat /dev/video0 > test.mpg)
> and play it on another machine just to rule out any installation specific
> problems or playback related issues, and by doing this I was able to
> confirm that the jumping is part of the captured stream (i.e. it jumps just
> as much on my other system).
>
> I've tried setting the different options about deinterlacing, jittering
> etc., but it does not seem to make any difference.
>
> Any hints/ideas on what I need to do to get rid of that jumpiness when
> watching live TV or capturing using the PVR 250?
>
> Thanks in advance,
>
> Marius K.
>
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