[mythtv-users] garbage at the top of the picture
lists at heathsworld.com
Wed Mar 29 02:52:50 UTC 2006
Michael T. Dean wrote:
> On 03/28/2006 01:44 PM, Andrew Heath wrote:
>>Yeah, over/underscan can be adjusted in the xorg.conf, but that would
>>take 1/4" from the other capture card/receiver which is ok.. If I
>>swap S-video cables on my sat boxes, the garbage line goes to the
>>other card, so this tells me the s-video signal is not quite right
>>from this replacement receiver.
> Actually, I would venture a guess that the receiver is outputting video
> that's completely within spec. One of my DISH receivers outputs a
> signal with "a bit of a black bar" (it's about 1" tall on my 67" TV or
> 1/4" on my laptop's 15.4" widescreen). The other has image from the top
> to the bottom of the signal. Both are good signals that, when plugged
> directly into the TV, show image from top to bottom of the screen.
>> I didn't know if there was an easy was to slightly crop one capture
>>card or not.
> No. Not at all. Overscan is the right answer (the one that was
> designed by the industry to solve the issue). And, yes, I realize that
> means you'll lose some image when watching recordings from the other
> card, but it's image you're supposed to lose (it wasn't designed to be
> shown because TV was designed to have overscan.
>>I could move to the composite which looks ok, but hate to drop
>>svideo. I would assume that composite would be better than coax though.
> Definitely better than RF modulated output (on coax). I still use
> S-Video, though, but ignore the black bar at the top. It's harder to do
> with garbage, so you'll probably want to overscan if you stick with S-Video.
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Thanks for the great input Mike. You are exactly right. If I go svideo straight into the TV, the picture is fine (due
to the TV's overscan). It's just irritating that one receiver does it and the other one not.
One test I did was hook up the svideo to the PVR 150, the coax directly to the TV and the composite directly to the TV.
Then I used the TV remote to toggle between the 3 modes. What I noticed is that the composite and coax pictures were
much more vivid than the svideo. I am guessing that is because the svideo was MPG2 encoded by the 150 and that process
dulled the color some. I also noticed that the svideo seemed like "full picture" VS the coax and composite that seemed
cropped or zoomed in slightly. ie you could see slightly more picture with svideo, but it had the garbage line. If
someone on the TV had their head near the edge on composite/coax, when I switched to svideo there would be some space
(sides, top and bottom). Not what I expected, but something to be aware of.
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