[mythtv-users] Flickering lines at the bottom of TV
Allen Edwards
allen.edwards at oldpaloalto.com
Tue Jul 22 02:15:21 UTC 2008
Brian Phillips wrote:
> Brad DerManouelian wrote:
>> It's being broadcast that way. There is nothing to fix on your end.
>> Usually a television's overscan will hide this sort of thing but
>> since you're displaying the entire video, you're getting the garbage*
>> edges as well.
>> For info on Overscan here:
>> http://www.mythtv.org/wiki/index.php/Overscan
>>
>> To hide this, you can play back your videos 1% or 2% larger than they
>> actually are (whichever works for you) or you can crop your
>> recordings by transcoding them with crop settings.
>>
> http://www.mythtv.org/wiki/index.php/Overscan#TV_Playback_Overscan_Adjustmen
> t_Settings
>> *The "garbage" is actually encoded information being sent along with
>> the broadcast like metadata information about the program, closed
>> captioning text, etc.
>
> I was a bit skeptical of overscan being my issue for a couple reasons. 1)
> It only happens on a single channel. 2) It doesn't happen 100% of the time
> (but often enough it's worth delving into.).
>
> I'll look into the scan displacement settings.
>
> Brian Phillips
>
This is standard stuff. I have been watching HDTV for about 6 years and
this stuff drove me nuts for a long time. The "garbage" is a data
signal and it is not there on all broadcasts. I think it is in the
analog programs and it comes along for the ride on the DTV transmission
if not removed by the broadcaster. Perhaps it is CC data, I don't know.
Anyway, it is perfectly normal to see it and perfectly normal to add 3%
or so of overscan. You never noticed it on your analog sets because
they all have overscan to get rid of this stuff.
Allen
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