[mythtv-users] Black Bars in Mythtv

Michael T. Dean mtdean at thirdcontact.com
Sat Feb 9 06:23:43 UTC 2008

On 02/08/2008 08:18 PM, K Madman wrote:
> I recorded a show and saw on the left and right sides
> there are black bars in the actual recordings. I thought at first it
> was a problem with my pvr-150.  Now I just put together a completely
> different mythtv box with a brand new pvr-150 and when it records it
> also has black lines on the side.  The black lines are not from aspect
> ratio.  On my old box everything was ok until I ran an update for
> mythtv.  What causes them and how do I get rid of them?  Please help.
> This is a snap shot from mythweb where you can clearly see the black
> bar on the left side of the recording. (little black bar on the right
> also)
> http://www.geocities.com/k7_madman85/SAMPLE.jpg

You definitely have a problem.  That problem is called NTSC (or, 
perhaps, PAL).  In other words the problem is you're using an analog 
format that was defined to have unclean edges.

If you want to get rid of the black bars:
a) overscan the video output so that the black bars are "displayed" 
beyond the edges of your TV,
b) transcode the file and crop while transcoding
c) use the crop filter to crop the black bars while playing back the 

Note, though,

So, the only real solution is to go to a format that has clean edges:  
digital TV.  Note, though, that if you get digital TV signal from 
satellite/cable to a set top box and output to a PVR-x50, you'll get 
black bars because the STB will be outputting analog (which is designed 
to require overscan because of the unclean edges)...  If you have analog 
to the PVR-x50 (i.e. cable/antenna plugged directly into the capture 
card), you may not see the black bars.  Instead, you'll likely get 
green/purple lines and jaggies and rainbows and waviness and other stuff 
to replace the black bars.

In other words, don't worry about it.  It's an artifact of your use of a 
50+ year old technology for TV.


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