[mythtv-users] Interlacing [was: Pvr250 issues - any suggestions?]

[Nick Craig-Wood]

On Sat, Apr 03, 2004 at 12:54:19PM +0200, Henk Poley wrote:
> I've thought about this before, why doesn't MythTV keep track of a video 
> source is interlaced or not. So you can specify per recording/transcoding 
> profile (should also be seen as a video source) and front-end if you want to 
> deinterlace, without the possibility of deinterlacing twice which would 
> introduce more artifacts.

Or alternatively why doesn't mythtv display interlaced video the way
it was intended to be displayed?

Mythtv is currently displaying frames at 25 (PAL), 30 (NTSC) Hz which
look like this

aaaaaaaaaaaaaaaaaaaa
bbbbbbbbbbbbbbbbbbbb
cccccccccccccccccccc
dddddddddddddddddddd
eeeeeeeeeeeeeeeeeeee
ffffffffffffffffffff

However the signal was designed to be shown at 50 Hz (60 Hz) as two
frames 1/50th (1/60th) of a second apart

aaaaaaaaaaaaaaaaaaaa
                              bbbbbbbbbbbbbbbbbbbb
cccccccccccccccccccc
                              dddddddddddddddddddd
eeeeeeeeeeeeeeeeeeee
                              ffffffffffffffffffff

Did anyone try to simulate this on a progressively scanned monitor
like this at 50 Hz (60 Hz)?

aaaaaaaaaaaaaaaaaaaa          ....................
aaaaaaaaaaaaaaaaaaaa          bbbbbbbbbbbbbbbbbbbb
cccccccccccccccccccc          bbbbbbbbbbbbbbbbbbbb
cccccccccccccccccccc          dddddddddddddddddddd
eeeeeeeeeeeeeeeeeeee          dddddddddddddddddddd
eeeeeeeeeeeeeeeeeeee          ffffffffffffffffffff
....................          ffffffffffffffffffff

I would have thought that would work a whole heap better than
de-interlacing which has always seemed to me to be a horrid hack, and
never quite works as well as you might like...

(I use myth with a DVB-t card and so all the video I get is
interlaced...)

-- 
Nick Craig-Wood
ncw1 at axis.demon.co.uk