[mythtv] [mythtv-commits] Ticket #2429: Autodetect video scan is confused by 1080i recordings

Jack Perveiler perveilerj at yahoo.com
Thu Sep 21 03:03:03 UTC 2006

> Well, that shouldn't be happening.  Sounds like the bob filter's in place,
> but 
> it's not doing the proper output..
Hmmm.  I used to see it on 720p FOX back before the autodetect stuff went in,
and I saw it the other day on a wierd DVD title.  I just checked again now
(played 720p recordings from 2 different channels, changed video scan to
"interlaced") and it seems fine.  So I guess whatever the problem was went away
somewhere along the line.  I'll keep an eye out for bad dvds in the future now
that I know the problem isn't that the deinterlacer shouldn't be running, but
that the deinterlacer isn't working right.

> I dunno if I like the idea of another setting for this.  Be better just to 
> improve the handling of these situations.
Ok, glad I checked then ;)

> For instance, see NVP::AutoDeint(VideoFrame *frame)..  It's only going to
> flip 
> between interlaced/progressive after a couple frames of the opposite type to 
> what's current have been seen, instead of on the actual frame that needs it. 
> That'll lead to a couple frames of interlaced content being displayed as 
> progressive, etc..
I recently asked David (original patch author) if maybe increasing the
hysteresis would help with my problem channels, but he said that in his
experiments some channels were just REALLY BAD with respect to this.  I.e. it
was hundreds of consecutive frames wrong, not just a couple.  I know Curious
George on digital PBS always detects as progressive for me, but I definitely
get the banding (or whatever the correct term is) suggesting it's really
interlaced.  Switching the video scan to "interlaced" corrects it.  It's
possible it's really switching back and forth, but it's wrong the vast majority
of the time.  

Of course it's also possible that I really am getting progressive content, but
that the provider isn't deinterlacing it before they send it.  It looks like
NVP::AutoDeint(VideoFrame *frame) is already instrumented, I'll run with
playback verbosity next time I get a chance.


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