[mythtv] bobdeint: vertical jitter behaviour

[jeroen at fotoniq.nl]

> On Tue, 8 Feb 2005, Jeroen Brosens wrote:
> ]I found that when using bobdeint the image sometimes starts to go 'out of
> sync'
> ]and the nice fluid motion goes into a horrible vertically jittering one.
> It
> ]manifests erratically and without apparent reason. Can anyone confirm
> this
> ]behaviour? I am using an ASUS Pundit with SiS integrated video, X.org
> 6.8.1,
> ]march=pentium4, MythTV CVS (current).
>
> It sounds like the fields are getting reversed, what are you using for
> capture (card, encoder & resolution)?

I am using a PVR-250 @ 720x576 (Netherlands, PAL).

>
> But to eliminate other possibilities...
>
> First, are you using CVS from today? There have have been a lot of
> bobdeint changes in the last few days.

Actually, I am running CVS from february 7th, so it is one day old. I saw
the bobdeint developments and wanted to see whether things have improved,
but unluckily not.

>
> Second, are you using XV or XvMC? (does the other one work?)

I am using Xv since the SiS driver doesn't support XvMC (to my knowledge).

>
> Third, what is the video resolution and display resolution when you see
> this problem, and when you don't see this problem?

I haven't checked video resolutions other than 720x576, because that is
the native PAL resolution and I don't want to go for anything less. Of
course, with the other deinterlacers, the picture doesn't jitter but they
don't display 50 fps. The X resolution is 800x600; when I set it to
720x576 the desktop gets displayed only partially, like a virtual desktop
setting (moving the mouse around makes the desktop slide towards the
edges).

>
> Fourth, do you know if this was happening with 0.16?

No I don't, I started using bobdeint only since my CVS upgrade, so I have
no reference there. The strange thing is, that like you said, the fields
get reversed, but only sometimes. Suppose when I play a recording one time
it could start ok but start jittering after a few minutes. Then, when I
start it a next time the jittering can be there from the start already and
go on and off periodically for instance. I usually fix the problem by
pausing and then playing again. Like I said, quite erratic behaviour.

I suspect that field timing is not as good as it should be, could it be
that incorrect rounding of numbers is the reason? After each
pause-and-play the image is normal, that should be a clue! Hopefully this
can be sorted, because bobdeint is by far the best option, but it must
work 100% then.

-- Jeroen

>
> -- Daniel
>
>