> ODD:
>
> bbbbxxxx
> xxxxxxxx
> ...
> xxxxxxxx
> xxxxxxxx
>
> EVEN:
>
> xxxxxxxx
> xxxxxxxx
> ...
> xxxxxxxx
> xxxxbbbb
>

I indeed saw half a line at the bottom too

> Strictly speaking, you get a "1/2 pixel" flickering, not 1 pixel.
I don't understand the 1/2 pixel notation, what I see is about 70 pizels
that are quite black (with some noise)


>
> As you say, cams generate PAL signals this way, it has nothing to do
> with the decoder. BT8x8 chips can detect the field parity, but several
> time (= consecutive fields) is required in advance so that it stabilises
> (see chip specs). This is not possible when switching cameras, since
> there is never time enought to stabilise (provided you switch fast).
> Well, it is possible if you use phase syncronised cams., which I believe
> is not your case.

yup :(

we added a LM1881
> (a sync detector) chip in our board design and wired its ODD/#EVEN
> output directly to one of the GPIO pins. This HW info IS reliable.

what is LM1881 and how does IT know what is even and what is odd?

> What we do is take any parity and if frames are odd, mark them at
> interrupt time and interpolate (linear algorithm, just the mean of both
> upper and lower pixels) them so that they "ressemble" even ones.
>
great  tip, but it heavily depends on distinguishing even/odd frames, so the
previos question...


Michael Zayats



_______________________________________________
Video4linux-list mailing list
[EMAIL PROTECTED]
https://listman.redhat.com/mailman/listinfo/video4linux-list

Reply via email to