bttv 2.6.16: wrong VBI_OFFSET?

[Trent Piepho <xyzzy (at) speakeasy.org>]

On Fri, 5 May 2006, Edgar Toernig wrote:
> >
> > For NTSC, the burst gate delay is set to 93 Clk*2 pixels.  /HRESET width is
> > 128 Clk*2 pixels.  93+128 = 221, observed value of vbi delay.  But changing
> > bgdel has no effect.. oh well.
>
> Btw, the hscale effect I mentioned in my old posting was observed with a Bt878
> Rev 2.  It seems that's a pretty old revision as my current DVB card has a
> Bt878 Rev 11 (at least 9 bugs less *g*).  I cannot remember how strong the
> effect was - I think it was not as big as Daniel's diagram would suggest.

I'm using a cx23880, so maybe that's one of the changes.  I have an old bt848
card in another computer, maybe I will have to take it out and check.

> seems those guys have to edit the registry and set VBI_HDELAY by hand: 7 for
> NTSC and 25 for PAL.  Oh, I just read in Typhoon's FAQ that CC does not work
> when the video window is smaller than 240 pixels ...

It appears that the cx23880 has a similar problem.  If I increase HSCALE past
11377, which gives 199 active pixels on a nominal NTSC line, line 21 capture
stops working.  Adjusting HACTIVE and HDELAY have no effect.  I can set
HACTIVE to 4 pixels and still get VBI captured with HSCALE=11377, but at
HSCALE=11378 it's just black.  Even weirder, line 20 is still there!  It's
just line 21 that is all back once the HSCALE gets to 11378.

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