[mythtv-users] Asus Pundit and Interlaced Output, part III :)

[Will Dormann]

At 08:46 AM 6/24/2003 +0100, you wrote:
>Another thing I thought of - do you need to be using an interlaced X mode?
>Surely this can be the only way that any app running within X can hope to
>output interlaced video correctly. I mean to sort this out myself pretty
>soon but havent got round to it yet.

Yes, I am running the 3rd-party SIS driver from:
http://www.winischhofer.net/linuxsisvga.shtml

I had also thought about the interlaced X mode myself too.   I played
around with with different modelines trying to get an interlaced X mode,
but without much luck.   The SIS driver seems to override what monitor
settings you have when a TV is connected.   (using predefined built-in modes)

Anyway, I ended up emailing the author of that SIS driver, and I got a
reply which pretty much sums things up clearly.   (and allows me to quit
tinkering)
>From Thomas Winischofer, in reply to "can it be done":

*******
No. See:

The video bridge can only convert non-interlaced material to interlaced. 
There is hardware-wise no way to feed the bridge with interlaced output.

The bridge does this conversion internally, without any way to interact 
software-wise. The bridge also applies some image-enhancements during 
this conversion process which cannot be entirely disabled.

Furthermore, there always a certain amount of scaling involved; the 
resolutions that the driver supports, are in many cases no even 
multiples of the native TV resolution. (And the scaling the bridge does 
is not of the highest possible quality, I might add)

> Is there any trick to keep the SIS TV output in its "pristine" 
> interlaced format without having any resizing occur?

No. I am afraid I have to remind you that this video bridge costs about 
$0.50 - and what we have is the best to expect.

Conclusion: You _have_ to deinterlace your video material before sending 
it out.

Thomas
*******


So with the hardware I've got, it seems like de-interlacing is the way to
go.   I wonder why the option is there in the first place, though?     Is
there some video card / video bridge that does allow "true" unadulterated
interlaced TV output?     Or perhaps it is for low-end systems that don't
have SSE or aren't fast enough to deinterlace on the fly?

-WD