Intel GMA 900 (915G) - interlaced modes?

Krzysztof Halasa khc at
Wed Jan 10 04:37:13 PST 2007

"will" <nodenet at> writes:

>>Anyway, with interlaced CRTC mode you basically sync to 25 or ~30 Hz
>>and things work automatically.
> Are you absolutely sure about this?

Sure. Of course it must be properly configured, i.e., correct field
first (or the results will be wrong all the time) and the software
must sync to full frame.

When you pause the player your display still shows two fields (flashes
if the frame contained motion).

It was possible with cards such as S3 64V I think (not tried it, though).

> I thought if you had no common frame of
> reference then this would not work reliably. I thought that vsync and buffer
> swapping occur at the field rate not the frame rate.

I assume it can do both, we need full frame. I have done it in the
past with Radeon and it was fine. The only problem is I have no Radeon
near the TV monitor :-)

Actually I'm not sure about CLE266 - I think one could be able to
get it to work using S-video output (I think I was getting always
wrong field parity (not random) with X, I would have to try with NTSC
mode as it uses bottom-first).

> I've only ever heard of the Matrox cards as being able to output interlaced
> video with the correct field parity and not when used under X as field
> parity may not be supported?

Interlaced mode on i915 is not supported at all, I hope I will add it
and that includes full frame sync.
Krzysztof Halasa

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