[vdr] Re: choosing a FF card

[Tony Houghton <h@realh.co.uk>]

In <420B3942.9070400@gmx.de>, Joerg Knitter wrote:

> Sorry to disappoint you, but apart from Matrox cards, there is no way to 
> output a video 1:1 i.e. without deinterlacing and with correct field-parity.

What about FF and DXR3 cards? If they don't support parity, their
deinterlacing filters (at least in the DXR3, because I haven't seen a FF
card) must be very good. The main reason I replaced my DXR3 was because
I generally watch more DivX than TV on my PC, and I couldn't always get
it to scale correctly. Sound output was a bit weak too.

> At least on Windows, you have this DVDMax mode which allows you to 
> output the video like it would be with a stand alone device. While a 
> G400 and G450 is only able to output upper field first, on a P650/750 
> you can even set the field parity - which is the proof that those cards 
> can do an output as you (and me) want. But I havenīt followed the 
> discussion on tv-out on linux in details, so I canīt tell how it works 
> on linux.
> I have read that nVidia and ATI cards have a tuner that works on a fixed 
> frequency while on Matrox cards, this frequency can be slightly adjusted 
> to maintain the sync.

I've heard that you can vary the frequency on Matrox cards, but only on
the primary head (or at least not on the TV-out), while field parity is
only supported on the second head's TV out.

The main problem IME is that while the clock in my G450 seems to be
close enough to the broadcaster's clock to play video alone very
smoothly while keeping it in sync with the TV output, my cheap sound
card has a less accurate clock which drifts significantly from the video
card's. I don't know whether things would be much better with a more
expensive soundcard, but without perfect sync between the two cards I
think I'm going to have to try to write a sound resampling filter for
softdevice so the sound can be subtly adjusted to keep it in sync.

BTW, I don't remember seeing an announcement about softdevice - I'm
getting some emails very late though - but it now supports Matrox field
parity in CVS. Nice work, Stefan.

-- 
TH * http://www.realh.co.uk