[vdr] 576i output on DVI->HDMI?

Jukka Vaisanen Jukka.Vaisanen at exomi.com
Tue Jul 15 15:59:49 CEST 2008


Well the 100Hz is just a kludge to fit 576i on the HDMI signaling. My understanding is that the following happens:

PC sends 1-1-2-2-3-3-4-4.. but the a/v receiver just ignores every other frame because it knows about the 576i kludge also.. so it is just seeing 1+2-3+4 going into the deinterlacer + scaler. The 100Hz thing is just a workaround to get enough data on the link so that the HDMI handshake will happen :P

- Vaizki

-----Original Message-----
From: vdr-bounces at linuxtv.org [mailto:vdr-bounces at linuxtv.org] On Behalf Of Ville Aakko
Sent: 15. heinäkuuta 2008 16:53
To: VDR Mailing List
Subject: Re: [vdr] 576i output on DVI->HDMI?

2008/7/15 Jukka Vaisanen <Jukka.Vaisanen at exomi.com>:

> My understanding is that 576i in HDMI is actually done as a 100Hz
> displaymode where each frame is sent twice. This is because the HDMI
> spec doesn't allow "speeds" as low as required by true 576i..

I'm not actually answering your question (I couldn't since I don't
have any experience with these modern TVs), but, AFAIK, you wouldn't
get very good results by doing what you describe. If every frame of
50Hz interlaced moving picture is shown twice, you'll get annoying
blurriness and / or jerky movement. Anyhow, the movement won't be
"smooth" as you might expect (because the frames are shown like this:
1-2-1-2-3-4-3-4-5-6-5-6-7-8-7-8 instead of 1-2-3-4-5-6-7-8). You'll
get much better results by doing "true" deintercaling, and showing
every "full" frame just once (i.e. 1+2-3+4-5+6-7+8 and so on). So what
you want would be quite useless, IMHO, though I could be wrong.
Someone correct me if you know better =).

If you really want to show interlaced material as they are supposed to
- i.e. you are a Hifi-lover - then the only "real" solution is to get
a display that can (truly) show 50Hz interlaced - perhaps via a DXR3
card, as you used to =).


> I am using xineliboutput currently as the software output device. Of
> course I would prefer it to use 576i for only the interlaced SD channels
> / recordings and change to 1080p for media player with HD content ;)

I'd just deinterlace via software (or hardware), and then upscale x2
(576 * 2 = 1052). Or, maybe forget the upscaling and send 576p (n *
50Hz) trough the HDMI/DVI.

-- 
-- 
Ville Aakko - ville.aakko at gmail.com

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