Howto: Enable 720p50 and 1080i25 with ATI Catalyst 6.6

[thiskl]

I found this ATI knowledge base article;

737-22853: 50Hz refresh rate not available for European TV, HDTV and projectors

Basically, the article describes a registry tweak that enables the following HDTV modes;

720p50 standard (1280x720 @ 50Hz)
720p50 optimized (1152x648 @ 50Hz)
1080i25 standard (1920x1080 @ 25Hz)
1080i25 optimized (1776x1000 @ 25Hz)

To read the article, start at ATI Customer Care, enter 22853 in the search field, and click Go.

Note: You should reboot after adding the registry entry.

If you are using ATI's component video connection, then the screen shots wont match your configuration. Instead, you'll need to enable "Use Custom Formats" under Component Video Properties->Formats, and select 720p50 and 1080i25 from the list of custom formats.

Once you done that, the modes listed above can be found under Component Video Properties->Advanced.

This is definately worthwhile if you're in a PAL TV country.

[knutinh]

I would think that you can accomplish the same (and more) using powerstrip?
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http://forums.entechtaiwan.net/index.php

-k

[thiskl]

If you need more, then by all means use Powerstrip.

For me, it's a case of not needing Powerstrip any longer, and that means one less application I need to configure.

[knutinh]

I agree.

But for me, 50 Hz is only half the solution. I want 1:1 pixelmapping as well, and for that I think that powerstrip is best, although not very userfriendly.

regards
Knut

[thiskl]

Can you please explain what you mean by 1:1 pixelmapping?

Never mind. I found this http://pixelmapping.wikispaces.com/P...ping+explained

[knutinh]

Most tvs dont have 1280x720 physical pixels. They have 1366x768. Or 1280x768. Or 1024x768. Or 1024x1024. Etc.

Since the HD-ready standard defines resolutions as either 720@50/60p or 1080@50/60i, these tvs has to scale and if needed de-interlace the signal. In addition, they will often do overscan, to remove a bit of video around the borders. Most tv stations transmitt some "extra" signal to allow for old CRT tvs with bad precision (as well as cannon travel). This is ok and probably satisfies many customers.

However, if you are connecting a PC to the tv, you will soon be aware that fonts does not look good after scaling. As a matter of fact, all of this processing is redundant and wasteful for a PC image. The windows start-button is perhaps impossible to see, the fonts look washed out etc. This is an unknown problem to PC users since they are used to PC monitors that report their resolution via the DVI/VGA cable to windows and windows sets its rate accordingly.

Now, tv manufacturers dont know what a PC is. They just want to make a "HD-ready" tv fast and sell it with maximal margins. Therefor, they dont report their resolution via DVI/HDMI/VGA, or at least not their optimal resolution. Most (notably ALL Philips flatscreens) are hardwired internally in that they can NOT accept their native resolution (commonly 1366x768).

If you are going to purchase a lcd tv for HTPC use I advice againt purchasing any Philips model. LG is good.

This is where the controversy over "1:1 pixel" comes from. For many video sources this is not as visible as for clear windows fonts. But you are passing your video through a totally redundant scaling/cropping stage.

For instance, my 40" low-end lcd tv allows either 1366x768@66Hz or 1280x720@50/60Hz. If I choose the first, I have crystal clear image, but "jumpy" movement for 50/60Hz video. If I choose the second, I have smooth movement, but my SD PAL nice DVB-T television picture is first scaled up from 720x576 pixels to 1280x768 pixels by the HTPC, then my tv scales the image further up to perhaps 1450x820 pixels, then cropps the borders so the content (which is sourced from perhaps 680x510 "real" pixels) fits into the 1366x768 native panel.

Clearly not an optimal signal path...

-k

[thiskl]

Thankyou for the detailed response. Very informative.

Well, I'm using a 36" Sony CRT via component. It support 720p50/60 & 1080i25/30, but achieving 1:1 is not a realistic option. However, getting smooth DVB-T playback is now very simple.


Cheers

thiskl

[jackelectronics]

Talking about the first post, I spent hours and hours researching whether the ATI would do 50Hz modes instead of 60Hz as everything is 50Hz in the UK. I had a Matrox card, which urgently needed upgrading. I decided to go for the NVIDIA because their Control Panel settings are fully documented, including adding HDTV modes (Both 50Hz and 60Hz) as used it as evidence that it does 50Hz output. If ATI made this precious document visible, I would have considered ATI as NVIDIA. But I'm happy with my NVIDIA 6800GT 256MB AGP.

[NLS]

ah... the complexities imposed by the stupidity of the designers (or their bet on the ignorance of their buyers... a bet they are winning)

then I got a nice 1920x1080 TV, capable of syncing at 30/50 and 60Hz... 1:1 pixel-mapped

[CHli]

Yes Amoi is one of the only LCD seller that proposes a 1920x1080 panel supporting progressive scan @ 50 Hz.

Anyway the new sharp's serie is going to hit the market soon in Europe and this gonna hurt