Finaly SCART RGB TV-out with Matrox P750/Parhelia works !!!

[greinedo]

Hi !

It tooks some time for me to try (because of Radiospares delivery shift) but I just received the components and couldn't wait more.

The idea I explained in an other thread is quite simple (but see this thread please ) :

http://forums.murc.ws/showthread.php?postid=459169#post459169

Since Matrox gave up the RGB TV-out feature, wich gave to the G400 the very best TV-out, I searched how I could tweak my actual P750 in order to add that missed function.

Finaly It works, and really works fantastic with my P750 (must also work with the Parhelia or P650). Ok, it's some work but those who are searching a high quality configuration for HTPC must be interrested :

1) Dowdload Matrox Monitor Manager

2) Define a new res (depending of your TV standard PAL or NTSC). For PAL, take 720x576, interlaced, 25Hz, see the picture for other parameters)

3) Affect that res to the 2nd or 3rd head and activate that head as usual.

4) make a DIY sync converter as described here (yes composite sync feature is still missing in the drivers) :

http://www.hut.fi/Misc/Electronics/circuits/vga2rgbs.html

5) connect your TV on the RGB signals of the choosen head + the modified composite signal

6) Switch on your TV, and voila ! The TV is seen like a monitor connected to one head.

7) Ok if you made a mistake, may be something could explode ....

The achieved TV-out quality is really far better than the poor standard S-VIDEO signal comming out from the P750. It is as good as the RGB TV-out picture of the G400, wich is THE reference for me.

For those who are planning to build a high quality HTPC, I would now advise to take a fanless P650, and connect a TV like this.

Hope this can help someone !

regards

[DC]

when my P750 arrives, I will give it a try. Thenks for the info.

DC

[Kurt]

Good job. I wonder if we can find a place to make it in a "professional" way...(I'm kind of soldering avert )

[dkazaz]

I was wondering if it might be possible to do something like this, but I'm amazed at the work you've done! It would indeed be great if e could get these done professionally somewhere - IU'm sure many people here would order this kit. There are various cable shops and electornics outlets that do work like this, I wonder if we might get one of them to produce these from your spec...

Interestingly, I found a device which seems to do the oposite of your set-up - it takes RGB SCART input and converts it to S-Video and composite. If only kit like this was customisable...

[greinedo]

Hi,

@dkazaz :
You can find something like that to buy.

http://209.3.61.141/cgi-bin/iec/framefly?;ADP5120

But If you have a G400, I would advise you to stay with that card for a Media center PC.

I said the TV-out quality achieved with the P750 + mod is as the G400 TV-out quality, but after A/B comparison, is is not exactly the case. With the P750 I loose a little bit some details, wich are sharper with the G400 on the TV. But at 1600X1200 on the PC monitor, the P750 is sharper than the G400.

It is as if the P750 has optimised output filters for hi-res output and G400 has optimised filters for lower resolutions. I have heard somewhere about removing those filters to improve sharpness (those filters are to respect EM certification I suppose).

If I try, sur I'll post it here

regards

[greinedo]

ooops !!!

I certainly made a mistake here : the commercial sync mixing device I gave the link above is perhaps no usable for our purpose.

It must be a TTL level sync mixing device, and not a video level one. So it could be fatal for your TV if you try. After browsing the web I didn't found a ready to use device.

So the only solution to connect via RGB a P or Pxxx to a TV is to take the solder iron. It's worth to try. I wonder if the differences I see between G400 SCART RGB and P750 SCART RGB are not due to different internal video scaling processes.

@dkazaz :
I tried to use my G400 AGP 4X (1.5V certified, G4+M4A16DG + dual head / TV-out module) with a ASUS A7N8X-X motherboard and it failed. It seems thats those new motherboards are not working even with a true AGP 4X graphic card !!!

[greinedo]

Hi !

As a conclusion to my thread I must add here somthing quite important, thanks to a good guy from AVSFORUM. The Matrox hardware forum is perhaps not the right place to put that, but it's the logical sequel to my threat "SCART RGB connextion to TV".

For those who want to have the best TV-out, I advise a RGB connection to TV with a G400 or a Pxxx and the way described earlier. But for the owner of a 16/9 TV, there is something really important to know to optimise the picture quality.

Since the Pal or the NTSC standard are 4/3 aspect ratio, when you send a 1.85:1 or 2.25:1 DVD film to the TV, 55% of the signal are black pixels, a shame ! To fill the 16/9 TV screen, you have to zoom with your remote. The picture is perhaps bigger, but without more informations. I used to do so for a long time until yesterday :

In addition to the SCART RGB connection object of this thread, I put 5V on pin 8 of the SCART connector in order to switch the TV in 16/9 enhanced mode : in this mode all the vertical resolution of the incomming signal (576 lines for Pal) is stretched and all the lines are drawn on the visible TV screen. Otherwise, witout that pin 8 enabled, only 400 lines(for Pal) are drawn on the TV screen because of the zoom needed to fill the screen.

Ok, that way the aspect ration is not maintained, but this is not a problem : you have a windows desktop with truly 720x576 otherwise only 720x400. When it comes to watch DVD, you can use Zoom Player and choose Anamorphic aspect ration. Doing this, the player stretches the picture so that on TV the picture looks not deformed.

Conclusion :

If you don't use the SCART pin 8 trick and use your remote to fill your expensive 16/9 TV screen, the real resolution of the movie you watch is 720x400 for pal or 720x330 for NTSC.

If you put 5V on pin 8 to fill the 16/9 TV screen and choose Anamorphic aspect ration in the player, then the real resolution is 720x576 (Pal) and 720x480 (NTSC) !

With that additionnal trick to the SCART RGB connection, you have 44% more lines -> incredible improvement in picture quality on TV. I just watched my favorite parts of Lord Of The Ring, wich is know to have less compression : sorry but my english is not so good to explain what I feel. Only thing I can say is : don't forget to put 5V on pin 8 !

Some links that explain better as I can the Anamorphic stretch and what it brings to TV picture quality :

http://www.hometheaterhifi.com/volume_6_4/feature-article-enhanced-widescreen-november-99.html

http://www.dvdfile.com/news/special_report/production_a_z/anamorphic.htm

http://gregl.net/videophile/anamorphic.htm

[dZeus]

with Matrox G-series, you can just set DVD-MAX to keep aspect ratio with 16:9 output device and get the same results

If M would add SCART-RGB support officially in P-series drivers, the same would apply to them.

[greinedo]

That's right, but at that time, when I had my G400 sticked in (before the P750), I was not aware of the Scart Pin 8 behavior.

I played with that undocumented 16/9 output option of the G400 and just got a bad stretched picture. So I stayed with the 4/3 settings.

Even, if you can find links on the net for interfacing the G400 with the SCART, I don't remember having seen something about the 16/9 enhanced mode combined with the SCART RGB. As I wrote above, it works quasi like a line doubler. For those who have already a G400 + 16/9 TV, it's a great opportunity to improve even more the picture quality.

With the P750, and the lack of that option, Zoom Player allows adjustable aspect ratio wich allows correct viewing of the video, but also of the pictures, wich is, I think, not possible with DVDMAX.

[dZeus]

undocumented? what's undocumented about that feature?

btw. nearly all widescreen TV sets except for the very oldest models allow you to set the 'pan&scan/stretch' mode manually to do 1:1 playback of 16:9 signal, so you don't need that SCART pin 8 trick at all. I've been using my G400+widescreen TV set for years like that.

[greinedo]

On mine, wich is not an old one, if you switch the TV with the remote to 16/9, it stretches verticaly, thats ok, but also horizontaly, thats unwanted (no deformation in the center to a lot on the edges) -> straight lines become a S for ex.

I cannot easily have only vertical stretch. Only with the scart input, wich was intended to be driven by a standalone dvd players.

[dZeus]

sounds like a problem with your tv. Ah well, if the pin-8 trick solves it, it's fine.

to nitpick: in 16:9 input mode, no stretching is done. It's in the 'zoom' mode for letterboxed 4:3 contents that the image is stretched. Often, if you play back a letterboxed-source avi file through your G400, it'll look much better in 16:9 output mode, since the stretching will be done by your videocard, and often the stretching algorythm is horrible on TVs (it is on my Sony Wega).

[G400-TV]

g400 at 25hz

Hi, I've a G400 and thankx to another recent post I success to output at 720x576 (without using DVDMAX) with a real interlace output, meaning that if I play an interlace MPEG-2 video, the playback is perfect, but only 50% times, field order is ok, and 50% is field inverse.

This is becouse my g400 tv output (in clone mode) is 50hz, and seems to be impossible to switch to another frequence (powerstrip let change frequency, but it doesn't do nothing in reality, showing 25hz but output remain 50hz).
There isn't any way to output (with a G400, on tv out, in clone mode) at 25hz?

If no way to do this, with your cable I'll always obtain an interlace playback 100% correct field order?

It's possible to build this cable without the composite sync (that is really hard to build): only red, green and blue output?
what will be the difference (also becouse on my RGB > SCART conversion, from xbox, there isn't place for a composite sync rca, only 3 rca for r,g,b)

Thank you.

[greinedo]

The G400 is a marvelous card. It supports both composite sync and interlaced res output. You don't have to build a sync converter at all. You just connect your G400 2nd head to a scart connector (R+G+B+Sync) and tweak the signal via Powerstrip.

Please read this link. It explains how to do it with a radeon. But it's quit the same with the G400 :

http://www.idiots.org.uk/vga_rgb_scart/

I can send you later the timings wich are working good (a bit different from those in this link).

[G400-TV]

many thankx for the replay.
I think the big problem (according to my test) is that it's imposible to change frequence when a TV is connected to the external box (it's a G400-tv) also with powerstrip, but maybe if I build this cable (and the G400 don't recognize it's a tv, but a generic monitor), it let me change the frequence to 25hz.

If you have any cable, but the frequency set to 25hz, you can confirm me mpeg2 output is 100% properly interlace (correct field order).