New feature: YPbPr/RGsB output

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Sorgelig
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Re: New feature: YPbPr/RGsB output

Postby Sorgelig » Wed Feb 08, 2017 10:38 pm

All-In-One cable. Developer version :)
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Re: New feature: YPbPr/RGsB output

Postby DrOG » Thu Feb 09, 2017 5:28 am

What does 'All-In-One' mean?
It has VGA plug on both ends, so I suppose it needs an adapter to connect it to standard SCART or component socket...
May I ask it's wiring diagram?

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Re: New feature: YPbPr/RGsB output

Postby Sorgelig » Thu Feb 09, 2017 7:03 am

I connect MiST to scaler which has VGA input, but in fact it accepts RGBHV, RGBS, RGsB, YPbPr. One switch enables HSync and VSync, another switch adds Sync to Green/Y. So, i don't need to change the cables.

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Re: New feature: YPbPr/RGsB output

Postby DrOG » Thu Feb 09, 2017 7:56 am

Wow! That's awesome! I don't have a scaler (yet), waiting the news about your own designed scaler you mentioned earlier in this topic:

viewtopic.php?f=101&t=27019&p=310749#p310705

Best regards: Gábor

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Re: New feature: YPbPr/RGsB output

Postby DrOG » Sun Feb 12, 2017 9:22 am

Hi All!

I made further investigations in the case of the MIST's different video outputs.
I used now the Amiga AGA (minimig) latest core modded by Sorgelig (YPbPr out).

Used the same methods during the test as decribed in the post below:
viewtopic.php?f=101&t=31006&start=25#p310037

As I see, the brightest and sharpest picture is over native VGA.
The second place is a 'dead heat', scandoubled component and scandoubler disabled SCART gives the same sharpness, but the YPbPr is brighter, therefore a little bit better.
The scandoubler disabled component output results the most blurred video.

That was a surprise to me, I thought the component input's quality is much superior compared to SCART connector. Perhaps the problem is in my TV set, or the advantage depends on the difficulty of adaptor: the VGA2SCART cable doesn't contain any active electronic part, unlike the VGA2YPbPr converter, which contains transistor, capacitor
and resistors too.

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I found further interesting phenomenon: in High Res Laced mode, if scandoubler is enabled, the picture is flickering, in this case the framebuffer's content is blocky. It works inversely as expected: disabling the scandoubler the picture does not flicker anymore.

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Re: New feature: YPbPr/RGsB output

Postby Sorgelig » Sun Feb 12, 2017 10:54 am

The difference in video quality is 100% related to your specific TV. Originally "sharpness" and overall quality of RGB and YPbPr video are the same. YPbPr may have a little (hardly noticeable) discoloration due to RGB-YPbPr color conversion. I don't think you will see this discoloration even on Minimig core.
Your TV has different circuits to process RGB and YPbPr. Probably there are even different chips handling different video - so result may vary from TV to TV. Greatest thing of YPbPr - it supports 31KHz natively, while SCART doesn't.

About scandoubler on Minimig - the way it implemented is absolutely wrong. Originally scandoubler is supposed to be used on progressive TV resolutions 240p/288p to make them 480p/576p. Since most retro cores provide those progressive video (with slight variations) scandoubler works perfectly. On Amiga, interlace mode is often used. And if every field will be scan doubled, we see alternating 2 different frames producing such flickering effect. So, either use non-interlace mode (like 640x256) with scandoubler, or disable scandoubler with interlaced mode - TV will provide de-interlacer and eventually will make better progressive video.

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Re: New feature: YPbPr/RGsB output

Postby DrOG » Sun Feb 12, 2017 11:20 am

Thanks for the explanation!

I was sure in the case of VGA input it's optimized for PC, that's why the video very sharp.
Using other connectors perhaps the picture smoothing is stronger, and the result is softer (not adjustable using the TV-s setup menu - perhaps next time I will look around in the service menu).

I wonder only why the 'high end' component is almost the same compared to the 'common' SCART (comparing scandoubler disabled SCART against 240p component the latter is actually weaker, but it shouldn't be).

Has anyone the same (or different) experiences on another TV? Mine is a Samsung LE40B650 LCD manufactured in 2009.

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Re: New feature: YPbPr/RGsB output

Postby Sorgelig » Sun Feb 12, 2017 12:06 pm

The main purpose of YPbPr is 31KHz video where you can have either higher resolution (core developers should be advised to tweak their cores to support standard TV 480p/576p/720p resolutions) or scandoubler with HQ2x - so you will get nice picture.
Another usage of YPbPr output are TVs outside of Europe where SCART is not available.
YPbPr doesn't enhance the original picture - it only can provide higher resolutions without going out of standard (unlike SCART or VGA connections). 240p/288p/480i/576i - all these resolutions technically exactly the same for RGB and YPbPr - same sharpness, same brightness, same contrast - just different color space. If you have SCART then you can simply use original video output.

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Re: New feature: YPbPr/RGsB output

Postby DrOG » Sun Feb 12, 2017 1:03 pm

I understand everything, and all of your work is very important and advantageous!

I am preferring the original methods where possible: that's why I use my TV in 4:3 AR instead of 16:9. Playing old games with my kids and friends on a 40" LCD is much more fun than on old 14" CRT (I've a Philips CM8833, but it's so small...).

Unfortunately my big TV does not support non-standard VGA signals, so using PAL cores is only possible if connected via SCART or YPbPr.

Didn't want to criticize your work, just share my experiences. Relally like the YPbPr out opportunity, it's especially practical together with the new firmware's possibility to switch between RGB<->component using the MIST's front buttons: thanks for implementing that! The 'per core settings override' is very useful as well, in connection with it one more (offtopic) question: which core's hardcoded name is PACE? (Found it on the Wiki's DocIni section, the others are clear).

Greets: Gábor

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Re: New feature: YPbPr/RGsB output

Postby Sorgelig » Sun Feb 12, 2017 3:14 pm

PACE is a common core for many arcade cores. Probably one of those arcade cores didn't change the name to specific one.

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Re: New feature: YPbPr/RGsB output

Postby mambrino » Tue Mar 07, 2017 7:33 pm

I've tested the YPbPr cable with my TV and interlaced modes works perfectly, but progressive ones only works for Amiga and NES cores, For Spectrum 576p works at basic/128k menu but loading games just get black screen, and for 576p C64 core always get black screen (NTSC 480p works fine). It seems that my TV has some sort of problem with 576p resolutions and certain refresh rates. Would it be possible to adjust Spectrum/C64 refresh or something to get the same behavoir as Amiga or NES core? or should I try with a scandoubler / scaler?

In any case, thanks for adjusting these cores in order to use YPbPr cable, is a very interesting solution for those (as me) who have problems with VGA modes ;)

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Re: New feature: YPbPr/RGsB output

Postby Sorgelig » Wed Mar 08, 2017 2:08 am

It's impossible to adjust video on cores directly. It will break HW compatibility. Original ZX spectrum and C64 would have the same problem on your TV through YPbPr cable. Actually i'm not sure about C64 (it's not my core but i assume it's more or less compatible with original HW), but i'm 100% sure about ZX. Actually ZX core has 3 video timings. Probably ZX128 or ZX48 should work on your TV.

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Re: New feature: YPbPr/RGsB output

Postby mambrino » Wed Mar 08, 2017 12:16 pm

None of these video timings (48,128,pentagon) works in progressive modes, i'll try with Lenkeng LKV353 scaler, hopefully it should work.

Thanks ;)

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Re: New feature: YPbPr/RGsB output

Postby magecite » Mon Mar 20, 2017 5:17 am

So what is someone with zero soldering skills and no idea what anyone is talking about here supposed to do?

All I really want to do at the end of the day is make it so my TV can handle the Amiga cores on the Mist. Everything I have looked up is either ridiculously expensive or sounds like heaps of mucking around.

I am kinda hesitant to keep throwing money at it, as there doesn't seem to be a solution which is said to work 100%.

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Re: New feature: YPbPr/RGsB output

Postby Newsdee » Mon Mar 20, 2017 2:05 pm

The MiST SCART cable should do the trick? It's not too expensive. Or you don't have SCART perhaps?

That reninds me I still haven't tried to build mine...

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Re: New feature: YPbPr/RGsB output

Postby bernouilli » Mon Mar 20, 2017 2:50 pm

I just soldered a ypbpr cable yesterday. And it works great. Now I can use my mist on the TV.
However it wasn't easy to solder, as always when it comes to soldering connectors.

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Re: New feature: YPbPr/RGsB output

Postby Sorgelig » Mon Mar 20, 2017 5:34 pm

Amiga core is a special case. Basically it generates "valid" video signals only when you choose standard PAL/NTSC modes.
All other resolutions from Amiga core requires very special multisync monitor sold for Amiga computer. Even scalers won't accept these resolutions.
The only way to output higher resolutions from Amiga is to implement soft scaler inside the core. Unfortunately MiST has not enough resources to implement such scaler.

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Re: New feature: YPbPr/RGsB output

Postby seastalker » Mon May 22, 2017 10:05 am

@magecite

This link is VERY imformative on image technology in layman's terms, and great for anyone be it USA based or not...
https://ancientelectronics.wordpress.co ... n-the-usa/


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