MIST and AV signal

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RobeInie
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MIST and AV signal

Postby RobeInie » Thu Mar 16, 2017 11:42 pm

Hello !!

I would like to know if there is any way to connect MiST to AV monitors ,
I have two AV monitors (one Commodore and one sanyo 'green') with no SCART conector, only AV.

Thanks !

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Re: MIST and AV signal

Postby DrOG » Fri Mar 17, 2017 4:11 am

You can build a VGA-to-YPbPr cable, the details are in this topic: viewtopic.php?f=101&t=31006

This will result a 'luminance' (brightness) signal on the Y plug, which is identical to monochrome composite video. You can feed this signal to your monitors, they will accept it, but there will be no colour (ideal for green Sanyo). Unfortunately only a few cores support this video mode. For your Commodore monitor it would be even better an 'S-Video' output, the Y signal is given, and a C (chroma/colour) instead of Pb or Pr, but it's not implemented (yet).

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Higgy
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Re: MIST and AV signal

Postby Higgy » Fri Mar 17, 2017 7:07 am

Is your Commodore monitor for an AMIGA? Because if it has a 9 pin dtype input you can connect the MiST and all other SCART devices.

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Re: MIST and AV signal

Postby RobeInie » Fri Mar 17, 2017 2:54 pm

HeLLo, thank you for your answers !

My monitor is Commodore 1702, no 9pin. With front AV and rear Chroma , Luma and Audio (mono)

Sanyo green phosphore is only AV, no sound.

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Re: MIST and AV signal

Postby bernouilli » Fri Mar 17, 2017 3:24 pm

You must use some video converter to convert RGBHV to composite.
There are devices that do this and are quite cheap :
http://www.ebay.com/itm/272579761437

But I don't know how would the quality be since there is, in such device, modification of the resolution.

I think it's best if you use some direct converter, either some homeade cable based on the yPbPr cable or something like this :
https://www.electronicsinfoline.com/pin/13466

Or here you can order a converter ( v3.1 will do) :
http://jrok.com/hardware/RGB.html

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Re: MIST and AV signal

Postby seastalker » Mon May 22, 2017 11:29 am

@bernouilli: Curiously, that device has VGA in and VGA out. What's the point/purpose converting to the same output (like those HDMI boxes with HDMI in to out)?

@RobeInie: I have two Commodore CRT monitors that accept RGB (1902 has 9 pin male and 1084S-D1 has 9 pin female) so am very interested too.
Maybe best is some adapter to convert either monitor's input to SCART female input. Something maybe like this:
http://www.ebay.co.uk/itm/PHILIPS-CM883 ... 0754731999

Would that work? Oddly it says C64 is not compatible. I wonder when using my real Atari 800xl/C64 with Scart cable if ANY picture results.
Which provides best video option on a Dell UltraSharp LCD monitor, Samsung LED TV, or Commodore CRT monitor:

-XL and 64: via SVIDEO on all
-MIST via VGA (except on Commodore CRT monitor via above linked adapter)

Would an upscaler provide any benefit at all?

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Re: MIST and AV signal

Postby bernouilli » Tue May 23, 2017 8:26 am

seastalker wrote:@bernouilli: Curiously, that device has VGA in and VGA out. What's the point/purpose converting to the same output (like those HDMI boxes with HDMI in to out)?

Its VGA input is a not a real VGA input, the signal in input is something like the one provided by the mist in 15khz mode, here VGA only stands for the connector. The input signal is then converted to a VGA signal by doubling the lines.

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Re: MIST and AV signal

Postby Higgy » Tue May 23, 2017 1:03 pm

@seastalker - I have a 1084S-D1 and use it with RGB from the MiST but I have to use a Sync Stripper. Some people say they don't need one, but I do. I have a DTYPE-9 PIN to male SCART cable, I plug this into a FEMALE-FEMALE SCART adaptor, which inside I fitted a sync stripper, I then have 5v in (to power the stripper chip) and a 3.5mm audio out jack to feed the 1084 or separate speakers.

Once you have this device you can feed any old console/computer with an RGB output signal to it. NTSC or PAL.

My father-in-law just fixed my 1084S so I have not used it for a few months. I was getting horizontal black lines. He found there was a dry solder joint on a resistor in the vertical sync circuit.

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Re: MIST and AV signal

Postby seastalker » Tue May 23, 2017 6:47 pm

Interesting... I've just been using the MIST with a standard VGA cable plugged into the Dell or LED tv's "PC in." Is that solution lesser than some other cable? I do have Lotharek's scart cable for it but... like the Xl/64 scart cable, they currently sit unused because the crap upscaler box has horrid audio buzz and that was my only scart input. This RGB stuff is so complicated but I know if I find a solution I don't have to think about it again. :) So I may need to add this ebay item so both monitors use the same gender to use the same cabling:
https://tinyurl.com/l5fvpak

@Higgy: How do I know if I need a Sync Stripper or not? Would you graciously provide links to the gear I'd need to buy?

Now I just found this cable and wonder if this would be the best connection on one of the two Commodore monitors:
https://tinyurl.com/mwvxmxk

I do like the idea of future proofing any console/computer I may get later with a simplified universal RGB connection type.

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Re: MIST and AV signal

Postby Higgy » Wed May 24, 2017 7:18 am

Hi,

I don't think there is a way to tell unless you try feeding in a signal. I think Commodore had monitors labelled the same, but they used electronics/tv tubes from other manufactures. Mine I am pretty sure is from Korea.

I used this guide for the Sync Stripper - http://www.mmmonkey.co.uk/composite-syn ... er-lm1881/

Because I already had a MiST VGA/SCART cable for my other CRT's I bought one of these - http://www.ebay.co.uk/itm/21-Pin-Scart- ... XQDnpTXCJh

And placed the electronics inside. You might be able to make things smaller and have a 1084 9PIN DTYPE to SCART FEMALE cable with the sync stripper inside the SCART housing. Being a cheapskate I also found the FEMALE-FEMALE couple cheaper than buying just a SCART FEMALE socket!!

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Re: MIST and AV signal

Postby DrChaos » Wed May 24, 2017 10:37 am

@seastalker:
Testing if you need a sync stripper is quite simple if you know that your monitor is able to handle 15Khz. Just use your VGA cable and switch to 15kHz in one of the 31Khz/15Khz cores. If you don't get a picture with 15Khz you can be pretty sure that it is a sync issue...

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Re: MIST and AV signal

Postby DrOG » Sun Feb 18, 2018 7:11 am

Hi!

I don't know if it's still actual or not, but ordered an RGB-to-Composite/S-Video converter from China:

https://www.aliexpress.com/item/Arcade- ... 0.0.h2g83Y

Tested it briefly compared to a real PAL C64 (see attachments), it gives with MiST source a better quality picture than the original device! Of course MIST RGB is the best, but if you want to use a vintage monitor you already own, this might be a solution.

I could test the S-Video signal only with my EasyC(r)ap USB digitizer, which is a piece of sh*t in aspect of quality, but my TV has no S-Video input (this type of connector is uncommon in Europe), and still better than nothing.

The screenshots are:
1. Original hardware RF out
2. Original hardware Composite out
3. Original hardware S-Vid EasyC(r)ap
4. MIST+Converter Compotite out
5. MIST+Converter S-Vid EasyC(r)ap
6. MIST RGB.

Cheers: Gábor
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Re: MIST and AV signal

Postby Newsdee » Sun Feb 18, 2018 9:20 am

Doesn't SCART support SVideo? You can get one of the simple converters (pin adapter really)

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Re: MIST and AV signal

Postby DrOG » Sun Feb 18, 2018 9:40 am

In theory it might work, but in pracrice this is rare as a white raven...

I gave it a try, but the result was horrible, even corrupted the framebuffer of the TV. The cause of the red artifacts is in my opinion the fact that pin 15 of SCART shares the Red and the S-Video color/chroma signal.
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Re: MIST and AV signal

Postby DrOG » Sun Feb 18, 2018 10:52 am

Made some more tests with the following results:

1. The converter needs a 15kHz (interlaced) sync signal, VGA standard 31kHz (progressive scan) won't work.

2. (Near) standard resolution and framerate recommended (576i@50Hz or 480i/240p@60Hz).

3. The PAL-NTSC switch must be set manually to the appropriate video standard of the input signal, because the converter doesn't autodetect it, and cannot make a flawless conversion between them.

The following cores work well in scandoubler disabled mode, converted to composite:

PAL Standard:
Acorn Electron, Amstrad CPC, Apogee BK-01, Atari 800, Atari ST, BC Micro, C16/Plus4, C64, Didaktik family, Dummy/Menu, Elektronika BK0011M, HT1080z, NES, Primo, Sam Coupé, SMS, Sinclair QL, Specialist MX, Vector 06C, VIC-20, Videoton TVC, ZX Spectrum.

NTSC Standard:
Atari 800, Atari 5200, Bally Astrocade, Chip8/Superchip, Colecovision, C16/Plus4, C64, PET 2001, MSX, SMS, Genesis.

These cores have problems:

Amiga/minimg: oversaturated but generally dark picture, can be (partially) compensated by adjusting the trimmers of the converter.

Atari 2600 and PC Engine cores give a Black&White picture. Sinclair ZX-81 produces a vibration.

Cores with no SDTV standard refresh rates/resolution won't work (i.e. Macintosh, GameBoy).

Didn't test the Arcade cores, but all of them with standard resolutions and refresh rates should work, if they are RGB (15kHz) capable.

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Re: MIST and AV signal

Postby Newsdee » Sun Feb 18, 2018 2:24 pm

Can you try the Apple II core? It gave me some odd results on a PVM... so perhaps the scandoubler disable option isn't working that well on it.

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Re: MIST and AV signal

Postby DrOG » Sun Feb 18, 2018 4:54 pm

As I see, the Apple ][ core does not have a scandoubler disable option (or it's just incompatible with all of my devices in 15kHz mode).

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Re: MIST and AV signal

Postby DrOG » Mon Feb 19, 2018 5:57 am

Yes, there are 2 cores (Apple ][ and Videopac), which output standard 640x480@60Hz VGA, but with POSITIVE Horizontal and Vertical Sync. VESA Standard is NEGATIVE Sync, these cores don't work with my RGB->YUV converter if I use the standard sync merger (BC547 transistor witk 1K and 680 Ohm resistors). I had to XOR the separated POSITIVE H&VSYNC to NEGATIVE CSYNC with a logical IC, both 4070 and 74LS86 works (see attachments.)
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Re: MIST and AV signal

Postby Newsdee » Mon Feb 19, 2018 12:07 pm

Maybe polarity can be reversed in the HDL? Is it just a matter of doing a NOT gate?

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Re: MIST and AV signal

Postby DrOG » Mon Feb 19, 2018 2:13 pm

Perhaps, I'm not sure. The really interesting question is the case of PAL cores: there's no 720x576@50Hz VGA standard, the nearest neighbors are 768x576@60Hz with negative HSync and positive VSync, and 800x600@56Hz with positive HSync & VSync.
There's a list of standard resolutions and refresh rates, and sync polarities: http://tinyvga.com/vga-timing

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Re: MIST and AV signal

Postby seastalker » Mon Feb 19, 2018 8:04 pm

Hey guys, I may repeat this info in a couple of related threads, but I've come up with a potential solution. I'm at least 90% there. It involved the purchase of a few products:

Amazon links:
https://www.amazon.com/gp/product/B01MZ ... UTF8&psc=1

and

https://www.amazon.com/gp/product/B01E5 ... UTF8&psc=1

Connect the latter to the MIST and the former to your monitor: Disclaimer- I am still testing! So far S-video only. This works well on a Sony Triniton huge CRT tv, as well as on my Dell flat panel monitor with an S-video input. Apple II core with Oregon Trail look glorious as does the snowy default "choose your core" core. Amiga looks great too.

Minor glitches do seem to come up with resolution changes. Monitors with adapters plugged in without an input give color bars until you fire up the video source like the MIST. SOMETIMES the colorbars show up temporarily as you wait for a core to load, or if say the Amiga AGA core boots and then you load a game.

I also tested this on a Commodore 1084s monitor... the core select screen looks great but the Apple II mentioned test zoomed in and the monitor had a hard time adjusting. I believe this is a resolution issue so I will experiment with toggling 1 and 0 in each core's .ini file. I must give the Commodore CRT credit- modern tvs just go to black screens when they can't accept an input. The 1084s at least goes "I'll do my best." :)

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Re: MIST and AV signal

Postby DrOG » Tue Feb 20, 2018 6:27 am

See my answer in another topic.


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