RGB to HDMI does this work with a ST

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Oldskool
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RGB to HDMI does this work with a ST

Postby Oldskool » Sun May 15, 2011 12:03 pm

Dear Forum,

Connecting a ST or STE to TV or monitor is not as easy as it used to be.
On this forum I saw a solution which uses a RGB to Svideo converter (in combination with a Svideo to VGA converter).

On Ebay you can buy Scart RGB to HDMI converter devices (about 40 euros).

Theoretically RGB to HDMI should give be better quality than Svideo to VGA.

I was wondering if such a device will work in combination with a ST (scart RGB).
Does anybody have any experience?

simbo

Re: RGB to HDMI does this work with a ST

Postby simbo » Mon May 16, 2011 5:16 pm

yes it will work

well you can try and let us all know
becouse if it does ill buy one
ive bought stuff before and hoped it worked
and do you know that everything worked
except a sdcard to cf adapter and also this works now that uwe fixed hddriver

it cost $1.99 inc post

if its a cheep cable go for it
ill help you wire up the scart side
to a normal atari plug

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Re: RGB to HDMI does this work with a ST

Postby Oldskool » Mon May 16, 2011 8:34 pm

Hi Simbo,

Thanks for your answer.
Maybe I should buy one then. It seems that these devices don't work on an Amiga (read it somewhere on a Amiga forum).
However don't know if the ST RGB output differs much from the Amiga.

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Re: RGB to HDMI does this work with a ST

Postby alexh » Mon May 16, 2011 10:28 pm

I think he's talking about one of these :

http://www.hdcable.co.uk/scart-hdmi-converter.html

A SCART input (via a standard Atari ST RGB SCART cable) to HDMI adapter. Says it takes 50Hz RGBs and 60Hz RGBs so it's the right thing.

Not sure why you'd want one if you're in the UK as your HDMI enabled TV will usually have an RGB SCART input?

simbo

Re: RGB to HDMI does this work with a ST

Postby simbo » Mon May 16, 2011 10:50 pm

as usual its all down to support and output


dont know

i use rgb to vga and be done with games

why use a good atari work horse for games and 'muse'

it makes no sense
use these machines to control areas of your life atleast
where you need a reliable machine ...

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Re: RGB to HDMI does this work with a ST

Postby Shredder11 » Tue May 17, 2011 9:24 am

Muse? Music? Music production and sequencing is the strong point of the Atari and usually needs only monochrome, so that is easy enough to sort out. However if you meant something else by muse, well err carry on! :mrgreen:

Games are all about nostalgia and fun, something that is very therapeutic I find and I should do more of. So they are important in their own way.

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Re: RGB to HDMI does this work with a ST

Postby ICS » Tue May 17, 2011 9:47 pm

Shredder11 wrote:Muse?


Maybe he meant amusement?

Anyhow I was thinking...
Why waste 40€ on a RGB to HDMI converter when you can get a nice used RGB Monitor for 40 bucks or less on ebay that'll make a fantastic picture?
That's what I would invest my money into if I had to choose.
But I'm a weird person.

Cheers.

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Re: RGB to HDMI does this work with a ST

Postby nativ » Tue May 17, 2011 10:47 pm

ICS wrote:
Shredder11 wrote:Muse?


Maybe he meant amusement?

Anyhow I was thinking...
Why waste 40€ on a RGB to HDMI converter when you can get a nice used RGB Monitor for 40 bucks or less on ebay that'll make a fantastic picture?
That's what I would invest my money into if I had to choose.
But I'm a weird person.

Cheers.


Not weird! practical! so many really great pieces of kit go to skips! I have checked out CRT monitors and yep for a 21" Vga you can pay £1 to £35 maybe more, some were £750+ new
I ended up getting a Mitsubishi 33" crt svideo/bnc(vga) beast! for a £1

even an LCD with analog tuner would be a good pickup. In Dorset we've been digital a while and those tv's have made it onto freecycle!
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Re: RGB to HDMI does this work with a ST

Postby joska » Wed May 18, 2011 7:07 am

ICS wrote:Why waste 40€ on a RGB to HDMI converter when you can get a nice used RGB Monitor for 40 bucks or less on ebay that'll make a fantastic picture?


Because with an RGB to HDMI you can connect your ST to any modern monitor with HDMI. If you buy a separate (huge!) CRT for the ST you also need somewhere to put it.
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Re: RGB to HDMI does this work with a ST

Postby wongck » Wed May 18, 2011 9:23 am

joska wrote: you also need somewhere to put it.

use it as a table.... :P
My Stuff: FB/Falcon CT63/CTPCI+ATI+RTL8139+USB 512MB 30GB HDD CF HxC_SD/ TT030 68882 4+32MB 520MB Nova/ 520STFM 4MB Tos206 SCSI
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My Atari stuff for sale - click here for list

simbo

Re: RGB to HDMI does this work with a ST

Postby simbo » Wed May 18, 2011 10:10 am

there is a big problems with converting non interlaced atari signals
to interlaced vga
not to mention the added flicker
and thats the scaller used to make it the right size

perhaps someone needs to take a vhdl chip and redesign the shifter
to give a plug in shifter replacement that outputs as normal
and also has a standard vga output direct
ive bleeted on about it before as far as finding the right ic's
someone even made an external one
but imho replacing the shifter is a the only reliable way

you can then simply work on and flash the code block of the vhdl fpga or micro
from the atari to iron out any bugs

i have modeled the shifter in c++ callback code dll if someone wants the sources
in proteus vsm simulator i have an st machine 80% built

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Re: RGB to HDMI does this work with a ST

Postby alexh » Wed May 18, 2011 3:28 pm

simbo wrote:there is a big problems with converting non interlaced atari signals to interlaced vga

Can you please explain what you mean?

I thought that both Atari low resolution and VGA were progressive?

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Re: RGB to HDMI does this work with a ST

Postby joska » Wed May 18, 2011 5:41 pm

simbo wrote:there is a big problems with converting non interlaced atari signals
to interlaced vga


HDMI, not VGA.

I have seen a s-video -> HDMI converter in use (in a AV receiver) and it works really, really well.
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Re: RGB to HDMI does this work with a ST

Postby simbo » Sun May 22, 2011 9:54 pm

this is good news joska becouse it means this adapter may work quite well
as you know
non interlaced signals provide two frame stepping like a car
21 32 43 ... etc atari X
where an interlaced signal is pc X
1 2 3 4 as frames and what is used by tv's that scale up etc to vga
on modern wide screens

as frames of display and setttings
as most modern lcd etc have 'forgotten' the retro use
as by there core programmers have done

the problem comes with 50/60hz games
and st setup before a game etc
by far the best LCD or better LED TV
must have scart and svideo and VGA AND ETC
as most do
however early 15" lcd or plasma tv has a better hold of scart
rgb is what most need to as best as vga
you will not get a better picture using VGA
you will just get a different time frame setup
wake up use rgb {scart } and be done with it
why moan
its usualy the dot pitch of the monitor lcd tv or etc that make it look nice or not


and thats that

the best result i had was with a scart 15" square LCD TV
it used the non stretch frame
so new wide screen was the one scalled

not the atari stretched to fit wide screen

buy one on ebay and a switch box or two and be done with it!!!

simbo

Re: RGB to HDMI does this work with a ST

Postby simbo » Sun May 22, 2011 10:08 pm

perhaps some idiot programmer for the cores of lcd wide screen tv
will allow for the retro etc
then he will make a few quid for sure
otherwise we are stuck to ?multistandard?? 'tv'

its a point to note 'some' most lcd monitors
can uses other standards if you 'tweek' a few track links etc change the 0R links
much like radios coms units 'black boxes'
links on the pcbs inside can 'unlock' features of some TV's and lcd led monitors

best to investigate lcd etc stuff carefully
make sure it supports both 19Khz and 15Khz rates

best is 20 - 50Khz and 15" square screen

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Re: RGB to HDMI does this work with a ST

Postby StEeLz » Sat May 26, 2018 6:02 am

Hi everyone,
I also wanted to try connecting my ST on some modern display. I bought and tried various SCART->HDMI solutions and made a quick video to show the results.
I compared the different models, and shared my findings to the community:
https://www.youtube.com/watch?v=c25dlHFW584
Only based on my preferences and experience but at least there are options!
Cheers

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Re: RGB to HDMI does this work with a ST

Postby mikro » Sat May 26, 2018 6:51 am

StEeLz wrote:I compared the different models, and shared my findings to the community:
https://www.youtube.com/watch?v=c25dlHFW584

Hey, this is really a neat idea! Naturally, these converters don't care about Hz/V frequencies, only about colour signals. I'm wondering how come nobody has thought about this before. Thumbs up!

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Re: RGB to HDMI does this work with a ST

Postby wietze » Sat May 26, 2018 11:22 am

StEeLz wrote:Hi everyone,
I also wanted to try connecting my ST on some modern display. I bought and tried various SCART->HDMI solutions and made a quick video to show the results.
I compared the different models, and shared my findings to the community:
https://www.youtube.com/watch?v=c25dlHFW584
Only based on my preferences and experience but at least there are options!
Cheers


First of all, great work, seems like the same research i did over the years ;).

What i lack from your presentation report is: 50hz actual refreah or not. From experience i know that the 2nd active videoconveeter you describe doeant outpht true 50fps feom the atari.

Im curious to see if this is the case with your recommended solution.

Regarda
Wietze

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Re: RGB to HDMI does this work with a ST

Postby evil » Sat May 26, 2018 12:13 pm

wietze wrote:
StEeLz wrote:Hi everyone,
I also wanted to try connecting my ST on some modern display. I bought and tried various SCART->HDMI solutions and made a quick video to show the results.
I compared the different models, and shared my findings to the community:
https://www.youtube.com/watch?v=c25dlHFW584
Only based on my preferences and experience but at least there are options!
Cheers


First of all, great work, seems like the same research i did over the years ;).

What i lack from your presentation report is: 50hz actual refreah or not. From experience i know that the 2nd active videoconveeter you describe doeant outpht true 50fps feom the atari.

Im curious to see if this is the case with your recommended solution.


I've done the research like Wietze as well.

The video mention that no monitor of the last 30 years support 15 kHz horizontal frequency; this is not quite correct: http://15khz.wikidot.com/
All projectors I've connected with a ST-VGA colour cable have also eaten the signal fine as well.

The first choice is to get a monitor that supports 15 kHz and a VGA cable, here are two variations of cables:
1. https://goo.gl/1hBBSv -> Direct cable ST RGB-VGA
2. https://goo.gl/FuSp1X -> A switchbox that let you select RGB or Monochrome mode (Search for MCSWITCH), just add a normal VGA cable


Second choice convert the image to VGA/31kHz or HDMI

The GBS-8220 is a budget scan doubler that will turn the ST RGB into a VGA 31kHz signal. The caveman got a review of it: https://www.youtube.com/watch?v=q3J4QJsn0ig

All those cheap HDMI converters; I've bought a ton of them and none have done 50 Hz motion. They have either dropped every second field of the PAL signal or added a de-interlace that merges fields. Either way, the end result is 25 Hz motion. Not good enough.

The classic grand daddy of RGB-HDMI converters is the XRGB mini framemeister (https://goo.gl/13LjjF). It's very costly, about 290 euros plus shipping and vat. That one have proper 50 Hz motion, but carries some input lag.

The new kid on the block (ok, it's been out a couple years..) is the Open Source Scanline Converter (https://goo.gl/mmLBTB), or OSSC for short. It's still an expensive device, but not quite like the XRGB. The OSSC is completely lag free and I've connected the ST to both it's VGA and RGB-Scart inputs, it works well. Of course the OSSC will output proper 50/60 Hz motion.

I've also tested the OSSC on Falcon; it will turn the Falcon VGA signal into perfect HDMI and the Falcon RGB signal works equally like on ST. However; when the Falcon switches between non-interlace to interlace there is a blackout time of a second or two. I had hoped to be able to frame grab the HDMI-signal to capture Falcon demos in premium quality, but the blackout ruined those plans. I read the that XRGB mini is a lot worse and the blackout can last over five seconds. Another thing with the black out is that the HDMI-audio will cut off during those couple of seconds.

Another note about OSSC is that it will convert audio to HDMI (stereo audio from the STe phono jacks/Falcon 3.5mm rather than the mono sound from the monitor port).

Ok, end of rant :)

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Re: RGB to HDMI does this work with a ST

Postby mikro » Sat May 26, 2018 7:09 pm

evil wrote:All those cheap HDMI converters; I've bought a ton of them and none have done 50 Hz motion. They have either dropped every second field of the PAL signal or added a de-interlace that merges fields. Either way, the end result is 25 Hz motion. Not good enough.

Excuse my lack of proper eyesight :) - so the demo at the end of the YT video is actually running 25fps? Can't really tell even when viewing in HD, looked very smooth to me.

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Re: RGB to HDMI does this work with a ST

Postby evil » Sat May 26, 2018 8:21 pm

mikro wrote:
evil wrote:All those cheap HDMI converters; I've bought a ton of them and none have done 50 Hz motion. They have either dropped every second field of the PAL signal or added a de-interlace that merges fields. Either way, the end result is 25 Hz motion. Not good enough.

Excuse my lack of proper eyesight :) - so the demo at the end of the YT video is actually running 25fps? Can't really tell even when viewing in HD, looked very smooth to me.


The video uploaded to Youtube is 30 FPS so it's difficult to frame-step it to see if it's missing frames, I did download the file to inspect closer. The particular device tested lastly in the video I can't recall having tested, so it's good news if it really does the job properly.

The fullscreen MPP-image shown from the demo (https://youtu.be/c25dlHFW584?t=630) is dual field and flickers slightly on a true 50 Hz screen, I can't see any of that from the video here. But it is blurry and the camera captured it at 30 Hz so the slight flicker would likely blend together anyways.

A way to test is running a program that alters between two colours every second frame. If it flickers like mad, it's good, if it doesn't, it's bad. So I made a quick one for testing: http://ae.dhs.nu/tmp/flicker.zip

The screen will cycle between green and purple every second VBL. A converter that only show one field will either have a green or purple image and a converter that add together the fields will likely be grey-ish.

Oh and of course the demo in the video look smooth, it's a dhs demo ;-) haha

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Re: RGB to HDMI does this work with a ST

Postby wietze » Sun May 27, 2018 11:12 am

mikro wrote:
evil wrote:All those cheap HDMI converters; I've bought a ton of them and none have done 50 Hz motion. They have either dropped every second field of the PAL signal or added a de-interlace that merges fields. Either way, the end result is 25 Hz motion. Not good enough.

Excuse my lack of proper eyesight :) - so the demo at the end of the YT video is actually running 25fps? Can't really tell even when viewing in HD, looked very smooth to me.


GBS actually does 50 fps conversion. The HDMI solutions I examined do a 25 fps solution. I have no idea what the thing in the video does; Id like to know :)

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Re: RGB to HDMI does this work with a ST

Postby StEeLz » Sun May 27, 2018 10:05 pm

All right, first of all, thanks you all for the valuable comments. I was not expecting this thread to revive after all these years.
It seems most of you were concerned about the ability to render 50/60Hz properly, I must admit I didn't plan this, my main concern was to be able to plug some modern TV through HDMI.
Fair enough, I actually tested further and will compile a quick video with the findings. I will upload it in 60FPS, and will also do slow motion (as best as my generic capture devices can do it).

Long story short:
- The VGA-> HDMI DOES 50 & 60 Hz with no problem
- The VGA-> HDMI DOES output proper 50/60 motion and does not blend frames
- The VGA-> HDMI DOES pass the flicker test (Flickers, both green and purple)

- The SCART Upscaler does NOT render 50Hz properly (and I actually discovered it's the reason for the bouncing on the demo from the first video)
- The SCART Upscaler does NOT output proper 50/60Hz motion and does a poor field blend job
- The SCART Upscaler does NOT pass the flicker test (No flicker, Grey output)

Thanks @evil for the flicker program btw!

My theory (please keep me honest) is that the Monitor RGB output is progressive as most VGA resolutions out there. I can't even see a reason why it would be interlaced in the first place as the Atari Monitors are not TVs, and it was simpler to implement a progressive frame versus interlaced. (I wish I had a real high-speed camera to see the actual raster!). I will maybe check the monitor's schematic later to confirm. However, I can understand why the Modulator needs to interlace the signal for the TVs. There has been multiple threads debating all this and I am not sure where the truth lies.

Note 1 : Yes, SOME monitors can render 15KHz but the choice is somewhat limited. I was trying to be as generic as possible for someone who wants to plug it on a modern TV.
Note 2 : I found some even cheaper VGA->HDMI converters on Amazon, as low as CAD$14.00 but haven't tested those, maybe the "bad" ones tested by @evil.
Note 3 : I should have mentioned, I live in Canada so I found the VGA->HDMI on the Canadian store, prices also in CAD.

Cheers!

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Re: RGB to HDMI does this work with a ST

Postby wietze » Mon May 28, 2018 5:49 am

Thanks for confirming that the vga>hdmi works at 50hz output. I have just ordered one to add to my collection of converters. The VGA > HDMI converter I already have does not produce any output. Im interested to see if this one does in my case!

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Re: RGB to HDMI does this work with a ST

Postby mikro » Mon May 28, 2018 4:27 pm

Glad I had ordered the converter earlier and now it's on its way to me. :) I second StEeLz, there's no reason why it shouldn't work -- there's no TV crap anywhere, just pure R/G/B signals converted to the HDMI standard. But after hearing Evil's experience I wasn't so confident anymore, glad to hear my doubts cleared. :)


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