Best/newest method to convert RGB to Composite

The place for all discussion on gaming hardware
daty2k1
Posts: 69
Joined: Mon Mar 09, 2020 9:31 am

Best/newest method to convert RGB to Composite

Post by daty2k1 »

Hello,

Not sure if this was already answered recently but I was looking for the best method to convert RGB to composite. I like the sharpness of RGB as much as the next guy but I'd like to be able to switch to composite for some games.

My understanding is that it's not as simple as one would hope. What is considered the best way to do it? Or is there any newer method I have not heard of?

Thanks
neorichieb1971
Posts: 7667
Joined: Wed Jan 26, 2005 1:28 am
Location: Bedford, UK
Contact:

Re: Best/newest method to convert RGB to Composite

Post by neorichieb1971 »

What produces RGB but not composite?
This industry has become 2 dimensional as it transcended into a 3D world.
daty2k1
Posts: 69
Joined: Mon Mar 09, 2020 9:31 am

Re: Best/newest method to convert RGB to Composite

Post by daty2k1 »

Nothing but the goal would be to daisy chain this after a gscartsw so that it can be used with all my consoles.
User avatar
orange808
Posts: 3196
Joined: Sat Aug 20, 2016 5:43 am

Re: Best/newest method to convert RGB to Composite

Post by orange808 »

I use a Time Harvest Supergun as an encoder. Looks fine. Genesis/MD has a certain authentic charm that looks really nice on a consumer television, but clean RGB is better on the big screen. I imagine some people also use emulation boxes and they might chain a DAC (and sync combiner?) in front of an encoder.
We apologise for the inconvenience
User avatar
kitty666cats
Posts: 1270
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: Best/newest method to convert RGB to Composite

Post by kitty666cats »

https://www.ebay.com/itm/174151197805

https://www.ebay.com/itm/153893570916

https://www.ebay.com/itm/162243288930

Honestly you’re probably gonna get better composite using Svid out from one of these and then a 2nd separate device like an Extron YCS
User avatar
kitty666cats
Posts: 1270
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: Best/newest method to convert RGB to Composite

Post by kitty666cats »

There’s also the AxunWorks unit but it’s super expensive.

Another option is JROK encoders.
https://www.ebay.com/itm/284936665148?m ... media=COPY

There’s other arcade encoders on eBay sometimes, I don’t see any right now though

Also:
https://www.js-technology.com/store/ind ... r=category
daty2k1
Posts: 69
Joined: Mon Mar 09, 2020 9:31 am

Re: Best/newest method to convert RGB to Composite

Post by daty2k1 »

Thank you all for the suggestions. Seems like it's still not as straightforward as I'd like. I wish Mike Chi offered an RGB2Composite.

I remember seeing the one from AxunWorks last time I searched for that. It is indeed expensive. I would almost make the jump but $45 for shipping is just ridiculous. Almost half the price the unit itself.

Maybe I'll just wait until a good solution is available for the MiSTer.
User avatar
orange808
Posts: 3196
Joined: Sat Aug 20, 2016 5:43 am

Re: Best/newest method to convert RGB to Composite

Post by orange808 »

Still a bargain if you figure in the cost of all the stolen downloaded roms.
We apologise for the inconvenience
User avatar
Fudoh
Posts: 13015
Joined: Mon Mar 06, 2006 3:29 am
Location: Germany
Contact:

Re: Best/newest method to convert RGB to Composite

Post by Fudoh »

I wish Mike Chi offered an RGB2Composite.
Mike did design a RGB to composites solution though. It's the design sold by retroupgrades UK (current out of stock though).
daty2k1
Posts: 69
Joined: Mon Mar 09, 2020 9:31 am

Re: Best/newest method to convert RGB to Composite

Post by daty2k1 »

Fudoh wrote:
I wish Mike Chi offered an RGB2Composite.
Mike did design a RGB to composites solution though. It's the design sold by retroupgrades UK (current out of stock though).
Ah good to know, thanks. I think I'll try that once it's back in stock.
User avatar
kitty666cats
Posts: 1270
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: Best/newest method to convert RGB to Composite

Post by kitty666cats »

https://www.ebay.com/itm/174578156353

There’s also a scart version of the linuxbot unit.

And yeah, I suggest actually chaining any of the linked units with a Extron or Kramer transcoder that converts Svid to Composite for best results
User avatar
Ed Oscuro
Posts: 18654
Joined: Thu Dec 08, 2005 4:13 pm
Location: uoıʇɐɹnƃıɟuoɔ ɯǝʇsʎs

Re: Best/newest method to convert RGB to Composite

Post by Ed Oscuro »

kitty666cats wrote:https://www.ebay.com/itm/174151197805

https://www.ebay.com/itm/153893570916

https://www.ebay.com/itm/162243288930

Honestly you’re probably gonna get better composite using Svid out from one of these and then a 2nd separate device like an Extron YCS
Looked these up for posterity because I like your suggestions: 1) "RGB VGA to NTSC S-video and composite transcoder/encoder" with 5V USB-C and HD15 for RGBHV on front, 2) "FSR RN-1 Converter Module RGB To NTSC Encoder RN1" 3) "MITO RGB/NTSC ENCODER MODULE 68-333 RGB IN/OUT COMPOSITE VIDEO MONO OUT IR IN"
User avatar
NoAffinity
Posts: 1018
Joined: Mon May 07, 2018 5:27 pm
Location: Escondido, CA, USA

Re: Best/newest method to convert RGB to Composite

Post by NoAffinity »

Wei-ya CV-04 is very good for s-video, but image is a bit "crawly" for composite output. Cant find any for sale, so maybe a double bust but I mention it for posterity.

Sent from my SM-G955U using Tapatalk
User avatar
kitty666cats
Posts: 1270
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: Best/newest method to convert RGB to Composite

Post by kitty666cats »

Ed Oscuro wrote:
kitty666cats wrote:https://www.ebay.com/itm/174151197805

https://www.ebay.com/itm/153893570916

https://www.ebay.com/itm/162243288930

Honestly you’re probably gonna get better composite using Svid out from one of these and then a 2nd separate device like an Extron YCS
Looked these up for posterity because I like your suggestions: 1) "RGB VGA to NTSC S-video and composite transcoder/encoder" with 5V USB-C and HD15 for RGBHV on front, 2) "FSR RN-1 Converter Module RGB To NTSC Encoder RN1" 3) "MITO RGB/NTSC ENCODER MODULE 68-333 RGB IN/OUT COMPOSITE VIDEO MONO OUT IR IN"
Unfortunately the 3rd one uses a weird 13pin (Atari ST?) input, so would need to figure out the pinout.

The FSR one might have proper NTSC subcarrier and not need to run through any secondary device, haven't tried it so I can't be sure.

The Linuxbot one, I forget if it needs RGBHV or RGBS on the input side (or if it can take either... I would message the seller)
User avatar
kitty666cats
Posts: 1270
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: Best/newest method to convert RGB to Composite

Post by kitty666cats »

https://ultimatemister.com/product/mist ... e-s-video/

Looks like this site stocks the Antonio Villena one now
User avatar
NewSchoolBoxer
Posts: 369
Joined: Fri Jun 21, 2019 2:53 pm
Location: Atlanta, GA

Re: Best/newest method to convert RGB to Composite

Post by NewSchoolBoxer »

I prefer S-Video over RGB for some (maybe most?) SNES games and native Composite for nearly all Genesis where the artist's intention was to use blurry video for dithering. I've seen a YouTube review for a Chinese product that must be converting RGB to S-Video for Genesis/Mega Drive.
kitty666cats wrote:https://www.antoniovillena.es/store/pro ... o-adapter/

IDK how I forgot this one
I'm impressed the description tells you it uses AD723. Guess what I would try as first pass at DIY but announcing the chip you use is kind of unprecedented since it removes a barrier to cloning. RetroTINK and PixelFX blurring out the text on their IC pics is hilarious imo but it's to fight cloning efforts.

I think €35,00 is a fair price. I presume cost to manufacture is half that and $17.50 would be very hard to beat buying at non-bulk quantity serving a niche market. Ships globally so that's cool. What surprises me just as much is not marketing it to arcade PCB / super gun owners.

AD723 from Mouser:
Image

So ultimatemister selling what I also think is the exact same product for €29,90 (excl. VAT), they must have made a huge bulk order or bought a mass amount on clearance.
Last edited by NewSchoolBoxer on Thu Aug 25, 2022 6:02 pm, edited 1 time in total.
fernan1234
Posts: 2175
Joined: Mon Aug 14, 2017 8:34 pm

Re: Best/newest method to convert RGB to Composite

Post by fernan1234 »

This is something I've wanted to do with my RGB setup for a long time to take advantage of the clean audio from my custom RGB cables while being able to switch it up with composite video as needed, but never found what feels like a good enough solution.

I've been really curious about trying one of those FSR encoders for a while, looks promising with the usual RGBS inputs, but it needs you to wire a power supply for it and I lack the ability for this. For a long time there was one which included a PSU but it was bundled with some huge JBL receiver that I didn't want to deal with.

The MITO one uses sync on blue according to the description, guess some arcade boards use that, but would be pretty inconvenient for the usual RGBS stuff.

I've tried both the Linuxbot converter and the Axunworks, the Axunworks does have a cleaner output for both s-video and composite compared to the Linuxbot, but composite is still too noisy to be acceptable. Might as well use the original composite cables and accept the noisy audio instead. Also I'd say the difference for most people in s-video won't be big enough to justify the extra cost of the Axunworks--I just got lucky with a second-hand deal for my unit.
kitty666cats wrote:And yeah, I suggest actually chaining any of the linked units with a Extron or Kramer transcoder that converts Svid to Composite for best results
This is the next thing I'm going to try. S-video from the Axunworks into an Extron YCS. From what I understand encoding from s-vid to composite should preserve 240p, unlike the other way around.
User avatar
NewSchoolBoxer
Posts: 369
Joined: Fri Jun 21, 2019 2:53 pm
Location: Atlanta, GA

Re: Best/newest method to convert RGB to Composite

Post by NewSchoolBoxer »

fernan1234 wrote:I've tried both the Linuxbot converter and the Axunworks, the Axunworks does have a cleaner output for both s-video and composite compared to the Linuxbot, but composite is still too noisy to be acceptable. Might as well use the original composite cables and accept the noisy audio instead. Also I'd say the difference for most people in s-video won't be big enough to justify the extra cost of the Axunworks--I just got lucky with a second-hand deal for my unit.
Thanks, that's useful to know. I have a 2009 LCD TV that takes RF, composite, component and progressive RGB over VGA but no s-video. I thought to combine the luma and chroma into composite with cheap passive adapter but the video is rainbowed to hell and back and SNES composite looks better. The datasheets for AD723 and AD725 gave me the idea of forming a luma trap filter. Theory is make a Twin-T notch filter that removes the 3.58 MHz NTSC luma information or 4.43 MHz PAL to sacrifice a small amount of brightness in exchange for avoiding the rainbow artifacts and dot crawl when luma and chroma get combined then separated imperfectly by the TV.

There is a MiSTer thread on Reddit I posted in to give advice on making the notch filter without an inductor by using 3 capacitors and 3 resistors since you're looking at 5% tolerance on the inductor + magnetic field interference versus 1% or better for the capacitors. I think the inductor approach is okay if you're shooting for 'realistic blurry' composite video. I found reference to a more complicated bandstop filter design with 500 kHz bandwidth that uses 2 inductors. I assume looks worse in practice due to the sizeable about of luma removed. Could look better on the 1950s TVs with primitive Y/C separation and lower quality capacitors it was designed for.

Scanning the AD723 and AD725 specs, AD725 has lower error but costs more. Seems self-serving then to say AD723 is best-in-class but I haven't spent the money to confirm.

I'm curious what approach the Extron and Kramer transcoders take then to turn s-video into composite. This isn't rocket science. The part of the 1950s design I think is worth considering is the slight added delay on the luma, such as with a small series capacitor, to keep the timing synced to the delay chroma gets in the video processing. I think it's interesting that the NESDev backwards approach to turn composite into bad s-video puts a 1nF capacitor on the chroma, essentially giving it the delay it would have gotten from Y/C separation. At least I think that's the reasoning. Smaller 470pF used here.
User avatar
kitty666cats
Posts: 1270
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: Best/newest method to convert RGB to Composite

Post by kitty666cats »

https://www.ebay.com/itm/324871598663

This looks exceedingly awesome, hah

Image
ldeveraux
Posts: 1113
Joined: Thu Mar 01, 2018 10:20 pm

Re: Best/newest method to convert RGB to Composite

Post by ldeveraux »

kitty666cats wrote:https://www.ebay.com/itm/324871598663

This looks exceedingly awesome, hah

Image
Send a best offer or I will [WINKING FACE]
User avatar
kitty666cats
Posts: 1270
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: Best/newest method to convert RGB to Composite

Post by kitty666cats »

https://www.aliexpress.com/item/3256804076944933.html

This looks interesting, and specifically designed for games
viletim
Posts: 550
Joined: Mon Aug 07, 2006 6:44 am
Location: Sydney, Australia
Contact:

Re: Best/newest method to convert RGB to Composite

Post by viletim »

All the video encoders listed in this thread, with the exception of the professional ones like Extron, are not very good for video games. To make good composite video the colour carrier needs to be synchronised to the incoming video signal with a PLL. Without this you get a horrible crawling effect on sharp edges. Game consoles tend to derive the carrier frequency used by internal the internal composite video encoder by dividing down the clock from the graphics system. It's synchronised already. As a result, the native composite from consoles has the potential to be better quality than what these converter boxes can produce.
daty2k1
Posts: 69
Joined: Mon Mar 09, 2020 9:31 am

Re: Best/newest method to convert RGB to Composite

Post by daty2k1 »

Yeah well now I'm even more lost :mrgreen:
kitty666cats wrote:https://www.ebay.com/itm/324871598663
This looks exceedingly awesome, hah
This one is almost tempting though...
User avatar
kitty666cats
Posts: 1270
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: Best/newest method to convert RGB to Composite

Post by kitty666cats »

daty2k1 wrote:Yeah well now I'm even more lost :mrgreen:
kitty666cats wrote:https://www.ebay.com/itm/324871598663
This looks exceedingly awesome, hah
This one is almost tempting though...
If that last one allows you to input a black burst signal on the 'Reference' input (not certain if that's what it's for) then maybe it'd provide some near-"perfect" composite? NTSC needs a 3.558 MHz subcarrier, PAL needs 4.43MHz (I think those are the numbers, IDK...).

Using a black burst generator just for RGB to composite from a video game console would be ridiculously 'extra', though

~~~~~~~~~~~~~~~~~


There was a Harmonic Research component to Svid/composite encoder on eBay recently, I think that unit would have out-performed most anything here
https://marc.info/?l=mythtv-users&m=109885072912662&w=2
"From their website:
|"If you can furnish broadcast-quality RGB or Component signals, then these
|units can generate broadcast-quality video*. All sync and timing signals
|are regenerated from the input reference and include a true phase locked
|subcarrier."<snip>
|"The inputs must be analog, and they must be reasonbly close to the video
|scan rates (15,750 Hz for NTSC, 15,625 Hz for PAL)."

Unfortunately those are impossible to find. Shank, that YouTuber, picked it up when I linked it in the CRT Discord. From the photos he took, it looked like a better composite output that what I have seen from others
fernan1234
Posts: 2175
Joined: Mon Aug 14, 2017 8:34 pm

Re: Best/newest method to convert RGB to Composite

Post by fernan1234 »

fernan1234 wrote:This is the next thing I'm going to try. S-video from the Axunworks into an Extron YCS. From what I understand encoding from s-vid to composite should preserve 240p, unlike the other way around.
Finally got around to testing this out, and this combination works really well!

The Axunworks actually has an NTSC 3.58 trimpot on the bottom side that can be adjusted to minimize crawling artifacts, and this also benefits the S-video -> Extron YCS encoding. In contrast to the very soft, blurry, and dull composite output from the RGB2YC, the YCS's composite output is very sharp and colors are great, maybe close to the original composite from the console itself (tested with a Super Famicom's RGB -> RGB2YC -> YCS 100). In fact, it may be too sharp to the point that it doesn't 100% blend pseudo transparency patterns (checked with Kirby 3), which ironically is one of the reasons why I'd care about doing this kind of silly thing. That said, the blending is enough IMO and should work well with PS1, Saturn, and such.

I expect the YCS to work well with the more easily accessible Linuxbot's s-video, though this does lack the 3.58 adjustment of the RGB2YC, so there may be more crawling noise with it.

Pretty happy with this solution, which I'll probably end up using only once or twice lol. I think my search for an all-in-one encoder can be put to rest.
User avatar
kitty666cats
Posts: 1270
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: Best/newest method to convert RGB to Composite

Post by kitty666cats »

https://aliexpress.us/item/3256804355690020.html

https://aliexpress.us/item/3256804542825189.html

New stuff! 2nd one has Svid out but not composite

The photos in the description for the first link look nice
User avatar
VEGETA
Posts: 425
Joined: Mon May 31, 2021 10:40 am

Re: Best/newest method to convert RGB to Composite

Post by VEGETA »

Hello

it is very easy, just use AD725 (very cheap from Rochester) and you will get S-video and composite. easiest DIY project if you have the right connectors you plan to use.

For me, I am designing a product to convert either VGA or SCART RGB into component, composite, and s-video as well as strip H,V, and CSYNC signals. Kinda good but gonna be on the pricey side since all components are high quality. maybe retails for 125$ or so. here are some preliminary pics. still needs time to be finished, as I am about to evaluate my first product (dreamcast low noise powers supply).

you could go the other route of digitizing your rgb signals then use a video DAC which can do this, like ADV7391 or so. but this one requires microcontroller and so on, not as straightforward as AD725 solution.
fernan1234
Posts: 2175
Joined: Mon Aug 14, 2017 8:34 pm

Re: Best/newest method to convert RGB to Composite

Post by fernan1234 »

VEGETA wrote:Hello

it is very easy, just use AD725 (very cheap from Rochester) and you will get S-video and composite. easiest DIY project if you have the right connectors you plan to use.

For me, I am designing a product to convert either VGA or SCART RGB into component, composite, and s-video as well as strip H,V, and CSYNC signals. Kinda good but gonna be on the pricey side since all components are high quality. maybe retails for 125$ or so. here are some preliminary pics. still needs time to be finished, as I am about to evaluate my first product (dreamcast low noise powers supply).

you could go the other route of digitizing your rgb signals then use a video DAC which can do this, like ADV7391 or so. but this one requires microcontroller and so on, not as straightforward as AD725 solution.

This looks nice, but you should make it accept not only RGBHV via the D-Sub connector, but also RGBS via D-Sub, and also make sure it works with both TTL and video level sync. Then it would be perfect in terms of connection options!
Post Reply