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GreenAntz RGB to component transcoder

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The GreenAntz RGB to component transcoder is now complete and finished versions are available!!  :applaud:

NEWS: GreenAntz v1.9 is now available, with significant improvements. More here

*What does it do?*

GreenAntz can take RGB from your PC/VGA and give you a high quality analogue component (YPbPr) output suitable for most SDTVs (CRTs).

The entire unit is about the same size as a small packet of cigarettes. It takes VGA RGBHV (D-SUB-15) input and standard RCA component outputs. It takes 5v input (max. 5.5v) via USB but can also accept direct input of 5v from almost any decent source including internal PC power ("MOLEX"), DC power supply for arcade PCBs or from a internal console source.

The only other things you'll need will be some standard cables: a VGA male to VGA male cable, a set of component video cables and a USB-C charging cable for power.

*Why is it special?*

GreenAntz gives very high quality colour-space conversion. We've done the math, spent months collecting data, bared our eyeballs until they are dry, and tweaked everything as much as we can. This, combined with superior csync generation and mixing into the luma gives a YPbPr picture quality that is almost indistinguishable from RGBs. In fact, I can't tell its not butter™

Some short demo videos:



If you still aren't happy there are "colour balance" and "luma" pots, which come preset to "ideal" values. Tweak them if you dare ::)

You just plug it in and it works. It is so easy I've started using GreenAntz and a component-modded TV for all my desktop arcade PC development setup.  With GreenAntz, component TVs will take video modes generated by CRT_emulator as effortlessly as any RGBs arcade monitor or TV - possibly better because of the inbuilt csync generation. It is "zero-delay" and GreenAntz will not interfere with any 15khz video modes, allowing them to pass directly through.

GreenAntz will accept separate raw H&V sync input and combine that via XNOR logic into a csync suitable for most SDTVs (CRTs) with component inputs. That means you don't need to worry about generating composite sync by the driver or any other means. The sync is then filtered, trimmed and injected into the Y signal at the right level. It is designed for seamless use with CRT_emulator based PCs, and other devices, that output 15khz. It will also work with other 15khz RGBHV inputs such as from ArcadeVGA cards or other software like Soft15khz.

The PCB footprint also allows GreenAntz to be built for SCART input from consoles and other devices. SCART builds usually have no need for XNOR csync, so GreenAntz can alternatively be built with a "sync stripper and cleaner" circuit to make it more suitable for insertion into the Y signal.

With a little adaptation, GreenAntz can also be made to work with arcade game PCBs. We designed it for maximum flexibility and included separate 5v + GND landing pads for alternative applications. Using the XNOR sync is entirely optional for custom builds. It is also possible to do blended builds or to attenuate the XNOR sync logic to better suit your exact purpose.


Our original idea was to make kits available cheaply, so that hobbyists and arcade repairers could access GreenAntz cheaply for their projects. That is why we've stuck with mostly through-hole components. However, a few SMD parts have snuck in (THS7374 amplifier IC, 3 logic gate chips, and the USB-C port!) which are making it difficult to offer that option reliably. I'm hoping that we can have a discussion about the possibilities so let's talk more.  :blah:


Retrogaming *easily* on component SDTVs has long been in the back of my mind. PC/arcade RGBHV outputs don't translate well without expensive and big boxes, and/or complicated setups.

Many people have easy access to component TVs, especially in the US, but finding RGB input TVs is usually much harder (unless you live in Europe). Some of those people would come here looking for help, but often go away sad.

Fast-forward to three years ago, and I picked up four 20" TVs that I thought I could RGB mod, but I wasn't able to. However, I was able to component-mod them. Trouble was, I had no handy transcoder to run component signals into them! So I researched a few old designs from the Sega forums ("Ace"), read some datasheets and stuff, and improved on them. I bread-boarded my design and got a reasonable result. However my life was steamrolling forward and I'd run out of time to develop the project, so I published my progress & designs on the Aussie Arcade forums about two years ago:

From there I met a fellow Aussie from Melbourne, "dekdek", who took the design, added some flair, and turned it into a prototype PCB. We started collaborating directly to improve the prototype designs. We helped each other and both learned a lot.

One way to say it: this is our COVID-19 social innovation project. We have have used the COVID lockdown period to focus on collaborating and maturing this GreenAntz RGB to Component Transcoder to reality.

*How can I be sure it works?*

We've been working on this for about three years, and I have a box full of old, reliable yet progressively better prototypes. Lots and lots of testing and analysis. It works.

*Why announce it here?*

Because we always intended to make this project available for community use, and to help us make it better. It is a way of giving back to everyone. We see a huge potential for using component TVs for retrogaming and even as monitors for arcade machines.

*Can I get one already???*

Member price is US$45

If you want to buy a GreenAntz please message me directly, don't ask me on this thread.

If you are a new member, note that you must make a post before personal messaging is unlocked.


Q. What frequencies does it support?

A. GreenAntz works best with component input SDTVs at 15khz in video modes up 480i or 576i.

Q. Does GreenAntz work just like RGB?

A. Yes, with GreenAntz your SDTV works just like an RGB input or RGB modded TV would.

Q. Does it support 31khz?

A. GreenAntz is designed for SDTV applications and does not officially support VGA or HDTV video modes 480p or above. You still need to generate a 15khz signal from your PC or other device using CRT_emudriver or ArcadeVGA or similar.

Q. Can I use GreenAntz with my HDTV then?

A. It comes down to your TV. Some HDTVs recognise component inputs below 480p, but some do not. I've tested it with my older Panasonic Smart TV, and it works as it scales the image to 480i or 576i. But it doesn't work with my newer LG smart TV. So - you may require a scaler as well. This is a common issue for older consoles. *Fortunately*, you can usually output from PC or Pi etc. to HDTV via VGA or HDMI or DVI or DP instead, so that isn't really an issue for PC or CRT_emudriver users.

GreenAntz will still happily pass sync + colour signals at 480p+, but HD-component video requires a different colour coding matrix, meaning even though you might get a picture the colours would probably look weird (exact results depend on your TV or monitor).

Q. What sync does GreenAntz support?

A.  GreenAntz supports RGBHV with either negative or positive sync, and now also supports RGBs (composite) sync input.

GreenAntz might not work so well with mixed polarity sync (+-, -+).

Q. What makes GreenAntz sync so good?

GreenAntz composite sync generation is cleaner than many, including a "deglitching" filter. The sync tip integration into luma (Y) is also superior (compared to many other products on Ali/ebay), involving less loss of luma signal amplitude. This means you get a clearer and brighter picture with no loss of colour brightness or definition. Yellows look more yellow, white looks more white, blue not so dark etc.

Q. Does GreenAntz support composite sync input as well as separate H+V sync?

A. Yes, GreenAntz supports composite sync input. You can choose between sync input types with a simple slide-switch. If you have one of the very earliest versions, read post below to upgrade.

Q. How do I power GreenAntz not using a PC/USB device, like a games console or arcade cab?

A1. use a normal USB2.0/3.0 to USB-C cable and plug it into a normal USB charge brick, like what you might use for a mobile phone.

A2. GreenAntz comes with 5v and GND landing pads/holes, making it easy to route alternate power. They are marked, at the GreenAntz logo, right between the USB port and the VGA jack. Using these, you can connect GreenAntz directly to the 5v from your DC power supply. Don't get your 5v and GND lines mixed up!

From v1.9, GreenAntz will include a diode for reverse-polarity protection on this connection.

The 5v/GND landing pinholes are 5.08mm (2/10 inch) separated, making it easy to drop/solder in a screw terminal header. This makes it simple to remove the GreenAntz unit as needed in the future.

Q. What are GreenAntz power requirements?

A. GreenAntz uses very little power. It can run with 3.3v - 5.5v, ~5v recommended. At ~5v it will draw ~80-90mA, less than 1/2 watt.

Q. Do you get any lag with GreenAntz?

A. GreenAntz is "zero lag", an analog device with no digital processing. Comparing inputs with outputs, signal response latency is about 20 nanoseconds (comparing rising or falling edges on an oscilloscope), though when signal inputs go from extreme LOW to extreme HIGH or vice-versa, there can be up to 100ns (0.1 microseconds) before signal output fully peaks/bottoms.

So I think an estimate of "tens of nanoseconds" latency is about right, which would qualify as "zero lag". About as fast as it gets.

NOTE: This post will be updated occasionally with new info so may change over time

Posted in the other page, but why not more than once!  Very cool, nice job!


--- Quote from: Arroyo on December 29, 2020, 09:52:08 am ---Posted in the other page, but why not more than once!  Very cool, nice job!

--- End quote ---


My Aussie buddy "dekdek" deserves a lot of credit too.

I can finally use all the Sony Trinitrons I have here without the fear of destroying them by blowing it on an RGB mod you say...?!?

This is rad.  I want one.

Maybe two if I can afford it


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