Simple RGB to YPbPr Module

The place for all discussion on gaming hardware
strygo
Posts: 506
Joined: Sun Mar 05, 2017 5:47 am
Location: Snohomish, WA

Re: Simple RGB to YPbPr Module

Post by strygo »

My RGB2COMP arrived and I was eager to test it given the issues I've been observing with my Shinybow (see the Linuxbot thread). I didn't have a ton of time, but I was able to test a few scenarios.

From a performance perspective, it behaves indistinguishably from the Shinybow. For the price, and as an alternative, this is great.

On the downside, the issues I have been seeing with the Shinybow are present here. As a quick example, I have comparison shots of the Xbox menu running 720p. With the YPbPr direct, the image is notably crisper and properly centered on the display. Going through the RGB2COMP, the image is blurrier and also offset slightly. FWIW, this is the exact same behavior I see with the Shinybow. I'm not sure if it has to do with the Xbox, 720p, or something else.

https://imgur.com/a/R0RofFk

The previous example is a bit contrived, but I also tested the Xbox through the OSSC to a Vizio 4K TV. YPbPr direct works fine, whereas going through the RGB2COMP doesn't sync. I also saw this problem with the Shinybow. If anyone has ideas on things to test or tweak, let me know. I unfortunately don't have any HD Retrovision cables, so I am only able to test the standard YPbPr consoles (PS2, Wii, Xbox, GC, PSP).
User avatar
orange808
Posts: 3185
Joined: Sat Aug 20, 2016 5:43 am

Re: Simple RGB to YPbPr Module

Post by orange808 »

Hi strygo,

I am going to send some test patterns through the Shinybow and grab them with my capture card this weekend.

I am curious if I'll see the same results.
We apologise for the inconvenience
mikechi2
Posts: 269
Joined: Sat Jul 01, 2017 6:56 am

Re: Simple RGB to YPbPr Module

Post by mikechi2 »

strygo wrote:My RGB2COMP arrived and I was eager to test it given the issues I've been observing with my Shinybow (see the Linuxbot thread). I didn't have a ton of time, but I was able to test a few scenarios.

From a performance perspective, it behaves indistinguishably from the Shinybow. For the price, and as an alternative, this is great.

On the downside, the issues I have been seeing with the Shinybow are present here. As a quick example, I have comparison shots of the Xbox menu running 720p. With the YPbPr direct, the image is notably crisper and properly centered on the display. Going through the RGB2COMP, the image is blurrier and also offset slightly. FWIW, this is the exact same behavior I see with the Shinybow. I'm not sure if it has to do with the Xbox, 720p, or something else.

https://imgur.com/a/R0RofFk

The previous example is a bit contrived, but I also tested the Xbox through the OSSC to a Vizio 4K TV. YPbPr direct works fine, whereas going through the RGB2COMP doesn't sync. I also saw this problem with the Shinybow. If anyone has ideas on things to test or tweak, let me know. I unfortunately don't have any HD Retrovision cables, so I am only able to test the standard YPbPr consoles (PS2, Wii, Xbox, GC, PSP).
Thanks for testing! I think this is a fundamental issue with the conversion process. YPbPr direct is likely synthesized in the digital domain and the output via the Xbox's video DAC, so that's about as perfect as you'll ever get.

If you output RGB then convert (be it Shinybow, RGB2COMP), etc., you've introduced an extra analog conversion step, which will degrade the high frequency content, hence resulting in blurriness. The offset is due to the fact that the RGB sync line has to be stripped then reinserted into the luma signal, which adds a tiny offset to the image.

So bottom line - if your console can output YPbPr directly, a converter doesn't make sense since any analog conversion process is lossy.

Edit -- after taking a closer look, the results do SEEM blurrier than I would expect. If it was just one converter, I'd say there's an issue with the unit's circuit. But if you're seeing this on both the Shinybow and RGB2COMP, I wonder if there's something else going on there...
strygo
Posts: 506
Joined: Sun Mar 05, 2017 5:47 am
Location: Snohomish, WA

Re: Simple RGB to YPbPr Module

Post by strygo »

Thanks for the reply Mike. I'll see if I can get some better shots. As you likely noticed, the room was well lit so there was a pretty bad glare.

In an effort to unify my setup, I've converted every YPbPr signal to RGB and where needed (specifically 2 consumer CRTs) converted RGB to YPbPr, thus resulting in a full round trip for these few YPbPr systems.

Until recently, I had struggled mightily to find a good YPbPr to RGB converter. So far, the Linuxbot one has performed the best. I'm curious how your upcoming one will perform.

I hadn't noticed any degradation using the Shinybow until my recent experiments. I think this may have been due to the fact that I hadn't been testing the YPbPr->RGB->YPbPr roundtrip and my focus had been more on 240p content.

It seems like a roundtrip of higher resolution content would have a greater likelihood of signal degradation. Would you expect worse performance with 720p vs. 480p vs. 240p?
mikechi2
Posts: 269
Joined: Sat Jul 01, 2017 6:56 am

Re: Simple RGB to YPbPr Module

Post by mikechi2 »

strygo wrote:Thanks for the reply Mike. I'll see if I can get some better shots. As you likely noticed, the room was well lit so there was a pretty bad glare.

In an effort to unify my setup, I've converted every YPbPr signal to RGB and where needed (specifically 2 consumer CRTs) converted RGB to YPbPr, thus resulting in a full round trip for these few YPbPr systems.

Until recently, I had struggled mightily to find a good YPbPr to RGB converter. So far, the Linuxbot one has performed the best. I'm curious how your upcoming one will perform.

I hadn't noticed any degradation using the Shinybow until my recent experiments. I think this may have been due to the fact that I hadn't been testing the YPbPr->RGB->YPbPr roundtrip and my focus had been more on 240p content.

It seems like a roundtrip of higher resolution content would have a greater likelihood of signal degradation. Would you expect worse performance with 720p vs. 480p vs. 240p?
No problem! At 240p, I would expect very little degradation, except at sharp color boundaries (e.g., green -> magenta on the SMPTE bars) where you'll likely see an edge artifact. But this is more likely due to the display imposing a low-pass filter on the Pb, Pr signals than the conversion process. I'd definitely expect the image to be softer at 480p and 720p.

Maybe a stupid questions but have you double checked your SCART cable into the converter and the RCA cables coming out? If there's an issue with the cable, or if they're just too long, that might account for what you're seeing.
Thanks for testing! I think this is a fundamental issue with the conversion process. YPbPr direct is likely synthesized in the digital domain and the output via the Xbox's video DAC, so that's about as perfect as you'll ever get.
mikechi2
Posts: 269
Joined: Sat Jul 01, 2017 6:56 am

Re: Simple RGB to YPbPr Module

Post by mikechi2 »

strygo wrote:Thanks for the reply Mike. I'll see if I can get some better shots. As you likely noticed, the room was well lit so there was a pretty bad glare.

In an effort to unify my setup, I've converted every YPbPr signal to RGB and where needed (specifically 2 consumer CRTs) converted RGB to YPbPr, thus resulting in a full round trip for these few YPbPr systems.

Until recently, I had struggled mightily to find a good YPbPr to RGB converter. So far, the Linuxbot one has performed the best. I'm curious how your upcoming one will perform.

I hadn't noticed any degradation using the Shinybow until my recent experiments. I think this may have been due to the fact that I hadn't been testing the YPbPr->RGB->YPbPr roundtrip and my focus had been more on 240p content.

It seems like a roundtrip of higher resolution content would have a greater likelihood of signal degradation. Would you expect worse performance with 720p vs. 480p vs. 240p?
I just looked at your pictures again and saw that you're running @ 720p. If so, then yeah, I'd say this is definitely par for course. The 720p component signal coming out of the XBOX's DAC is going to blow away what you're going to get from any analog converter, especially with multiple round trips. At 720p having cables and connectors with the correct impedance will also make a difference.
User avatar
maxtherabbit
Posts: 1763
Joined: Mon Mar 05, 2018 4:03 pm

Re: Simple RGB to YPbPr Module

Post by maxtherabbit »

I remember hearing rumors of original xbox revisions < 1.6 having shitty RGB output and stellar YPbPr output, and the inverse being true for the 1.6

it could be the console itself is blurring the signal in the DAC when in RGB mode for some reason
strygo
Posts: 506
Joined: Sun Mar 05, 2017 5:47 am
Location: Snohomish, WA

Re: Simple RGB to YPbPr Module

Post by strygo »

I had briefly tested RGB with this Xbox prior to discovering the limitations around progressive content, but ended up going with the HD cable so I could get progressive content. All of these shots are using the HD cable with YPbPr.
strygo
Posts: 506
Joined: Sun Mar 05, 2017 5:47 am
Location: Snohomish, WA

Re: Simple RGB to YPbPr Module

Post by strygo »

mikechi2 wrote:I just looked at your pictures again and saw that you're running @ 720p. If so, then yeah, I'd say this is definitely par for course. The 720p component signal coming out of the XBOX's DAC is going to blow away what you're going to get from any analog converter, especially with multiple round trips. At 720p having cables and connectors with the correct impedance will also make a difference.
Orange808 posted some captures of the Shinybow in another thread - these captures accurately represent the signal distortion I've observed.

Mike: is there something intrinsic about the typical conversion of YPbPr to RGB that causes this? It seems like going the other direction (both in these transcoders and the ones built into displays) is much less prone to these issues. Being less familiar with the analog domain, is this something where you would need to in effect "dial in" each signal conversion to produce the best possible results, or could a more complicated circuit produce better results?
mikechi2
Posts: 269
Joined: Sat Jul 01, 2017 6:56 am

Re: Simple RGB to YPbPr Module

Post by mikechi2 »

strygo wrote:
mikechi2 wrote:I just looked at your pictures again and saw that you're running @ 720p. If so, then yeah, I'd say this is definitely par for course. The 720p component signal coming out of the XBOX's DAC is going to blow away what you're going to get from any analog converter, especially with multiple round trips. At 720p having cables and connectors with the correct impedance will also make a difference.
Orange808 posted some captures of the Shinybow in another thread - these captures accurately represent the signal distortion I've observed.

Mike: is there something intrinsic about the typical conversion of YPbPr to RGB that causes this? It seems like going the other direction (both in these transcoders and the ones built into displays) is much less prone to these issues. Being less familiar with the analog domain, is this something where you would need to in effect "dial in" each signal conversion to produce the best possible results, or could a more complicated circuit produce better results?
The only thing that I can think of is that the YPbPr source may have gone an extra conversion step, which will degrade the signal. Sharp edges are tough for analog conversion processes since they require high amplifier bandwidths and often cause ringing artifacts.
User avatar
Bahn Yuki
Posts: 228
Joined: Thu Oct 15, 2015 11:33 pm
Location: Salem OR
Contact:

Re: Simple RGB to YPbPr Module

Post by Bahn Yuki »

Displays I currently own:
LG 83C1(OLED),LG 77C2(OLED), LG 42C2(OLED),TCL 75R635(MiniLED),Apple Studio Monitor 21(PCCRT),SONY 34XBR960x2(HDCRT)
SONY 32XBR250,Samsung UBJ590(LED),Panasonic P50VT20(Plasma),JVC NZ8
User avatar
cyborc
Posts: 308
Joined: Wed Mar 25, 2009 6:26 am
Location: USA

Re: Simple RGB to YPbPr Module

Post by cyborc »

I compared the Retrotink with the Kramer FC-14 and they are virtually identical. I ran them both thru an extron matrix switch and I switched back and forth between them several times and couldn't tell a bit of difference.
Since the Kramer is so rare and expensive these days, the Retrotink is, in my opinion, the best transcoder on the market right now, and I've tried most of them.

Here's some cellphone pictures of the Kramer and Retrotink on my LCD TV via the OSSC, and also via my JVC broadcast monitor. I forgot to make a note of which picture is which device! :oops: But they are so close it doesn't really matter.
Spoiler
Image
Image
Image
Image
User avatar
badwhite40
Posts: 120
Joined: Mon Dec 02, 2013 9:15 am
Location: Spain

Re: Simple RGB to YPbPr Module

Post by badwhite40 »

I’ve ordered one few days ago.
Best way to introduce it into the extron matrix bncs?
What bncs to rgbs scart recomend?
I am trying to avoid sync issues of Jvc dtv and bvm A20 with some console signals.
May be this converter could be a great solution For this?
TheJeffChen
Posts: 25
Joined: Mon Oct 07, 2019 1:53 am

Re: Simple RGB to YPbPr Module

Post by TheJeffChen »

Thank you so much for the test result.

I was hesitating on RGB modding my FV300, found this RGB2COMP device on Google, and started swinging. However with the result you posted, clearly the RGB2COMP device is ruining the image quality and there is no way I would buy it.

I guess it's finally time to RGB mod my $40 FV300. Wish me luck.
Darkglobe1977
Posts: 10
Joined: Thu Dec 01, 2016 12:44 am

Re: Simple RGB to YPbPr Module

Post by Darkglobe1977 »

Is there an ETA on when the RGB2Comp will be back in stock to order? I've been checking regularly and it's been out of stock for a few weeks.
User avatar
cyborc
Posts: 308
Joined: Wed Mar 25, 2009 6:26 am
Location: USA

Re: Simple RGB to YPbPr Module

Post by cyborc »

TheJeffChen wrote:Thank you so much for the test result.

I was hesitating on RGB modding my FV300, found this RGB2COMP device on Google, and started swinging. However with the result you posted, clearly the RGB2COMP device is ruining the image quality and there is no way I would buy it.

I guess it's finally time to RGB mod my $40 FV300. Wish me luck.

If you're talking about the pictures I posted, I must simply ask.."wut??"

The RGB2COMP looks nearly identical.
XtraSmiley
Posts: 622
Joined: Fri Apr 20, 2018 9:22 am
Location: Washigton DC

Re: Simple RGB to YPbPr Module

Post by XtraSmiley »

Darkglobe1977 wrote:Is there an ETA on when the RGB2Comp will be back in stock to order? I've been checking regularly and it's been out of stock for a few weeks.
I asked Mike and he said in the next two weeks. I'm waiting too!
intro7
Posts: 2
Joined: Mon Nov 26, 2018 7:40 pm

Re: Simple RGB to YPbPr Module

Post by intro7 »

strygo,



I have read that all Original XBOX motherboard revisions before 1.6 had bad RGB output -do you know what your XBOX's motherboard revision is?



Here are some ways to tell (from a reddit page):



1) XBOX revision 1.6 consoles have an AV port that looks slightly different than pre-1.6 consoles. Linked below is an image that shows you how to tell:


https://i.imgur.com/CDWzjju.png




2) Original XBOXs have serial numbers that are formatted like seven digits, a space, and then five digits (like this: XXXXXXX XXXXX). If you look at that second group of digits in your XBOX's serial number (the 5 digit group) - does that group of digits start with the number four? I'll put a number four where it is important to look in an example because this is hard to describe: XXXXXXX 4XXXX. If your XBOX's serial number has a 4 in that spot, it is very likely that it is a revision 1.6, and if it does not have a 4 in that spot, it is very likely that it is not a revision 1.6.



3) Is your XBOX one of the see-through models? If it is, there is a spot you can look at on the bottom that can indicate whether or not it is a revision 1.6. Picture that shows you how to tell is linked below:



https://i.imgur.com/hugd33h.png




4) If you look at sticker where the serial number is, uou will see the console's manufacturing date listed in Year--Month--Day format. If your console was manufactured on or after 2004--09--13 (so The 13th of Septemper 2004) it is a revision 1.6. If the listed date is earlier, it is not a revision 1.6.




What RGB cable are you using?



Thank you
Brett_D92
Posts: 10
Joined: Tue Mar 10, 2020 7:00 am

Re: Simple RGB to YPbPr Module

Post by Brett_D92 »

Has anyone tried the RGB2COMP with N64 that's had an RGB mod wired for CSYNC? Made the mistake of getting an RGB modded N64 and requested CSYNC over Luma, thinking that it'd still work with the SNES HD Retrovision cable, but it didn't and had a green tint over it, though I did actually research beforehand and couldn't find any solid info about it. Had to get a CSYNC SCART cable later to actually make sure the mod worked fine which it did.

I do already have the Shinybow SCART to Component transcoder which works really well with anything else I fed RGB into, but not with the N64, where it looks overly bright and black tearing in areas, so I can't exactly use it on my CRT.

Image
Image


Would the RGB2COMP make any difference with this by any chance?
User avatar
kitty666cats
Posts: 1266
Joined: Tue Nov 05, 2019 2:03 am
Location: Massachusetts, USA

Re: Simple RGB to YPbPr Module

Post by kitty666cats »

Brett_D92 wrote:Has anyone tried the RGB2COMP with N64 that's had an RGB mod wired for CSYNC? Made the mistake of getting an RGB modded N64 and requested CSYNC over Luma, thinking that it'd still work with the SNES HD Retrovision cable, but it didn't and had a green tint over it, though I did actually research beforehand and couldn't find any solid info about it. Had to get a CSYNC SCART cable later to actually make sure the mod worked fine which it did.

I do already have the Shinybow SCART to Component transcoder which works really well with anything else I fed RGB into, but not with the N64, where it looks overly bright and black tearing in areas, so I can't exactly use it on my CRT.

Image
Image


Would the RGB2COMP make any difference with this by any chance?
I've had no trouble with sync on luma on the 'Tink, the Linuxbot3000 on eBay, or even the CSY-2100 clone. Is this a normal thing for the Shinybow?
Brett_D92
Posts: 10
Joined: Tue Mar 10, 2020 7:00 am

Re: Simple RGB to YPbPr Module

Post by Brett_D92 »

kitty666cats wrote:I've had no trouble with sync on luma on the 'Tink, the Linuxbot3000 on eBay, or even the CSY-2100 clone. Is this a normal thing for the Shinybow?
This is using CSYNC mod here, not Luma. But odd thing is I believe my Mega Drive and Playstation SCART cables are wired for CSYNC as well, yet both work fine on Shinybow. Not entirely sure what'd be different with N64 here.
nmalinoski
Posts: 1974
Joined: Wed Jul 19, 2017 1:52 pm

Re: Simple RGB to YPbPr Module

Post by nmalinoski »

Brett_D92 wrote:But odd thing is I believe my Mega Drive and Playstation SCART cables are wired for CSYNC...
I'm going to be a little pedantic here. PlayStation SCART cables cannot be wired for clean composite sync, because that signal isn't available on the AV Multi-out; any CSync cable for a PS1/PS2/PS3 is going to be wired for either sync-on-composite or sync-on-luma, with a sync stripper in the SCART head.

MD/Genesis, on the other hand, does offer clean composite sync on its AV port, so SCART cables for those consoles can be wired for it.

Where your N64 is concerned, I think you need to take a look at how the sync for your RGB mod is configured, whether it's 75Ohm or TTL, and then you need to verify whether your cable is expecting 75Ohm or TTL and whether it's directly wired for CSync or, for some reason, has a sync stripper in it. If your RGB mod is feeding TTL, and your cable isn't wired to attenuate that down to 75Ohm, then you're overvolting the Shinybow and potentially causing it damage.
Brett_D92
Posts: 10
Joined: Tue Mar 10, 2020 7:00 am

Re: Simple RGB to YPbPr Module

Post by Brett_D92 »

nmalinoski wrote:I'm going to be a little pedantic here. PlayStation SCART cables cannot be wired for clean composite sync, because that signal isn't available on the AV Multi-out; any CSync cable for a PS1/PS2/PS3 is going to be wired for either sync-on-composite or sync-on-luma, with a sync stripper in the SCART head.

MD/Genesis, on the other hand, does offer clean composite sync on its AV port, so SCART cables for those consoles can be wired for it.

Where your N64 is concerned, I think you need to take a look at how the sync for your RGB mod is configured, whether it's 75Ohm or TTL, and then you need to verify whether your cable is expecting 75Ohm or TTL and whether it's directly wired for CSync or, for some reason, has a sync stripper in it. If your RGB mod is feeding TTL, and your cable isn't wired to attenuate that down to 75Ohm, then you're overvolting the Shinybow and potentially causing it damage.
I don't remember exactly, would look back at the listing but already no longer exists (thanks Ebay), all I know was that it used a THS7374 board. I do think it was wired directly for CSYNC but using a cable that's attenuated. The cable I was using was the RGC-UK SNES CSYNC 470Ω, was the only one that was in stock then.

Good to know about the potential damage on Shinybow, only had it in for a few minutes though I'll have to double check with another console in case to see if it's fine. If it's an issue that can't be resolved, then no worries, I have an OSSC I can still use for it, just can't use my CRT TV and setup the same time with it.
mikechi2
Posts: 269
Joined: Sat Jul 01, 2017 6:56 am

Re: Simple RGB to YPbPr Module

Post by mikechi2 »

I wish we can just all dump this TTL CSYNC nonsense and use 75 ohm sync on composite or luma, which is what the SCART "standard" is designed to operate with :-)
Brett_D92 wrote:
nmalinoski wrote:I'm going to be a little pedantic here. PlayStation SCART cables cannot be wired for clean composite sync, because that signal isn't available on the AV Multi-out; any CSync cable for a PS1/PS2/PS3 is going to be wired for either sync-on-composite or sync-on-luma, with a sync stripper in the SCART head.

MD/Genesis, on the other hand, does offer clean composite sync on its AV port, so SCART cables for those consoles can be wired for it.

Where your N64 is concerned, I think you need to take a look at how the sync for your RGB mod is configured, whether it's 75Ohm or TTL, and then you need to verify whether your cable is expecting 75Ohm or TTL and whether it's directly wired for CSync or, for some reason, has a sync stripper in it. If your RGB mod is feeding TTL, and your cable isn't wired to attenuate that down to 75Ohm, then you're overvolting the Shinybow and potentially causing it damage.
I don't remember exactly, would look back at the listing but already no longer exists (thanks Ebay), all I know was that it used a THS7374 board. I do think it was wired directly for CSYNC but using a cable that's attenuated. The cable I was using was the RGC-UK SNES CSYNC 470Ω, was the only one that was in stock then.

Good to know about the potential damage on Shinybow, only had it in for a few minutes though I'll have to double check with another console in case to see if it's fine. If it's an issue that can't be resolved, then no worries, I have an OSSC I can still use for it, just can't use my CRT TV and setup the same time with it.
User avatar
maxtherabbit
Posts: 1763
Joined: Mon Mar 05, 2018 4:03 pm

Re: Simple RGB to YPbPr Module

Post by maxtherabbit »

mikechi2 wrote:I wish we can just all dump this TTL CSYNC nonsense and use 75 ohm sync on composite or luma, which is what the SCART "standard" is designed to operate with :-)
I wish we can just all dump this 75 ohm sync on composite or luma nonsense and use TTL CSYNC, which is what the VGA "standard" is designed to operate with :-)
mikechi2
Posts: 269
Joined: Sat Jul 01, 2017 6:56 am

Re: Simple RGB to YPbPr Module

Post by mikechi2 »

Good point ;-)
maxtherabbit wrote:
mikechi2 wrote:I wish we can just all dump this TTL CSYNC nonsense and use 75 ohm sync on composite or luma, which is what the SCART "standard" is designed to operate with :-)
I wish we can just all dump this 75 ohm sync on composite or luma nonsense and use TTL CSYNC, which is what the VGA "standard" is designed to operate with :-)
Post Reply