shmups.system11.org

Shmups Forum
 
* FAQ    * Search
 * Register  * Login 
It is currently Tue Nov 19, 2019 8:14 pm View unanswered posts
View active topics



Post new topic Reply to topic  [ 77 posts ]  Go to page Previous  1, 2, 3
Author Message
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Sat Sep 14, 2019 12:11 am 



Joined: 05 Mar 2017
Posts: 376
Location: Woodinville, WA
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).


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Sat Sep 14, 2019 12:15 am 


User avatar

Joined: 20 Aug 2016
Posts: 1370
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 apologize for the inconvenience


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Sat Sep 14, 2019 12:55 am 



Joined: 01 Jul 2017
Posts: 41
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...


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Sat Sep 14, 2019 1:24 am 



Joined: 05 Mar 2017
Posts: 376
Location: Woodinville, WA
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?


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Sat Sep 14, 2019 1:36 am 



Joined: 01 Jul 2017
Posts: 41
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.


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Sat Sep 14, 2019 1:40 am 



Joined: 01 Jul 2017
Posts: 41
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.


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Sat Sep 14, 2019 1:44 am 


User avatar

Joined: 05 Mar 2018
Posts: 958
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


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Sat Sep 14, 2019 2:00 am 



Joined: 05 Mar 2017
Posts: 376
Location: Woodinville, WA
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.


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Sat Sep 14, 2019 6:11 pm 



Joined: 05 Mar 2017
Posts: 376
Location: Woodinville, WA
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?


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Sat Sep 14, 2019 10:52 pm 



Joined: 01 Jul 2017
Posts: 41
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.


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Tue Sep 24, 2019 3:20 am 


User avatar

Joined: 15 Oct 2015
Posts: 134
Location: Salem OR
https://youtu.be/4AwaFiTMMH0
_________________
PC,PS4>DENONX4300H>LG OLED65C7
DC,Xbox,SS,GEN32XCD,SNES,N64>Samsung 55Q8FN
3DO,360,Wii>SONY 34XBR910


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Wed Sep 25, 2019 7:38 am 


User avatar

Joined: 25 Mar 2009
Posts: 242
Location: USA
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: show
Image
Image
Image
Image


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Sun Sep 29, 2019 8:47 am 


User avatar

Joined: 02 Dec 2013
Posts: 118
Location: Spain
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?


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Mon Oct 07, 2019 2:02 am 



Joined: 07 Oct 2019
Posts: 19
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.


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Wed Nov 06, 2019 6:22 pm 



Joined: 01 Dec 2016
Posts: 10
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.


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Thu Nov 07, 2019 11:22 pm 


User avatar

Joined: 25 Mar 2009
Posts: 242
Location: USA
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.


Top
 Offline Profile  
 
 Post subject: Re: Simple RGB to YPbPr Module
PostPosted: Fri Nov 08, 2019 12:14 pm 



Joined: 20 Apr 2018
Posts: 42
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!


Top
 Offline Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 77 posts ]  Go to page Previous  1, 2, 3

All times are UTC


Who is online

Users browsing this forum: bigbadboaz, Extrems, highzeth and 11 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Space Pilot 3K template by Jakob Persson
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group