HDMI to VGA+YPbPr that properly outputs full range 0-255

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kitty666cats
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HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by kitty666cats »

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After peeking around for quite a while, I stumbled upon this thread - https://misterfpga.org/viewtopic.php?t=2514 which mentioned an adapter that properly processes full range RGB. I ordered one, it arrived the other day, I tried it with my PS4 and confirmed it indeed does!

I guess there is a different board revision which uses a Lontium chipset (see the 2nd page of this thread - https://misterfpga.org/viewtopic.php?p=13379#p13379 )... and I believe Lontium chips do the weird thing (not that weird, as full range RGB over HDMI isn't common for a lot of TVs and gear) where they expect limited range on the input and adjust the image accordingly. But mine is one of the units that says 'HDMI' on top of it, which also properly processed 0-255. Looks like ones that say 'HDMI' on them are the one to look out for, and not the EnjoyGadgets ones.

I believe Fudoh has also said the StarTech HDMI to VGA/YPbPr also properly processes full range? It seems like ones that output both signals seem to be the way to go. Atlona has one that appears to be the same exact thing as the StarTech, and can consistently be found for a lower price. There is also a SIIG one that I have yet to try, but it looks promising. It had a DVI-I input, too, as well as digital audio out. Looks nice! The EDID stuff may prove to be useful on these SIIG units. These, too, can be found for cheap on eBay.


Atlona
Spoiler
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(StarTech rebrand)



SIIG
Spoiler
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(Untested as of yet)

I'm very pleased to finally have one that doesn't fuck around with the signal. It's not the most drastic, noticeable difference... but it's noticeable to me and gives some sort of weird, nerdy peace of mind.

If more people can chime in with units they have which pass a proper 0-255 through, it would be great to compile a list! I've been seeing more and more people trying to find these things as more and more people realize MiSTER direct video is, technically, nicer-looking than the I/O boards (for the time being). As well as compatible with interlaced, which I believe the I/O board isn't (correct me if I'm wrong!)
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kitty666cats
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by kitty666cats »

…according to documentation for the TVone 1T-FC-425, these are a likely candidate as well.

https://www.ebay.com/itm/373878139873

A bit of a inconvenience that, since it’s DVI in, there’s no audio extraction here. But these are likely very similar to that StarTech/Atlona (I think the original manufacturer for a lot of these things is probably CYP).

I’ve also ordered this HDMI audio extractor / splitter / VGA converter from AliExpress. For $18, it was a no-brainer! Will chime in with results whenever it arrives -
https://aliexpress.com/item/2251801839677795.html
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elvis
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by elvis »

kitty666cats wrote:After peeking around for quite a while, I stumbled upon this thread - https://misterfpga.org/viewtopic.php?t=2514 which mentioned an adapter that properly processes full range RGB. I ordered one, it arrived the other day, I tried it with my PS4 and confirmed it indeed does!

I guess there is a different board revision which uses a Lontium chipset (see the 2nd page of this thread - https://misterfpga.org/viewtopic.php?p=13379#p13379 )...
Hey that's my post!

It's been a good little unit, still using it today. Only downside still is that it doesn't properly sync to MiSTer's HDMI output when 15KHz modes over YPbPr. RGB is fine though, and oddly enough HDMI out of a Raspberry Pi in 15KHz modes works fine on YPbPr, so it seems to be something specific to MiSTer's output. 31KHz+ resolutions for anything I throw at it are fine in any mode.

Sadly the main chip has a heatsink glued down on it, and I'm not brave enough to force it off to try and find out what it's marked as. But it served me nicely when I was doing those NES palette comparisons from that linked thread.
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kitty666cats
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by kitty666cats »

elvis wrote:
kitty666cats wrote:After peeking around for quite a while, I stumbled upon this thread - https://misterfpga.org/viewtopic.php?t=2514 which mentioned an adapter that properly processes full range RGB. I ordered one, it arrived the other day, I tried it with my PS4 and confirmed it indeed does!

I guess there is a different board revision which uses a Lontium chipset (see the 2nd page of this thread - https://misterfpga.org/viewtopic.php?p=13379#p13379 )...
Hey that's my post!

It's been a good little unit, still using it today. Only downside still is that it doesn't properly sync to MiSTer's HDMI output when 15KHz modes over YPbPr. RGB is fine though, and oddly enough HDMI out of a Raspberry Pi in 15KHz modes works fine on YPbPr, so it seems to be something specific to MiSTer's output. 31KHz+ resolutions for anything I throw at it are fine in any mode.

Sadly the main chip has a heatsink glued down on it, and I'm not brave enough to force it off to try and find out what it's marked as. But it served me nicely when I was doing those NES palette comparisons from that linked thread.
Thanks very much for sharing this information! People are always hunting down DACs trying to find ones they can push the absolute highest possible resolutions/bandwidth/frequencies through, but nobody is ever documenting which ones actually process the damn colors properly, haha. Have you tried seeing how high this one can go on a PC CRT, however? I may give that a try someday, as I have a 110kHz PC CRT (for reference, that means it can go to high resolutions such as 2560x1440p at 72Hz, 1600x1200p at 85Hz, etc). But I also don’t wanna fry the thing, since they’re a bit hard to come by for cheap nowadays… heh
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elvis
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by elvis »

kitty666cats wrote:Have you tried seeing how high this one can go on a PC CRT, however?
Highest I've pushed this is 1024x768 @75Hz out to a small 17" CRT I'm using for DOS gaming. All seems fine and dandy, full range RGB works well.

I've got a couple of good Sony 21" SVGA monitors, so I'll try some other resolutions on those one day.
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by Fudoh »

I am pretty sure that the expected range on those HDMI to VGA converters isn't necessarily universal, but can vary from resolution to resolution (as in SMPTE vs VESA timings). While full range input to full range output with a signal like XGA should be a given, it's those HD variants (720p and 1080p) which can tend to cause a mismatch.
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kitty666cats
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by kitty666cats »

Fudoh wrote:I am pretty sure that the expected range on those HDMI to VGA converters isn't necessarily universal, but can vary from resolution to resolution (as in SMPTE vs VESA timings). While full range input to full range output with a signal like XGA should be a given, it's those HD variants (720p and 1080p) which can tend to cause a mismatch.
That makes perfect sense - explains why grayscale from my OSSC looked perfect with my Vention AFVHB converter, but PS4 output looked ‘off’. Well, at least there’s some options for people who need full range from those pesky console-output TV timings!

Makes me wonder if a cheap HDMI/DVI-D EDID emulator would be a good bet for ‘tricking’ those otherwise good converters that don’t play nice w/ full-range 720p+ SMPTE RGB

Now I wanna try chaining my DSC 301 HD with PS4 and some DACs and set it for VESA 1920x1080p…
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kitty666cats
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by kitty666cats »

@elvis Is your HDMI to VGA/YPbPr unit somewhat dim compared to other video devices of yours? Maybe I just need to try a different PSU with mine, but it is noticeably more dim than anything else I connect to my monitor
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by NewSchoolBoxer »

I'm into this discussion. I guess I haven't seen it discussed before. This breakdown of limited versus full range by BenQ is surprisingly good. For PC and modern consoles, sure we want full range 0-255 RGB. I'm more into 16 bit consoles and games made for CRTs, where along with Blu-ray and DVD video, isn't 16-235 more accurate? The source code for blargg CRT filters shows conversion to 16-235 from PC RGB as well.

Basically, if the converter from HDMI doesn't do full range correctly, is that the same as saying it does limited range, and is there any device that can be switched to do both?

Multiple questions, I know. A topic that should get much more attention than it does. I'm much more used to seeing how to avoid black crush going from analog to HDMI.
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by elvis »

kitty666cats wrote:@elvis Is your HDMI to VGA/YPbPr unit somewhat dim compared to other video devices of yours? Maybe I just need to try a different PSU with mine, but it is noticeably more dim than anything else I connect to my monitor
Nope, mine's been good when tested on several displays for both VGA and YPbPr.

I'm powering mine just from 5V USB adapters.
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by cfx »

I have the Atlona converter, which I wrote a bit about five years ago, here:
viewtopic.php?f=6&t=59860&start=68

As I wrote then, I have some issues with it. I didn't use it in the intevening years as I put everything aside as I wasn't getting what I wanted out of the setup. I just do not like the JVC DT-V1710CG with its very pronounced scanlines; that isn't the look I want. The lack of availbility for me of CRTs of the type I actually want and dissatisfaction with experiences with every XRGB I ever tried had me just give up for many years.

Very recently I got a Retrotink 5X, primarily for use on an LCD monitor, but also wanted to try using it on the NEC FE992 PC CRT mentioned in that old post. In trying that, I found a new or different problem with the Atlona. At some repeated interval, it makes a "snap" sound like an intermittent short, and when it does this the CRT clicks, the picture rolls and then it resets like it has to re-lock onto the signal.

I don't know if this is an issue with the Atlona in general or if mine is defective. I've opened it, and one small chip has a solder bridge across two pins, that I assume should not be there. Those two pins both appear to be connected to the ground plane on the board though so if correct that bridge doesn't matter.

The Atlona is very explicit about not supporting HDCP; it's printed right on the case as shown in the pictures above. The Startech specs state that it supports HDCP 1.1. Based on that alone, are we sure they are identical? There's a programmable chip in the Atlona with an Atlona sticker on it, not that that necessarily means anything, but made me think perhaps if it's identical hardware at least the firmware may be different.

I still want a converter that actually works which is why I would like to verify somehow if the Startech is actually identical.

As an aside, the Retrotink 5X with its CRT mask options finally gives me scanline options I can live with, and I hope I can sell the two JVC DT-V1710CG monitors.
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by fernan1234 »

I have a Startech that I use regularly with a Retrotink 2X's passthrough 240p output going into a DTV as well. Never had any issues. I recall briefly using it with a 2X's line-doubled output on a PC CRT too, but maybe not long enough to notice any potential problems.

Something curious about the Startech/DTV is that the YPbPr mode works fine on a DTV, but not on other monitors like Ikegamis, and exactly the opposite with a Portta's YPbPr, works on the Ikes but not the DTV.
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by cfx »

I ordered the Startech in hopes it won't have the issues I have with the Altona.

At least I'll be able to compare them and can verify if they are truly the same or different.
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by cfx »

Now that I have both, I can confirm the Startech and the Atlona converters are not identical.

As I got a rather different image from the two, I opened them. The circuit boards are completely different with different components. Disclaimer: my Atlona is over 5 years old, so it's feasible it's been redesigned at some point.

Internally, the Atlona uses a Silicon Image Sil901CLU chip and a TI THS58200; there is a third socketed chip with an Atlona sticker on it, so I do not know what it is.

The Startech uses an EPF011A that I don't recognize the company marking for, and has another chip with a heatsink so I do not know what it is.

With a Super Famicom connected to a Retrotink 5x via RGB and feeding each of these converters with their VGA output going to a NEC FE992 CRT monitor, the Startech image looks correct with the Retrotink output set to either limited or full range. With the Atlona, there is black crush and/or a gamma problem. It's there with either setting, but it is far worse with full range. Retrotink output is set to 480P since that's the only real 4:3 output of the device and this monitor doesn't really work well at 1080 or above anyway.

I don't have a more scientific way to test full versus limited so I don't know if that is useful.


The Startech doesn't have the problem I had with the Atlona previously, but trying the Atlona again it isn't doing it now either. :| :oops: :?
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by kitty666cats »

Thanks for confirming that! Guess I should know by now that the same shell does not equate to the same innards...

I’ve heard good things about this one:

https://a.co/d/7ySTG2a

——————

Also, there’s someone on the MiSTER forums that has been doing some testing on these things. Glad to see someone doing something like this -

https://tinyurl.com/crt-hdmi2vgadacs

I’ve got quite the little collection of odd ones that all have different chipsets than what this person has tried thus far. I’ve spoken to them and am probably gonna mail them the 6 or so that I have lying around, see what happens.
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by almnk »

TVone 1T-FC-425 (it has EPF011A and another chip with a heatsink inside as well as Startech). Added input lag is about the same as my hdfury3. Worked well with limited range YPbPr and limited RGB, but I've got some issues while testing full range with this test (it might be my fault though) https://www.youtube.com/watch?v=R90qjpzhq-Y

https://imgur.com/a/eDI2sEV
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Re: HDMI to VGA+YPbPr that properly outputs full range 0-255

Post by alamone »

I have a Moome EXT-FULLHD V3. It claims to auto-detect limited or full RGB input, and has a dip-switch to select limited or full RGB for the output. I don't think the device is available anymore though.
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