June 26, 2020 at 3:49 AM #39222
I would first would like to ask if the component or SCART from an original Xbox through an OSSC to HDMI out has black crush issues on regular HDTVs (limited signal converted to full range being interpreted by a limited range HDTV), and if there is, then whether the OSSC gain and offset adjustments actually fix the output properly instead of just manipulating an image that has already lost detail from being crushed.
While I wait for the OSSC to arrive, I can add to the growing list of similar reports that my Portta component to HDMI converter, like almost all converters, even those made for the Xbox, causes black crush when fed to my HDTV display. On my desktop monitor, there is no black crush and the picture appears mostly correct other than it showing the source 720×480 signal in 1.5 ratio without properly squeezing it to 1.33. This strongly implies that component to HDMI converters convert the color range to full, which only makes sense if you are using a display capable of properly interpreting a full color range signal.
It boggles my mind that converters primarily meant for home theater (televisions and not computer monitors), and even converters specifically designed for the Xbox, are converting the signal color range instead of just leaving it alone. Even better, they should have a toggle switch for source or converted. Do people not usually use their consoles with TVs? Maybe I don’t really know what people use these converters for.June 26, 2020 at 8:32 AM #39226marqsParticipant
You can set OSSC TX mode to “HDMI (YCbCr444)” if your display does not support full-range RGB.June 26, 2020 at 11:04 AM #39230
Ah, very cool. I’ve seen reports that the SCART from the Xbox ends up looking worse than component even though SCART theoretically should look better because its RGB. Would the SCART input on the OSSC help this at all or should I just stick to component?
Also, it’s been confusing trying to understand YCbCr vs RGB color spaces. To my current understanding, YCbCr 24-bit color range in digital is 16-235/240, while RGB 24-bit is 0-255. And is there a reason there is no limited-range RGB output mode on the OSSC?June 26, 2020 at 11:24 AM #39232BuckoA51Keymaster
SCART on the Xbox limits you to 480i so that should be avoided.June 26, 2020 at 11:56 AM #39234
Thanks! Ok so I think I do understand the RGB thing a bit better now and why there isn’t a limited RGB output. The term “limited” was only ever coined for digital TVs because of YCbCr. The first Digital TVs were based on 24-bit YCbCr (for whatever reason), which is represented on a scale of 16-235 luma and 16-240 for chroma. That standard carried into the future even up to modern HDTVs, where some of which, like my Sharp 2014 model, still only supports a 16-235 scale even if it is able to process RGB. I believe digital could have all been RGB from the beginning, but there are probably good reasons why they chose YCbCr. Limited RGB is not really a thing because all of our equipment has the bandwidth for 24-bit RGB, meaning there is no need for it. Basic CRTs also show roughly 24-bit color. I still don’t understand why YCbCr 444 has to use a more limited range to fit into 24-bit while RGB can use the full 0-255 range in 24-bit, if someone wants to explain that I’d appreciate it.June 26, 2020 at 1:13 PM #39237ZacabebParticipant
YCbCr is limited range to avoid clipping under- and overshoot when capturing an analog signal, and give additional head- and legroom for processing. It was carried over from the professional realm where (in the day) the signal might not stay in digital form but be converted back and forth between digital and analog multiple times. Limited range RGB is a descendant of this.June 26, 2020 at 1:48 PM #39239
Alright, but while TVs should accept YCbCr 444 over component cables, can they accept it over HDMI like say from the OSSC? This is a Sharp HDTV from 2014…there’s no option in the settings to enable 444 or change black levels.
I read a bit here: https://www.rtings.com/tv/learn/chroma-subsampling and it said for TCL TVs, if the source isn’t detected properly then you can rename the input label to Computer. On my Sharp, I indeed can rename the input label to lots of different names, with one being PC. There is no section there for Sharp TVs so I don’t know. But that could be the whole reason that the Portta adapter was showing crushed blacks, that it’s just sending the signal as YCbCr 444 and my TV can’t recognize it.
I probably just don’t understand YCbCr yet. Now I’m thinking, are 444, 422, and 420 ALL in 16-235 across all channels, and the b and r components in 422 for example are simply compressed then doubled but still expressed over a 16-235 range? Because if that’s the case then the TV would ALWAYS interpret 16-235 across all channels no matter what the chroma subsampling is. And at worst, the TV converts 444 to 420, but because the same RGB range is used that couldn’t possibly result in any crushing or even saturation. It just results in less detailed color steps, not a difference in color balance or maximum range. Am I right here? So now it seems it’s just the converter getting the wrong EDID from the TV and thinking the TV needs RGB? Then setting the OSSC to YCbCr 444 should solve that problem, whether or not the TV supports full 444 the colors should still look relatively correct if converted to 422 or 420.
BOYS. IT’S TIME. I hooked up my PC via HDMI to my TV and BOOM. Nvidia control panel, switch between RGB full/limited, YCbCr 444 and 422. Both YCbCrs look correct in saturation and black levels relative to RGB limited, and RGB full looks crushed/saturated. I can see a difference between 444 and 422! 422 has a bit of color noise around the edges of font, but 444 looks great! So my TV can handle the 444 over HDMI automatically. SICK BRO.June 26, 2020 at 4:53 PM #39246shakexParticipant
Thank goodness I found this topic. I was playing the first Max Payne yesterday on my Xbox through component and the OSSC. The beginning with the Subway part was COMPLELTELY black. I couldn’t figure out what was wrong. So after reading what marqs posted, I changed the setting on the OSSC from RGB to YCbCr444 and bam, its playable! Thanks for the tip.June 28, 2020 at 4:34 PM #39307Jarrah WhiteParticipant
SCART on the Xbox limits you to 480i so that should be avoided.
Ahem. SCART on the Xbox is only a downgrade if you have an NTSC console. If you have a PAL Xbox, RGB SCART might be a better option. In my tests I found RGB SCART has much more pronounced colours than component. YPbPr seems noticeably darker. The only advantage to using component are games that run in 480p, 720p and 1080i. But Microsoft disabled these resolutions in PAL regions. Even if you hacked the console to output those resolutions, you still need compatible NTSC games to take advantage of them. I software modified my PAL Xbox a few years ago and regretted it. It forced my PAL games to run at 480p and it actually looked WORSE than 576i, full more pronounced jaggies and a generally compressed looking image. Plus at the time I was directly recording with my Elgato, which deinterlaced them to 576p – a higher res than I could get out with the hacked console and the games I had access to.June 28, 2020 at 6:50 PM #39312ZacabebParticipant
How RGB SCART and standard definition YPbPr looks on the Xbox varies brutally depending on which revision motherboard the Xbox has.
The original video encoder used in the Xbox, Conexant CX25871, had very aggressive lowpass filtering of both luma and chroma (the signal was handled as YCbCr 4:2:2 internally with a 1.3 MHz bandwidth for the color components). This caused color bleed and an overall soft picture. This was succeeded by the Focus Enhancements FS454 video encoder. I don’t know how its filtering looked, but it too handled the signal in YCbCr 4:2:2 internally. The bespoke video encoder used later, Xcalibur, has full bandwidth color over both RGB SCART and YPbPr.
The flicker reduction filtering also varies between them.June 29, 2020 at 9:27 AM #39324
Wow that’s great info to know about the Xbox revisions. I’ve seen people say the Xbox does YCbCr 4:4:4 but it’s good to know that only applies to some of the revisions. Or is it that they always output YPbPr 4:4:4 over component, but some revisions internally work in YCbCr 4:2:2 and some 4:4:4?
I assumed my console was an older revision because it had save data for some ’03 sports games, but then I looked at the manufacturing date and it says July, 2004 (serial: 320115242806). This guide says it’s a version 1.6 from Taiwan.
I read that newer revisions had worse component out but got better SCART out. Is that true? Or are both better in the newer revisions? Does it depend on if you’re doing 480p or 480i over component? I’m just now testing Ninja Gaiden on my Xbox at 480p over component vs on an X360 set to YCbCr601, forced to 480p. Besides the extra AA the X360 does, the quality and colors look about the same to me. So am I missing something or is the 1.6 with Xcaliber not actually bad, at least at 480p over component? Sometimes I read 1.6 looks bad over component, one report says ok at 480p but not 480i over component, and the majority just repeat that they’ve read someone else say something so it’s a lot of regurgitated info. Maybe it depends on the component cable quality? Maybe the power supply or outlet power quality? For example, the Pound HD Link was adding banding to some Xbox 1.4 revisions with a specific power supply or sometimes bad caps, solution was often to plug in the USB power on the HD Link.
If someone with a 1.6 Xbox wants to explain exactly what they see wrong with 480p over component I would love to hear from you. The games I currently have access to are Ninja Gaiden, Halo 2, Fable, Voodoo Vince and Grabbed by the Ghoulies. Let’s find a spot and compare what we see because I’m really interested. Again, the only difference I see between the Xbox and the Xbox 360 (set to 480p/YCbCr601), which theoretically should have much better output since it’s newer tech and all digital, is that the X360 applies very light anti-aliasing. I don’t see any banding, ringing, artifacting, bad colors, etc. Only artifacts would be from aliasing and is visibly the same type on both consoles, just slightly less on the X360 due to AA.
And a question about the OSSC, why does the junkerhq wiki say all processing is done in RGB with no conversion to YCbCr available, but then there is a feature to output YCbCr in the HDMI mode? Is that just a remnant from pre-v0.83 firmware not having YCbCr output?
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