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This topic contains 10 replies, has 5 voices, and was last updated by  Bananmos 1 week, 3 days ago.

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  • #16894

    Bananmos
    Participant

    Hi everyone – pardon a somewhat lengthy and rambling post.

    I’ve got my OSSC for a little over a week now… and while I am pretty impressed with the potential of it and all the configurability, the bad news is I still haven’t managed to make it work satisfactory for my setup 🙁

    Short story long, I’ve tested the OSSC with three different displays so far, and each of them has had its own set of quirks.

    Sony KDL-40BX400
    My old workhorse, a medium range HDTV from 2010, but does take 240p signals. (albeit sometimes erroneously syncs the image to a squashes half-screen, requiring a re-sync)

    Samsung LE46M87BD
    A 2007 model 46″ TV I got as a freebie from work. Thinking it’d be a nice free upgrade from 40″ -> 46″, I was severely disappointed when this TV wouldn’t even take a 240p signal, and this was what prompted me to get the OSSC in the first place.

    Dell ST2410 monitor.
    A standard 1080p computer monitor, used just for comparison. (as monitors are said to be less problematic than TVs)

    While NES is my favorite system, I didn’t really need the OSSC for it, as I’ve got a NES with Kevtris’s hi-def mod outputting HDMI directly. So the main use for the OSSC would be my SNES: A PAL console I modded myself with a simple 50Hz/60Hz switch a few years back. I then tried all 3 displays, primarily in 60Hz mode. OSSC was displaying “15.59kHz 59.53Hz” on its LCD.

    Sony Bravia KDL-40BX400:
    1x: Won’t work
    2x: Won’t work (somewhat surprising, given 2x is usually the highest compatibility mode) …but does work when switching the SNES to 50Hz
    3x: Works!
    4x: Won’t work
    5x: Works!

    The picture looks very pretty in 5x standard 4:3… except that it is far from pixel-perfect, and the pixels even have a jaggy edge in some places. It doesn’t look totally awful, but not really the crisp look I was hoping for. https://photos.app.goo.gl/th5bYRjOFdaeCapf1

    Switching to 256×240 optim mode does give perfect pixels as expected… but the pixels are now flickery, as if the output was jittered… which kind of makes sense, as both the NES and SNES have a video signal where every other frame have one scanline that’s shorter that’s one pixel clock shorter (340 instead of 341). https://photos.app.goo.gl/kvYRW1xY327na9Qg2

    Adjusting the sampling phase make the picture more stable (pixels no longer flicker between frames). But the pixels still look like a blend between the real pixels. https://photos.app.goo.gl/Z3q8or4LPlwLYCqO2

    The even bigger dealbreaker though, is that this TV seems to lose sync about once every minute. Switching to 50Hz fixes this, suggesting that the 59.53Hz signal is a bit too off-spec for this TVs liking. This happens in all modes.

    Samsung Samsung LE46M87BD:
    1x: Won’t work at all
    2x: Works!
    3x: Won’t work
    4x: Won’t work
    5x: Won’t work

    So in summary, only line-doubling works with the Samsung TV. What’s more disturbing is that there is a very subtle vertical jitter in 2x mode on this TV (though not at all like the 1-scanline-high de-interlacing jitter it had when trying to feed it a 240p signal directly) in 60Hz mode. It almost makes this HDTV look like a cheap CRT reminds me of a CRT. But switching to 50Hz removes this jitter, again suggesting that the 59.53Hz signal being off-spec could be the problem. The picture is also squashed in 50Hz mode (as expected when the TV is trying to upsample a 480P PAL signal)

    Dell ST2410
    1x: Works! But aspect ratio is not 4:3, but stretched. (IMG_20171101_005616.jpg)
    2x: Works! But aspect ratio is not 4:3, but stretched. Also has both horizontal and vertical borders. (IMG_20171101_010715.jpg)
    3x: Works! And aspect ratio looks kind of close to 4:3. Also has both horizontal and vertical borders. (IMG_20171101_010954.jpg)
    4x: Works! But aspect ratio is not 4:3, but stretched. Also has both horizontal and vertical borders. (IMG_20171101_011143.jpg)
    5x: Won’t work (monitor says: “The current input timing is not supported by the monitor display / Please change your input timing to 1920×1080@60Hz or any other monitor listed

    There are no sync issues… but I am curious how this monitor won’t support the 5x mode, despite being a 1080p monitor. It could be the offspec 59.53Hz signal again, although I would expect it to affect more than one single mode. Switching SNES to 50Hz has no effect either: 1x-4x still works, 5x does not.

    NES:
    Finally, I figured I would try an (NTSC) NES with Tim Worthington’s RGB mod applied. OSSC LCD was displaying “15.74kHz 60.08Hz”.

    I won’t go into as much detail for the NES, but in summary this was a much more pleasant experience:
    * No problem with lost sync on any of the displays
    * No vertical jitter on the Samsung TV
    * 5x mode still doesn’t work on the ST2410 display… so probably not the off-spec frame rate.
    * Flickering pixels are still there in 256×240 optim mode…
    * …but this time around, adjusting sampling phase eventually results in a sharp, pixel-perfect image! Success at last!
    * …for the Sony&Dell. But not so for the Samsung display, as 256×240 optim won’t work on it at all (no matter how the sampling phase is adjusted). Interestingly, 320×240 optim works (but is not a good setting for the NES)

    The OSSC already does wonders in how awesome it looks with the NES-RGB mod. And the NES is actually the console most dear to me, so big stars to the OSSC for that feat alone! But having a hi-def NES that outputs HDMI directly, I kind of doubt I’ll be using my RGB-NES much with the OSSC anyway… even if the OSSC does offer the 5x scaling solution the hi-def NES lacks.

    Now, I know that SNES is reported to be a tricky console for the OSSC to support. At the end of the day, I’m trying to make up my mind about where to go from here… that is, how much more to invest in a SNES gaming setup for the OSSC. My 40″ Sony TV that achieves 5x scaling seems to be the overall winner for now… as long as I play my SNES games exclusively in 50Hz only to avoid the lost sync issue.

    So I’m considering getting a Super Famicom (as I can’t stand the thought of having an atrocious-looking US SNES in my home 🙂 …or perhaps a SuperCIC-modded 1chip console if I can find one on eBay. But am still not 100% convinced it will solve the sync issues on the 40″ Sony display (as the different quirks of the displays aren’t behaving 100% consistently to begin with) And even then, there’s the question of whether the 256×240 optim mode will eventually get improved to fix the odd-looking pixels.

    So if anyone has any more experience with SNES gaming and the OSSC to compare, I’d be really keen to know whether you’ve had similar issues (or not). In summary:

    1) Has anyone else here had the experience of SNES+OSSC causing your display to lose sync about every minute?
    1a) …was this happening on a modded PAL console running at 60Hz?
    1b) …and have you had the opportunity to try a true NTSC console (Famicom/US SNES) on the same display for comparison?

    2) Has anyone else here had the experience of SNES+OSSC causing your display to show a very subtle vertical jitter?
    1a) …was this happening on a modded PAL console running at 60Hz?
    1b) …and have you had the opportunity to try a true NTSC console (Famicom/US SNES) on the same display for comparison?

    3) Does anyone have any idea what would cause all displays to always have blended pixels in 256×240 optim mode?
    3a) …have you experienced this issue with a SNES in 256×240 optim mode on your particular display?
    3b) …or have you NOT experienced it? (I’d be keen to know if this is a universal flaw in 256×240 optim mode)
    Both the NES and the SNES supposedly have the exact same quirk of every other frame having one scanline that’s shorter than the others (340 instead of 341), but for some reason it is only the SNES which cannot be fixed by adjusting the sampling phase, which I find very odd.

    // Michel

    #16912

    Harrumph
    Participant

    Regarding picture quality, everything you describe is normal for a non-1-chip SNES. It’s simply down to the blurry rgb output (you can read about that phenomenon here: http://www.chrismcovell.com/gotRGB/snesblur.html .

    For generic 4:3, I’ve found scanlines to help quite a bit. By the way, I also have slight jitter in the horizontal direction, but it is not visible at normal viewing distance (modded PAL console with 59.53Hz output). I have a 1-chip, but it is being repaired, so I cannot confirm if this removes jitter in this case.

    You will not be able to get an acceptable image in optimized mode, unless you also use the new deblur (“reverse LPF”) feature of the 0.79 firmware. However, the results will also vary with particular console, because some are more blurry than others (I had one where it worked nicely, another where the image could not be improved without artefacts appearing). And from the looks of the images, yours seems to have quite severe blurring, so don’t expect too much from that feature…

    I suspect your image drops would be improved by using a proper NTSC console, or a SuperCIC moded 1-chip PAL.

    #16913

    paulb_nl
    Participant

    Switching to 256×240 optim mode does give perfect pixels as expected… but the pixels are now flickery, as if the output was jittered… which kind of makes sense, as both the NES and SNES have a video signal where every other frame have one scanline that’s shorter that’s one pixel clock shorter (340 instead of 341)

    This happens with every analog source not just NES/SNES. The flickering happens because its sampling at the edge of the waveform and because the clocks are not perfect there is jitter in the waveform. So you have to change the sampling phase to sample at the center of the waveform.

    You can see what I mean here: http://www.hdretrovision.com/jitter/ The sync jitter they describe there is another issue but you can see the moving waveform captures further down the page.

    Check out the firmware 0.79 topic for more information about the SNES deblur. https://www.videogameperfection.com/forums/topic/firmware-0-79/

    It is recommended to buy a 1-CHIP SNES but keep in mind that some 1-CHIPs need the brightness fix and newly found ghosting fix.

    #16919

    BuckoA51
    Keymaster

    There is also a new mod for SNES in the works that may help with these issues.

    #16938

    Bananmos
    Participant

    Thanks for that link Harrumph! Looks like another one of Chris’s great pages that I somehow missed 🙂

    So that page pretty much tells me there’s no way the OSSC could get a pixel-perfect video signal for the 2-chip SNES, given that the blurry falloff is about a pixel large.

    I do understand that the sample period needs to be delicately aligned to sample at a stable point. It’s just that I was convinced the OSSC was having problems with the shorter scanline, which seems to have been a red herring.

    I did just try the new LPF feature, and it doesn’t seem to help at all with my SNES. Just gives me bright edges instead (as someone else has already reported). Guess it only works on less blurrier models…

    Out of interest, I note that Chris’s page only checked the output from the cable. But I assume it’s been confirmed that the slow colour change is a property of the internal PPU circuitry, and not due to any discrete components on the board which could be replaced?

    Anyway, I guess getting a 1-chip SNES is the only way to really use the OSSC with a SNES at this point. 1chip consoles do seem quite a bit pricier than the standard (unidentified) ones going for sale. The brightness fix seems like a trivial mod though, so that shouldn’t be a problem. And it looks like the ghosting just needs replacing a surface-mounted resistor as well?

    Is there any web store that sells ready-made SuperCIC 1chip SNESes? eBay.co.uk does seems to have loads of SuperCIC-ready SNES models for sale, but they don’t mention whether it’s a 1chip, so I’d assume not.

    Is there any definite verdict about which SNES/Famicom is better? The 1-chip version with the original look, or the Mini/Famicom Jr variants?

    BuckoA51: Is that a mod for the 2-chip SNES? Any possibility to say anything more about it at this stage, or a possible announcement date? 🙂

    And thanks for your input people, it’s really appreciated! I know way too many technical details about the NES, but my SNES knowledge is very limited so far. I was so close to ordering a Famicom on eBay, which would likely have been just another console with blurry output…

    // Michel

    • This reply was modified 2 weeks, 1 day ago by  Bananmos.
    #16948

    Harrumph
    Participant

    Is there any definite verdict about which SNES/Famicom is better?

    Retrorgb recently showed that any 1-chip model can output equal RGB quality. Any perceived differences are just down to variability in component age/quality/usage, and if an RGB bypass board is installed, the output becomes equal (excluding ghosting or white line fixes, which have to be separately applied).

    By the way, the new brightness/ghosting fix cannot easily be applied to a 1-chip that has had Borti’s SuperCIC board installed already, because the capacitor that needs to be replaced is located under the SuperCIC PCB.

    #16950

    paulb_nl
    Participant

    I did just try the new LPF feature, and it doesn’t seem to help at all with my SNES. Just gives me bright edges instead (as someone else has already reported). Guess it only works on less blurrier models…

    Can you post a closeup picture of the bright edges that you see? It might be fixable. Did you try it on every lineX mode?

    What kind of RGB cable are you using? Composite video sync, luma or sync stripper?

    The cheapest way to find a 1-CHIP would be by looking at the serial numbers. I found a cheap PAL 1-CHIP-02 that way. Here is a list of serial numbers: https://docs.google.com/spreadsheets/d/1HYLy_TTDop_FzuX6qnxuQI43upg4raXfno582taO744/pubhtml

    #17018

    Bananmos
    Participant

    Can you post a closeup picture of the bright edges that you see? It might be fixable. Did you try it on every lineX mode?

    I only tried it in 5x mode, but when trying other modes now I’ve come to the conclusion that the latest firmware update caused the OSSC to have fewer modes working on my 40″ SONY TV… 🙁

    Trying in 50Hz:
    In Generic 4:3, only 2x and 5x work
    In 256×240 optim, only 5x works

    …though don’t take this firmware-gone-worse-claim at face value – it might very well be some other change I missed, although I did do “reset settings” before trying the various modes. I’ll try to find some time to in the weekend to go through all the steps and/or firmware comparisons and see if I can confirm exactly what went wrong.

    For now – since the filter only makes sense in 256×240 optim mode AFAIU – I’ve taken 3 closeups at 5x in 256×240 optim mode, with a reverse LPF setting of 0, 15 and 31

    0: https://photos.app.goo.gl/NbkIhM0TElosD1fX2
    15: https://photos.app.goo.gl/wzWF22JoMeulM7hP2
    31: https://photos.app.goo.gl/i2acsD0kLSRTgyVl2

    What kind of RGB cable are you using? Composite video sync, luma or sync stripper?

    The straight answer is I don’t really know 🙂 – But I did read up quickly on this, and think I get the difference. Given that my colours have a very distinct checkerboard pattern to them, and that the cable inside is just a bunch of wires and some resistors ( https://photos.app.goo.gl/wzFd2iMnKDL0rlSC3 ), it sounds to me like it’s a composite video sync one rather than the cleaner sync-on-luma and sync-stripper variants you mentioned?

    I noticed there were two cables sold on retrogamingcables.co.uk, which I assume are sync-on-luma and sync-stripper, from the description?
    https://www.retrogamingcables.co.uk/super-nintendo-pal-rgb-av-scart-cable-lead-cord-for-sale
    https://www.retrogamingcables.co.uk/SUPER-NINTENDO-SNES-PAL-RGB-SCART-COMPOSITE-SYNC-CSYNC

    From a quick skim-through, it sounds to me like the more expensive sync-stripper one should have has better compatibility with more displays and would be worth paying extra for? But is there any downside to it? It does sound like a wise thing to invest in one of these cables… although I am starting to worry if there’s yet more model differences I’d need to consider here, depending on if I get a replacement 1-chip NTSC/PAL SNES of a particular model? (as this has already opened up a rabbit hole of SNES tech stuff… which is kind of fun to learn, as long as there’s luminance at the end of the video tunnel… 🙂

    Thank you very much for the link, I’ll be on the lookout for those serial numbers… My own 2-chip is “UP10895189”, which predates any others in the PAL chart. Although I’m not sure how useful that would be to add to the spreadsheet anyway, as it clearly predates all the other confirmed 2-chip SNES consoles…

    // Michel

    #17026

    Hypetreme
    Participant

    I have a tip that might help. I had some sync issues with my Super Famicom. It kept losing sync from time to time. I tried to find some tips from the forums and the wiki and it turned out that raising the “Analog sync vth” value found under “Sync opt.” worked out for me. I set it to 169 mV and the sync stayed stable.

    #17028

    paulb_nl
    Participant

    The photos of 256×240 with reverse LPF look like you didn’t tweak the sample phase perfectly. Set reverse LPF to 4 and tweak sample phase some more.

    Your RGB cable indeed looks like a cheap composite video sync cable. I have a bunch of those purple ones from back in the day because they were so cheap. Looks like yours has been modded for PAL.

    Its best to avoid cables with sync strippers. Its really only needed if you have some device that requires clean sync but luma sync will work without issues on the OSSC. The standard luma sync cable is fine but if you want to avoid audio interference you can buy the shielded packapunch cable.

    For the different SNES models you only need to consider that PAL uses a different cable than a NTSC SNES. I also would not recommend using csync for your NTSC SNES as it can give a lot of problems. One of those is that a PAL SNES outputs 12 volt on the same pin so if you accidentally switch the cable you might damage the OSSC.

    #17132

    Bananmos
    Participant

    t raising the “Analog sync vth” value found under “Sync opt.” worked out for me. I set it to 169 mV and the sync stayed stable.

    I brought it up to 270mV (higher values would drop the picture completely) and it would still lose sync. The sync loss behaviour is a bit intermittent though. Often when I boot my SNES powerpak up, it won’t even stay for more than a few seconds. But more commonly, it’ll lose sync every minute or so. But if you got a real Super Famicom rather than a PAL console with a 60Hz switch, I think you’d be fine with my 40″ TV – it works well in 50Hz mode after all.

    The photos of 256×240 with reverse LPF look like you didn’t tweak the sample phase perfectly. Set reverse LPF to 4 and tweak sample phase some more.

    I have tried lots of combinations of LPF and sample phase, but no setting seems to do it. (although some do make 256×240 optim mode look a bit more pleasant) Here’s an LPF setting of 4 and two different values for the sampling phase:
    90 degrees: https://photos.app.goo.gl/9RgUVY8Rg5nCtMCw1
    258 degrees: https://photos.app.goo.gl/r54qL723Irm3edAL2

    I am a bit surprised why some people report such success with the LPF filter though… looking at the forums, I see screenshots that seem to completely remove the blur. So I am wondering whether my lack of success is just a case of different 2chip models having different amounts of blur?

    Or could it be the cable interference making the problem worse? (increasing LPF to max did sharpen the intensity of the composite checkerboard pattern in solid colours as well)

    Or yet another setting I haven’t considered? I did try the various settings mentioned in the firmware update thread… but the reverse LPF would still not give great results… just a dimming of the blur at lower settings, and a brighter edge after it at higher settings.

    // Michel

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