jarp
@jarp
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Ah makes sense I see… It’s pity TVs have such a limited amount of settings but understandably average viewer want’s full screen picture always. Oh well, in any case OSSC is great device, scaled or not…
Yeah seems some monitors behave differently than others when h.samplerate is adjusted. My new 4k monitor does the same, image shifts to the right. My old monitor did not. That’s a bummer.
But I wonder… for me adjusting settings and not adjusting are like day and night, difference is insane (as expected if you think about it). From your wording (“native resolution”) I think you have scaling enabled in your monitor so your monitor always scaled the picture to full screen? Then it makes 100% sense that you won’t notice big differences; your monitor will ruin the result anyways.
Try to disable scaling, how it behaves after that?
Ps. It’s not only scaling per se which is the problem… it inheritently blurs the result. But it’s that some monitors have crappy scaling algorithms. Like my new cheap 4k monitor, it’s horrible, there is weird scaling artifacts etc. My old monitor had much nicer scaling algorithm and I did not mid using it. With my new… no.
“jarp, you do have advanced timing settings for PAL Hi Res but you also list LineX3 for these. Since I am only using LineX2, do I still need to tweak these settings? I am able to use full overscan with the defaults.”
Please ignore my all other posts, take a look of the opening message only, that has up to date timing settings. Everything else is just stream of thought. I wish I could delete all the other posts I’ve made, they are misleading.
Use only LineX2 or LineX4 to get best results and tweak advanced settings to get perfect picture. With default settings you re throwing away full potential of the OSSC and could use any generic scan converter instead. This may not obvious with games, but use checkerboard pattern as WB background and you will see it.
My 5 cents again… It’s highly likely that SCART cable is unbuffered, hence not optimal. I had troubles with SCART cable and any other mode than PAL. For some reason PAL worked, others did not. Your VGA adapter, I do not know if it’s buffered or not, but buffered VGA adapter helped a lot for me. But since you have NTSC machine, that adapter from retro68k does not work with them.
Also I think you are expecting too much. Most likely there will be vertical banding always and nothing you can do about it when using external scandoubler. Keep in mind that what you have there is consumer grade product from early 80s made as cheap as possible – no way video out would be without analog artifacts. In real life, in real use cases, vertical banding most likely goes unnoticed. I only notice it when screen is black and stationary.
Noise patterns, I think it has something to do with sampling phase algorithm which is not perfect in the OSSC or something like that. There were some discussion on the other forums about it. When you use “wrong” H. samplerate there won’t be noise anymore because OSSC no longer syncs perfectly to outputted pixels. Again, when you set samnpling phase correctly, noise is hard to notice in real life scenarios.
Of course I am talking about my Amiga only, if yours have more visible banding then it may be different case.
Boards from retro.68k.pl arived. I can confirm that “AMIGA RGB TO BUFFERED VGA, COMPOSITE AND S-VIDEO” works well with the OSSC. All screenmodes I tried worked well including productivity. I did not try composite or s-video but those are nice options as well. Build quality seems to be very good as well, so I can recommend this setup with the OSSC.
I contacted him, he was willing to sell boards to me. If you are not in hurry, wait a while, I’ll report if the board works well with the OSSC or not after I get it. I guess that it is buffered no doubt so that will not be a problem, but dunno if it uses schmitt trigger as well and if that matters or not…
On Amiga related forums there are supplier who sell these DIY adapters. Commodore made these adapters back in the days but they are very hard to come by. I’ve seen adapters in eBay also, but one must take care to actually order *BUFFERED* adapter, not just straight wire adapter.
Like said, this is no fault in the OSSC. Amiga users have the same problem with VGA monitors. If monitor happens to load sync signals too much, Amiga assumes it should lock to external sync and things go downhill.
Ah sorry about delay, I am not online that often anymore… Anyways, I’d like to add to BuckoA51’s answer that at least my Amiga 600 seems to put out quite dirty and/or weak sync signals and the OSSC has troubles to sync to anything else than standard PAL no matter what LPF settings. Or perhaps Amiga goes to gensync mode, dunno. This happened with both SCART and VGA inputs.
This was fixed by using simple DIY buffered VGA adapter. I used schmitt trigger, that should clean dirty signal a bit more than just a simple buffer. Please notice that this is no fault in the OSSC since you are *supposed* to use buffered adapter with Amiga in any case (due to Amiga going to gensync mode if RGB output is loaded too much).
Added advancaed timing settings for HighGFX modes (http://aminet.net/package/driver/moni/HighGFX40_6). The OSSC misdetectes those modes (as expected) and my monitors refuses to sync until better values have been dialed on.
Those modes are actually quite usable, e.g. HD720 mode is true 16:9 mode which scales nicely:
While at it could we have manually selectable lineX1 mode also?
Not sure if there’s *usually* need for it but Amiga’s DBLNTSC mode puts out 744x467p @ 59Hz and 29.02kHz which is misdetected by the OSSC (it says 494p on info screen and 640×384 under advanced timing settings). As end result lineX2 mode is force enabled even though it makes no sense for this 467p mode. I can set up all the advanced timing settings properly to get perfect picture, except that lineX2 is on and as end result aspect ratio is totally wrong.
So if one could override lineX* mode under advanced timing settings then situation like these could be handled manually. Not sure if there’s any point to make OSSC detect these Amiga modes properly though I have to say that
-J
Edited new settings to the first post. Got DBLNTSC to work as well (sometimes OSSC won’t sync and rebooting OSSC fixes it). Also slightly adjusted other settings and added comments. Ditched lineX3 settings since my settings produced either incorrect aspect ratio (Linetriple mode 16:9) or were wrong (Linetriple mode 4:3).
Perhaps somebody could do lineX3 settings but I think those lineX2 settings are as perfect as it gets.
Ah interesting thanks, I’ve overlooked that setting. I’ve been also tweaking advanced timing settings a lot with my Amiga and I can confirm that Acer K272HUL can display just about anything OSSC can throw for it.
And then NTSC modes:
NTSC:HiRes, NTSC:LowRes in lineX2 mode:
240p/288p lineX3: Off
H. samplerate: 910
H. synclen: 60
H. active: 724
V. active: 241
H. backporch: 76
V. backporch: 16
Sampling phase: Adjust until you get stable and crisp pictureNTSC:HiRes, NTSC:LowRes in lineX3, NTSC:Super-HiRes mode:
240p/288p lineX3: ON
H. samplerate: 1820
H. synclen: 72
H. active: 1448
V. active: 241
H. backporch: 198
V. backporch: 16
Sampling phase: Adjust until you get stable and crisp pictureDBLNTSC:High Res No Flicker, NTSCPAL:Low Res No Flicker:
OSSC does not syncThat should be all except interlaced modes, perhaps somebody else would have energy for those 🙂 Oh and as you noticed, my settings will always show whole overscan area since I want Workbench screen to be as large as possible. For gaming you could shrink active values to match nominal resolution and backporch to center it to avoid getting black bars. Samplerate should not be modified.
Then double PAL modes…
DBLPAL:High Res No Flicker, DBLPAL:Low Res No Flicker:
H. samplerate: 976
H. synclen: 96
H. active: 744
V. active: 564
H. backporch: 100
V. backporch: 10
Sampling phase: Adjust until you get stable and crisp pictureNothing out of ordinary here. Amiga’s min. resolution for double PAL is 640×512 and max. 744×564 when using full overscan. One could dial in V. active 540 which would result not into full overscan resultion but would be half of the 1080p and quarter of 2160p and thus pixel perfect for upscaling purposes. If your display does not sync to 564 or 540 then 576 could be tried (PAL) but that’s not pixel perfect with anything.
Huh, I think I finally fully understood how advanced timing settings do work and what each setting does. So I was able to dial in settings based on knowledge instead of trial and errors (resulting settings are more or less the same though). So here are definitive settings working on my Amiga 600 for PAL modes when using OSSC’s lineX2 mode:
PAL:HiRes, PAL:LowRes:
240p/288p lineX3: Off
H. samplerate: 908
H. synclen: 60
H. active: 724
V. active: 288
H. backporch: 77
V. backporch: 24
Sampling phase: Adjust until you get stable and crisp pictureExplanation: Amiga’s minimum resolution for PAL is 640×256 and resolution when utilizing overscan is 724×283. Using checkerboard pattern it seems H. samplerate 908 is pixel perfect setting. H. active 724 allows capturing everything Amiga outputs. V. active 288 is actually more than Amiga outputs (283), however 288 is PAL standard and may sync better than 283. As a added bonus 5 x 288 = 1440 which allows pixel perfect scaling on 1440p displays (if your display does not manage to mess it up like mine does, waiting for 5x mode…)! Backporch settings just centers the picture, adjust if yours requires different values, not sure if this depends on Amiga.
If you want to use lineX3 mode, just double H. sample rate and H. active and adjust H. backporch. Oh this allows also capturing Super-HiRes resolution (min. 1280×256 max. 1440×283) properly, lineX2 modes does not output high enough resolution for that.
PAL:HiRes, PAL:LowRes, PAL:Super-HiRes:
240p/288p lineX3: On
H. samplerate: 1816
H. synclen: 72
H. active: 1448
V. active: 288
H. backporch: 198
V. backporch: 24
Sampling phase: Adjust until you get stable and crisp pictureSuper-HiRes outputs only 1440 pixels so you could reduce H. active to 1440 for it, but then you would have to re-adjust for LoRes and HiRes modes. Best to leave it to 1448 and it’s compatible with all modes.
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