OSSC (Open Source Scan Converter) with an Amiga

[MrClump]

This YouTube video is worth a watch:

[ Show youtube player ]

Although it's configuring the OSSC for a SNES, it was the video that for me finally made the penny drop on how to setup my Amiga with the OSSC. It shows really nicely the process of starting from scratch through to dialling in pixel perfect settings.

[rabidgerry]

Originally Posted by Shaytan

First thing first, is your OSSC firmware updated to the latest version (0.88)?

My advice is to read the wiki to better understand the various options available:

http://junkerhq.net/xrgb/index.php?title=OSSC

Besides the Advanced timing tweaker, most of the settings are shared between video modes, you can either use the onscreen feature or the display of the OSSC itself to navigate through the menu (useful when you don't have a video output).

This is what I would do in your situation:

-Set a known working workbench screen mode like PAL HiRes 640x256.
-Change the Allow upsample2x on the OSSC to ON.
-Set 480p/576p proc in Output opt. to 2X.
-Set Line2x mode to Generic 4:3
-Go back to ScreenMode Prefs and using the Test button try the DblPAL 640x512 no flicker mode and see if you get the test pattern working.

Let us know if you make any progress

Yes Firmware is up to date, I flashed it with the most recent like 2 days ago. The remote then stopped working and I had to reprogram.

I will look through the wiki but it kind of glosses over stuff assuming I know what everything is. I know basic stuff but don't really get resolution theory and in the past I was used to get one setting and when it works stick with it. Where as now I am after perhaps better quality since I have the hardware that is supposed to get me pixel perfect.

Ok I will follow your steps

I guess my main gripe is there isn't a series of steps really documented like you have and @MrClump.

So one thing I was unsure of is the selection, it just seems to be flicking aimlessly through a menu.

Anyways..........

So nothing else works other than 480p/576p at passthru

so how do I use the other sizes like 980/1024 or whatever it is?

Are these not selectable options?

And once I select an option say like 480p/576p then do I mess with the line modes options below? Just the way it's laid is bizarre, the all look like separate choices.

May be I'm just stupid

Originally Posted by MrClump

I've got it set to off with DBLPAL, if I set it to on I still get an image but it get shifted over to the far right.

I don't really understand what that setting does!

Yes I get this too once I get an image. Then have to mess with those settings to try and get the picture in the centre. It's actually a horrendous nightmare.

Originally Posted by MrClump

I think it's unlikely your OSSC is faulty, as it seems to be basically working. When I've fiddled with it, a black screen seems to one the most common symptom of having a setting wrong.

When you get a black screen is that following some sort of on screen message such as "No sync", "Out of range" or similar, or more that the monitor is just displaying the colour black?



This is actually good news! It tells you that your monitor does support 50Hz at least at 640x512, so may very well do at 1280x1024!

Well here is hoping, you sound like you know what half that jargon means so I am confident it is possible despite being like this right now

Originally Posted by MrClump

IMO that wiki is part of the problem for someone coming to the OSSC and trying to figure out how the hell to get the thing working. It's full of terms that assume you already have a good level of knowledge, and little explanation to help noobs.

I read it multiple times and just got more and more confused and have only managed to figure out the basic level of knowledge I've managed to gain from watching multiple how-to videos on YouTube instead.

Yes I agree, I basically say that above, it's like for people who already know what stuff is and how it all relates to one another. I don't understand what the selectable video outputs are and why the Amiga one is affected by the 480p mode unless I fuck about with some more setting somewhere else and fight my way back from having a black screen again.


Truly appreciate your help guys

[MrClump]

Originally Posted by rabidgerry

Well here is hoping, you sound like you know what half that jargon means so I am confident it is possible despite being like this right now

There's not much understanding of it from here

Originally Posted by rabidgerry

I don't understand what the selectable video outputs are and why the Amiga one is affected by the 480p mode unless I fuck about with some more setting somewhere else and fight my way back from having a black screen again.

Output options, this is how I understand it, it may be completely wrong, but it's how I got my head around it. Here goes.....

Of the five modes at the top of the output options list (240p/288p proc, 384p/400p proc), the option closest to your vertical resolution seems to be the one that applies. So for an Amiga low res screen mode, it would be 240p/288p, and for DBLPAL High Res No Flicker 480p/576p.

Once you've identified the correct proc line, you need to think about how many times your vertical output resolution needs to be scaled to fit onto the vertical resolution of your display. If you're lucky, there will be a multiple of 1x, 2x, 3x or 4x that provides a perfect match for your monitor. Therefore with your 1280x1024 screen and a low res 320x256 (with no overscan) display mode, you would want Line4x as that'll give you a vertical resolution of 1024, which fits perfectly!

You then want to choose the appropriate mode for the scaling you have selected above. If you're trying to dial in a 320x256 screen using Line 4x for the mode choose again the closest, so in this instance, that would be 320x240 optim (don't worry that the vertical resolution doesn't fit at this stage - you can address that in the Sampling Options). I don't know what this does, other than when you go to the sampling options, everything seems to work much better for the screen mode you're trying to dial in!

If one of the modes doesn't fit at all, then choose Generic 4:3; this is the case for DBLPAL.

It's worth messing with these settings while bringing up whatever OSD on your monitor shows what input resolution it is receiving. Through experimentation, you should understand how making changes to the output options screen affects what the OSSC spits out to the monitor. I would suggest doing this with a low res screen mode as they seem to be the easiest to avoid getting the dreaded black screen.

The settings you choose in output options are what drives which profile you are offered in Adv. Timing, and to a certain extent, they will be pre-configured. So if you've chosen 320x240 optim, then under Adv. Timing your H.active and V.active will already be set to 320x240; you then just increase the V.active to match the PAL Amiga's 256 vertical resolution, and you're good to start fiddling with the samplerate etc.

This gets clever because it allows you to have multiple settings dialled in for the same screen resolution based on what Line multiple you select on the remote. On my profiles for my A1200 I have a pixel-perfect set of settings for low res at 320x256 using a combination of Line 4x and 320x240 optim mode (and then the appropriate settings in the Sampling options) and then for games that use overscan I use Line 2x, with Generic 4:3 and again the appropriate settings in the sampling options.

What this allows me to do is switch to Line 4x on the remote for games that don't use overscan and have a pixel-perfect screen-filling image, and for games that use overscan, switch to Line 2x and have a display that's not quite pixel perfect but doesn't chop information off the edges.

If you're able to get some image with DBLPAL in Line2x mode, but it's either a mess or way off centre, I'm pretty confident it's then just a matter of messing with the settings to get it right.

If it's any consolation, I spent probably two whole evenings getting the damned thing set up. But it was worth it, I think; just don't ask the missus what I was doing as she was utterly bemused at me sitting there staring at the screen and messing with various menus for hours on end! I think to get the most out of the OSSC; you need to be something of an anally retentive perfectionist, so that'll be me to a tee!

I fear I may have made it worse with this waffle, but that's how I understand the relationship between the Output opt. and Sampling opts. The two are quite closely related, making it all the more confusing to understand them when they are located in two different menus.

It's worth putting the effort in to understand how it works. I've now done the same for my ZX Spectrum 128k toastrack and my +3 and the +3 with it's already very clean RGB output looks absolutely stunning and almost indistinguisable from a native digital output.

[frozen]

Originally Posted by MrClump

There's not much understanding of it from here




Output options, this is how I understand it, it may be completely wrong, but it's how I got my head around it. Here goes.....

Of the five modes at the top of the output options list (240p/288p proc, 384p/400p proc), the option closest to your vertical resolution seems to be the one that applies. So for an Amiga low res screen mode, it would be 240p/288p, and for DBLPAL High Res No Flicker 480p/576p.

Once you've identified the correct proc line, you need to think about how many times your vertical output resolution needs to be scaled to fit onto the vertical resolution of your display. If you're lucky, there will be a multiple of 1x, 2x, 3x or 4x that provides a perfect match for your monitor. Therefore with your 1280x1024 screen and a low res 320x256 (with no overscan) display mode, you would want Line4x as that'll give you a vertical resolution of 1024, which fits perfectly!

You then want to choose the appropriate mode for the scaling you have selected above. If you're trying to dial in a 320x256 screen using Line 4x for the mode choose again the closest, so in this instance, that would be 320x240 optim (don't worry that the vertical resolution doesn't fit at this stage - you can address that in the Sampling Options). I don't know what this does, other than when you go to the sampling options, everything seems to work much better for the screen mode you're trying to dial in!

If one of the modes doesn't fit at all, then choose Generic 4:3; this is the case for DBLPAL.

It's worth messing with these settings while bringing up whatever OSD on your monitor shows what input resolution it is receiving. Through experimentation, you should understand how making changes to the output options screen affects what the OSSC spits out to the monitor. I would suggest doing this with a low res screen mode as they seem to be the easiest to avoid getting the dreaded black screen.

The settings you choose in output options are what drives which profile you are offered in Adv. Timing, and to a certain extent, they will be pre-configured. So if you've chosen 320x240 optim, then under Adv. Timing your H.active and V.active will already be set to 320x240; you then just increase the V.active to match the PAL Amiga's 256 vertical resolution, and you're good to start fiddling with the samplerate etc.

This gets clever because it allows you to have multiple settings dialled in for the same screen resolution based on what Line multiple you select on the remote. On my profiles for my A1200 I have a pixel-perfect set of settings for low res at 320x256 using a combination of Line 4x and 320x240 optim mode (and then the appropriate settings in the Sampling options) and then for games that use overscan I use Line 2x, with Generic 4:3 and again the appropriate settings in the sampling options.

What this allows me to do is switch to Line 4x on the remote for games that don't use overscan and have a pixel-perfect screen-filling image, and for games that use overscan, switch to Line 2x and have a display that's not quite pixel perfect but doesn't chop information off the edges.

If you're able to get some image with DBLPAL in Line2x mode, but it's either a mess or way off centre, I'm pretty confident it's then just a matter of messing with the settings to get it right.

If it's any consolation, I spent probably two whole evenings getting the damned thing set up. But it was worth it, I think; just don't ask the missus what I was doing as she was utterly bemused at me sitting there staring at the screen and messing with various menus for hours on end! I think to get the most out of the OSSC; you need to be something of an anally retentive perfectionist, so that'll be me to a tee!

I fear I may have made it worse with this waffle, but that's how I understand the relationship between the Output opt. and Sampling opts. The two are quite closely related, making it all the more confusing to understand them when they are located in two different menus.

It's worth putting the effort in to understand how it works. I've now done the same for my ZX Spectrum 128k toastrack and my +3 and the +3 with it's already very clean RGB output looks absolutely stunning and almost indistinguisable from a native digital output.

I did the same thing even though it takes a lot of patience.
In the end, however, incredible results can be achieved.

[rabidgerry]

Originally Posted by MrClump

There's not much understanding of it from here

Output options, this is how I understand it, it may be completely wrong, but it's how I got my head around it. Here goes.....

Of the five modes at the top of the output options list (240p/288p proc, 384p/400p proc), the option closest to your vertical resolution seems to be the one that applies. So for an Amiga low res screen mode, it would be 240p/288p, and for DBLPAL High Res No Flicker 480p/576p.

.

I will reply to this in bits. Ok so without knowing, this is sort of what I have come to work out in my head but it's like a stab in the dark. Thanks for a little clarity. So I pick a setting on the amiga and then see which it matches up with.

Don't under stand why 480p/576p x2 isn't affected by 2xLine mode options?

More later.

[MrClump]

Originally Posted by rabidgerry

Don't under stand why 480p/576p x2 isn't affected by 2xLine mode options?

I believe only 2x scaling can be used for 480p, not sure why that is though.

[Shaytan]

I agree with everything MrClump said

One more thing @rabidgerry, if you're getting inconsistent results messing with the options, it could be useful to reset the settings on that profile just to get e fresh start (and remember to change TX mode to DVI )

[Shaytan]

Originally Posted by MrClump

I believe only 2x scaling can be used for 480p, not sure why that is though.

I think the OSSC was made with 1920x1080/1920x1200 displays in mind, so anything above that resolution has not been considered.

A PRO version is in development and that should handle more resolutions (1440p, 4k, etc)

[rabidgerry]

ok I feel I understand a lot better.

In my experimentation though, when I select a lo res option, everything is blown up huge.

When I use the 640 x 512 DBLPal option I get a black screen unless 480p is set to pass thru. So if this is ideally what I want to achieve using 2x how on earth can I get rid of that black screen?

So far the only workbench option I have had success with is a multiscan one. However it has a wavey tear line on the top title bar. No idea how to get rid of that. Playing with the phase doesn't help.

[Shaytan]

Originally Posted by rabidgerry

ok I feel I understand a lot better.

In my experimentation though, when I select a lo res option, everything is blown up huge.

When I use the 640 x 512 DBLPal option I get a black screen unless 480p is set to pass thru. So if this is ideally what I want to achieve using 2x how on earth can I get rid of that black screen?

So far the only workbench option I have had success with is a multiscan one. However it has a wavey tear line on the top title bar. No idea how to get rid of that. Playing with the phase doesn't help.

Is VGAOnly present in your Devs/Monitors drawer?

If it is remove it (or if it's not add it), reboot and retry.

Also how are you connecting your amiga to the OSSC, Vga or Scart?
If your using a VGA cable what kind of adapter are you using? Commodore one, self made, buffered, unbuffered

[rabidgerry]

Originally Posted by Shaytan

Is VGAOnly present in your Devs/Monitors drawer?

If it is remove it (or if it's not add it), reboot and retry.

Also how are you connecting your amiga to the OSSC, Vga or Scart?
If your using a VGA cable what kind of adapter are you using? Commodore one, self made, buffered, unbuffered

Yeah it is currently in my devs drawer. I'll put it back into storage.

I connect to my Amiga using RGB Amiga d-sub to Scart. Then HDMI to DVI cable.

[Shaytan]

Originally Posted by rabidgerry

Yeah it is currently in my devs drawer. I'll put it back into storage.

I connect to my Amiga using RGB Amiga d-sub to Scart. Then HDMI to DVI cable.

Your setup is pretty much like mine, the only difference is the monitor, I'm using a Benq BL912 so I'm starting to suspect the issue could be your monitor.

I've tried a variety of displays with the OSSC, even a 17" crt and all worked fine with my A1200 and a DblPAL Workbench.
The only one which gave me issues was an Asus VH226H (22" FullHD). It worked fine using standard PAL screen modes, even laced ones, but there was no way to make it work with DblPAL in 2x mode, always a black screen.

Can you try another monitor?

[rabidgerry]

So removed VGA Only and this didn't solve anything using DBLPal. Really Strange.

[rabidgerry]

I dunno if you got a chance to look at the spec I posted for my monitor, but from what I can see it prefers a 60Hz signal. So may be using the DBLPal will not work so well with the OSSC and my monitor. May be I should use an NTSC one? Then I might get no pixel perfect.

I'm going to try DBL Lo res and see what happen if I 2x line mode that.

[Shaytan]

Originally Posted by rabidgerry

I dunno if you got a chance to look at the spec I posted for my monitor, but from what I can see it prefers a 60Hz signal. So may be using the DBLPal will not work so well with the OSSC and my monitor. May be I should use an NTSC one? Then I might get no pixel perfect.

I'm going to try DBL Lo res and see what happen if I 2x line mode that.

Maybe I missed it, you said that productivity mode was working, but does ANY standard PAL 50Hz mode (pal hires, pal lowres, pal hires laced...) work?

[MrClump]

Originally Posted by rabidgerry

Yeah it is currently in my devs drawer. I'll put it back into storage.

I connect to my Amiga using RGB Amiga d-sub to Scart. Then HDMI to DVI cable.

I think the SCART cable may be your issue. I can't get DBLPAL to work over scart on my BL912, but works perfectly with a VGA cable.

Out of interest what make and model is your monitor?

[MrClump]

Originally Posted by Shaytan

Your setup is pretty much like mine, the only difference is the monitor, I'm using a Benq BL912 so I'm starting to suspect the issue could be your monitor.

I've tried a variety of displays with the OSSC, even a 17" crt and all worked fine with my A1200 and a DblPAL Workbench.
The only one which gave me issues was an Asus VH226H (22" FullHD). It worked fine using standard PAL screen modes, even laced ones, but there was no way to make it work with DblPAL in 2x mode, always a black screen.

Can you try another monitor?

Are you using DBLPAL with SCART on your 912?

[Shaytan]

Originally Posted by MrClump

Are you using DBLPAL with SCART on your 912?

Yes I do, right now I'm using a tweaked DblPAL monitor in combination with a custom overscan.prefs to obtain a 825x564 resolution (you can find it here).

The regular DblPAL.info works fine as well with my setup.

[rabidgerry]

Originally Posted by Shaytan

Maybe I missed it, you said that productivity mode was working, but does ANY standard PAL 50Hz mode (pal hires, pal lowres, pal hires laced...) work?

Let me check again, as I was switching back and forth so much I can't recall now if they were just working with passthru (my monitor can take Amiga 15khz signal)

Yes Multiscan worked but with a stupid wavey title bar.

Originally Posted by MrClump

I think the SCART cable may be your issue. I can't get DBLPAL to work over scart on my BL912, but works perfectly with a VGA cable.

Out of interest what make and model is your monitor?

So you connect to OSSC via VGA?

I was always told scart was the way to go. I go do that using my buffered adapter. Also have non buffered adapter.

Ok my Monitor is an NEC Multisync ea192m

[MrClump]

Originally Posted by rabidgerry

So you connect to OSSC via VGA?

I was always told scart was the way to go. I go do that using my buffered adapter. Also have non buffered adapter.

Ok my Monitor is an NEC Multisync ea192m

For my Amiga, yes I use an unbuffered VGA cable into my OSSC, the same cable I previously used to connect directly to my monitors VGA input.