not accurate scaling?

[gos]

greetings.
this problem's been bothering me for a while, and i really would like to seek a help and an answer...
i am playing the supported scummvm games on a vga crt, using the native res of each game.
however, every game i tried so far (COMI, DW2, BLADERRUNNER, etc...) which all run at 640x480, they just don't look as sharp as running them from their original exe! (yeah, i compared them on same monitor, side by side)
i tried everything possible, i tried every scaling & stretching option in scummvm, no dice. i even tried the very early builds of scummvm, same same.
an explanation is much appreciated, as it annoys me, since these games are not quite stable to run from original exe on windows 10.

[Praetorian]

greetings.
this problem's been bothering me for a while, and i really would like to seek a help and an answer...
i am playing the supported scummvm games on a vga crt, using the native res of each game.
however, every game i tried so far (COMI, DW2, BLADERRUNNER, etc...) which all run at 640x480, they just don't look as sharp as running them from their original exe! (yeah, i compared them on same monitor, side by side)
i tried everything possible, i tried every scaling & stretching option in scummvm, no dice. i even tried the very early builds of scummvm, same same.
an explanation is much appreciated, as it annoys me, since these games are not quite stable to run from original exe on windows 10.

Could you provide a few more details? Like:
- Which version of ScummVM are you running?
- Did you try disabling the "Filter Graphics" option from "Options..."->"Graphics" (Global setting) in the ScummVM launcher? And if so, can you check if you overrided that option in the game specific settings, by selecting the Game from the list in the ScummVM launcher, and checking the setting in the pertinent tab via "Edit Game..." -> "Graphics"
- Also, do not use any of the HQ scaling options from Graphics Mode. Either set one of the normal 1x (no scaling), 2x, ... 4x (first options in the dropdown) or the OpenGL (last in the dropdown list) option.
- Keep defaults for "Render mode" and "Stretch mode", and check that you do not override them in the game specific settings, too.
- Can you provide two screenshots for us to compare?

[gos]

greetings.
this problem's been bothering me for a while, and i really would like to seek a help and an answer...
i am playing the supported scummvm games on a vga crt, using the native res of each game.
however, every game i tried so far (COMI, DW2, BLADERRUNNER, etc...) which all run at 640x480, they just don't look as sharp as running them from their original exe! (yeah, i compared them on same monitor, side by side)
i tried everything possible, i tried every scaling & stretching option in scummvm, no dice. i even tried the very early builds of scummvm, same same.
an explanation is much appreciated, as it annoys me, since these games are not quite stable to run from original exe on windows 10.

Could you provide a few more details? Like:
- Which version of ScummVM are you running?
- Did you try disabling the "Filter Graphics" option from "Options..."->"Graphics" (Global setting) in the ScummVM launcher? And if so, can you check if you overrided that option in the game specific settings, by selecting the Game from the list in the ScummVM launcher, and checking the setting in the pertinent tab via "Edit Game..." -> "Graphics"
- Also, do not use any of the HQ scaling options from Graphics Mode. Either set one of the normal 1x (no scaling), 2x, ... 4x (first options in the dropdown) or the OpenGL (last in the dropdown list) option.
- Keep defaults for "Render mode" and "Stretch mode", and check that you do not override them in the game specific settings, too.
- Can you provide two screenshots for us to compare?

i am totally aware of these stuff you mentioned, though i know you are just making sure.
the best description i can provide is to describe how it looks, cuz i highly doubt i can capture what i am seeing, maybe i can try on a camera and set the monitor to 60hz, cuz its impossible through a screenshot, since this issue of scummvm is mostly visible on CRTs (and yeah i am aware of changing the driver's display scaling method but that's surely not the issue cuz i tried anyways).
if any of you still has a CRT hanging around, its appreciated to try and compare between scummvm and original exe.
i even tried scummvm through retroarch, same thing.

the best way to describe it is: like between hardware acceleration turned on or off in grim fandango! but not as much visible. these 2d games on scummvm are looking like a game without acceleration.
so is it so noticeable? NO, I've shown it to my partners, and they were like: that's nitpicking! but it bothers me personally.

i tried the latest nightly-stable releases, and i tried the old releases as well.

EDIT: here i captured images from a camera, look at the line around his eye, and the middle line on his shirt, very different. both at same position at the start of the game, didn't move the character at all.
https://drive.google.com/drive/folders/ ... sp=sharing

EDIT2: this lines thingy is also present on digital displays.
but my main issue is with the overall sharpness on a crt, not just this.

[sev]

I do not think it is ScummVM-specific but could be a general SDL issue.

Since you have the CRT monitor, is the mode matching the original? E.g. the original was switching to SVGA 640x480, 50Hz, for instance. Does ScummVM switch to the same? Or perhaps it is a higher resolution that is then upscaled by SDL or OS?


Eugene

[gos]

I do not think it is ScummVM-specific but could be a general SDL issue.

Since you have the CRT monitor, is the mode matching the original? E.g. the original was switching to SVGA 640x480, 50Hz, for instance. Does ScummVM switch to the same? Or perhaps it is a higher resolution that is then upscaled by SDL or OS?


Eugene

ahoy there
scummvm usually doesn't switch res for me when going exclusive fullscreen, it does that sometimes when using opengl but it doesn't matter anyway, cuz i usually put games on ((normal/no scaling)) and it looks exactly the same as opengl when it does exclusive. thats why i mostly set my desktop res to 640x480 and use ((normal/no scaling))

about the OS part, i think this could be a legit point if the program is relying on windows 10's scaling. system used: intel hd 630 internal gfx (direct vga, no conversions involved) windows 10 OS (latest update). i can easily say that the desktop scaling on windows 10 on a crt is really not as good as windows 7 for instance. but games don't rely on that as far as they can go exclusive fullscreen, dunno about scummvm.


and since you mentioned the SDL part, i was thinking about this, so is there any way to tweak some settings related?
maybe like using directx?
and not sure if retroarch does that already when you change the driver options to directx, cuz if it does, then it don't matter.

however, aside from the overall crt sharpness part, why there are differences on the sprites in the pictures i provided? and as i mentioned above, this difference can be seen on any digital display too, you guys can check it yourselves.

[sev]

In order to truly see if there are difference in the produced output, you could make screenshots in DosBox and in ScummVM and compare the output. I am talking here about computer-generated screenshots. Then we could understand, is something in the post-processing by SDL or OS or we truly have pixels with a different color.

Would you be able to do it?

Regarding tweaking SDL, you may read in their docs, there are plenty of configurations, including the selection of the backend, such as DirectX.


Eugene

[gos]

check this out: https://drive.google.com/drive/folders/ ... YQP911uLFe

since COMI is a windows 95 game, i took lossless screenshots, one from scummvm (OGL), one via dgvoodo, one via virtualbox (windows95).
the screenshots are captured on native 640x480, non upscaled.
i can't capture upscaled images because neither dgvoodo or virtualbox is good at upscaling (software based), while scummvm uses gpu to upscale, which is like day & night.

edit: i also uploaded the ripped sprite, and since the game uses dynamic sprite scale, none of the captures look identical to the main sprite.
but scummvm's capture is overall missing more details.

i am using your original scummvm app btw, not retroarch's, so i was asking about it.

[sev]

Wow, interesting. I see on the sprite that every 8 pixels there are vertical color artifacts, which suggest that perhaps we are not decoding them correctly. I wonder, how nobody noticed it before. I will take a look, eventually. You could help me by filing a bugreport and attaching these to it, because I am busy with other stuff right now and could potentially forget about this problem.

To illustrate, this is the difference:

Screenshot 2021-04-28 at 01.38.46.png (125.06 KiB) Viewed 5340 times

Eugene

[Praetorian]

That is indeed interesting. Nice catch.

I do wonder though, whether this is a COMI specific issue. The OP mentions that other titles look different (Blade Runner and Discworld 2 are explicitly named as additional examples).

@gos Is the effect there the same?

[eriktorbjorn]

I do wonder though, whether this is a COMI specific issue. The OP mentions that other titles look different (Blade Runner and Discworld 2 are explicitly named as additional examples).

Probably COMI-specific. My completely unsubstantiated guess would be something in or around AkosRenderer::codec1(). (In this case, it seems Guybrush is both scaled and mirrored, but at least he doesn't seem to have a custom scale table...)

[gos]

That is indeed interesting. Nice catch.

I do wonder though, whether this is a COMI specific issue. The OP mentions that other titles look different (Blade Runner and Discworld 2 are explicitly named as additional examples).

@gos Is the effect there the same?

i actually was talking about the sharpness of these titles on native res, not the sprite differences. however i re tested this and made sure i was wrong about it.

and as for the sprite differences, i just did plenty of strict comparisons in both (blade runner, DW2). they are totally fine, no issues, certainly.

[Praetorian]

That is indeed interesting. Nice catch.

I do wonder though, whether this is a COMI specific issue. The OP mentions that other titles look different (Blade Runner and Discworld 2 are explicitly named as additional examples).

@gos Is the effect there the same?

i actually was talking about the sharpness of these titles on native res, not the sprite differences. however i re tested this and made sure i was wrong about it.

and as for the sprite differences, i just did plenty of strict comparisons in both (blade runner, DW2). they are totally fine, no issues, certainly.

Thank you for the feedback. This makes things a lot simpler

[gos]

That is indeed interesting. Nice catch.

I do wonder though, whether this is a COMI specific issue. The OP mentions that other titles look different (Blade Runner and Discworld 2 are explicitly named as additional examples).

@gos Is the effect there the same?

i actually was talking about the sharpness of these titles on native res, not the sprite differences. however i re tested this and made sure i was wrong about it.

and as for the sprite differences, i just did plenty of strict comparisons in both (blade runner, DW2). they are totally fine, no issues, certainly.

Thank you for the feedback. This makes things a lot simpler

yw.
check this one out guys, it is more interesting
https://drive.google.com/file/d/1zaocr6 ... sp=sharing (please download the video, don't try to watch it through gdrive )
the whole screen position here is getting different too, and objects names position.
the one with a red pixel on his earring is scummvm's.

stable images: https://drive.google.com/drive/folders/ ... 3TYTyka88m

[Praetorian]

i actually was talking about the sharpness of these titles on native res, not the sprite differences. however i re tested this and made sure i was wrong about it.

and as for the sprite differences, i just did plenty of strict comparisons in both (blade runner, DW2). they are totally fine, no issues, certainly.

Thank you for the feedback. This makes things a lot simpler

yw.
check this one out guys, it is more interesting
https://drive.google.com/file/d/1zaocr6 ... sp=sharing (please download the video, don't try to watch it through gdrive )
the whole screen position here is getting different too, and objects names position.
the one with a red pixel on his earring is scummvm's.

stable images: https://drive.google.com/drive/folders/ ... 3TYTyka88m

The screen position might be a scrolling issue (?). I am not sure.

The text looks like it's displayed at the "bottom" row for subtitle text -- which kind of makes sense, since it's only one line, but it looks like that is not what the original game does; the original displays it in the "default top" row. That's probably something that can easily be fixed.

[gos]

I do wonder though, whether this is a COMI specific issue. The OP mentions that other titles look different (Blade Runner and Discworld 2 are explicitly named as additional examples).

Probably COMI-specific. My completely unsubstantiated guess would be something in or around AkosRenderer::codec1(). (In this case, it seems Guybrush is both scaled and mirrored, but at least he doesn't seem to have a custom scale table...)

Not COMI specific!
looks like it is an AKOS issue on scummvm
i was making tests on full throttle now, and it has the same problem.

here a video: https://drive.google.com/file/d/1gFR48P ... sp=sharing (scummvm & virtualbox)

still images: https://drive.google.com/drive/folders/ ... sp=sharing

apps used for the test: scummvm - virtualbox windows 95 - official windows re-release 2006.
to make sure that virtualbox wasn't doing anything fishy, i tested the official re-release, and they are exactly the same. tho the re-release is stretched vertically to ((480)) instead of windows 95's ((400)).