AGS incorrect scaling

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nozomi
Posts: 56
Joined: Tue Nov 01, 2005 9:28 pm

AGS incorrect scaling

Post by nozomi »

I've been playing some of the AGS games from AGD Interactive such as "Quest for Glory II" and "King's Quest I", these have a video of the AGD logo at the start of the game and i'm pretty convinced that the video is not scaled correctly when using the pixel perfect option. They seem stretched to fill the screen and it makes them look odd.

This only seems to affect the video, not the game itself.

Can anyone else confirm this? Is it a scaling option or setting I need to change? When playing the games not in ScummVM the videos seem to display at a lower resolution that the game itself and look sharper, when played in ScummVM the videos look noticable worse.
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criezy
ScummVM Developer
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Re: AGS incorrect scaling

Post by criezy »

You may need to disable the Aspect Ratio Correction for these games. They have a resolution of 320x200 pixels, and if Aspect Ratio Correction is on, ScummVM assumes that the correct resolution should be 320x240 and stretches the game vertically. That is usually correct for old games from the era of CRT screens, but may not be correct in this case.

Although, interestingly the original AGS interpreter seems to stretch the game itself to 320x240, but not the video. There is currently no way to do that in ScummVM. Either both are stretched, or neither.
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MusicallyInspired
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Re: AGS incorrect scaling

Post by MusicallyInspired »

I can indeed confirm that the AGDI and IA Sierra remakes' graphics were created WITHOUT aspect ratio correction so it should be disabled when playing.
nozomi
Posts: 56
Joined: Tue Nov 01, 2005 9:28 pm

Re: AGS incorrect scaling

Post by nozomi »

I must not be describing it correctly. The AGS games by "AGD Interavtive" all start with a video of the AGDI logo. This video should be played in a 16:9 aspect ration with black bars at the top and bottom.

But ScummVM stretches the video to always fill the 320x200 screen. Making the video look stretched and distorted.

scummvm-01.png
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AGS-01.png
AGS-01.png (48.04 KiB) Viewed 5287 times
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criezy
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Re: AGS incorrect scaling

Post by criezy »

nozomi wrote: Mon Apr 10, 2023 5:45 pm This video should be played in a 16:9 aspect ration with black bars at the top and bottom.
Ah, I was missing that information and indeed misunderstood what you meant. I checked quickly the code and we do seem to respect the "stretch" flag specified by the script when playing a video. So either we have a non-obvious bug, or the game specifies the video should be stretched (and for some reason in the original this is not respected).
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criezy
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Re: AGS incorrect scaling

Post by criezy »

I have now run the game in the debugger both with ScummVM and with the original AGS executable. I can confirm that the game uses the stretch flag for this video. However running it through the debugger also made me realise that we interpret that flag incorrectly. When the stretch flag is not set both ScummVM and the original AGS centre the video on the screen, but when it is set the original AGS stretches the video while preserving the aspect ratio while in ScummVM we do not preserve the aspect ratio (as you noticed). So there was a simple explanation after all, and it should be easy to fix.

Edit: and the fix has now been pushed.
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