4:3 Aspect Ratio

Subforum for discussion and help with ScummVM's PocketPC/HandheldPC port

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df7nw01
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Joined: Fri Nov 11, 2005 12:22 am

4:3 Aspect Ratio

Post by df7nw01 » Fri Nov 11, 2005 12:26 am

Hello.

First I have to say ScummVM is really good (I'm using the version for PocketPC), but there something I'm thinking about.

The usual aspect ratio for the games is 4:3 (like a monitor), and a PPC with a resolution of 320x240 pixel also has an aspect ratio of 4:3, so it would fit nice if there weren't the ScummVM menu bar taking a part from the display.

The picture gets a bit crushed and the aspect ratio isn't 4:3 any more, is it?
Why doesn't the game gets stretched to full screen when disabling the menu bar?

Stefan

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frank_m24
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Location: Germany

Post by frank_m24 » Fri Nov 11, 2005 6:29 pm

Hello,

since most scumm games are using 320x200 Pixel (NOT 240) (except some FM-TOWNS games and the VGA titles), the PC Versions are providing a feature called "aspect ration correction", which scales the games from 320x200 to 320x240. PocketPC ScummVM unfortunately does not support this feature since it looks awful. PC Versions are using 2x or even 3x scalers, there are enough lines for the scaling process, which looks much better.

kind regards

Frank

df7nw01
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Post by df7nw01 » Fri Nov 11, 2005 10:24 pm

Hm ok, so the games look correct on my PPC :o)

But I didn't understand whether the aspect ratio correction now isn't good at all or whether it just would look awful on the PPC (if it were possible there).
I enabled the aspect ratio correction on the PC version for testing purposes and came to the conclusion that it doesn't look very good, so I won't miss it.

But why has the PocketPC version such an option if it has no functionality? I think the option should be removed then, otherwise it might confuse people.

And can you tell me why the image is vertically stretched on PocketPCs when you do not use the fullscreen mode?

Thanks

Stefan

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frank_m24
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Post by frank_m24 » Sat Nov 12, 2005 9:58 am

Hello,

on the PC with 2x or 3x scalers the games are using 640 or even 960 lines. This means, the aspect ration correction has much more lines for interpolating a stretched image. It means not just to show some lines twice, but also some kind of anti aliasing algorithm is feasible.

On PocketPC the games has to be stretched from 200 to 240, which can only be done by showing some lines twice. For anti aliasing the PPC has not enough processing power, and showing a few lines twice looks just awful.
And can you tell me why the image is vertically stretched on PocketPCs when you do not use the fullscreen mode?
I'm not sure what you mean since on my Axim X50v the games look the same with or without fullscreen enabled.

regards

Frank

badbob001
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Post by badbob001 » Sun Nov 13, 2005 4:30 pm

frank_m24 wrote:
And can you tell me why the image is vertically stretched on PocketPCs when you do not use the fullscreen mode?
I'm not sure what you mean since on my Axim X50v the games look the same with or without fullscreen enabled.
Could he mean portrait-mode when he says fullscreen? In portrait mode, scummvm will drop vertical lines from the game so it fits a width of 240 pixels. Unfortunately, the ppc build still thinks there are only 240 horizontal pixels on a vga device with 480 horizontal pixels.

Cirion81
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Post by Cirion81 » Sun Nov 13, 2005 6:49 pm

No badbob001, I think what Stefan is relying to is the fact that there exists a checkbox for activating apect ratio correction, but activating it doesn't change anything.

For example, I own a VGA device and thus can use 2x or advmame2x as a scaler. Activating aspect ratio correction on any 320x200 game like The Dig, Day Of the Tentacle etc. still leaves the image squeezed (it is still scaled to 640x400) and the rest of the screen remains black (or shows the toolbar if activated).

This could be due to the fact that for compilation of PocketSCUMM one has to switch the scaler into "fast and ugly mode" (because EVC4.0 has some problems with the used templates), which then uses different code for scaling in comparison to the desktop version.

The "fast and ugly" code does seem to me to do some work on a quick glance, yet I haven't dug into that more deeply. Maybe there is no effect to see, because it compiles with a warnign (possible stack overflow) - yet I think this should at least be a visible problem if this indeed happens. Maybe the aspect ratio correction is deactivated somewhere else in the code. But these are just my two cents ...

Anyway since I often read that VGA devices are to slow for VGA games etc. here in the forum. To this I can only say that I own a device with 624Mhz which is fast enough to run CMI with ogg and zLib compression used (even the videos are not out of sync and play quite fluent). My assumption would be, that such a device would also be fast enough to handle aspect ratio correction - again just my two cents :D

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