A Few Basic Questions...

[chronoboy]

Sorry for the lack of information in the title, but I did not know how to describe this in one simple sentence.

Firstly, which Emulators actually utilize both CPUs in the GP2X?

Second question is, why do games originally meant to fit on your TV not correctly fit under emulation?
For example, with FCEUltra on the GP2X, when playing games via TV-out, you notice that the interlacing is a tad off, mainly in games which can scroll virtically. Is there a way for these emulators to actually output correctly at 640x480i NTSC for optimum quality? Or are we stuck with the TV-out upscaling from the GP2X LCD resolution to 480i?

Is there a way to correctly view or perhaps center a gpSP game on the TV, instead of having it look a bit weird on the screen?

Well, those are my questions, if anyone wants to have a go at it.

Thanks for your answers in advance.

 

[zacaj]

1. Picodrive and gngeo

 

[mrsnature]

you notice that the interlacing is a tad off, mainly in games which can scroll virtically. Is there a way for these emulators to actually output correctly at 640x480i NTSC for optimum quality? Or are we stuck with the TV-out upscaling from the GP2X LCD resolution to 480i?

where did you get 640x480 from?

I would guess the emulators are written to work on the LCD, if they were written specifically for the tv-out then maybe it would work better, but i'm not sure how the gp2x converts the digital image to analogue. Try setting v-sync on.

 

[chronoboy]

480i is the shorthand name for a video mode. The i, which is sometimes uppercase, stands for interlaced, the 480 for a vertical frame resolution of 480 lines. The digitally transmitted horizontal resolution is usually 720 or 704 pixels with an aspect ratio of 4:3 and therefore a display resolution of 640 × 480 (VGA); that is standard-definition television (SDTV).

All the console systems which the GP2X emulates were made to work on SDTV, in either NTSC or PAL regions.

 

[mrsnature]

ok. I thought PAL standard was 576 horizontal lines, and NTSC was 486?
And I thought tv's where operating on these figures long before numbers like 640x480 came about.

nes resolution: 256x240 ( i guess this gets scaled 2x to fit on tv? EDIT: ok, i suppose this will also make use of the tv interlace)
snes max resolution: 512 X 448.

i just don't understand how a 640x480 signal would be a true representation of these consoles, nor how it would fit on a tv screen?

 

[chronoboy]

Older video game consoles such as the Nintendo Entertainment System generated a non-standard version of NTSC or PAL in which the two fields did not interlace, and instead were displayed directly on top of each other, keeping the orientation of the scanlines constant. This would be 240p and 288p respectively.

The NTSC PlayStation, for example, was capable of true 480i output, but most games used 240p mode due to limited graphics and CPU power.

More recent systems now always use properly interlaced NTSC or PAL, except when running games designed for older, but compatible systems. The PS2 will generate 240p/288p if a PS1 game calls for this mode. Similarly, the Wii switches to a 240p mode in the Virtual Console for games designed for it, excluding the N64, for which games are rendered in 480 lines.

240/288 lines is pre-SDTV, which is called LDTV(Low Definition). Wonder if you could play a next gen console on a TV from the 80s or even 70s?

I guess this answer my question on why the GP2X does not/cannot correctly display emulators on TV-out. However, it doesn't explain why it chops off some of the top and bottom of my screen?!?! The Tv-out settings needs a "squash" or "fit" option. When you turn TV-out on, what type of parameters can you give it when programming it in C? Are there any bits you can set to size the display on the TV?

EDIT/ADD: The emulators should really have an option like how Quake2x works. With Quake, you have a few executables, two of which are NTSC and PAL, which display Quake nicely on the TV. I imagine what quake does, is limit where the graphical output goes to make sure it doesn't chop off anything. Correct me if I'm wrong. When INITing SDL, you can select the resolution that SDL uses. Is this what quake2x does to size it properly to an NTSC/PAL TV? If so, adding an option, or even re-compiling the emulators and changing the output resolution should do it, besides having to possibly change the alignment of the emulator graphics or frontend. Is there a way for applications to detect if TV-out is currently enabled? If so, this would be a great feature to take advantage of, the emulators can resize themselves accordingly.

 

[woogal]

Quake creates a 320x240 area, and if it's displayed on tv then it displays this area in the centre of a 360x288 or 360x240 screen. This is what stops it scaling badly and helps to avoid overscan problems. As far as I'm aware there are a handful of other apps that use this method, but most don't really do anything special to help improve the display on tv.