Request: Continous Screenshot Record

SailorSat · Post by **SailorSat** » Tue Nov 09, 2004 11:13 am

I would like to have an 'continous' Screenshot feature so i could take small (say 10sec) 'clips' of my games.

Even cooler would be if you could skip any 2nd Frame so i get 30 screenshots / sec in NTSC games.

blackmyst · Post by **blackmyst** » Tue Nov 09, 2004 12:11 pm

F1 -> SNAPSHOT/INCR FRM

Does exactly what you asked, it even skips every other frame as far as I know (something which people have apparently complained about in the past).

Post by **grinvader** » Tue Nov 09, 2004 12:12 pm

And it has to do so in order to preserve emulation timings.

Noxious Ninja · Post by **Noxious Ninja** » Tue Nov 09, 2004 5:55 pm

grinvader wrote:And it has to do so in order to preserve emulation timings.

Why again?

Post by **grinvader** » Tue Nov 09, 2004 9:31 pm

Well, if I remember what pf said in the old Michael Flatley vs. the Board thread, the real snes outputted interlaced screens... meaning, you must wait two frames to get a complete picture. If you stop between the two, you break vblank timings.

Or something. I remember he said that a Super Metroid movie at 30 FPS would keep the blinking.

illegal eagle · Post by **illegal eagle** » Tue Nov 09, 2004 9:57 pm

Theoretically, an emulator should be able to output a picture of the screen at any given moment. Even at 300 fps or more.
Some parts of the screen may not be updated for a while, but if the user wants it ...?

Post by **grinvader** » Tue Nov 09, 2004 10:32 pm

illegal eagle wrote:Theoretically, an emulator should be able to output a picture of the screen at any given moment.

Well, I guess how the feature is coded isn't "flush VRAM to buffer"... as VRAM is only one line is snes iirc.

kevman · Post by **kevman** » Tue Nov 09, 2004 11:35 pm

grinvader wrote:Well, I guess how the feature is coded isn't "flush VRAM to buffer"... as VRAM is only one line is snes iirc.

Huh? I don't understand what you said at all.

Post by **grinvader** » Tue Nov 09, 2004 11:41 pm

I meant:
To dump screenshots 300 time per second without screwing timings, the dumping methods would have to be real simple, like 'save VRAM in file'.
I think something like that wouldn't break timings.
But VRAM is only 1 line on a snes. So that wouldn't give 'screenshots'...

The current screenshot feature has to wait for a screen to be completed, and important stuff timing-wise to be over. Trying to dump 300 screenshots per second would mess everything badly.

Nightcrawler · Post by **Nightcrawler** » Wed Nov 10, 2004 2:18 pm

Hmm.. I think your terminology is not quite right. VRAM is the PPU memory and contains data for the entire screen. It has all sprites, tiles, and tilemaps needed. Dumping VRAM is ineffective however since you will get a big garbled mess because VRAM does not appear like your screen. The screen needs to be generated from data in VRAM and the register settings on how to interperet that data.

You are right that the SNES draws per line and not per screen hence why you can have HDMA effects such as gradient text windows in an RPG. So it is necessary to wait for a completed frame before dumping the screen. That's all I can add. I don't know anymore details on the specifics of the screen drawing. I don't need to know that to code for it! hehe

illegal eagle · Post by **illegal eagle** » Wed Nov 10, 2004 4:11 pm

Nightcrawler wrote:You are right that the SNES draws per line and not per screen hence why you can have HDMA effects such as gradient text windows in an RPG. So it is necessary to wait for a completed frame before dumping the screen.

Yes, for a complete screen you need to wait one frame (two fields). But some games change their graphics between the fields, so incomplete screens would have to be captured.

One of my goals is to add a tool window to vSNES that allows controlling other emulators... even screenshots after each CPU instruction should be possible.
It's not quite ready yet...

ShadowLord · Post by **ShadowLord** » Thu Nov 11, 2004 7:39 am

Nu uh. Since all SNES games rendered 224 lines vertically, the games always rendered an odd or even field. Unlike regular 640x480 TV displays, it didn't alternate between an odd or even field to make a "complete frame". It was always 60 half-frames per second, which is why the scanlines were so appearant at such a resolution (and also why there was no flickering).

michael flatley · Post by **michael flatley** » Sat Nov 13, 2004 2:04 am

Well, if I remember what pf said in the old Michael Flatley vs. the Board thread, the real snes outputted interlaced screens... meaning, you must wait two frames to get a complete picture. If you stop between the two, you break vblank timings.

Or something. I remember he said that a Super Metroid movie at 30 FPS would keep the blinking.

But in ZSNES the screens are not displayed like this. We have 60 unique frames per second in Super Metroid. When we cut half of them out we lose half of the info. Bullets, bad guys, etc. don't get displayed when we capture at 30fps. SNES9X handles video recording just fine, it's not like it just CAN'T BE DONE.