Some technical questions about PCSX2

[Dant]

Hi, I have several technical questions regarding PCSX2. Sorry, if you already answered them somewhere else. Please tell me if you haven't understood my questions, I will rewrite/specify them.
So:

1. This one is pretty hard to explain but, why does the FRAPS tool show frame rate of the emulator, and not of the particular game. For example, there are games that occasionally drop the frame rate, like MGS3. So, when such a game runs at the emulator's full speed, FRAPS shows 60 fps, instead of the real frame rate of the game (which at that moment could be 25, for instance). In ePSXe FRAPS shows the real frame rate. In Gran Turismo 2, at the beginning of the race, the fps could drop to 20-25 fps, and FRAPS shows it, even though the game runs at full speed (the plugin's frame tab shows full speed). In MGS in battle with Rex, for the most time, frame rate stays at 20 mark, and FRAPS displays it. I know that PCSX2 and ePSXe are two completely different emulators, but still, why is there a difference in showing fps in FRAPS?

2. Regarding interlacing in Gsdx. Why does it exist at all? Dolphin shows progressive picture (even though most games on the GameCube were 480i), ePSXe and PCSX do the same, as the emulators of other platforms, although original systems had support only for interlaced mode. Has it anything to do with the way PS2 works? In theory, is it possible to force PCSX2 to show progressive picture even in interlaced games? You may say it's not a problem, but it is. The judder stays even in Bob ttf mode, and blending, obviously, is not a good option.

3. Again, in theory, is it possible to force games to render in real 60 fps? For instance, MGS3, the real frame rate of the game is 30 fps and lower. Is it possible to make this game work at 60 (real) fps? Or any other game, that works at 30 fps? Or they are hardwired to some part of PS2 and can't be rendered at higher fps than they have?

[nosisab Ken Keleh]

Actually what PCSX2 expect is to keep the steady 60 FPS which is equivalent to the base PS2 "Refresh rate".

In analogy to PC, let's say your monitor + video driver is set to run at 60 Hz RR, that value does not change (nasty things would occur if it did), still the actual FPS of a game might and probably will change a great deal. For PC that's not a problem, the events are synchronized by real time and the FPS does not change the pace the action happens (just that a greater FPS makes things smoother because the number of steps is increased and the length is reduced).

But PS2 is based on TV standards and have a lot of things synchronized by the frames (almost like in a real film movie). Besides the refresh rate is hardware defined and is stead on real PS2 to the point it can and is used as reference for general sync.

The point is in the real PS2 the FPS is not the same as the refresh rate, like it's not in PC also and PCSX2 is already emulating that base as FPS to what concerns the PC so it has not as emulate the PS2 FPS other than drawing that "pace things are changing on the image", or PS2 FPS into PCSX2 actual FPS. That is the value shown by PCSX2 in the title bar, it's FPS, not PS2 FPS.

The relative independence provided by the PC methodology allows for things that are good on one side and might become odd in another way, for example the known example from excess VU cycle stealing making the game sluggish despite the "PCSX2" FPS is increased. That's because that hack may be interrupting EE module more than it should and then effectively stalling the general emulation flow, what means the flux is slowed and that can be more than the FPS increase (limited to 60 FPS in NTSC) can compensate.

About the game rendering at 60 FPS, yes, I think that could be done and attempts have been made actually, just that is something to be done game by game, via patches and was found is harder than it seems because general synchronization failure. Not to mention it means a lot more demand on the emulator.

PS: To try and make all the above simpler... it's about understanding the differences between the refresh rate, the FPS and actual pace the things are changing in a video image. Although somewhat related they are relatively independent also.