Is Amiga Emulation better than the real thing?

[AmigaHope]

It depends.

Compared to a stock A500, emulation is going to run rings around it.

...but then that's like asking if Windows is better on real hardware or emulation if you're comparing it to a 386SX. =)

The other issue with emulation is that you lose the cool exact-sync display. I still struggle trying to get emulators to work properly in this respect. It emulates things faster than the fastest 060, but it still can't manage the display to an exact 50hz with perfect smooth scrolling and no tearing? =/

I'm beginning to think that emulators need to have their own video card drivers. =P


And so far nothing emulates my A4k/604e233

[AmigaHope]

Er, I've been sending/receiving software over the net on my Amiga since 1988 or so. o.O

Admittedly my x86 box can transfer stuff way faster (it has gigabit ethernet whereas my Amy has only 10bT ethernet =) but since my internet connection never goes above 10Mbit anyway, it's only really relevant when transferring files between my own systems in my house. =)

[AmigaHope]

As long as the host can update the display faster than 50fps the display will be good. Especially since LCD displays don't actually use a refresh cycle.

The LCD panel itself does not use a refresh cycle, but the video card and how it communicates with the monitor DO.

When your video card is sending 60 frames per second to the monitor, and your emulator is putting out 50 frames per second, and assuming you're using vsync to avoid tearing artifacts, *every fifth frame will be doubled*. Scrolling will not be smooth!

That said, your particular eyes may or may not notice.

For best results, you need to use a 50Hz or 100Hz screenmode. Whether or not your monitor logic supports these properly is another issue.

This should yield FAIRLY good scrolling -- because the clock rate is not 100% identical there will still be dropped/doubled frames every so often (depending on whether the 50Hz of the monitor is clocked every-so-slightly slower or faster than Amiga 50Hz). These errors should be very infrequent (but noticeable if you have a golden eye).

I can definitely see the difference when I run an emulator at 50Hz in a display at 60Hz.

[AmigaHope]

An example? o.O It's simple math. o.O

Framerate pulldown happens. It's why 24fps film does not look right on an NTSC TV, and why PAL versions of films on VHS, Laserdisc, and poorly-mastered DVDs are sped up to 25fps (making the sound pitch slightly higher, the action slightly faster, and the movie slightly shorter).

It's why good modern flat-panel TVs support 24fps input on their HDMI ports (if you have HDDVD or Blu-ray make sure you enable this!) and why when you're playing movies via a VGA input you should set your refresh to 72Hz (24fps frametripled).

In the case of your Amiga emulator, your video card is sending a new image to your monitor every 60th of a second, assuming your refresh is 60Hz. There is no way for it to space 50 frames evenly apart across 60 frames that are spread evenly apart. The smoothest you can get is by sending every fifth frame twice (50/60 with all common factors divided out, yields a lowest term of 5/6).

In other words, only every sixth frame will be displayed at the accurate moment, the following five frames will consist of a repeated frame, followed by four delayed frames (with progressively decreasing delay, until the sixth frame which will again be properly synchronized).

[AmigaHope]

I was referring to a Classic Amiga PAL demo with smooth scrolling.

Super frog game is smooth on my ASUS G1S laptop (via WinUAE).

You might not be able to see the jerkiness -- different people have different tolerances for it. If you actually took video of your screen with a high speed camera and played it back slowly, you'd see the jerkiness. It really is happening.

An A/B comparison between a properly synced display and one that isn't would show the difference well -- you could probably see it then.

Are you claiming jerky frame rates while playing back 24FPS on 60hz LCD with PureVideo HD or Avivo HD video processor?

NVIDIA PureVideo HD (Geforce 8)covers the following(quoting nVIDIA)...

All of those features you're listing focus on *recovering the original frames* of the film. All of the features listed are basically motion-detection techniques to try to reconstruct the original frames from the fragments generated by various telecine conversions (including reconversion to progressive).

All this does though is recover the original frame! Once you have your nice original frames, it *still* has to perform a framerate conversion, which still leads to jerkiness unless the source frame rate can be evenly divided into the target framerate.

It *does* reduce jerkiness in the sense that it removes any jerkiness caused in the mastering of the source materal. The reconstructed video data that results is in fact not jerky. When you actually *DISPLAY* it though you're introducing jerkiness in your final pulldown conversion. It's just better than the much-worse jerkiness you'd get from cascaded pulldown conversions.

It can't magically make 24fps or 50fps fit into a 60fps framerate smoothly.

Run the emulated Amiga in NTSC mode.

This actually works. There will still be the occasional glitch due to very slight differences in framerate (unless you can 100% accurately synchronize the mode -- this is hard to do unless your emulator has direct access to the timing controls of the video drivers), but it will mostly look great.

The only problem is that tons of software on the Amiga is carefully timed to run synchronized with a 50Hz display, and simply won't play or sound right when run in NTSC mode.

[AmigaHope]

http://www.troubled-mind.com/output.mp4

and...?

The clip on that link shows *exactly* the kind of jerky scrolling I'm talking about. =/ If you watch it you'll notice that the scrolling is not as silky smooth as on a real Amiga.

To see why this is the case, play it back frame-by frame while the player is running past the trees. Advance one frame at a time and you'll see that every 6th frame is a repeat (i.e. it will scroll for 5 frames, and then the 6th will have no motion at all).

[AmigaHope]

The differences are probably due to slight clock differences. Remember there really are *TWO* kinds of "NTSC Amiga" and "PAL Amiga".

An NTSC Amiga running in PAL mode runs at a slightly different speed than a PAL Amiga running in NTSC mode. This is because the bus in NTSC machines was clocked slightly differently.

I'm not entirely sure which of these UAE emulates. Either way, there will be occasional missed frames because it will not exactly sync to your 60Hz video display -- especially if your video display is "NTSC-style" 60Hz, which is really 59.94Hz. Amigas tend to put out a 60Hz signal that is not *exactly* 59.94 unless you installed a genlock, but it was close enough such that NTSC displays could handle it.

If you installed a good, real Amiga genlock something cool happened -- it threw out the internal clock and synced the machine to the NTSC clock. If you played a game while synced the difference in speed was noticeable. xD