Lag Compensation

[ErikM]

Been quiet so I'll throw in this topic now.

I'd like to suggest a feature that could make a big difference in playability for some folks: Lag compensation. Many modern monitors and TVs lag a few frames in displaying the input signal. And of course pinball games are very sensitive to precise timing. Last week trying to play Fantastic Journey, I couldn't hit any shots using my current LCD monitor because of the lag. It was fine after switching back to my old CRT.

Could the Pro Pinball program architecture support this for the Ultra editions? Basically it would need to keep a few frames of game state, and back up and re-simulate those frames whenever the input state changes. Guitar Hero and Rock Band are the most well known games with display lag compensation, as an example.

[Huggybaby]

Awesome idea Erik. I didn't know this might be possible.

[Ade]

That's a very interesting point Erik, something I hadn't considered before. It raises all sort of interesting thoughts as to what could happen if you overcompensate. Also, there must be a danger of getting discontinuities in the ball movement as a ball can move very quickly. However, with motion blur active that would help to mask the ball jumping from one location to another.

The existing architecture would make it far from straightforward to do, but It's going in our backlog as it's something I'd like to look into further when time permits. Thanks!

[settingsons]

All of us running cabs tend have have the game mode activated (on my LG 42" it is called JustScan) which means all image interpolation, etc. is turned off so in theory there should be no lag (although maybe it varies from model to model / make to make).

Also for anyone planning on buying a TV for a cab don't worry about 100/120 hz as you will never use it unless you don't mind lag. This a is due to the screen holding a view frames back so it can generate and insert additional frames every other frame. Also when rotating a monitor remember to have bottom of monitor on left side if you also plan to use Visual Pinball tables.

[LoB]

I find the idea interesting as well. It is well known from online gaming for network latency, but I've never heard about it regarding input lag / GFX lag. It might cause other glitches though: If you "fall back" a few frames, this would look like stuttering I guess.

[Vince]

[insx]

Would it work to slightly change the angle that the ball travels at as if it had been hit a few frames earlier? No need to go back to any earlier frames then and nothing noticeably strange on screen.

[ErikM]

[LoB]

ErikM, I've never played those Guitar Hero games. Do players notice when the lag compensation jumps in? Do animations stutter notably?

[ErikM]

It's noticeable if you know what to look for. You see the fretboard note scroll slightly past the hit-line before it burns into the note-hit animation.

For Pro Pinball on a laggy display, you would always see the ball roll slightly past where you thought you hit it. But then with lag compensation, the flipper and ball would make a small jump into the positions that would be correct from where you thought you hit it. Better to let the visuals jump slightly to keep the timing accurate, rather than having all your shots delayed and missing. Of course you could turn it off if you don't like that.

I trust Ade to get the implementation right if he decides it's feasible.