Double Precision

[golgoth]

Hi Laurent,

Would it be possible to convert any reference to time like Clock::GetElapseTime and sf::Sleep from float to double?

[Laurent]

Double is better but still not enough. Only integers can guarantee 100% accurate values. So if I change this, I'd rather choose uint32 (milliseconds).

But this is still not decided.

[golgoth]

even better, go for it!

[golgoth]

While you’re at it, Window::SetFramerateLimit should take a real number or micro sec precision, add GetFramerateLimit() would also be useful.

let us know if you made the changes.

[Ceylo]

While you’re at it, Window::SetFramerateLimit should take a real number or micro sec precision, [...]

What for?

[golgoth]

NTSC for instance requires 29.97 frame per seconds.

[Grimshaw]

That's peeky man

Really? will the 0.03 seconds make an hell out of your game?

[Ceylo]

NTSC for instance requires 29.97 frame per seconds.

Nothing prevents you from displaying 29.97 frames per second. The framerate limit is only a "limit". Besides, if your movie playback speed relies on this limit, you won't be able to to keep the display speed when the computer is too slow.

[golgoth]

Your assuming I’m making a real-time application and you are partially right but, regarding video playback, with this kind of latency, a movie will be 1.8 sec late after playing for a minute. Its seams picky but it’s a huge gap.  

[Laurent]

I wouldn't rely on SetFramerateLimit for video playback timing. It's far from accurate.

[Ceylo]

My english is still very bad :lol: .

[golgoth]

Nothing prevents you from displaying 29.97 frames per second.

This is mind boggling, AFAIK, when playing video, there is no point exceeding the display calls higher than the monitor refresh rate. I’m also guessing when precision is a must, v-synch should be disable. Otherwise, Swapping buffers will have to wait until the next monitor refresh, even if a frame is ready to display. Thus, adding delay.

I wouldn't rely on SetFramerateLimit for video playback timing. It's far from accurate.

Is GetFrameTime reliable?

Milliseconds precision would be nice indeed!  

[Laurent]

Is GetFrameTime reliable?

Yes, almost 100% (there's a bug with the high-performance timer on Windows with certain configurations).

What's not reliable is a call to sf::Sleep (in case that's what you want to use).

[Ceylo]

This is mind boggling, AFAIK, when playing video, there is no point exceeding the display calls higher than the monitor refresh rate. I’m also guessing when precision is a must, v-synch should be disable. Otherwise, Swapping buffers will have to wait until the next monitor refresh, even if a frame is ready to display. Thus, adding delay.

You don't need to get a higher frame rate if the only thing you're displaying is your movie. I don't know whether this is your case.

And with vertical synchronization one indeed add delay, but one also get perfect pictures. This can be important if you have a lot of (fast) movements in your movie.

[golgoth]

(there's a bug with the high-performance timer on Windows with certain configurations)

Sorry what bug?

What's not reliable is a call to sf::Sleep (in case that's what you want to use).

I definitely need Sleep to be as precise as it could get.

I’m having a hard time synchronizing video playback, if there is something unreliable regarding timing, it would make my like much more healthy, because so far, I feel like I’m taking crazy pills.

I made a little test whish almost gave me an heart attack! l_time doesn’t return 0 but ~2 sec… whish doesn’t make any sense.

Code: [Select]

sf::Clock l_clock;
l_clock.Reset();
Float l_time = l_clock.GetElapsedTime();
 :shock: