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Comment Re:Latency (Score 5, Informative) 159


Even with a stable framerate, this technique intentionally delays the next frame to add compensation frames.

As an example, let's have a magic VR helmet running at 120Hz and instant processing (ie, 0ms GTG time, which doesn't exist) and a video card capped at a perfectly stable 30 FPS (aka 30Hz).

We will split a second into ticks - we'll use the VR helmet's frequency of 120 Hz, so we have 120 ticks, numbered 1 to 120. (Just to annoy my fellow programmers!)

We therefore get a new actual frame every 4th tick - 1st, 5th, 9th, etc.

Without motion compensation, we would display a new frame every 4th tick - 1st, 5th, 9th, etc.
With ideal (instant) motion compensation, we can't compute a transition frame until we have the new frame. So we could, theoretically, go real frame #1 on 1st tick, computed frame based on #1 and #2 on 5th tick, real frame #2 on 6th tick, computed frame based on #2 and #3 at 9th tick, etc.

This would also be jerky - 2 motion frames then 3 at rest? We could push the frames back a tick and fill the interval with three compensation frames, but then we increase the delay, which is always higher than this example (and is multiplicative). So we'd have frame #1 at 5th tick, computed frames at 6th/7th/8th, frame #2 at 9th tick, etc. You've now introduced a minimum 4 tick delay, which at 120Hz is 1/30 of a second, or 33ms! To an otherwise impossibly-perfect system!

What about historical frames instead to PREDICT the next blur? Well, then, when something in-game (or, really, on screen) changes velocity, there would be mis-compensation. (Overcompensating if the object slows, undercompensating if it speeds up, and miscompensation if direction changes).

There's more problems, too:
- This doesn't help when the video card frameskips/dips.
- Instant GTG and instant motion frame computation do not exist. At best, they're sub-tick, but you'd still operate on the tick.
- Input delay already exists for game processing, etc.
- Increased input delay perception would be exponential to the actual length of the delay. For example, 1-2ms between keypress and onscreen action? Hardly notable. 50ms delay just to start registering a motion on screen and course correct? Maybe OK, maybe annoying. 150-200ms? Brutal.

Comment Re:Or just sign your own (Score 1) 72

No, there's another big difference. First time visitors, if they are visiting a site with a non-trusted key, are asked about it, right? Sounds good, right?

The point of SSL is to ID a server as a certain server. Let's say you do ecommerce, and your very own pages explain this behavior away. Great idea, until your domain get hijacked (registrar isn't paid, DNS spoof, etc). Lo and behold, users come to expect this behavior, and click away.

This is the key fact, however. You need someone you can trust - a third party that puts a huge amount on the line - to certify that the server is who it says it is.

CACERT is a potential answer, but it needs to be integrated into Firefox and IE. But you do need that 3rd party authority. Otherwise, you it's like someone sending you an IM saying, "Hey, I'm me. What's you password/credit card/SSN?"

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