Latency: Difference between revisions
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A lot of electronic logic, connected directly, is often measured in nanoseconds, | |||
faster than most anyone would care about. | |||
If there was no design consideration, then you should assume any one device can deviate from the | The more complex things are, | ||
the more that that each designed device does their own thing, | |||
and the more than it does it according to ''its own'' timing. | |||
There are other devices around that you need to talk to, sure, | |||
but that is often a 'when you get to it' on both ends, | |||
and we start talking about microseconds or even milliseconds. | |||
And the harder it becomes to coordinate devices precisely. | |||
If there was no design consideration, | |||
then you should assume any one device can deviate from the plan. | |||
If computer is part of your plan, you should assume more. | |||
===Does that even matter?=== | ===Does that even matter?=== | ||
'''If you are not comparing it to something else then it does not matter''', | '''If you are not comparing it to something else, then it does not matter''', | ||
for the dumb reason that there is nothing to be late | for the dumb reason that there is nothing compared to which you can be late. | ||
Even if your video starts playing 5 seconds after you told it to, | |||
once it plays you are not comparing it to anything, | once it plays you are not comparing it to anything, | ||
so there is nothing to be late relative to. | so there is nothing to be late relative to. | ||
But if the video is more than ~50ms late (or early) ''compared to the audio'', it will look bad. | |||
That comparison very much matters, and happens continuously by the observer. | That comparison very much matters, and happens continuously by the observer. | ||
If will matter ''even more'' if you have created an experiment to measure response time[https://en.wikipedia.org/wiki/Mental_chronometry], | |||
as you probably want to know when the video started and/or stopped playing, ''to the millisecond'' if possible. | |||
Now, some things you can plan ahead of time, and ''in theory'' get shown/heard | |||
and you see and hear the result. | |||
It matters in a different way when cause and effect are involved - input that needs to lead to different output. | |||
A computer game is interactive, | |||
and there is a difference between the moment you click a button | |||
and you see and hear the result. | |||
Now consider that | Now consider that | ||
an average computer keyboard should be assumed to | an average computer keyboard setup should be assumed to get the key to the program 10ms later. | ||
an average monitor | an average game will render a frame in ~10ms or so, | ||
an average monitor may only display a rendered frame ~10ms after the game drew the frame. | |||
Gamers call this '''lag'''. | Gamers call this '''lag'''. | ||
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Electronics can do a ''lot'' better than a millisecond, | Electronics can do a ''lot'' better than a millisecond, | ||
but needs | but needs | ||
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