Re: sending UDP frames at a fixed rate

"Ben Voigt [C++ MVP]" <rbv@nospam.nospam>
Tue, 2 Oct 2007 16:01:07 -0500
"PaulH" <> wrote in message

I have an application where I would like to send UDP frames at a fixed
rate. (for example, 200 byte frames at 50 frames per second.)
But, using the example above, I may only get 320 frames sent in 10
seconds instead of the 500 I would expect.

You're already quite close. I don't think you want busy waits, the network
is going to add jitter on the order of several ms anyway.

However, to guarantee the correct average rate, this is what you must do:

You have been computing the time between packets and sleeping that long.
This is wrong, because errors build up forever. Instead, calculate, based
on the time of the first packet and the packet number, when the next packet
should be sent. CreateWaitableTimer allows you to wait for a specific time
instead of a specific delay. If Windows slept too long in one instance, the
next sleep you receive will be shorter, and the average rate will be exactly

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