Re: Accurate timer
- From: Jan Panteltje <pNaonStpealmtje@xxxxxxxxx>
- Date: Mon, 04 Sep 2006 11:37:30 GMT
On a sunny day (Sun, 3 Sep 2006 22:59:22 +0100) it happened Tony Houghton
<this.address.is.fake@xxxxxxxxxxx> wrote in
<20060903225922.48b7e556@xxxxxxxxxxxxxxxxx>:
I'm trying to write a video player which will use vsync to time the
video playback and subtly adjust audio playback rate through resampling
to keep it in sync. I need a fairly accurate clock to measure any drift
between audio and video.
Some thing to take into acount are that although the video card may
update the screen at an exact frequency, that same screen is _not_ refreshed
by the software at that same frequency, because of task switching the
software may be halted for several milliseconds every now and then.
Doing a true 'slave' to an external V sync is not simple on a system that
is not a real time system.
Is that what you are doing?
Normally I would let the audio DA and DMA set the speed, and have the update
of the video screen set to that, resampling audio sucks in my view anyways.
In hardware one would control the system clock (Amiga) to be able to slave
a display.
PC is not really (without extra hardware) a suitable platform for slaving
to external sources with high accuracy.
Maybe I misunderstood what you are doing?
If you just want audio video sync, look at the mplayer source.
.
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