On Mon, Feb 18, 2002 at 07:03:29PM +0100, Peter Surda wrote:
> Dear co-developers,
> turn "autoquality" off in the config and while playing the file, right-click,
> choose properties and slide the slider. With mplayer, use -pp 0 or -pp 4.
-pp 0 means no postprocessing
>
> Zdenek's (aviplay maintainer) and my current theory is that calling the
> XvShmPutImage returns before it is actually run. A player then does XSync, so
> that I can actually see the picture appear on screen, and calling another X
> function until it's finished causes X to "hang" and this "eats" CPU time.
To cleanup this information noice a bit -
I believe this is what is going on:
Movie players usually wait for for XFree operation completition by calling
XSync. Thus when XSync returns to the user space program there is assumption
that all XFree operation has been finished and player continues with
handling another frame.
However for now it looks like XFree is actually returning sonner than
all pending operations (image transfers) are finished - as mplayer
is waiting in this stage then usually nothing tragical will happen
as long as you have fast enough CPU so mplayer could wait enough time
before it will decide it's about right time to decode next frame.
(might be simulated in aviplay as well - but as avifile has some
threaded prechaching it will show this behaviour instantly and you
do not have to turn on any postprocessing level).
Aviplay almost immeditally after return from XSync call
wakes up decoding thread - if all the memory transfers would be
finished by this time everything would be just fine - however
if the Xserver is still transfering the memory then there will be
noticable slowdown as both operation will be completed slower then
they could be if these operation would be running in serial.
Quit noticable is this on SMP machine where XFree is accessing memory
at the same time as decoder is decoding next frame.
Ok I hope now it should be more clear.
--
.''`. Which fundamental human right do you want to give up today?
: :' : Debian GNU/Linux maintainer - www.debian.{org,cz}
`. `' Zdenek Kabelac kabi@{debian.org, users.sf.net, fi.muni.cz}
`- When in doubt, just blame the Euro. :)
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