[vlc-devel] swscale painfully slow on slow machine

[jboileau]

>Software scaling is going to be slow no matter how
>optimized the algorithm is.
>The *whole* point of the overlay is to do hardware scaling. If you turn it
>off, it shouldn't come as a surprise that VLC gets slow.
I would agree if I I had not seen MPlayer play flawlessly without hardware
overlay. I even tried 4 MPlayer playing an h264 file simultaneously all with
software scaling with a total CPU usage of only 20%!

I am not trying to compare MPlayer and VLC on which is the best player here,
I am just trying to figure out if it is possible to do more efficient
software scaling. I need VLC with all its features not MPlayer.

Hardware scaling does not even work properly on that card or VLC can't use
it properly. The scaling only works when the window is larger than the video
it plays. When the window is made smaller it is cropped, not scaled. And in
any case, hardware overlay works for the first player only. If two players
are started, the second will be denied hardware overlay. Since we are
playing more than one video at a time, the problem is just an instance away.
We are displaying surveillance cameras.

Jacques Boileau



2009/10/6 Rémi Denis-Courmont <remi at remlab.net>

> Le mardi 6 octobre 2009 17:33:48 jboileau, vous avez écrit :
> > I have tried playing with some of the preferences without any luck. Does
> > anyone have any ideas of what options I could play with that might help
> get
> > the cpu usage down? Is swscale known to be inneficient with some hardware
> > configurations? Is there an alternative to swscale?
>
> Yes. Hardware scaling. Software scaling is going to be slow no matter how
> optimized the algorithm is.
>
> > The machine configuration: Celeron 1ghz using Windows XP embedded and a
> > basic graphics card, the kind that is part of the motherboard. I am
> trying
> > to play h264 video 320x240. My tests where done with 'overlay' disabled
>
> The *whole* point of the overlay is to do hardware scaling. If you turn it
> off, it shouldn't come as a surprise that VLC gets slow.
>
> --
> Rémi Denis-Courmont
> http://www.remlab.net/
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