vlc 0.2.90 observations on ppc

Christophe Massiot massiot at via.ecp.fr
Sat Oct 13 00:47:22 CEST 2001

À (At) 11:13 -0400 12/10/01, Jack Howarth écrivait (wrote) :

>     I wanted to pass along a few observations about the
>improved performance of vlc 0.2.90 on a G4/450 running
>Debian ppc sid. The new version seems to play without
>any noticable artifacts. Before with 0.2.83 and some
>test altivec patches from Michel Lanners I would get
>noticable jerkiness in playback and a variation in the
>framerate from between 16-17 to 24 fps. Now on this
>new release with both the imdct and motion compensation
>altivec codecs in use I get a rock solid 23.98 fps as
>measured using the -v flag and the patch below...

--stats would have given you pretty much the same kind of information...

>At this frame rate on a PowerMac G4/450 I am getting (using Xvideo)
>this 23.98 fps framerate at about 30% cpu usage on vlc and 25% cpu
>usage on XFree86 4.1. If I stress the machine I don't see any measured

These numbers are much lower than I expected, seems that our Altivec 
routines dramatically improved things...

>change in fps (although I may be sampling to coarsely for that) but
>I see a couple late frames skipped. However the video still looks pretty

That's a normal X behaviour.

>      I do have one question. It seems that the only plugin we don't have
>accelerated compared to mmx on our altivec equiped machines is the yuv
>one. Does anyone know how much that would help and what sort of cpu load
>reduction we should expect if we had it?

Since you're using Xvideo, you don't use software YUV. So none. But 
some routines still needs to be Altivec-enabled, for instance imdct 
and downmix in the AC3 decoder...

Christophe Massiot.

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