[Mplayer-users] libac3 and sse

Felix Buenemann atmosfear at users.sourceforge.net
Fri Jul 27 17:40:35 CEST 2001


Hello Falk,

Friday, July 27, 2001, 4:33:18 PM, you wrote:

>> I mean do you have Pentium III, Celeron II, ...

> I have a Mobile Celeron 700Mhz...it's in a Dell Inspirion 4000 with 128MB
> RAM...
it does support SSE extensions so it might be problem of your kernel,
if you get yourself a recent gdb version we can debug it.

> I think that divx with ac3 should be watchable quit fluent with this
> maschine or do think the hardware might be the delimiting factor for the
> slow video output? 
there are many point that limit spped, but having no sse
optimiztazions at all has quite some impact, another one is the need
for a fast graphics adapter with good drivers, which is very
important.
Which graphics chip do you have?
I know that my PIII 850 Notebook with S3 Savage MX/8MB I use for
decoding is very heavily loaded when decoding dvd and only manages it
fast enough when using XVideo acceleration (or maybe dga out with
limited bandwidth, through -bpp 16). So although much of the needed
power goes to graphics card/driver here (when benchmarking I have 30%
cpu load even with XVideo Extension, maybe due to bad drivers and it
much more with x11 out). You should use the -benchmark -nosound option
to see how much cpu time is spend to the system outside of mplayer,
here's a nice example:
Playing on my server PIII 500, 512KB L2 @250MHz, 256MB RAM, Matrox G400 AGP
32MB: needs ~44.8seconds to playback my 2:30 divx test trailer
(640x272, ~1200kbps) using -vo mga, systime here is ~0.4seconds.
Compared with my notebook PIII 850, 256KB L2 @850MHz, 128MB RAM,
Savage MX 8MB AGP: needs ~49.5seconds for the same clip using -vo xv,
but with ~12.7seconds systime, that's about 26% of cpu load compared
to 0.9%!!!
This might be due to 1) Bad Drivers of savage, 2) S3 Savage chip
beeing slower then the exellent Matrox chip.

So if you look at this, you'll see that every percent gained by
assembler optimizations helps to decrease cpuloadf and get fluid
playback. And libac3 contains a lot of SSE optimizations!

-- 
Best regards,
 Felix                            mailto:atmosfear at users.sourceforge.net



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