[MPlayer-users] Optimizing mplayer on MIPS

[Michael Niedermayer]

Hi

On Thursday 11 December 2003 02:29, Josh Green wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> I emailed this list a while back concerning running MPlayer on a MIPS
> development board that lacks an FPU. The information I received at the
> time about most video decoders being implemented with integer math
> proved very helpful, and after switching to libmad for integer only MP3
> audio decoding things are much better.
> I'm still running into some performance issues though and I haven't yet
> been able to track down what exactly is causing it. I just recently
> discovered that outputting video to the fbdev takes a huge amount of CPU
> time compared to -vo null. This is probably due to the software scaler
> which is used to do color space conversion (and sometimes aspect ratio
> correction). I've looked briefly over the swscale.c source file and it
> seems there is some usage of doubles in there. I have yet to get a
> profiler working on this system so I'm discovering things somewhat
> blindly at the moment. Does anyone on this list know if there is a
> scaler implemented in integer only math? If anyone has any other tips on
the floating point code in the swscaler is used only for initalization, the 
scaling is purely integer based

> areas that might be using lots of floating point I would appreciate the
> info. I would also be interested in knowing what kind of performance
> others have been getting with FPU/MMX-less systems.
>
> Here are some benchmarks I performed if anyone is interested. The
> benchmark.avi is a 640x480 MPEG PES 23.976 fps 1800 kbps file I encoded
> from DIVX to MPEG 1 using mencoder. The test was done on 1200 frames of
> video without sound (which should come out to 50 seconds of wall clock
> video).
>
> NULL video
> ----------
>
> mplayer -nosound -benchmark -vo null -frames 1200 benchmark.avi
>
> BENCHMARKs: VC:   0.063s VO:   0.072s A:   0.000s Sys:   3.515s =
> 3.650s
> BENCHMARK%: VC:  1.7293% VO:  1.9688% A:  0.0000% Sys: 96.3019% =
> 100.0000%
>
>
> FBdev video
> -----------
> mplayer -nosound -benchmark -frames 1200 benchmark.avi
>
> BENCHMARKs: VC:  35.265s VO:  24.540s A:   0.000s Sys:   1.524s =
> 61.329s
> BENCHMARK%: VC: 57.5019% VO: 40.0132% A:  0.0000% Sys:  2.4849% =
> 100.0000%
>
>
> So with NULL video it takes 3.65 seconds to decode 50 seconds worth of
> video. With FBdev video output it takes 61.329 seconds! (16.8 times as
> long). Using other codecs like MPEG 4 yield rather poor results with
> this platform, anyone know of some rough minimum specs to decode
> different types of video? Thanks in advance for any advice or
> information. Cheers.
i hope u did use -vc mpeg12 or ffmpeg12 for the benchmark, otherwise the 
numbers a meaningless, as the file wasnt decoded at all with -vo null

[...]
-- 
Michael
level[i]= get_vlc(); i+=get_vlc();		(violates patent EP0266049)
median(mv[y-1][x], mv[y][x-1], mv[y+1][x+1]);	(violates patent #5,905,535)
buf[i]= qp - buf[i-1];				(violates patent #?)
for more examples, see http://mplayerhq.hu/~michael/patent.html
stop it, see http://petition.eurolinux.org & http://petition.ffii.org/eubsa/en