[MPlayer-users] too SLOW to play HD file

[Morris Beverly]

Oliver Seitz wrote:
>>>  If you have to use mjpeg for
>>> playback, go buying several of the fastest harddisks (like 10000rpm
>>> types) and connect them in RAID0 or RAID5 array. That might give
>>> bandwith that can cope with mjpeg.
>>>       
>> Wouldn't storing the file on a RAM disk potentially also work, if disk
>> throughput is the problem?
>>     
>
> It most surely would. If there's enough RAM for it. I've got a mjpeg
> encoded 720p-video without sound here. It plays less than five minutes and
> the file is 885MByte. 
>   

Faster is always better, but I've been using mjpeg encoding for quite a 
while (for various reasons) and seldom run into any throughput problems 
with it.  In fact one of the reasons I use it is because it uses very 
little cpu power and I can run it on very underpowered machines.  With 
newer video chipsets of course the decoding isn't really a problem even 
with "real" codecs, but I've gotten used to using mjpeg at high quality 
settings and am happy with it.

As a reference,  I have a 1264 x 528 mjpeg file that's about 3 1/2 
minutes long.  It's 571 MB and runs at about 22 mbps.  This works out to 
around 2 1/2 MB per second which almost any drive can handle.  I use a 
cache setting of 8192 and get smooth playback on a 1.8 Ghz Sempron 
processor with 1 Gig of ram, a 5400 rpm drive, and an nvidia 5700 
graphics card.  The video has lots of solid blocks of graphics moving 
from right to left across the screen and it all runs very smoothly on 
this machine (using about 30% cpu under windows xp). 

If however, I add sharpening to the mplayer command line, the cpu goes 
to 85% and the clip starts stuttering pretty badly.  This is of course 
all with mplayer; windows media player doesn't like the odml files 
created by mencoder and quicktime just doesn't play back smoothly enough 
with low powered machines - at least under windows.

I can even play 1024 x 768 mjpeg clips on a via cpu with on board 
graphics with little problem either, but only under linux.

While mjpeg does use a lot of disk space and bandwidth, I really not 
sure that it's your core problem.  As I mentioned above, sharpening or 
other filters can add a lot of overhead and maybe a little tweaking of 
your command line can yield some information as to what's going on.

good luck,

morris