[K12OSN] Pixelation with MPlayer

James P. Kinney III jkinney at localnetsolutions.com
Mon Mar 5 04:52:00 UTC 2007


On Sun, 2007-03-04 at 22:41 -0500, "Terrell Prudé Jr." wrote:
> Try upgrading your video card.  The problem that you're discussing has
> nothing to do with CPU, but rather is a video card speed issue.  I
> replaced an ancient S3 Trio64 with a Matrox Millenium G400, and my
> issues with slow video playback went away.  The thin client is a
> Pentium II-300MHz.  My server is a dual Athlon MP 1.2GHz with 2GB
> DRAM.  Now, unless you're trying to run a LTSP *server* on a Pentium
> II-300MHz  or something else ridiculous like that, CPU ain't your
> problem, dude.

Upgrading the video card is not an option since these are brand new HP
T5125 thin clients and I deployed 2200 of them. The process of viewing
video clips using thin clients requires that the server do the heavy
lifting, not the client. For the same reason than 3D-accelerated
graphics won't work in a thin -client setup, neither will using the
graphics card to do the video decompression.

The servers - all 24 application/boot servers - are dual CPU/dual core
Opteron 1.8GHz w/ 8 GB RAM and 6 Gb NICs with 4 bonded for data pipe to
the thin clients are all connected with 1000BT networking down to the
gig switch in each classroom. The clients are the only thing running
slower.
> 
> As for the network "problem" that you outline, that isn't your problem
> either unless you're running 100Mbps on your server (you should be
> running at least Gig-E on the LTSP server).  TuxType eats up a
> measured 73Mb/sec--way more than your number below--and it has no
> problems with up to 14 simultaneous sessions.  If you do have Gig-E on
> the server, then check your cables, your switches (you *are* using
> switches, right?), and your NICs to make sure that they're actually
> working.  I have no problems whatsoever w/ apps that use lots of
> network bandwidth.

I have an average of 90 clients per server. In actuality, I have one
with 123 clients and a couple with 110. 
> 
> Please stop the FUD and ask questions before you go spouting off
> erroneous conclusions,

Not to sound like I'm biting your head off for the FUD statement, but I
have tested this and found that it simply isn't a workable process to
use thin clients _reliably_ to watch video clips. The synch between
sound and video gets off pretty quick depending on server load, the
video is halting and pixilated. 

I have not been replying much for the past 6 months on this list as I've
been a bit busy installing those 220 clients and 24 servers here in
Atlanta.
> 
> --TP
> _______________________________ 
> Do you GNU!? 
> Microsoft Free since 2003--the ultimate antivirus protection! 
> 
> 
> 
> James P. Kinney III wrote: 
> > I have had _NO_ success with streaming video and linux thin clients. The
> > cpu it takes to decompress and then the bandwidth it takes to send the
> > final video stream exceeds what can be done with LTSP.
> > 
> > A 320x240 video at 30 fps and 16 bit color requires 36.864 Mbps
> > sustained bandwidth. Pump that through an ethernet connection and add
> > 30% for connection overhead. 47.9 Mbps. The network systems can handle
> > it but not for more than 1 system.
> > 
> > In short, playing a TV set over a thin client network doesn't work. 
> > 
> > Yes, standalone windows machine can play streaming video. Educate the
> > teachers so the understand that passive entertainment like watching
> > films and movies is done at the full class level in the media center. It
> > is not something to be done on thin client. They have some limitations.
> > This is a major one.
> > 
> > On Sun, 2007-03-04 at 10:05 -0500, David Hopkins wrote:
> >   
> > > During playback, the picture pixelates (is that a word?) rather badly
> > > during any scene with lots of motion.  Playback is using Xv, and audio
> > > is esd.  The comments from teachers is that 'Microsoft plays it back
> > > perfectly so why doesn't Linux'.  I am just guessing that the
> > > difference is a local install (Windows) vs how the thin client works.
> > > So, any suggestions on how to improve the playback?  I tried using
> > > -framedrop, which helped sync the video/sound better, but did nothing
> > > to actually improve the picture.  I have also noticed that MPlayer
> > > detects a server lag (about 0.56s), but shows no network
> > > lag/compensation.  Has anyone else noticed this on with their
> > > installations?  If needed, I can look at upgrading the switches if
> > > that is the issue. The servers are dual 2.4GHz HT Xeon with 6Gb
> > > memory, but the problem occurs with even 1 user. 
> > > 
> > > Sincerely,
> > > Dave Hopkins
> > > 
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-- 
James P. Kinney III          
CEO & Director of Engineering 
Local Net Solutions,LLC        
770-493-8244                    
http://www.localnetsolutions.com

GPG ID: 829C6CA7 James P. Kinney III (M.S. Physics)
<jkinney at localnetsolutions.com>
Fingerprint = 3C9E 6366 54FC A3FE BA4D 0659 6190 ADC3 829C 6CA7
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