LinHES Forums
http://forums.linhes.org/

PII-450 too slow?
http://forums.linhes.org/viewtopic.php?f=2&t=528		 Page 1 of 1
Author:  graysky [ Fri Jan 16, 2004 4:02 pm ]
Post subject:  PII-450 too slow?
I read the hardware section on the main mythtv page, but it doesn't mention my specific hardware. Anyone out there using a PII-450 or something else similarly underpowered? All I want this system to do is act as a frontend and play MPEG-2 files (5000 kbps/7500 max) my backend server's PVR-250 has created. When I try to view them, the video and audio is very choppy. Is this setup just too slow, or is there some setting I should enable?

Hardware specs: PII-450 on a 440BX board. Onboard 4 meg S3 Trio 3D video, 512 meg EDO RAM, 12 gig HD (I think it's ATA/33 since that's all the BIOS can support but I do not know for sure), SB Live and 3COM 10/100 NIC.

Thanks all!
Author:  davem [ Fri Jan 16, 2004 4:38 pm ]
Post subject: 
Have you tried copying a recording to the front end box and see if mplayer can play it off the hard drive properly?
Author:  graysky [ Fri Jan 16, 2004 4:41 pm ]
Post subject: 
I can try that... does mplayer play mpeg-2 files?
Author:  Xsecrets [ Fri Jan 16, 2004 6:58 pm ]
Post subject: 
yes mplayer can play mpeg2 files. As a matter of fact you can play .nuv files directly if they were created by a pvr250/350, and not transcoded.

The problem here may just be the low end machine. Unfortunately decoding the mpeg2 file in software is probably the most demanding part of any mythtv setup. For a weak machine to work as a frontend it really needs to have a hardware mpeg2 decoder.
Author:  graysky [ Fri Jan 16, 2004 7:49 pm ]
Post subject: 
Well, when I play the video on this box, and have top running from an ssh session here's what I get:


top - 23:47:12 up 9 min, 3 users, load average: 2.16, 1.01, 0.44
Tasks: 68 total, 3 running, 65 sleeping, 0 stopped, 0 zombie
Cpu(s): 93.1% user, 6.9% system, 0.0% nice, 0.0% idle
Mem: 451144k total, 232156k used, 218988k free, 11064k buffers
Swap: 554232k total, 0k used, 554232k free, 142956k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ Command
1629 mythtv 19 0 43536 42m 11m R 50.3 9.6 1:05.54 mythfrontend
1626 mythtv 18 0 43536 42m 11m R 40.2 9.6 0:46.05 mythfrontend
444 root 7 -10 27300 22m 3248 S 4.9 5.1 0:36.18 XFree86
1627 mythtv 9 0 43536 42m 11m S 2.0 9.6 0:01.05 mythfrontend
1648 mythtv 14 0 968 968 780 R 1.6 0.2 0:00.90 top
457 mythtv 9 0 43536 42m 11m S 0.7 9.6 0:40.81 mythfrontend
1628 mythtv 9 0 43536 42m 11m S 0.3 9.6 0:00.01 mythfrontend
1 root 9 0 76 76 48 S 0.0 0.0 0:05.02 init
2 root 9 0 0 0 0 S 0.0 0.0 0:00.07 keventd
3 root 18 19 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd_CPU0
4 root 9 0 0 0 0 S 0.0 0.0 0:00.00 kswapd
5 root 9 0 0 0 0 S 0.0 0.0 0:00.00 bdflush
6 root 9 0 0 0 0 S 0.0 0.0 0:00.01 kupdated
8 root 9 0 0 0 0 S 0.0 0.0 0:00.35 kjournald
160 root 9 0 0 0 0 S 0.0 0.0 0:00.00 khubd
220 root 9 0 0 0 0 S 0.0 0.0 0:00.01 kjournald
248 daemon 9 0 388 388 324 S 0.0 0.1 0:00.00 portmap

As you can see, over 90% of the CPU goes to decoding the mpeg-2 stream. So you all think this is the problem: slow processor? There are some people on the mythtv user list running it decoding mpeg-4 without a problem with this same CPU.

What else could be causing the lag? And how can I verify it (i.e. if you think the problem is an incorrectly configured NIC, please suggest a solution too :)

Thanks again!
Author:  Xsecrets [ Fri Jan 16, 2004 9:12 pm ]
Post subject: 
record an mpeg4 file and you will see. Mpeg4 does not take nearly as much processing power to decode as mpeg2. Just out of curiosity did you try playing it back with mplayer?
Author:  graysky [ Sat Jan 17, 2004 1:51 pm ]
Post subject: 
Crap... looks like it's probably time to buy a case and CPU if I want this damn thing to work at all.
Author:  Xsecrets [ Sat Jan 17, 2004 4:59 pm ]
Post subject: 
well there are ways around that, but most of them will still involve buying something. The gforce4mx and up cards have xvmc (motion compensation) support which may help some. Then there are the dxr2/3 cards that do hardware mpeg2 decoding which are supported fairly well under linux.
Author:  graysky [ Sat Jan 17, 2004 6:47 pm ]
Post subject: 
yea, but like you said, I have to buy something. I have an ASUS A7M266 board in the box. Figure for under 200 I can give it a case, an Athlon 1900+, and a stick of 256 meg PC2100, oh and an ATI remote wonder. I have all the other parts I can use sitting around here to make it a networked frontend. And I can use that old Geforce 3 board to boot :)
Page 1 of 1 All times are UTC - 6 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/