Hi all, I'm running a Dell PowerEdge 400sc (which, based on research here, works just fine) and a Hauppage PVR-150. The video card is an ATI 9000 series (forget which model exactly, 9600 maybe). 512MB ram, 250GB Seagate SATA HD.

KnoppMyth installs fine, everything comes up as expected. During setup everything seems to be recognized fine and I can get through the MythTV config to setup the tv card and DirectData service with no problems.

However, the problem arises when I try to watch TV. The system switches to a black screen and just hangs, completely unresponsive (no key combos work, can't ssh to it from my main system). After reboot, there are two log entries in /var/log/messages:

ivtv0: All encoder XXXX stream buffers are full. Dropping data.
ivtv0: Cause: the application is not reading fast enough.

The system was down this morning so I can't get the exact error message (thus the XXXX, i don't know if it says VBI or MPEG there). I'll boot it up when I get home and post it, if anyone wants to see it. The next message is the syslog restart message, which is the first thing logged after a linux system reboots.

I can run this command fine:

cat /dev/video0 | xine stdin://mpeg2

Which shows the video stream from the cable no problem. I also grabbed the mythtv source from subversion and did a manual compile/install with no effect.

I'm a linux admin for a large networking company, and have a lot of experience with the OS (mostly Suse/redhat, not too much Debian/Knoppix), so if anyone has anything to try feel free to offer.

Buffer overflow is because the backend server isn't keeping up for some reason... As you might expect there are a number of potential causes.
http://mysettopbox.tv/phpBB2/viewtopic.php?t=14097&highlight=stream+buffers+full+dropping+data

Which video driver is X using?

If you ssh into the box what does top show when you try to watch TV?

Have you checked to make sure that the hard disks are using DMA?

You may need to adjust how the frontend app is configured (theme, eyecandy, ...) if that's a 400Mhz CPU like I'm assuming. Some of the effects are fairly CPU intensive especially with the wrong X driver.

Thanks for the reply. To answer your questions:

1) The 400SC is actually a P4 system, mine happens to be a 2.4Ghz system.
2) I believe the video driver is the ATI driver that comes with KnoppMyth. When I get home from work today my current plans of action are to first upgrade the driver to fglrx, and if that fails, to try and see if I have an old Nvidia card laying around to try.
3) When the system locks up, it's locked hard. SSH is unresponsive.
4) The HD is SATA, which if I understood correctly, doesn't utilize DMA. If i'm wrong there feel free to correct me.

I'll check out the thread you link and like I said, my current focus is on the ATI vid card.

OK, that should be plenty fast.


You definitely want the accelerated one from ATI.


Start the ssh session and top before doing this.


I think it does use DMA (lspci shows the controller as a bus master device), but it's always on.

Nothing good to report. Tried a different video card, though still ATI. The only nVidia card I have laying around doesn't have video out, so that's a bit of a problem.

I ran top like you asked, and it froze as expected. Here's the last state:


I have been unable to get the ATI driver to work, I am getting libstdc++ errors when X tries to start up. Apparently it's looking for libstdc++.5.so and this system has 6.so. I may try to fudge the link but that rarely works.

I checked BIOS for any SATA DMA settings, and the only ones there are for IDE. I did disable hyperthreading though, as recommended by the IVTV wiki, but it still locked.

I posted all this info to the ivtv users mailing list too, just to see if they had any ideas, but I don't think it's an IVTV driver issue since I can pipe the output to xine and see video there.

So, back to the drawing board.

On DMA, sorry I wasn't clearer... Don't bother to look for a setting to fiddle with. My response on that point was just an "overly verbose grunt of acknowlegement". Read it along the lines of "Yeah, nothing that needs adjusting there."

Do you have this problem watching prerecorded material too or just live TV? Watching recordings would eliminate ivtv.