[mythtv-users] Few questions

Ray Olszewski ray at comarre.com
Wed Jul 9 23:28:41 EDT 2003


At 10:35 PM 7/9/2003 -0400, MacNean wrote:
>I even went into FVWM and it's still not great, i need some help, should
>i use Debian i'm using mandrake 9.1 and it was easy to install
>everything for myth, i'm also having audio syncing problems, this
>shouldn't be right?
[rest deleted]

Yes, you are having problems. What is causing them is unclear, and I think 
that to figure it out, you are going to have to be a bit more systematic 
than you are (at least to judge from what you are reporting here). I'm 
assuming you are relatively new to Linux; in my experience, old hands 
aren't all that willing to change distros to get any particular app running.

First off, what is the problem? You refer above to "audio syncing 
problems", and you earlier said video was "choppy" ... which I interpret to 
mean that frames are being dropped in recording or playback. Do these 
problems occur when watching "live" TV or when recording, then playing back 
later? (Or both?)

Second, what are the important parts of the system that you have not 
described here ... specifically, the video display (card, whether it 
displays to monitor or TV, and X driver), the sound hardware, and the drives?

Third, are the observed problems associated with high CPU load? See what 
"top" reports CPU utilization at while the system is displaying a problem 
file (be sure to do this while the video playback is visible on the screen 
... easiest way I know is to run an ssh session to the Myth host from 
another host on the LAN). If it is high ... over 90% ... then something is 
making your CPU work harder than it should (given that you have a vidcap 
card that does hardware encoding). If it is high, notice (I'm now assuming 
the problem occurs with "live" TV viewing) whether mythbackend, 
mythfrontend, or both (or something else) is generating the high load.

Now for some guesses.

Fourth, do you have DMA enabled on your hard drives? Check this with 
"hdparm /dev/hda" (or some other hd?, depending on which drive you capture 
to). Set it (as root) with "hdparm -d 1 /dev/hda" (Same note as before).

Fifth, is your X driver using XV (XVideo) to display full-motion video on 
the screen? There is any number of ways to check this; I think mythfrontend 
will report what it is using, either to STDOUT, STDERR, or its log. If you 
have xine on your system, and some standard mpeg or avi file to test with, 
you can see if "xine -V xv filename_to_play" succeeds in playing the file 
or displays a bluescreen in the video box.

With only a rough description of your setup to go on, these are the two 
most likely configuration errors to be causing high CPU load leading to 
frame drops. If neither of them is it, perhaps a more systematic report of 
your setup will give me (or someone else here) some other idea.





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