[mythtv-users] Leadtek Winfast 2000 XP & Debian - segfaults

Ray Olszewski ray at comarre.com
Tue Oct 14 08:21:22 EDT 2003


Reply at end.

At 12:15 AM 10/14/2003 -0500, Mark Shoemaker wrote:
>I have recently installed Debian Woody (2.4.18bf-2.4), and I am
>trying to get MythTV working. At first I tried the Debian
>packages, and I was getting a segfault in the mythbackend. So, I
>downloaded the tarballs and compiled it manually.  My card works
>ok in XAWTV, and I can record if I use the -noxv option; However, I
>start up Mythfrontend and go to watch TV and it gives me a
>black screen, with audio.  Shortly after, it locks up the machine
>and/or gives me a seqfault in the backend.  I am using an
>NVIDIA TNT2 as the output card.  Is there something I can do to
>enable XV or something that will just make this work?  Being a
>semi-newbie with linux, I've run into a brick wall with this one.
>
>I have bttv configured using card=34 and tuner=2 (I'm in Canada, so
>NTSC is what I want)
>
>Mythbackend says this when I start it:
>
>Starting up as the master server.
>Probed: /dev/video0 - Television
>Probed: /dev/video0 - Composite1
>Probed: /dev/video0 - S-Video
>
>Mythfrontend says nothing and starts fine, and then when I go to
>watch TV, I get this:
>
>Opening OSS audio device '/dev/dsp'.
>player: Can't open audio device: /dev/dsp
>Over/underscanning. V: 0.000000, H: 0.000000, XOff: 0, YOff: 0
>Using XV port 67
>Changing from None to WatchingLiveTV
>
>When I do a ctrl-c to exit it, the audio continues.
>
>I'm using the newest NVIDIA driver.
>
>Here is what I get from xvinfo:

[details deleted]

It's *probably* not XVidio that's causing your problems.

 From what you wrote, I'd *guess* that you have an audio problem.

The audio you hear when you (unsuccessfully) watch "live" TV plays simply 
because the audio card is activated by mythbackend. But you do not have 
your audio devices configured correctly, so the sound card just plays the 
audio that comes directly from the TV card (through the patch cable), 
rather than recording that audio via mythbackend to the buffer, and playing 
back audio from the "live" TV buffer through mythfrontend to /dev/dsp .

Indications of this problem from what you wrote above are:

>player: Can't open audio device: /dev/dsp

>When I do a ctrl-c to exit it, the audio continues.

Since you did not report anything about your audio ... I'm even guessing 
that you use a patch cable ... I cannot give you specific advice about what 
to do to fix this. If you are using OSS, you might want to try switching to 
ALSA, which has better support for full-duplex on some sound cards than OSS 
seems to. The Myth HowTo discusses the details of the switch, if you want 
to try this approach, and the ALSA packages on Debian (at least on Sid; I 
don't know about Woody) are quite good.

I'm not sure why mythbackend segfaults (and I'm not sure what you mean by 
"locks up" ... a beginner may misinterpret a UI lockup as a system lockup). 
That may be a different problem.





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