[mythtv-users] Suddenly: no sound

Roger Heflin rogerheflin at gmail.com
Wed Apr 16 02:13:43 UTC 2008


Harry Devine wrote:
> I went to watch a recording a little earlier, and discovered that my 
> sound is no longer working.  When I run mythfrontend, try Watch TV, then 
> exit all the way out, I see the following error listed:
> 
> NVP: Disabling Audio, reason is: snd_pcm_open(default): no such file or 
> directory.
> 
> If I try to use the Soundcard Detection and press the Play button, I 
> hear nothing at all their either.  The sound devices found in there are 
> shown as nVidia CK804 AC97 audio controller using module snd-intel8x0 
> and PNPb006 using module snd-mpu401.  This has been the same since I 
> installed this box from day one and it's always worked until now.
> 
> Running alsamixer used to show a whole bunch of settings, but now it 
> only shows Conexant CX8801 and only shows Playback, nothing else.  I 
> didn't see anything in the logs except for the NVP error above.
> 
> Any ideas on why this suddenly quit on me?
> 

You rebooted, and/or updated the kernel, and or installed a new sound device 
that it found on reboot.

Some of the newer kernels have been adding drivers for newer sound devices 
(webcam's, tuner boards,...), and the OS udev driver nicely loads the driver for 
the input only sound device and then alsa nicely sees it is first and does not 
look for anything else and attempts to use it as the sound device.

There are several ways to fix it, setup a udev rule (I did not fix mine that 
way), add parameters into /etc/modprobe.conf to make the proper sound device use 
the first sound device, and the incorrect sound device use the the second sound 
devices (and reboot), or rmmod the bad sound device and restart X (I did this, 
it was the fastest), or configure alsa to use the proper sound devices (may not 
work correctly on some OSes).

There should be several detailed instructions in the archives for mythtv-users 
that detail how to fix in in the various ways, it appears to be very common with 
the recent kernels, I know it happens on F7 after kernel updates, and F8 as 
configured.

                                   Roger


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