My MythTV Gentoo box has recently started having issues recording sound.
The TV tuner re-plays audio through the "mic" interface on my soundcard.
It has worked for months, but now MythTV can't read anything from /dev/dsp.

Any device that uses ALSA directly seems to work fine (like TVTime which
plays TV with audio just fine) - only those that rely on /dev/dsp seem to
have trouble. My simple test shows this:

# cat /dev/dsp > /dev/null
cat: /dev/dsp: Input/output error

This was run as root. Perms are fine:

crw-rw---- 1 root audio 14, 3 2008-10-03 08:56 /dev/dsp

Myth user is in audio group (always has been).

Has something changed in ALSA that I didn't catch? I don't see anything in
my logs or dmesg that shows a problem. My /etc/asound.conf is as follows:
pcm.nforce-hw {
type hw
card 0
}
pcm.!default {
type plug
slave.pcm "nforce"
}
pcm.nforce {
type dmix
ipc_key 1234
ipc_perm 0660
slave {
pcm "hw:0,0"
period_time 0
period_size 1024
buffer_size 4096
#rate 44100
rate 48000
}
}
ctl.nforce-hw {
type hw
card 0
}


I have tried without this asound.conf and see the same issue.

--
// Andrew MacKenzie | http://www.edespot.com
// GPG public key: http://www.edespot.com/~amackenz/public.key
// I've touch'd the highest point of all my greatness;
// And from that full meridian of my glory
// I haste now to my setting. I shall fall,
// Like a bright exhalation in the evening
// And no man see me more.
// -- Shakespeare

On Thu, Oct 30, 2008 at 12:41 PM, Andrew MacKenzie <amackenz@edespot.com> wrote:
> My MythTV Gentoo box has recently started having issues recording sound.
> The TV tuner re-plays audio through the "mic" interface on my soundcard.
> It has worked for months, but now MythTV can't read anything from /dev/dsp.
>
> Any device that uses ALSA directly seems to work fine (like TVTime which
> plays TV with audio just fine) - only those that rely on /dev/dsp seem to
> have trouble. My simple test shows this:
>
> # cat /dev/dsp > /dev/null
> cat: /dev/dsp: Input/output error
>
> This was run as root. Perms are fine:
>
> crw-rw---- 1 root audio 14, 3 2008-10-03 08:56 /dev/dsp
>
> Myth user is in audio group (always has been).
>
> Has something changed in ALSA that I didn't catch? I don't see anything in
> my logs or dmesg that shows a problem. My /etc/asound.conf is as follows:
> pcm.nforce-hw {
> type hw
> card 0
> }
> pcm.!default {
> type plug
> slave.pcm "nforce"
> }
> pcm.nforce {
> type dmix
> ipc_key 1234
> ipc_perm 0660
> slave {
> pcm "hw:0,0"
> period_time 0
> period_size 1024
> buffer_size 4096
> #rate 44100
> rate 48000
> }
> }
> ctl.nforce-hw {
> type hw
> card 0
> }
>
>
> I have tried without this asound.conf and see the same issue.
Try using alsaconf as root.


--
Andrey Vul

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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+++ Andrey Vul [gentoo-user] [Thu, Oct 30, 2008 at 01:01:39PM -0400]:
> On Thu, Oct 30, 2008 at 12:41 PM, Andrew MacKenzie <amackenz@edespot.com> wrote:
> > I have tried without this asound.conf and see the same issue.
> Try using alsaconf as root.
alsaconf ran fine. I stopped 'alsa' (and noted that all snd modules were
unloaded), ran alsaconf, and noted that modules were now loaded.

Still can't get sound via /dev/dsp. It's my understanding that snd_pcm_oss
should be the one that handles /dev/dsp.

The following 'snd' related modules are loaded:
# lsmod |grep snd
snd_pcm_oss 41824 0
snd_mixer_oss 16640 1 snd_pcm_oss
snd_intel8x0 34024 0
snd_ac97_codec 117784 1 snd_intel8x0
snd_pcm 87256 3 snd_pcm_oss,snd_intel8x0,snd_ac97_codec
snd_page_alloc 9424 2 snd_intel8x0,snd_pcm
ac97_bus 2240 1 snd_ac97_codec

My kernel is 2.6.26-gentoo-r1. But I tried another couple from 2.6.24 and
didn't have success there either. I wonder whether it's a user-land lib
issue?

Installed:
alsa-lib 1.0.16
alsa-oss 1.0.15
alsa-tools 1.0.16
alsa-utils 1.0.16

--
// Andrew MacKenzie | http://www.edespot.com
// GPG public key: http://www.edespot.com/~amackenz/public.key
// There is an old time toast which is golden for its beauty.
// "When you ascend the hill of prosperity may you not meet a friend."
// -- Mark Twain