[mythtv-users] Re: Audio Woes
Ben Matthew
ben at thelemite.freeserve.co.uk
Wed Aug 25 07:45:36 EDT 2004
On 19/08/2004 03:42, Michael T. Dean wrote:
>Are you sure you were using OSS drivers? They've been deprecated in
>favor of ALSA for the 2.6 kernel series. Usually, you want to use ALSA
>drivers with ALSA's OSS emulation support.
Although deprecated they are still included with the 2.6.7 kernel. So I
Have tried both OSS emulation through ALSA and the OSS drivers.
>>worth of samples seem to get stuck in a loop jamming the system for
>>about 5 seconds; "dah-dah-dah-dah-dah..." to be scientific. Then
>>mythfrontend reappears and everything returns to normal.
>
>Most sounds cards do not provide hardware "direct mixing" support.
No this is not a blocked device issue. The samples being stuck are
Noticably from the DVB stream. Besides I made sure no other processes
Were running that might possibly try to open the sound device.
>If you used "-ao ALSA:driver=iec958" MPlayer should not have given you
>sound; "-ao alsa1x:iec958" (or "-ao alsa9:iec958" depending on your
>version of MPlayer) might have worked...
Well the version of Mplayer I have built; MPlayer 1.0pre5-3.3.3, uses
That argument format to specify ALSA devices. I can quite assure you
that
It does work; given I typed that in and it played back through my
digital
Output perfectly.
>So, how can you fix this? I recommend first creating a proper
.asoundrc
>....
Okidoki.
I have now created this file, forcing audio data through the dmix plugin
That autoconverts into 48000 hz. The results, however, are even worse!!
A/V sync is completely out; sound is just a load of jitters. I get lots
of
Audio buffer overrun messages and eventual seg fault. If I specify
digital
As my output device (instead of mixed-digital) I get exactly the same
result
As specifying ALSA:iec958 - i.e: perfect for 10 seconds then audio loss
with
A broken pipe error.
Mplayer works perfect using "-ao ALSA:driver=digital" now but refuses to
Work with "-ao ALSA:driver=mixed-digital" which makes me wonder if
something
Is amiss with my .asoundrc file, below. Any ideas?
(my soundcard chipset, for reference, is the via8235)
Cheers,
Ben Matthew
--
# .asoundrc for digital output over SPDIF on a snd_via82xx supported
# soundcard
pcm.digital {
type plug
slave.pcm "digital-hw"
}
ctl.digital {
type hw
card 0
}
pcm.mixed-digital {
type plug
slave.pcm "dmix-digital"
}
ctl.mixed-digital {
type hw
card 0
}
pcm.digital-hw {
type hw
card 0
device 1
subdevice 0
}
ctl.digital-hw {
type hw
card 0
}
pcm.dmix-digital {
type dmix
ipc_key 1235
slave {
pcm "digital-hw"
period_time 0
period_size 1024
buffer_size 4096
rate 48000
}
}
ctl.dmix-digital {
type hw
card 0
}
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