[alsa-devel] Invalid PCM pointer with CMI8738 and pcm.c buffer underuns

[andoru]

Raymond Yau <superquad.vortex2 <at> gmail.com> writes:


> http://www.alsa-project.org/main/index.php/XRUN_Debug
> 
> # Enable basic debugging and dump stack, check hardware pointer on the
> period update
> # Usefull to just see, if PCM stream is stopped for a reason (usually wrong
> audio process timing from scheduler)
> # And to check the values from driver
> 
> echo 11 > /proc/asound/card0/pcm0p/xrun_debug

Argh, seems the kernel I'm using doesn't have the debug options.
Any other ways around this?

> Check the system log whether the hwptr position are correct in first nine
> periods and xrun  occur on 10th period since the buffer contain 9.27
> periods when running vlc?

Which system log? Or maybe this is related to the above? I can't find
anything in any file under /var/log/ that contains anything you're talking
about. 
 
>
https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/plain/Documentation
>/sound/alsa/CMIPCI.txt
> 
> cat /proc/asound/card0/cmipci
> 
> What is the model of your sound card ?

____________________________________________________
$ cat /proc/asound/card0/cmipci
C-Media CMI8738 (model 55) at 0xe000, irq 18

00: 02 00 01 00
04: d0 0d 00 00
08: 83 00 09 00
0c: 00 00 01 0a
10: c0 00 00 00
14: 00 60 c0 00
18: 00 01 80 0e
1c: 00 00 ee ee
20: 10 40 f9 00
24: 8f ff ff 06
90: 20 09 00 00
____________________________________________________


> Does it support 4 and 6 channels in windows ?

6 channels. I don't use more than 2 channels anyway.