Re: [alsa-devel] seg fault in libasound

26 Jun 2008


      Clemens Ladisch wrote:
...
Jerry Geis wrote:
...
I am getting a seg fault in alsa.
#2  0xb7d7105f in __assert_fail () from /lib/tls/libc.so.6
#3  0xb741861f in snd_pcm_area_copy (dst_area=0x81cc62c, dst_offset=0,
    src_area=0x81cb7ec, src_offset=5223, samples=816,
    format=SND_PCM_FORMAT_S16_LE) at pcm_local.h:499
This is the "assert(bitofs % 8 == 0)" in snd_pcm_channel_area_addr()
in pcm_local.h.  In theory, this means that some sample is not aligned
to a byte boundary, but it should be impossible to get this error.
Do you have any .asoundrc or asound.conf file?  If yes, please remove
them and try again.
Regards,
Clemens
You are correct. I removed my /etc/asound.conf file and now it does not 
seg fault.
Below is my file. What is wrong with it?
aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: default [C-Media USB Headphone Set  ], device 0: USB Audio [USB Audio]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
lsusb
Bus 004 Device 001: ID 0000:0000  
Bus 003 Device 002: ID 0d8c:000c C-Media Electronics, Inc. Audio Adapter
Bus 003 Device 001: ID 0000:0000  
Bus 002 Device 002: ID 13fe:1f00  
Bus 002 Device 001: ID 0000:0000  
Bus 001 Device 001: ID 0000:0000
I have used this file many times with NON USB sound devices and it has been fine.
Also - after removing the asound.conf file my sound is a little choppy. Anything I can do about that?
Thank you.
Jerry
-----
# Set default sound card
# Useful so that all settings can be changed to a different card here.
pcm.snd_card {
     type hw
     card 0
     device 0
}
# Allow mixing of multiple output streams to this device
pcm.output {
     type dmix
     ipc_key 1024
     ipc_perm 0660 # Sound for everybody in your group!
     slave.pcm "snd_card"
slave {
          # This stuff provides some fixes for latency issues.
          # buffer_size should be set for your audio chipset.
          period_time 0
          period_size 1024
          buffer_size 8192
     }
bindings {
          0 0
          1 1
     }
}
# Allow reading from the default device.
# Also known as record or capture.
pcm.input {
     type dsnoop
     ipc_key 2048
     slave.pcm "snd_card"
## Possible artsd full duplex fix:
#     slave {
#          period_time 0
#          period_size 1024
#          buffer_size 8192
#     }
bindings {
          0 0
          1 1
     }
}
# This is what we want as our default device
# a fully duplex (read/write) audio device.
pcm.duplex {
     type asym
     playback.pcm "output"
     capture.pcm "input"
}
###################
# CONVERSION PLUG #
###################
# Setting the default pcm device allows the conversion
# rate to be selected on the fly.
# duplex mode allows any alsa enabled app to read/write
# to the dmix plug (Fixes a problem with wine).
pcm.!default {
     type plug
     slave.pcm "duplex"
}
# Apparently this is wrong (breaks mplayer for me opening the device)
#ctl.!default {
#     type plug
#     slave.pcm "snd_card"
#}
########
# AOSS #
########
# OSS dsp0 device (OSS needs only output support, duplex will break some stuff)
pcm.dsp0 {
     type plug
     slave.pcm "output"
}
# OSS control for dsp0 (needed?...this might not be useful)
ctl.dsp0 {
     type plug
     slave.pcm "snd_card"
}
# OSS control for dsp0 (default old OSS is mixer0)
ctl.mixer0 {
     type plug
     slave.pcm "snd_card"
}