Error message when trying to output to a52 alsa module.

thejims · 06-28-2009, 10:59 AM

I'm running a recent copy of slackware-current, with ffmpeg from their git server and alsa-plugins version 1.1.18 to match the version of the installed alsa. I'm only slightly lost on how to get my .asoundrc setup for the a52 encoding to work, this is what I have so far for it

Code:

pcm.a52encode {
  type a52
}

The device I would like to output to is:

Code:

card 1: CMI8788 [C-Media CMI8788], device 0: Multichannel [Multichannel]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 1: CMI8788 [C-Media CMI8788], device 1: Digital [Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Except, no matter what I try to do with the config to set device settings or anything, I get this same error message when I test it with speaker-test -Dplug:a52encode

Code:

ALSA lib pcm.c:2162:(snd_pcm_open_conf) Cannot open shared library /usr/lib/alsa-lib/libasound_module_pcm_a52.so
Playback open error: -2,No such file or directory

And the file is definitely there:

Code:

-rwxr-xr-x 1 root root 16423765 2009-06-28 10:22 /usr/lib/alsa-lib/libasound_module_pcm_a52.so*

rylan76 · 06-29-2009, 02:41 AM

Hmm...

Quote:

Code:

ALSA lib pcm.c:2162:(snd_pcm_open_conf) Cannot open shared library /usr/lib/alsa-lib/libasound_module_pcm_a52.so
Playback open error: -2,No such file or directory

And the file is definitely there:

Code:

-rwxr-xr-x 1 root root 16423765 2009-06-28 10:22 /usr/lib/alsa-lib/libasound_module_pcm_a52.so*

Asterisk at the end of the file name in the code block above? Or is it just a typo?

Maybe ALSA is looking in /usr/local/lib instead of /usr/lib?

Try putting a symlink in /usr/local/lib to link to /usr/lib - like so:

Code:

# cd /usr/local/lib
# mkdir alsa-lib
# cd alsa-lib
# ln -s /usr/lib/alsa-lib/libasound_module_pcm_a52.so* libasound_module_pcm_a52.so*

(Note I have included the asterisks at the end, just ignore if this was a typo)

This will then effectively make the file available in both directories, but with only one "real" copy - and maybe ALSA will be able to find it now?

Nille_kungen · 06-29-2009, 05:07 AM

The asterisks at the end is an shell/prompt setting to show that the file is executable and isn't typed when you type the name since filenames never includes an *

rylan76 · 06-29-2009, 05:22 AM

Ok, I stand corrected...

Is it a terminal setting or type of terminal emulator that does that? With Rh9, FC3, FC6, FC10 and FC11 no asterisks are displayed - can I turn it on somehow? Seems like a useful feature...

thejims · 06-29-2009, 07:31 AM

I have always used ls -laF, the -F is what makes it list file types at the end, * is for executable.

I tried

Code:

ln -s /usr/lib/alsa-lib /usr/local/lib

to no effect

Could the problem be with dependencies that a52 has? Maybe it finds the a52 library file and then when trying to open the library it has a problem linking to another shared library?

rylan76 · 06-29-2009, 08:04 AM

Ok...

Hmm - maybe you need to also try to ensure that the a52 library's package config file is in both /usr/lib/pkgconfig AND /usr/local/lib/pkgconfig?

I'm not sure if a52 even uses pkgconfig, but if it does, and you know the name of the a52 library's .pkg file, you can again do something like

Code:

ln -s /usr/lib/pkgconfig/liba52.pkg liba52.pkg

when you are in /usr/local/lib

...?

thejims · 06-29-2009, 08:15 AM

I installed this from source downloaded from alsa's website

thejims · 07-03-2009, 09:48 AM

I added a few lines to my .asoundrc

Code:

pcm.a52encode {
  type a52
  slavepcm "card3"
}
pcm.card3 {
  type hw  
  card CMI8788
  device 1
  format S16_LE
  rate 48000   
}

and I still get the same error message when using

Code:

bash-3.1$ speaker-test -Dplug:a52encode

speaker-test 1.0.20

Playback device is plug:a52encode
Stream parameters are 48000Hz, S16_LE, 1 channels
Using 16 octaves of pink noise
ALSA lib pcm.c:2171:(snd_pcm_open_conf) Cannot open shared library /usr/lib/alsa-lib/libasound_module_pcm_a52.so
Playback open error: -2,No such file or directory

But I tried using mplayer and it actually worked..

Code:

bash-3.1$ mplayer test.wav -ao alsa:device=a52encode
MPlayer SVN-r29408-4.3.3 (C) 2000-2009 MPlayer Team

Playing test.wav.
Audio only file format detected.
==========================================================================
Opening audio decoder: [pcm] Uncompressed PCM audio decoder
AUDIO: 48000 Hz, 2 ch, s16le, 1536.0 kbit/100.00% (ratio: 192000->192000)
Selected audio codec: [pcm] afm: pcm (Uncompressed PCM)
==========================================================================
[ac3 @ 0x8f72660]No channel layout specified. The encoder will guess the layo
 but it might be incorrect.
AO: [alsa] 48000Hz 6ch s16le (2 bytes per sample)
Video: no video
Starting playback...
[AO_ALSA] alsa-lib: pcm_hw.c:607:(snd_pcm_hw_start) SNDRV_PCM_IOCTL_START fai
: File descriptor in bad state

So I have been trying to sort out what could be going on between here and there, maybe some conversion of some sort that needs to be done? I haven't had much more luck past that, and:

Code:

pcm.upmix3 {
  type upmix  
  slave.pcm "a52encode"
}

making 2channels upmix to the 5.1 that I use.

cladisch · 07-07-2009, 10:04 AM

Quote:

Originally Posted by thejims

Code:

ALSA lib pcm.c:2162:(snd_pcm_open_conf) Cannot open shared library /usr/lib/alsa-lib/libasound_module_pcm_a52.so
Playback open error: -2,No such file or directory

And the file is definitely there:

Code:

-rwxr-xr-x 1 root root 16423765 2009-06-28 10:22 /usr/lib/alsa-lib/libasound_module_pcm_a52.so*

Maybe some shared library required be the pcm_a52.so is missing?
What is the output of "ldd /usr/lib/alsa-lib/libasound_module_pcm_a52.so"?

thejims · 07-07-2009, 06:40 PM

Code:

bash-3.1$ ldd /usr/lib/alsa-lib/libasound_module_pcm_a52.so
        linux-gate.so.1 =>  (0xffffe000)
        libasound.so.2 => /usr/lib/libasound.so.2 (0xb7541000)
        libc.so.6 => /lib/libc.so.6 (0xb73e1000)
        libm.so.6 => /lib/libm.so.6 (0xb73bb000)
        libdl.so.2 => /lib/libdl.so.2 (0xb73b7000)
        libpthread.so.0 => /lib/libpthread.so.0 (0xb739e000)
        librt.so.1 => /lib/librt.so.1 (0xb7395000)
        /lib/ld-linux.so.2 (0xb7f12000)

Everything looks to be in order here.