Config file for a52 plugin (60-a52-encoder.conf) produces no/garbled sound via optical digital out (S/PDIF)

[GitHub issues - opened]

alsa-project/alsa-plugins issue #38 was opened from jensgw:

Dear Maintainer,

this bug was originally reported on the debian tracker. They advised me to post it here.
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=998125

* What led up to the situation?
Fresh Debian 11 install. I want to output 5.1 sound via toslink.
Used KDE settings to switch from analog output to digital out 5.1.
This produced no or garbled sound and Youtube videos would play back way to fast without sound.
Then I switched to digital out stereo, this worked as expected but only stereo.

I could trace back the error to the shipped config file for alsa's a52 plugin: 60-a52-encoder.conf.

When I replaced that file with a much simpler one (see below) 5.1 digital out worked as expedted.

I tried with onboard sound (PCH9) and dedicated card (Audigy Z) with the same result, the inlcuded a52 config file does not work.

== Start a52.conf
pcm.a52 {
  @args [CARD]
  @args.CARD {
    type string
  }
  type rate
  slave {
    pcm {
      type a52
      bitrate 448
      channels 6
      card $CARD
    }
  rate 48000
  }
}
== End a52.conf

Therefore I assume the shipped config file with debian has an error somewhere. Please fix this.

Best reagards
Jens



-- System Information:
Debian Release: 11.1
Architecture: amd64 (x86_64)

Kernel: Linux 5.14.0-0.bpo.2-amd64 (SMP w/4 CPU threads)
Kernel taint flags: TAINT_UNSIGNED_MODULE
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages libasound2-plugins depends on:
ii  libasound2                         1.2.4-1.1
ii  libavcodec-extra58 [libavcodec58]  7:4.3.2-0+deb11u2
ii  libavresample4                     7:4.3.2-0+deb11u2
ii  libavutil56                        7:4.3.2-0+deb11u2
ii  libc6                              2.31-13+deb11u2
ii  libjack0 [libjack-0.125]           1:0.125.0-3+b1
ii  libpulse0                          14.2-2
ii  libsamplerate0                     0.2.1+ds0-1

Issue URL     : https://github.com/alsa-project/alsa-plugins/issues/38
Repository URL: https://github.com/alsa-project/alsa-plugins