Migration from rasbperry to virtual machine cause noise to appear

[Thierry-Dumont]

I have a perfectly working installation of mpd on a Pi4 running Debian 12.11. I want to migrate it on a virtual machine. The vm runs on an ARM 64 and is also a Debian 12.11. The DAC, usb connected, is the same (Burr-Brown). For high quality .flac files (24 bits 96khz) and internet radio (16bits 48khz) everything is perfect. BUT for .flac files with the "CD" quality (16bits, 44khz) the sound is noisy.
Configuration of mpd is the same on the vm and on the Pi. I have look to many posts on the net, none gave me an answer.

• mpd --version 0.23.12 (on both machines)
• my mpd.conf:
  music_directory "/usr/local/Musique"
  playlist_directory "/var/lib/mpd/playlists"
  db_file "/var/lib/mpd/tag_cache"
  state_file "/var/lib/mpd/state"
  sticker_file "/var/lib/mpd/sticker.sql"
  log_file "/var/log/mpd/mpd.log"
  log_level "verbose"

input {
plugin "curl"

proxy "proxy.isp.com:8080"

proxy_user "user"

proxy_password "password"

}
decoder {
plugin "hybrid_dsd"
enabled "no"

gapless "no"

}
decoder {
plugin "wildmidi"
enabled "no"
#config_file "/etc/timidity/timidity.cfg"
}
audio_output {
type "alsa"
name "My ALSA Device"
device "hw:0,0" # optional

mixer_type "hardware" # optional

mixer_device "default" # optional

mixer_control "PCM" # optional

mixer_index "0" # optional

}
replaygain "off"
filesystem_charset "UTF-8"

• May be this doen not come from mpd...

Thank you in advance

[MaxKellermann]

Your MPD version is too old and unsupported.

[Thierry-Dumont]

Ok, true. I just upgraded to 0.24.2
Nothing changed...

[borine]

the sound is noisy.

Can you be more specific, try to describe this noise so that others can imagine what might be causing it?

I would start by testing the system audio layers on the vm. Have you used any other applications to play CD recordings on this vm? Try

speaker-test -Dhw:0,0 -tsine -c2 -r44100 

You should hear a pure tone first from the left speaker, then from the right, repeating until you press ctrl-C. Does that sound "noisy" ? Try with -r48000 instead of -r44100 - does that sound any different? If speaker-test is noisy then the problem is in the configuration of the vm, and there is nothing that mpd can do about it.

[Thierry-Dumont]

Mhh.. The sound is perturbed as when you have bad connectors, not a "white" sound. Trying your proposed tests:

• speaker-test -Dhw:0,0 -tsine -c2 -r44100 NOISY
• with -r48000 and -r9600 every thing is perfect (not noisy)
  For information (as I fear it does not come from MPD): the virtual machine is an ARM Debian, which runs on an internet box we can get in France from the internet provider free.fr (I think you heard about this -we met once in Orsay,about Jupyter).

[borine]

So your vm has a broken audio system. You could work around it by forcing mpd to convert streams to 96000Hz or 48000Hz before sending them to ALSA by adding to the ALSA audio_output entry in mpd.conf:

allowed_formats "96000:24:2 48000:16:2"

or you could seek help from your distribution or a vm support site.

[Thierry-Dumont]

This day, I upgraded my vm from bookworm to trixie... and the noise problem disappeared.
I think it was not an mpd problem, but this will probably remain unsolved :-)
Thanks again.