How to force Shairport to play with 32 Bit Depth? (solved)


I´ve a little problem. I use the following configuration:

  1. Raspberry Pi 3
  2. Actual Volumio image
  3. Allo Kali
  4. Soekris dam1021 DAC

This configuration functions fine, but you have to change the “Target Bit Depth” to 32 Bit! Because dam1021 needs 32 Bit at the I2S signal.

When Airplay is used , there is no sound and the dam1021 doesn´t synchronize. This is normally the case, when the Bit Depth is not 32 Bit! So I think the shairport does not play with 32 bit. I´ve seen, that there is a shairport-sync.conf in /etc and that you can modify this file with the following command output_format = “S32”. But unfortunately after reboot of Volumio the change of shairport-sync.conf has disappeared. So the former version seems to be copied.

Additional informations:

When an Airplay stream is established, at Volumio all seems to be fine, but the stream has only a Bit depth of 16 Bit (see the info of volume.local/dev):

Player State

{“status”:“play”,“title”:“Chopin: Rondo In C Major, Op.73”,“artist”:“Daniil Trifonov”,“album”:“Chopin Evocations”,“albumart”:"/albumart?cacheid=328&web=Daniil%20Trifonov/Chopin%20Evocations/extralarge&path=&metadata=false",“uri”:"",“trackType”:“airplay”,“seek”:7764,“duration”:526,“samplerate”:“44.1 KHz”,“bitdepth”:“16

Is there a solution to force shairport to a 32bit output and which is the right method?

Thanks in advance for your help.


Hello Michelangelo,

my shairport-sync 32 Bit depth issue is definitely located at Volumio. Volumio overwrites the shairport-sync.conf with its own configuration file, so you can not change the output format with “output_format = “S32”;”

I´ve tested the following :

  1. sudo systemctl stop volumio
  2. Change the shairport-sync.conf
  3. sudo systemctl start airplay

When I do this, I have the 32 Bit output and my dam1021 synchronizations perfect! So I can use airplay.

Now, I need help. Where can I integrate “output_format = “S32”;”?


Add your code in /volumio/app/plugins/music_service/airplay_emulation/shairport-sync.conf.tmpl
That way should be ok for you.


this was the point! Thanks a lot :slight_smile: