HDMI distortions


my setup:
Volume control mixer: disabled
Playing Spotify from iPad Mini using airplay. Airplay volume is at its maximum.

Especially in the track “Creep” by deadmau5 I noticed annoying distortions when the piano starts to play after ~ 20 seconds. (open.spotify.com/album/3ScgavCVe7BOTrLWbKDTDN)
Listening to the same track using an analog audio cable i couldn’t hear any distortions. So I lowered the airplay volume on the iPad and the distortions were gone.

So my first conclusion was that this is an airplay fault.

Next I tried to play this song directly on the PI (flac - CD rip). And … tada distortions are back.

So maybe a HDMI fault by my Onkyo AVR?
To eliminate this possibility I played the song on max volume from my PC over HDMI - no distortions at all.

So is this a hardware fault of the raspberry or a decoding bug of volumio?

Best regards,

The problem is that ALSA PCM mixer supports volume up +4dB. If I set the Volume manually with amixer to 0db (amixer sset ‘PCM’ 0db) I can avoid distortions.
From my point of view, it’s a little bit strange that there is no hint that a volume level greater than ~96% results in amplifying the signal up to 4dB.

I just want the untouched uncompressed audio stream send over HDMI to my AVR. Are there any further settings which I have to set to get this behavior?

The problem is not finally fixed.

Playing Spotify directly on the volumio results in a clear sound but through Airplay I have vinyl like sizzling noise. Does anybody have the same problem?

Best regards

Edit: I switched back from Volumio to XBMC/KODI -> no sizzling noise. Maybe it’s a shairport bug. If I’ve got time I’ll try another dist with shairport and will report here.


I think i have the same problem

I have bad distortion when the valume is at 100% and spotify playing
I use HW Mixer, and HDMI output