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I'll say it again to be clear - ALSA on the command line works fine (after I delete/modify .asoundrc after it's auto-broken by PIXEL).

The most seemingly contemporary answer I've found on modern Raspbian ALSA config was here (I have no idea where @Housni read about the slots option being needed for recent versions of Raspbian, though). It seems that ALSA on Raspberry Pi is a bit funny and I don't see any official docs that are relevant to non-standard audio anywhere (just directions on HDMI or the PWM outputs). I have looked at MANY websites, including raspi forums, this SE site, Adafruit, and the ALSA docs.

My situation:

  • I can set my USB device to default for alsa, as either device 0 or 1, except...
  • .asoundrc gets regenerated each login to LXDE/PIXEL. Somehow it knows where the built-in device is and selects that card. Doesn't matter if a good .asoundrc was there vs. no such file.
  • So, by default, I get the built-in sound on the command line after login, but I can edit/delete .asoundrc and everything's fine on the CLI.
  • The GUI (e.g., pimixer aka "Audio Device Manager") ONLY seems to see the built-in audio. The USB card is visible via e.g., aplay -l, but not in the pimixer drop-down.

Based on the pimixer README, it seems PIXEL (aka sorta LXDE) is using Gstreamer for GUI stuff.

As far as I can tell, this issue could reside in:

  • LXDE
  • PIXEL LXDE mods
  • Gstreamer
  • the XFCE4 mixer settings (pimixer related stuff)
  • Pulseaudio

I trashed my .config directory, and this doesn't change any behavior.

I'm open to simply using a different distro - I'm on an RPi3. I welcome solutions at any level!

I will also happily upvote comments / answers shedding light on some of the mysteries above, like:

  • What is generating that .asoundrc?
  • What sound framework is Chromium talking to?

UPDATES

  • this rpi SE post describes the same issue. The fix doesn't work for me. It also doesn't explain what's going on - it feels like breaking the system, not understanding it.
  • this rpi forum post explains how that doesn't work for some people and how you can just disable the internal audio. This also doesn't work - pimixer says "No ALSA audio devices were detected." (aplay -l still shows my USB device - a Blackjack Onyx.)
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Dav Clark
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  • GUI apps use SDL for sound. Have you set the SDL-AUDIODRIVER environment variable to alsa – PaulF8080 Nov 28 '16 at 11:32
  • Thanks for the suggestion, but may I add that the world of raspberry pi seems to largely consist of unsubstantiated statements. Where are you getting this info? I see nothing about SDL and XFCE4 or PIXEL. SDL is certainly not a necessary component of audio on linux. That said, I tried setting SDL_AUDIODRIVER (note underscore), and it had no effect. pimixer was already showing "bcm2835 ALSA (Alsa mixer) (Default)" in the Sound Card drop-down. – Dav Clark Nov 29 '16 at 02:06
  • Are you saying that when you right click on the sound icon (top right of the desktop), you can't choose the default device ? – Matt Nov 29 '16 at 04:14
  • I got that from debugging a port of a graphic app for the PI for the last two weeks. Asking if you tried something is not the same as stating a fact. – PaulF8080 Nov 29 '16 at 05:35
  • @Matt I only see HDMI and analog (the two broadcom / built-in options) when I right-click. USB audio only shows up via alsa command line. I've also verified that pulse audio is not running by default. – Dav Clark Nov 29 '16 at 13:29

1 Answers1

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What is controlling the audio?

According to spl23 on the raspi forums, the program that's controlling audio settings is volumealsa.

What if I want audio right now?

I have verified that Ubuntu MATE works fine with the USB DAC I have (Onyx Blackjack) with Firefox and other GUI tools.

Strangely, streaming audio pages seem not to work still (Amazon Music, SoundCloud), but YouTube does.

Dav Clark
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