Sometimes it seems ALSA on my machine goes completely haywire:

  • Flash audio on Spotify doesn't produce any sound.
  • SMplayer plays audio just fine, or doesn't play at all (I've observed the latter today).
  • When I start a video in VLC it plays an extremely loud crack, so loud I'm afraid I'll lose hearing permanently and/or break a speaker. For comparison, I usually set the receiver volume to 25 when playing music, and 30-35 when watching movies. After detecting the previous two issues, I turned the volume to 6 before playing a video, and even then the crack was painfully loud.
  • After the crack, the VLC audio stream is barely audible behind a wall of noise.
  • I don't detect any extreme loudness, cracks or other distortion from speaker-test --device plughw:1,0 --channels 2.

How can this issue affect only Flash and VLC, but not SMplayer? They all use ALSA and the same sound card, after all. And these symptoms are relatively rare - only detected once every couple weeks or so. A reboot seems to solve them every time, but I would rather have some sort of guarantee that my ears will continue working.

The machine is set up from bare bones Arch Linux, and had as far as I can tell only the ALSA sound server installed when the problems were encountered.

The S/PDIF cable is connected to an Onkyo receiver, which is connected to a 5.1 speaker system.

  • The digital out from the soundcard is routed/connected to what device? Does this happen for all media played with VLC? What about an MP3? Are you sure you're using alsa and alsa alone - no pulseaudio involved? When smplayer doesn't play, what's the sampling frequency reported for the audio? – etherfish May 15 '14 at 8:08
  • I experienced a similar problem 4-5 times recently. I noticed they arise with skype turned on. I "patched" simply restarting skype. – Hastur May 16 '14 at 13:59
  • Interesting @Hastur. I do use Skype sometimes. I'll keep an eye out for errors after using it. – l0b0 May 21 '14 at 21:13
  • @etherfish I have added some more details, but I'll have to get back to you on the rest if I can reproduce the problem again. – l0b0 May 21 '14 at 21:20
  • Yesterday I've updated to Ubuntu 14.04 LTS. Today it did it again. Turned off skype. Disappeared. Turned on again no problem. I remember that one time, after a long run of firefox, and some freeze and restart of the laptop, I was able to fix it just killing the process /usr/lib/firefox/plugin-container. Then, after the reloading of the page, I had no problem again. (just all flash were stopped...). I know, just a little bit more soft than a full reboot. – Hastur May 21 '14 at 22:40

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