I've tested both my local build and the Mozilla provided Firefox developer edition which is beta 10 instead of 8 and sound also does not work for me there (it appears to try to use apulse with similar errors). Isn't there supposed to be a single option in the build spec file to enable ALSA support again in firefox shouldn't there be a use flag for that just like pulseaudio or perhaps just enable it by default unless pulseaudio is enabled? Or has support for ALSA been completely gutted? I also tried updating to apulse-9990 in case there were any fixes but ended up with the same results. Also note enabling the about:config path whitelist to /dev/snd/ did not make sound work it works fine in 57.0.1 though without the path whitelist. Also note I believe 58_beta4 and 6 worked previously I can retest if needed.
I've encountered this in www-client/firefox-bin-58.0 from the main portage tree. Looks like apulse doesn't work for child processes. Sound came back when I disabled multiprocess in about:config (search for browser.tabs.remote.autostart using the search box. There may be multiple results. Set them all to false and restart the browser).
Please feel free to reopen and update any bug report that can be duplicated with current esr builds, 60.x. If you feel your feature needs to be re looked at in any of these bugs reopen and update, please attach patches when appropriate. Thank you Mozilla Team
