For some time I’ve received a few reports about lightspark raising the system volume to 100% (and “killing ears”) whenever a YouTube clip was started. It took some time for me to figure out what was going on, since I was not able to reproduce the issue on my system and of course the code was not willingly touching the system volume.
It turns out that the issue was caused by the recently introduced “flat-volume” support in PulseAudio. When flat volume is enabled the volume of a stream is absolute and not relative to the system volume. Since the default volume in flash is 100% by spec then Lightspark was unwillingly setting the system volume to an extremely high value, and I’m really sorry for that.
I’ve just committed a fix in git master that should fix this problem for good by properly virtualizing the volume seen by flash and scaling it by the system volume. I hope this helps people with flat volume enabled.