Can we surely use cross-browser mp3 now? According to Wikipedia the patents have expired, although some of the patents related to encoding have not. https://www.reddit.com/r/gamedev/comments/68o4up/mp3_is_now_officially_patent_free/ If not, we could provide two formats:  OGG + ACC https://developer.mozilla.org/en-US/docs/Web/HTML/Supported_media_formats#Browser_compatibility

Please investigate which variant works for us (it might be ACC mp4). Testing should be done in ZBX-9522 as the messaging audio implementation there does depend only on vendor provided audio codecs (trunk allows to use host sofware, if installed (which most usually is) - so that still does not ensure audio to be heard 100% of time).

Convert our audio files.
Provide db patch if needed.
Adjust hardoced default values.