I know it's not a very popular audio format, but it would be useful to play audio tracks extracted from music DVDs without re-encoding.
AC3/DTS support
Both formats have complicated licence, fee required even to decode, as far as I know. Doesn't comply with Vox free status. AC3 was supported but had to be ommited for this reason. DTS uses it's own hardware to play so also not of great interest to us.