Mudlet might be able to. I use tintin, but I've only seen .wav files being supported. I am very, very tempted to try creating my own mud client in dart and flutter since I'm getting the hang of sockets and streams and all that good stuff, and if I did it would have ogg file support, along with the ability to script sounds and ambiences at the very least.

Back when I was into MUDs, I did a lot of work with tintin++ and sound packs. I used sox as the backend for sounds, and it supports practically everything, mp3, ogg, opus, wav, flac, etc. There are several of these still floating around in various git repositories, some of which are still actively developed, like the one for Alter Aeon. The latest one I did was for a MUD called End of Time MUD.

I've heard horror stories about how hard it is to make a soundpack because you have to use regular expressions, all the time. A dart CLI mud client, hmm. Could definitely do that and make sound support actually nice to work with. I don't necessarily have to do GUI.

@destructatron @storm tintin++ isn't that bad, and neither is using regexp for everything. It makes making triggers that don't conflict super easy, and rolling things like out of band soundpack messages or channels or history buffers into 1 trigger is super easy.

Not everyone knows how regular expressions work, I sure don't. I take one look at one of those and instantly get confused, plus there's also the kinds of regular expressions that are supported. Take the core utils on Linux for example, some support BRE, some support ERE, and some support both and you don't know what the default setting is until one of your expressions silently doesn't work.

@destructatron @storm very true. Tintin++ at least have this documented, it's PCRE