I have finally figured out how to make clicking on a mp3 link in firefox cause the url to be instantly passed to mpd and played. If this seems like it should be easy, think again..
Firefox makes it hard, because while it lets you configure an program to run for a mp3, if the mp3 is not streamed, it will first download the whole mp3, and then run your program, passing it the local file. That's not what we want: It's slow, and it's much easier to queue an url in mpd than a new file.
The trick to making it work is an addon called MediaPlayerConnectivity. Confusingly, this addon sometimes refers to itself as "MPC" -- not to be confused with "mpc(1)". Warning: This addon is a ugly mess that wants to do a lot of other stuff than play mp3s, so make sure to disable all that.
MediaPlayerConnectivity's preferences allows you to specify a command to run for mp3 files (but annoyingly, not ogg vorbis). This command will be passed the url to the mp3. So you need to write a little script that runs mpc add and starts the queued url playing.
My take on that is mpqueue,
which uses the mpinsert command from mpdtoys to add the url just
after the currently playing song in the playlist.
Then it uses mpc next to skip to it. This way, after whatever you clicked
on finishes playing, mpd continues with whatever was next in your playlist,
and the music never stops.
BTW, since I use a mpd proxy this is all done on whatever remote mpd the proxy is currently set to use, rather than my laptop. Clicking on a link and having the sound system in the next room switch to playing it is pretty nice. :)
Previously: My mpd setup
I tried music player minion, but did not see anything in it that caused mp3 links to be sent to mpd. Which seemed a glaring lack. Did I miss it?
Not sure how ipv6 would eliminate the need for a proxy. My mpd proxy is a retargetable proxy -- it can be changed to point to a different mpd host at runtime, and everything that uses it switches to seeing that host.