Signal-11
macrumors 65816
The Airport Express will only take the Apple Lossless codec, so you need to change "mpga" to "alac". Also VLC dislikes the ":8080" port specification, but it can be left off and it seems to connect fine. Setting volume=255 is a *very bad* idea when connecting to an Airport Express, as it will be quite loud, and it seems that the setting sticks around - so next time you run iTunes it'll play at maximum volume. I found that 32 is a much better choice if you still want to be able to hear afterward. Finally, you'll need to be sure the mp3 file is 44.1 kHz and not something like 32 kHz or 22.05 kHz, as that's all the Airport Express understands.
All that said, when I run VLC in that way (using "/Applications/VLC.app/Contents/MacOS/VLC" in place of "vlc"), it crashes. But it does make the speakers connected to the Airport Express click first, so it's probably just a bug that needs to be fixed.
Code:/Applications/VLC.app/Contents/MacOS/VLC --sout='#transcode{acodec=alac,ab=192,channels=2}:raop{access=http,mux=raw,host=xxx.xxx.xxx.xxx,volume=32}' foobar.mp3
Good points. I was just reading that transcoding isn't strictly necessary. Start with an alac file and just send directly to raop?
Wish I had my AX with me to test. 🙁