seems to be AACPlus. And it's not surprising given how good it sounds. I'm not so sure about device support though, and encoding it is a bit of an issue (see above). There is libaacplus, but streamTranscoderv3 doesn't *appear* to support it. I think Liquid Soap might though. There's also something called AACPlusEnc but I can't seem to get to its home page. While we're considering non-free options, Windows Media Audio would seem to be out due to the desire to encode under Linux, and people seem to be moving away from Real Audio. Of course, I'd prefer to use something open if people can actually listen to it. There would appear to be the following options: Ogg Vorbis: Using oggenc with libvorbis 20100325 (1.3.1) at quality -1 with a 44.1 kHz mono source, I can get the bit rate down to about 34 kbps. Stereo is more like 40 kbps. It actually sounds pretty good. Maybe if I took it down to 32 kHz it would go a little ower, or perhaps the quality -2 mode that at least was available in the aoTuV encoder would get it lower with perhaps a little more quality loss. I've not actually tried lower bitrate stuff in either vorbis encoder for some time. Encoding Ogg Vorbis won't present any problems. My concern about Ogg Vorbis is support in mobile devices. I know that iOS devices don't support it natively. Do any stream players for iOS support it, like say Tunein Radio? I believe Android devices do. Don't know about other devices used on the go. The other open option I can think of is Opus. I've not put it through its paces, I really should. But it aims at least to be good for this sort of thing. But I'm really not at all sure what software support is like yet, either for encoding or listening. Anyone know? Are there any other options that are worth looking at? Geoff.