mac continuous recorder

[sejtam]

Is there a audio stream recording software (for MP3 streams etc) which can keep a running recording in a ring-buffer (say a few minutes) and then be used to keep a longer recording when something of interest appears?

It's usually too late to start a fresh recording while listening to a live stream, as one will miss the beginning.

The recorder I'm envisioning would always have the last n minutes in the buffer, and when I start recording for good, would
allow me to start the recording sme time earlier by copying from its ringbuffer. of course, once recording proper is started it would go to a different file, and the recorder would continue
to write to the ringbuffer only after the recording proper is stopped.

Does such a beast exist?

I'd need this for OSX (Mountain Lion, maybe back to snow leopard)