Some sound cards allow the audio output to be used as an input so you can record from it directly. However, I don’t know if this is the case with all cards, so I’ve come up with a solution for cards that don’t support this. This is useful if you want to save, say, a MOD or MIDI file to disk as music. It also works for CD players which don’t support reading audio data over the IDE bus. You could, for example, record a track to disk as audio, then encode it as an MP3 for use with a portable MP3 player.
Note that you’ll need a full-dupex card to do this — your card must allow simultaneous recording and playback. Alternately, it should be possible with two sound cards, though I don’t know if BeOS presently supports more than one sound card. Here’s how:
Connect the line-out jack to the line-in jack with a patch cable. Go into Media prefs / Audio Output and mute the line-in. This doesn’t stop the input, but it will prevent it from feeding through to the output and causing a feedback loop.
Start recording, then play what you want to record.
If you’re using BamBam for recording and the file won’t record into RAM, note that BamBam has a Record to File function which records direct to disc. Be warned though, as audio data can eat disk space very quickly — stereo CD quality requires approximately 10MB per minute.
If your card has SPDIF input and output you can patch these ports together. This removes most if not all analogue signal paths, thus reducing the possibility of noise.