River Past Audio Converter is an easy-to-use, fast, and powerful batch audio conversion and extractor software.It outputs AIF, AVI, MKA (Matroska Audio), MP3, OGG Vorbis, WAV or WMA.

With River Past MPEG-4 Booster Pack installed, you can output to M4A (MPEG-4 AAC audio), the format used by iTune and iPod.
With MPEG-2 Booster Pack, you can convert to MPEG Audio layer-2.