AudioMove is a handy GUI-based batch audio file converter/copier program. It can convert various audio file formats to WAV or AIFF format (using libsndfile), and do high-quality sample-rate conversion at the same time (using libsamplerate). It is multi-threaded for maximum throughput, can handle thousands of files per batch, and does recursive directory scans.
CD Stack is an advanced CD ripping and encoding application. It features shortcuts for when you have a large number of discs to rip and allows precise control over MP3 encoding. It can optionally import songs into iTunes, complete with track information and cover art. It uses the LAME Encoder to encode MP3s. A Universal binary is available.
CastCluster provides access to additional content on iTunes, Apple TV, iPod, or a random podcast viewer. It currently supports YouTube, Google Video, Revver, local disks, and RSS feeds as sources of content. It uses ffmpeg for video conversion. It also provides some other bookmarklet functionality, like digg and del.icio.us.
Ecasound is a software package designed for multitrack audio processing. It can be used for simple tasks like audio playback, recording, and format conversions, as well as for multitrack effect processing, mixing, recording and signal recycling. It supports a wide range of audio inputs, outputs, and effect algorithms. Effects and audio objects can be combined in various ways, and their parameters can be controlled by operator objects like oscillators and MIDI-CCs. A versatile console-mode user interface is included in the package.
The FAAC project includes the AAC encoder FAAC and decoder FAAD2. It supports several MPEG-4 object types (LC, Main, LTP, HE AAC, PS) and file formats (ADTS AAC, raw AAC, MP4), multichannel and gapless en/decoding as well as MP4 metadata tags. The codecs are compatible with standard-compliant audio applications using one or more of these profiles.