From Sony Creative Software:
ACID Pro 4.0 software is a loop-based music creation tool that allows professionals to produce original, royalty-free music. Use ACID Pro software to create your own songs, remix those tracks, produce 5.1 surround audio mixes, develop music beds, score your own videos and create music for web sites and Flash animations. While this revolutionary tool is intuitive and easy to use, its powerful enough for professional production. Work with a huge assortment of loops in multiple genres. ACID Pro software lets users compose using unlimited tracks of audio and MIDI, import and Beatmap complete songs. ACID Pro software saves to a variety of formats such as WAV, WMA, RM, AVI, and MP3.