Virtual Composer is a graphical multichannel musical compiler, sequencer and analyzer, designed for perfect execution of complex polyphonic music using QuickTime's Musical Architecture. It is mainly intended for serious performers who want to simulate human-like performances or who wish to manipulate musical scores in ways similar to those when performing live. Playing is effected via QuickTime's internal Musical Instruments synthesizers so you don't need MIDI cables or external devices and all upsampling and downsampling is done automatically via QuickTime. The application provides a very extensive set of global and local music controllers for volume and staccato as well as unique acceleration/deceleration facilities, making possible humanlike performance simulations. The program provides the ideal environment for analyzing musical scores with powerful search facilities, including naive, intervalic and rhythmic searches, with passive (score) and dynamic (channel) transpose facilities, with a quick Fast Fourier Transform facility and a Statistics facility. The above facilities can be used to completely disassemble the inherent structure of any musical score and to identify various correlations between different pieces or even between different channels of the same piece. An extensive set of examples is provided, with emphasis on the music of J.S. Bach.