An Introduction to Music Application Formats
The iPod phenomenon has brought the use of computers for music applications to more people than ever before. Computers can represent music in two basic ways:
- An audio file represents music as sound. This is the type of the representation used in iPods, CDs, and other computer applications that play recorded music.
- A symbolic file represents music in terms of musical concepts relevant to performers who read music. This is the type of representation used in music notation applications like Finale and Sibelius, or digital sheet music applications like MusicNotes and musicRAIN.
Converting symbolic files into audio format is a booming business for music notation software developers, especially for classical composers who need to create demos in order to interest performers in their music. Symbolic files can also be converted into image-based formats like PDF and JPEG. These formats can display the printed music notation, but contain no musical semantics.
Converting audio files to symbolic format, on the other hand, has more in common with some of the most difficult problems in artificial intelligence. No applications solve this problem satisfactorily at this time in any but the most restricted circumstances. Symbolic and audio formats are related, but they are not interchangeable.
Many types of music applications use symbolic formats:
- Notation editors like Finale and Sibelius are used both to compose music and to prepare music for performance and publication.
- Music scanners like SharpEye Music Reader, SmartScore, and PhotoScore convert printed music into symbolic format using optical music recognition (OMR), similar to converting printed text into computer text files using optical character recognition (OCR).
- Sequencers like Cubase and Logic combine audio and symbolic formats for composers who work more independently of music notation. MIDI is the symbolic format of choice for these applications. Sequencers focus on sound output whereas notation editors focus on printed output. Notation-based sequencers like Notion are bridging the gap between these two categories.
- Digital music stands like MuseBook Score and OrganMuse display music electronically, listen to the performance, and automatically turn pages as needed.
- Digital sheet music applications like MusicNotes and musicRAIN are used to sell sheet music online. They usually offer the ability to play a piece of music and transpose it into a particular key before printing the file.
In the music market, the Macintosh platform is much more important than in many other application areas. This is especially true for high-end professional users. A successful symbolic music format needs to work with both Macintosh and Windows applications.
For many years, the Standard MIDI File (MIDI, 1996) was the only common interchange format for symbolic music files. However, MIDI was developed in order to exchange musical messages between electronic musical instruments, not to exchange music notation between applications. Therefore MIDI contains sophisticated representations for how to make music sound on an instrument, but primitive representations for how to make music appear on a printed page.
Many people tried to develop music formats to move beyond MIDI to a more powerful interchange format for music notation applications (Selfridge-Field, 1997). The most noteworthy of the 20th century efforts in this area were NIFF (Grande, 1997) and SMDL (Sloan, 1997). Neither of these formats was widely adopted. Music scanners were the only application category to adopt NIFF as a format for saving files. Despite approval as ISO 10743, SMDL was never implemented by a commercial music application.
