|MIDI is a compact, notes-based file format widely used for keyboard instruments. It stores how to play the music - which MIDI keys are pressed, and their strength and duration. It is not an audio file format like WAV that stores the full sound of the notes actually being played. Currently, Audacity only has limited support for MIDI.
MIDI and Audacity
Stable (1.2.x) releases of Audacity can currently only import MIDI files to view them.
Beta (1.3.x) releases of Audacity are now slowly adding support for MIDI. As of October 2008, MIDI files can be imported, cut-and-paste edited, then exported as MIDI. However this feature is still buggy, and there is no MIDI playback. Conversion from MIDI to audio formats, and from audio formats to MIDI is not supported.
Audacity cannot record MIDI input, only audio input.
Converting from MIDI to audio formats
MIDI files can be converted to sampled audio formats such as WAV either by recording them as they play, or by converting them with another application. This is currently the only way they can be edited in Stable Audacity versions. The file produced no longer contains any notation information that the MIDI had, but becomes in essence a recording of those notes being played at one particular time. How that recording sounds depends on the soundfonts or General MIDI banks that are used in the conversion.
WAV is the recommended format to convert to, because it is lossless and won't significantly degrade with editing. You can export to a format with smaller file size, such as MP3, after editing.
On Windows or Linux, depending on your sound card, you can record the MIDI into Audacity in real time simply by playing it on your computer, for example on Windows Media Player. On OS X you need to use a third-party program recording application such as Soundflower. For more help, see our FAQ on recording streaming audio.
Converting from audio formats to MIDI
Converting in the other direction is a challenging research problem requiring software that can detect the pitch of the notes being played. At present, only single melodic lines can be converted with any degree of accuracy. We'd be very interested in helping a developer who has made progress with such software in helping it reach a wider audience through Audacity. Meantime, here are a few programs you could try:
- WavetoMidi (Cross-platform, Open Source)
- AudiotoMidi (Windows)
- Intelliscore Polyphonic (Windows)
- Digital Ear (Windows)
- AmazingMIDI (Windows) free
- WidiSoft (Windows, OS X)
- Other shareware programs
Programs for working with MIDI
There are many excellent programs for recording and/or editing MIDI files. Many will display the MIDI notes on a musical staff. Here are some recommendations: