MIDImorphosis is an app for polyphonic audio to MIDI conversion. Traditional MIDI converters for guitar and bass require custom pickups and expensive hardware. MIDImorphosis avoids this through advanced signal processing and adaptive algorithms, bringing polyphonic audio conversion to your iPhone, iPad, or iPod Touch. The app tracks both single notes and chords quickly and accurately. You can use any guitar or bass to control MIDI synthesizers or transcribe your playing automatically.

MIDImorphosis captures the pitch of incoming audio, and converts it into MIDI notes that can be used to control iOS synthesizers or external equipment. The app supports both monophonic and polyphonic playing; this version has dramatically improved chord detection.

With support for CoreMIDI, Virtual MIDI, DSMIDI Wifi, Audiobus, and background audio, connecting MIDImorphosis is a snap. Connections to laptop and desktop computers can be made using WiFi or with MIDI adapter cables.

The app is designed to work best with a guitar or bass. We recommend dock-based instrument adapters; connections through the headphone jack frequently have crosstalk and poor frequency response. We also recommend running MIDImorphosis on an iPhone4s or better, or an iPad2 or better (this is especially true when using Audiobus).

Complex sounds can be created by combining a typical guitar effects app along with MIDImorphosis and a synthesizer app. The guitar effects app can provide tone control and immediate response, while the synthesizer can augment this with a deep, evolving sound.

Musicians transcribing their work will find MIDImorphosis to be an invaluable tool. The app can send MIDI notes to notation software such as GuitarPro (desktop version only) and Progression (available for iOS).

In addition to live conversion, MIDImorphosis can also convert recordings into MIDI (avoiding latency issues). The app can record audio; audio can also be imported using either Audio Copy or iTunes File sharing. Audio can be exported with Audio Paste. MIDI can be exported to other apps using the “open in” feature, or through iTunes. The app also allows scanning through audio files, to see the detected pitch at any given moment; this feature should be particularly useful to musicians interested in transcribing a recording. Recorded audio and converted MIDI can be played back through the app. The app is compatible with the Audiobus input and output slots.

A number of videos are available on the app web page, to illustrate typical performance, and playing techniques to get the most out of the app. For guitarists, a light palm mute should be used to prevent unwanted notes from ringing. Pitch detection is typically best with the bridge pickup, and with a clean tone.

With any conversion system, there is latency between a note played on an instrument, and when the note can be correctly identified; the slight delay motivates the combination of guitar effects and synthesizers. MIDImorphosis should be fast enough to work well for playing at moderate speeds. For accurate note identification and pitch tracking, it’s critical to play “clean,” and to mute unwanted notes; you may have to adjust your playing style to get the best performance from the app. For guitarists in need of a system that can handle “shredding,” we would recommend hardware converters by companies such as Roland or Fishman.

MIDImorphosis