See how this song was written.
Stems and MIDI put each part in your hands. Musical ideas then read the whole song: how it is built, how the chords move, and which chords were chosen on purpose. If the original sounds more machine-made, the track is marked.
- Musical ideas: form, particular chords, chord motion
- AI song check: a machine-made original is marked
- Analysis stays on this Mac. Audio is not uploaded
The writing of the whole song, read along the timeline
Open a song, and Prism does more than list chord names. Musical ideas put the writing back on the bars where it happens: what key this passage is in, which kind of motion it is, and which chord in the middle is a secondary dominant, a borrowed chord, a color chord, or a cadence.
There are two kinds of marks. A solid mark is the writing, a device the song actually uses. A dashed mark is a place to hear again: this chord may not have been read correctly. Uncommon does not mean misheard.
Open one, and you see the chord, key, Roman numerals, the reason, and a suggestion. You can change the chord, accept the suggestion, hide it for now, or write your own note beside it. The note stays in the project. The same song can be read as pop, classical, or jazz.
How this song is built
- The song is split into passages, and each passage has its own key
- A modulation is marked on its own, including a later lift into a higher key
- Tempo and meter changes sit on the same timeline
- Chords show the name, the bass, and the Roman numeral. Tonic, subdominant, and dominant are separated by color
How the chords move
A real progression often includes inversions, passing chords, and added tones. Musical ideas pull the backbone out of each passage and name the whole passage as one motion, for example:
1645
I–vi–IV–V
4536
IV–V–iii–vi
1625
I–vi–ii–V
6451
vi–IV–V–I
251
ii–V–I
Canon
I–V–vi–iii–IV–I–IV–V
Cadences are marked on their own: authentic, plagal, deceptive, and ii–V–I. Roots falling by fifths in a row are marked as a circle of fifths.
Which chords were chosen on purpose
- Secondary dominants, including a chain of them. Ones that land on their target, and ones that do not resolve, are both noted
- Borrowed from the parallel mode, such as a minor subdominant, a flat six, or a flat seven
- Color chords: augmented, diminished seventh, Neapolitan
- Tritone substitution
- Modal harmony, such as a Dorian or Mixolydian reading
- Parallel motion: a set of the same kind of chord sliding together
- Bass: a pedal that stays while the chords above change, or a bass that walks by step, including by semitone
- An inversion that can rest, with the bass on the third or the seventh
Places to hear again are marked as a possible misread, an uncertain read, a decorative chord, or something outside the key that still needs explaining. An uncertain chord comes with other candidates. Parallel fifths and octaves between parts, and a leading tone stacked inside a dominant, get a separate note. The notes on the score are not changed because of that.
Click a chord to hear it. Double-click to rename, split, merge, or delete it. A chord you changed stays changed.
Stems
Detailed, six tracks plus residual
Vocals, drums, bass, piano, and guitar. Sound that does not fall into those instruments stays on the residual track.
Fast four tracks plus residual
Vocals, drums, bass, and other.
Vocals and accompaniment
The vocal, and everything else as accompaniment.
Whole mix, straight to notes
No split. The whole song goes straight to notes.
Each track can be heard alone, muted, or turned up and down. The transcription can sit on top of the original, or you can hear the original on one side and the transcription on the other. The chord a musical idea marked can be checked with only the piano or the bass left in.
If you already have stems, drop them in. If you have stems and no mix, Prism builds a mix first so there is something to compare.
AI song check
Suspected AI-generated
When analysis starts, Prism looks at whether the original sounds more human-made or more machine-made. When it is fairly sure, a mark appears beside the track name. The hover text reads “Suspected AI-generated.” When it is not sure, it does not mark anything.
Stems you import are looked at one by one. If the vocal is a recording and the accompaniment sounds generated, only those accompaniment tracks are marked. Tracks the app split itself follow the judgment of the whole song.
This is a notice. Analysis does not stop. MIDI, scores, chord charts, and lyrics do not carry the conclusion.
A mark can be wrong, and a machine-made song can be missed.
Scores
The score is written as ABC first. The staff and the numbered notation both come from that one ABC. The score carries chords and lyrics, and the current note follows playback. Drum notation stays on the staff and is not turned into numbered notation. Guitar and bass have a fingering score. A chord chart, a guitar chord sheet with a capo suggestion, a lyrics file, and a PDF score can all be exported.
Vocals, piano, bass, guitar, and drums each get a MIDI file, on the original tempo. A pickup and a tempo change in the middle of the song are written into the file, so the bars still line up in your own software. In the piano roll you can fix a wrong note: move it, change its length, change its velocity, undo. Piano pedal that was already there is kept.
For practice, tempo can move from half speed to one and a half, with the pitch held, or the pitch can move by up to twelve semitones. Loop a passage. The metronome follows the detected beat, and a count-in can play before the start. The tonic, tonic chord, and scale follow the key of the current passage. The slower tempo, the transposition, and the metronome can be baked into a practice recording.
Analysis happens on your computer
Prism is a macOS app for Apple silicon. The song is not uploaded. Before the first analysis it needs a network connection, to prepare what it uses onto this machine. The project stays on this computer, or can be packed into one file and opened on another Mac.
Several songs can wait in a queue. Stop in the middle, and the next time it continues from the step already finished. If a recording is out of tune, Prism corrects it before analysis and writes down how far it was off.
When to use it
- You want to see how a reference song is built: passages, key, chord motion, and which chords were chosen on purpose
- You hear an unusual chord and want to know whether it is a secondary dominant, a borrowed chord, a modulation, or a possible mishearing
- You have a song and want to know whether it sounds machine-made before you decide what to do with it
- After the writing is clear, you take the parts and notes into your own software, or slow them down to practice
Specs
| System | macOS, Apple silicon |
|---|---|
| Input | Local MP3, WAV, FLAC, OGG, M4A; existing stems can be imported |
| Musical ideas | Form and modulation; chord motion (such as 1645, 4536, 251, canon); secondary dominants, borrowed chords, color chords, tritone substitution, mode, parallel motion, cadences, bass line, pedal, inversion |
| Hear again | Possible misread, uncertain read, decorative chord, outside the key and still to explain; parallel fifths and octaves between parts |
| AI song check | The original, and stems you import. When it is fairly sure, it marks “Suspected AI-generated” |
| Stems | Detailed (vocals, drums, bass, piano, guitar, plus the rest), a fast four-track split, vocals and accompaniment, or the whole song transcribed as it is |
| Compare | Original, stems, note preview, overlay, and split listening left and right |
| Scores and export | ABC, staff, numbered notation, drum score, fingering score, MIDI, MusicXML, chord chart, guitar chord sheet, LRC, PDF, practice audio, project bundle (.steam) |
| Practice | Tempo 50%–150%, transpose ±12 semitones, loop, metronome, count-in |
| How it runs | On-device analysis. A song takes a while. Results do not appear as it plays |
The AI song check stays on screen. It is not written into exported files. What you open is a file on this machine. Mixing, and writing further, happen in your own software.
PDF needs a notation setup already on this Mac.
Questions
What is Prism mainly for?
To read how a song was written. Musical ideas mark how it is built, how the chords move, and which chords were used on purpose. Stems and MIDI are for checking, editing, and taking with you.
Do musical ideas change the chords on their own?
No. They mark the writing, and the places to hear again, on the timeline, and they give a reason and a suggestion. Whether to change anything is up to you. A note you write stays.
What about a song that sounds machine-made?
When it is fairly sure, “Suspected AI-generated” appears on the track. When it is not sure, it does not mark anything. Analysis continues. Exported MIDI, scores, and chord charts do not carry that judgment. Stems you import are judged one by one.
Is the song uploaded?
No. Analysis finishes on your Mac. Before the first use it needs a network connection, to prepare what the analysis uses onto this machine.
Which computers can run it now?
macOS, on Apple silicon.
Can I arrange the song in here?
Prism turns what it heard into musical ideas, chords, scores, and notes, and lets you fix a note it heard wrong. Mixing, and writing further, happen in your own software.
Open a song, and see how it was written.
Form, particular chords, and chord motion are on the musical ideas. Something that sounds machine-made gets its own mark.
It currently runs on a Mac with Apple silicon.