1. What is BopBot?
BopBot is an iOS app that generates bebop solos on the fly over the chord changes of jazz standards, displaying the notation as it plays. Solos are not recordings — every solo is newly generated from music theory (linear harmony).
- Three personas — Parker, Pres (Lester Young), and Bud (Bud Powell), each with its own vocabulary and phrasing.
- Ten jazz standards with their chord progressions built in.
- Fully offline — no network connection is used, and no account is required.
2. Your first performance
- Tap the Play button at the bottom of the screen. The first chorus is generated and its score appears.
- After a two-bar count-in (metronome), the solo begins. The first phrase may start during the count-in (bars −2 or −1).
- Playback loops chorus after chorus indefinitely. Each chorus is a new solo from a new seed, and the seed shown in the header advances accordingly.
- Tap the Stop button to stop.
- While stopped, tap New solo to pick a fresh seed while keeping the current song, persona, and instrument (not available during playback).
3. Understanding the screens
Portrait — Cockpit
- Header — the song title (tap to open Performance Setup), a "persona · instrument · seed" line, the Chorus number with Bar/Beat counters, and the gear button (Settings).
- Solo score — the generated solo in three staff systems.
- Performance controls — Tempo, Swing, Outline mix, Accents, and New solo.
- Play/Stop button — pinned to the bottom of the screen.
Landscape — Deck
Rotate the device to switch to the three-column deck view (playback continues seamlessly). The left column holds the song title, status readouts, and Play/Stop; the center shows a larger score; the right column has vertical Tempo and Swing faders plus the "Outlines" button.
Tap HELP next to any parameter for a concise in-app explanation.
4. Song, persona, instrument & seed
Tap the song title in the header to open the Performance Setup sheet.
Songs
| Song | Key | Meter | Bars | Default tempo |
|---|---|---|---|---|
| Donna Lee | A♭ | 4/4 | 32 | 200 |
| Confirmation | F | 4/4 | 32 | 210 |
| Blues (F) | F | 4/4 | 12 | 180 |
| Rhythm Changes | B♭ | 4/4 | 32 | 220 |
| How High the Moon | G | 4/4 | 32 | 180 |
| Giant Steps | E♭ | 4/4 | 16 | 170 |
| All the Things You Are | A♭ | 4/4 | 36 | 140 |
| Stella by Starlight | B♭ | 4/4 | 32 | 120 |
| On the Sunny Side of the Street | C | 4/4 | 32 | 140 |
| Someday My Prince Will Come | B♭ | 3/4 | 32 | 150 |
Personas
| Persona | Style | Default instrument |
|---|---|---|
| Parker | Bebop | Alto |
| Pres · Lester Young | Swing-era tenor | Tenor |
| Bud · Bud Powell | Bebop piano | Piano |
Switching personas automatically selects that persona's default instrument; you can then override it with any of the four instruments — Alto, Tenor, Trumpet, or Piano. Generated motifs and development renew on every chorus.
Seed
The same combination of song, persona, instrument, and seed always generates exactly the same solo. Note down the seed of a solo you like and enter it later to reproduce it. The Random button picks a fresh seed (range 0–999,999,999).
5. Performance parameters
| Parameter | Range | Takes effect | What it does |
|---|---|---|---|
| Tempo | 60–300 BPM | Immediately | Playback speed. The generated notes stay the same. |
| Swing | 0.50–0.667 | Immediately | Where the offbeat eighth note lands. 0.50 = straight, 0.60 = default, 0.667 = triplet feel. Only timing changes; notation and pitch stay the same. |
| Accents | ON / OFF | Immediately | The dynamic shape. ON restores the full dynamic contrast at phrase starts, peaks, leaps, anticipations, and endings; OFF compresses it for a flatter, more even performance. |
| Outline mix | 0–100% each | Next solo | How often each of the three linear-harmony outlines is used as the solo's skeleton. |
Outline mix
- Outline 1 · Guide descent — a descending guide-tone line: the seventh resolves to the next chord's third.
- Outline 2 · Arpeggio up — an ascending ii arpeggio, often extending through the dominant ninth.
- Outline 3 · Down then up — a descending ii arpeggio that turns upward on the dominant.
Moving one slider automatically rebalances the others so the total stays at 100%. Changes apply from the next solo; while a score is on screen, a "Next solo" badge appears in the section header.
6. The score display
- Three staff systems with chord symbols, bar numbers, key signature, and time signature. During the count-in, bar numbers are negative (−2, −1).
- Pages turn automatically to follow the playback position. Each system shows two or four bars depending on screen width.
- The bottom-right label shows "instrument · pitch mode · key" (e.g. Alto · Transposed score · E♭).
- Use "Pitch display" in Settings to switch between transposed score and concert pitch. Concert pitch is octave-displaced when needed (8va etc.) for readable treble notation; playback pitch is unchanged.
7. Sound settings
Open Settings with the gear button.
Solo sound
- Dunne (built in) — the built-in engine for wind instruments (Alto, Tenor, Trumpet).
- Respiro — selectable when the Respiro AUv3 is installed. Uses its currently selected preset; BopBot maps expression to CC2.
- SWAM — selectable when a SWAM AUv3 matching the solo instrument is installed. Expression is sent as CC11.
Master volume
0–100%, applied immediately — even during playback.
8. Background playback & interruptions
- Playback continues in the background when you switch to the Home Screen or lock the device.
- When audio is interrupted (e.g. by a phone call), playback stops and the app shows a "Playback was interrupted" banner. Tap Resume to continue.
- Unplugging headphones stops playback — by design, to avoid unexpectedly loud audio from the speaker. Plug back in and press Play to continue.
- Lock Screen and Control Center playback controls are not supported; control playback from within the app.
9. Troubleshooting
No sound
Check the silent switch on the side of the device and the volume. If that doesn't help, make sure Master volume in Settings isn't turned down.
Respiro / SWAM shows "Unavailable"
The corresponding AUv3 app must be installed on the device. After installing, reopen the Settings sheet and the option becomes selectable.
New solo is disabled
New solo is available only while playback is stopped. Stop the performance first.
I want to hear the same solo again
Enter the same song, persona, instrument, and seed in Performance Setup to reproduce a solo exactly. Because the seed advances every chorus, the header shows the seed of the chorus you are hearing.
10. Requirements
- iOS 17 or later (iPhone / iPad)
- Works fully offline — no internet connection required.
For anything else, visit the support page or email hirose@hakaru.net.