AudioDjin
Pocket audio studio and spectrogram for iPhone.
AudioDjin turns an iPhone into a pocket audio studio: high-resolution recording, live spectrograms, ultrasound listening, live effects, signal tools, waveform editing, and WAV sharing, all running on device.
iOS 17+. Built-in microphone, USB audio interfaces, and Bluetooth audio input are supported when available. High sample rates depend on the connected hardware.
AudioDjin includes experimental sonar and SPL estimates. They are practical audio tools, not certified measuring instruments.
What it does
Hi-res recording
Capture from the built-in mic or a connected USB/Bluetooth interface with live spectrogram, level meter, timer, and input selection.
Ultrasound listening
A heterodyne bat-detector mode shifts 20-120 kHz input down into the audible range with oscillator and isolation-filter controls.
Tool bench
Signal generator, sync signal, sonar ranging, SPL meter, tuner, sweeps, white noise, pink noise, and pitch tools are built into the app.
Library and editor
Recordings are stored locally, replayed with spectrograms, edited destructively safe as new files, and shared as standard WAV exports.
Audio workflow
Capture
AVAudioEngine and AVAudioSession manage recording, monitoring, playback, generation, and sonar modes from one coordinated audio path.
Analyze
The measurement core handles DSP, spectrograms, level analysis, pitch detection, Doppler, sonar, room-acoustics helpers, and synthesis.
Create
Users can record, generate tones or sweeps, inspect spectrograms, apply effects, edit audio, and share finished WAV files.
Engineering notes
DSP-first core
AudioDjinCore is a dependency-free Swift package with unit tests for DSP math, spectrograms, synthesis, editing, Doppler, sonar, room acoustics, and entitlements.
Native audio shell
The app target owns SwiftUI, AVAudioEngine, AVAudioSession, StoreKit, theme, permissions, and file sharing while core audio logic remains testable off-device.
Freemium model
The app uses a 5-day full trial, a useful free tier capped at 3 clips of 30 seconds up to 48 kHz, and a one-time unlock for unlimited hi-res recordings.
Privacy model
- Recording and analysis run on the iPhone.
- Audio files are stored locally under the app recording library.
- There are no accounts, analytics, ads, tracking SDKs, or app-owned network requests.
- Sharing only happens through the iOS share sheet when the user initiates it.