Recording Core

High-fidelity Multitrack Layers

Stone supports layering up to 8 concurrent mono tracks. Build rich arrangement structures step-by-step in any environment:

  • 🎙️ Layer Types: Set designated tracks for Vocals, Guitars, Harmonies, Percussion, Spoken Intros/Outros, or Custom Overdubs.
  • 🎚️ Mixer Controls: Adjust track volume gain (up to +12dB boost), stereo panning coordinates, mute selectors, and solo buttons.
  • 🎛️ EQ Presets: Instantly apply metadata tone modifiers (e.g. Warm Vocal, Lofi Tape Guitar, Bright Harmony) to sculpt frequencies.

FFmpeg Mixing Filter Chain

When exporting, Stone builds a script command parsing track volumes, trim offsets, and pans, mixing them using the FFmpeg filter graph:

# Trimming and panning mapping
[0:a] atrim=start=0.5:end=180.2,
      pan=stereo|c0=0.8*c0|c1=0.2*c0 [voc];
[1:a] atrim=start=0.0:end=180.2,
      pan=stereo|c0=0.3*c0|c1=0.7*c0 [gt];
[voc][gt] amix=inputs=2:duration=longest [mix]
          

Interactive Cleanup Simulator

Drag the slider below to hear how Stone filters out environmental noise, electrical hums, and low-end street vibrations.

Raw Noisy Clean Isolated

Audio DSP

FFmpeg-powered Noise Removal

Street corners, tube stations, and bedroom studios have high ambient noise floors. Stone leverages local execution of the `ffmpeg_kit_flutter_new` libraries to process raw files in the background:

  • Denoising: Uses Fast Fourier Transform filters (`afftdn` with -25dB noise floor) to cancel continuous rumbles.
  • De-clicking & Hum Cutoff: Highpass cutoffs at 90Hz (voices) or 70Hz (guitars) isolate low-end traffic noise and electrical mains hum.
  • Silence Trimming: Trims inactive periods before vocals start, reducing overlapping noise floors.
Smart Algorithms

"Make It Sound Better" Auto-Mix Heuristics

How our simple, parameter-based auto-mixing algorithm analyzes layer types and arranges them into a clean stereo spectrum.

🎙️

Vocal Centering

The lead vocal is automatically anchored to the exact center of the stereo panorama (pan coordinate: 0.0), boosted to sit cleanly at the top of the mix.

🎸

Instrument Spacing

Acoustic guitars and backing tracks are slightly panned (e.g. 25% Left) and volume-attenuated to avoid masking vocal frequencies.

Harmony Pan Wide

Backing vocals and harmony lines are duplicated or panned far left and right (e.g. 30% Right) to create a wide, spacious acoustic soundscape.

Efficiency & Writing

Smart Lyric notebook & Hardware Awareness

Write and perform without fear of running out of space or draining batteries. Stone continuously monitors device health:

  • 📝 Lyric Notebook: Document song titles, drafts, chords, and structure. Keystrokes are automatically saved locally with a 700ms debouncer.
  • Power-Down Scaling: If your battery drops below 15%, microphone sample rate drops from 44.1kHz to 24kHz, and visual waveform complexity is halved to save energy.
  • 💾 Unused Take Deletion: Quickly query SQLite for files marked `is_used = 0` (e.g. discarded takes) and delete them with one tap, freeing up megabytes of disk space.

SQLite Data Models

Stone uses transactional relational tables under SQLite to link songs, layers, takes, and lyrics safely:

Table: projects id, title, local_folder_path
Table: tracks id, project_id, file_path, volume, pan
Table: takes id, project_id, file_path, duration_ms, is_used
Table: lyrics project_id, song_title, lyrics, chords, notes

SQLite constraints enforce ON CASCADE DELETE, meaning deleting a project automatically cleans up all associated records and folder files safely.

Ready to try Stone?

Download the free, zero-tracker mobile application and experience offline music production today.