Shepard Keyboard

[Concept: Maximizing Mobile Surface for Musical Expression]

Traditional mobile synthesizers often struggle with cramped interfaces by attempting to replicate multi-octave keyboards. The Shepard Keyboard takes a fundamentally different approach: by leveraging the "infinite pitch" nature of Shepard Tones, we have completely removed redundant octave keys. By reclaiming this valuable screen real estate, we have dedicated every available pixel to high-density expressive controls and tactile performance tools—allowing you to transform a limited mobile screen into a specialized musical interface.

[Detailed User Manual]

Master the infinite scale with our comprehensive visual guide:

https://docs.google.com/presentation/d/1fuiwogr7H3Mv6T7IUy5FcggWQ3p_RZXfCQXxu8idgj8/edit?usp=sharing

[Fact-Based Performance Controls]

- Vertical (Y-Axis) Expression: Assign and control parameters such as Volume, Vibrato, or Filter Cutoff in real-time based on the vertical touch position on each key.

- Horizontal (X-Axis) Slide Playing: Hold and slide across keys for smooth, guitar-like pitch transitions while maintaining a constant sound—ideal for glissando effects.

- Dual XY Pad Controllers:

- Pad 1 (Tone): Precise manipulation of Center Frequency and Frequency Gamma Range. (Turn on the new "High Follow Mode" for artifact-free, extreme modulation when pushing the pad to its limits.)

- Pad 2 (Filter): Real-time control of Low-Pass Filter (LPF) Cutoff Frequency and Resonance.

- Precision Sliders & Buttons: Dedicated controls for Modulation, Pitch Bend, Overdrive, and instant "Pseudo-Octave Jumps" to shift the frequency center.

- Expandable Interface: Collapse the control panels to expand the keyboard area, maximizing your focus on the performance.

[Immersive Performance Modes]

- Circular Keyboard: Experience the infinite scale through natural circular gestures for seamless, never-ending pitch movement.

- Scale Configuration & Equal Temperaments: Remove black keys and evenly distribute specific scales like Pentatonic or Whole Tone. Turn on the new "Equal Temperament Mode" switch to reveal a slider that sets the number of notes per octave, unlocking deep microtonal exploration anywhere from 5 to 17 equal temperaments (5-EDO to 17-EDO).

- Basic Random Sequencer: A straightforward, non-AI random playback feature. Just set three simple parameters—BPM, Note Value, and Note-On Probability—and let the app generate a completely random, endless stream of notes. While not traditionally "musical," this unpredictable sequence is surprisingly effective for sleep induction, ambient soundscapes, or just letting the synthesizer wander on its own.

[Technical Specifications]

- Professional Audio Engine: Built using Google’s Oboe (C++) for ultra-low latency tactile response.

- Adaptive DSP Engine & "High Follow" Mode: The core engine now dynamically calculates only the actively audible octaves, dramatically reducing CPU load and preserving battery life for mobile performances.

- Full Envelope Control: Precision ADSR settings with a "Fixed Duration" mode for creating percussive, glockenspiel-like tones.

- Customizable Audio Settings: Selectable Sample Rates and adjustable Buffer Sizes to balance performance and stability.

[Ideal For]

- Sound Designers: Creating seamless tension and "infinite" risers for cinema, games, or electronic music.

- Experimental Musicians: Exploring the boundaries of psychoacoustics and microtonal performance.

- Mobile Performers: Users requiring a stable, low-latency lead instrument with professional-grade gestural expression.

Developer's Note:

This instrument leverages professional-grade C++ audio libraries to minimize latency. By reclaiming the screen from unnecessary keys and dedicating it to Y-axis expression and intuitive XY pads, the Shepard Keyboard provides a unique platform to bring organic, evolving life to the mathematical beauty of the infinite scale.