About

This utility addresses the fundamental challenge in Digital Signal Processing (DSP): decoupling the auditory properties of Pitch (Frequency) and Duration (Time). In analog tape systems, these two variables are linearly linked - doubling the playback speed doubles the frequency (f ∝ v). This tool utilizes a browser-based implementation of granular synthesis and buffer manipulation to allow independent control.

Accuracy is paramount for musicians. A deviation of just 5 cents is perceptible to the trained ear. This engine uses 64-bit floating-point math for internal calculations before downsampling to 16-bit PCM for export. It is designed for:

Vocalists: Transposing backing tracks to match specific vocal ranges (e.g., Alto G₃ to E₅).
Producers: Sample manipulation, creating "Chopped and Screwed" or "Nightcore" aesthetics without artifacts.
Transcription: Slowing down complex jazz solos (Time-stretch 50%) while maintaining the original key.

The system operates locally within the AudioContext of your browser, ensuring strict data privacy and zero server latency.

Formulas

To calculate the required sample rate modification or detuning factor, we utilize the logarithmic relationship between frequency and pitch intervals. The frequency f after shifting n semitones is given by:

f_new = f₀ ⋅ 2^{n + c/10012}

Where n is the integer semitone shift and c is the fine-tuning in cents. The Time Stretch ratio σ is inversely proportional to the playback rate r when pitch is maintained:

T_new = T_origr

Reference Data

Musical Interval	Semitones (n)	Ratio (r)	Cents (¢)	Ref (A₄=440)	Vocal Range Note
Unison	0	1.0000	0	440.00 Hz	-
Minor Second	+1	1.0595	100	466.16 Hz	-
Major Second	+2	1.1225	200	493.88 Hz	-
Minor Third	+3	1.1892	300	523.25 Hz	C₅ (Soprano High)
Major Third	+4	1.2599	400	554.37 Hz	-
Perfect Fourth	+5	1.3348	500	587.33 Hz	-
Tritone	+6	1.4142	600	622.25 Hz	-
Perfect Fifth	+7	1.4983	700	659.25 Hz	E₅ (Belting)
Minor Sixth	+8	1.5874	800	698.46 Hz	-
Major Sixth	+9	1.6818	900	739.99 Hz	-
Minor Seventh	+10	1.7818	1000	783.99 Hz	-
Major Seventh	+11	1.8877	1100	830.61 Hz	-
Octave	+12	2.0000	1200	880.00 Hz	A₅ (Whistle)

Frequently Asked Questions

For real-time browser preview with minimal latency, we utilize the Web Audio API's native playback rate and detuning capabilities coupled with an overlap-add buffering strategy. For the "High-Res Export", we perform an offline render that minimizes the transient smearing often found in real-time processing.

The limit is determined by your device's RAM. The file must be decoded into an uncompressed AudioBuffer. Typically, files up to 150MB (approx. 15 minutes of WAV at 44.1kHz) are safe on desktop. Mobile devices may be limited to smaller files (approx 20-50MB).

You can use the built-in "Scientific Pitch" preset. Mathematically, this requires a downward shift of approximately -32 cents (or -0.32 semitones). Our tool handles this decimal precision automatically.

Yes. The output is a standard 16-bit PCM WAV file. The processing algorithm is clean enough for creative sound design, backing tracks, and demo production. For final mastering of lead vocals, hardware processors or dedicated offline VSTs might offer slightly better formant preservation.

When stretching audio beyond 20-30%, the algorithm must invent data that doesn't exist (interpolation). This creates "phasiness". We recommend keeping shifts within +/- 5 semitones or +/- 20% speed for the most natural results.