Tempo Detective
About Tempo & Beat Analysis
Tempo is the speed or pace of a given piece of music, measured in Beats Per Minute (BPM). While some songs maintain an absolute machine-like clock (such as electronic drum patterns), live music played by humans naturally fluctuates, creating an expressive tempo curve.
How Tempo Detection Works
The Tempo Detective uses the industry-standard AubioJS DSP (Digital Signal Processing) library, compiled to high-speed WebAssembly. It analyzes the transient characteristics of the audio wave (onsets) to construct an energy grid, then passes it through a series of comb filters to isolate the primary pulse rate.
Understanding the Confidence Indicator
A high confidence score (green) indicates that the music has a clear, repetitive rhythmic signature (e.g. drums, strong transients). A lower confidence score (red) usually occurs during drum-less sections, ambient intros, vocal breaks, or highly complex syncopations, where the pulse is felt rather than strictly accented.
Frequently Asked Questions
No. PitchMaster values your privacy. The audio is decoded and processed completely inside your browser using the Web Audio API and WebAssembly. No data is sent to a server, making it fast, private, and offline-compatible.
This is a common issue in computer beat-tracking known as an octave error. The algorithm may mistake eighth notes for the beat (doubling the BPM) or measure every other beat (halving it). The relative tempo variations, however, will remain accurate.
We support standard formats readable by your browser, including MP3, WAV, AAC, M4A, and FLAC. Because the entire file is decoded in your device's memory, we recommend tracks under 15 minutes to avoid high browser memory usage.