Transform ordinary video footage into rhythm-synchronized masterpieces
BeatFX is an iOS app that analyzes music to detect beats, drops, and energy levels, then automatically applies perfectly-timed speed effects—slow motion, speed-ups, and reverse playback—that pulse with the music.
Understands not just beat timing, but musical energy and intensity using FFT-based analysis
Decides when to slow down for emotional moments and speed up for drops automatically
Dramatic, TikTok-style reverse effects for maximum creative impact
On-device processing means your videos never leave your phone
Import from Camera Roll or use external music sources
Subscription with unlimited exports, advanced settings, and full-length video support
Advanced signal processing and AI working together to create perfect rhythm synchronization
Loads audio from the video file or external source and converts it to mono format using Apple's Accelerate framework for optimal processing.
Performs Fast Fourier Transform analysis on sliding windows of audio samples to calculate frequency band energy, specifically targeting bass frequencies where beats are most prominent.
Identifies energy peaks across time windows to detect beat moments with configurable sensitivity.
Uses Sugeno-style fuzzy logic with triangular membership functions to map beat energy and density into speed factors, determining whether to apply slow-motion, speed-up, or reverse effects.
Processes video segments in parallel using AVFoundation and VideoToolbox for hardware-accelerated encoding. Metal shaders handle pixel buffer operations for reverse playback.
Exports video in memory-efficient segments, concatenates them, and adds the audio track back synchronized to the processed footage.