YouTube Precision Slowdown

Pitch-preserving speed control, waveform view, and beat-quantized loop selection for any YouTube video.

Slow down and loop any YouTube video without losing pitch — built for practicing an instrument, transcribing a part, learning choreography, or just studying something frame-by-frame-ish. HOW IT WORKS Open any YouTube video and click the new "Loop" button next to fullscreen/settings in YouTube's own player controls. The first click scans that video's audio (a few seconds) to build a beat/measure grid; every click after that just shows or hides the tool. Nothing is scanned automatically, and the extension does nothing at all until you click Loop. On accounts with ads: the scan waits for ads to finish, and if an ad cuts a scan short, clicking Loop again rescans. Reloading the page fixes anything that looks stuck after an ad. FEATURES • Speed slider, 25%-100%, with pitch preservation — independent of YouTube's own playback-speed control. • Pitch shifting: a Transpose stepper (semitones) and a Fine-tune slider (cents), for playing along in a different key or matching a recording's own tuning. • A beat/measure grid estimated from the video's own audio, shown as a timeline under the player. Automatically detects separate musical segments and fits each its own tempo — so an instructional video with talking between performances, or the same phrase played slow and then up to speed, still gets an accurate grid for every section instead of one average tempo across the whole video. • Drag on the timeline to loop a section, quantized to measures by default (hold Alt for single beats, Ctrl for unquantized). • Zoom/pan the timeline (scroll wheel or Ctrl+Up/Down), with a minimap and autoscroll during playback. • Drag the playhead to scrub: the audio under the cursor plays in a short sustained loop, so a single note can be picked out by ear. • Manual correction tools for the well-known failure modes of automatic beat detection (tempo, downbeat offset, phase offset), since no algorithm gets this perfect on every track. Corrections are saved per video and reapplied automatically next time. • Full list of controls via Alt+/ anywhere on the page, or the "?" button on the panel. PRIVACY Everything runs locally in your browser. Audio analysis happens entirely on-device via the Web Audio API; nothing is ever uploaded anywhere. The only data stored is per-video beat-grid results, cached locally so a video doesn't need to be re-scanned on a later visit. No accounts, no analytics, no tracking, no data collection of any kind. Full policy: https://github.com/wsirota/youtube-precision-looper/blob/main/PRIVACY.md