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Detect a loop BPM and time-stretch it to your project tempo — manual BPM or a reference track, with the output BPM re-verified after stretching.
Details
The loop tempo comes from onset-envelope autocorrelation over the full track. The target is either a BPM you type or a reference track that gets the same analysis (great for building loop packs around an acapella or a live drummer). The stretch ratio drives a pitch-preserving engine: rubberband when the FFmpeg build has it (best quality), otherwise the atempo filter chained within its 0.5-100 per-instance range — atempo is the faster WSOLA-style stretcher and is the engine on most builds. A whole-bar trim option cuts the stretched result to complete 4/4 bars at the target tempo so the loop cycles cleanly. The output is re-analyzed after stretching and its measured BPM is reported next to the target, so the match is verified end to end. Extreme ratios (beyond roughly 0.5x-2x) sound smeared on any engine — prefer repitching or cutting a different loop.
Execution
Fill in the form, run the tool, and review the result in one place.
Samples
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Tool usage guide
Tempo Matcher analyzes the BPM of your audio loop and time-stretches it to match a target tempo or reference track while preserving its original pitch.
Background
A producer has a 120 BPM drum loop that needs to integrate into a 128 BPM house track.
Problem
Speeding up the track manually in some editors alters sample pitch or results in timing drift.
How to use
Upload the drum loop, select manual BPM set to 128, choose the atempo engine, and export to WAV.
Outcome
The drum loop is stretched to precisely 128 BPM with verified output tempo and unchanged pitch.
Background
An artist needs a rhythmic groove to sync with a vocal acapella of unknown tempo.
Problem
Estimating tempo manually causes timing mismatches across long sections.
How to use
Upload the percussion stem, choose reference track mode, upload the vocal file, enable 4/4 whole-bar trimming, and export as FLAC.
Outcome
The groove is matched to the detected vocal tempo and cropped to clean bar lengths for cycling.
No, both available engines adjust playback speed while maintaining the original musical pitch.
Rubberband delivers higher acoustic quality with fewer artifacts, while atempo provides faster WSOLA-based processing.
The tool uses onset-envelope autocorrelation on the reference track to detect its BPM and applies that target to your source loop.
It cuts the stretched audio cleanly at full 4/4 bar boundaries so the sample loops without timing gaps.
You can export the tempo-matched audio in WAV, MP3, FLAC, M4A, or OGG formats.