Song BPM Alignment, Stems & DAW Export

Models, parameters, and sources

Paper and benchmark notes

Parameter guide

• Leave empty to preserve speed, or enter 30–300 BPM to change the actual audio tempo. Constant stretching does not force every detected beat onto a grid.
• Uses one constant ratio for the whole song. Remaining beat drift is reported, not corrected with hidden local speed changes.
• Applies one transparent stretch ratio across the complete song.
• Explicitly stretches between beats. Local speed can vary; review the reported range and timing warnings.
• Use the detected tempo, half-time or double-time. A manual source BPM takes precedence and is never multiplied again.
• Meter of the song. Keep automatic detection, or pin 2 to 12 beats per bar when the downbeat grouping is known.
• Empty target keeps the original speed. A numeric target changes the audio tempo; constant mode preserves natural timing differences.
• Preserves duration and pitch. MIDI carries the source tempo map; original WAVs do not request automatic tempo stretching.
• Target version plus the original full-song reference and its MIDI tempo map. Stems, when selected, are created only for the target version.
• Final source BPM used to calibrate the beat grid. Beat and downbeat detection still runs; this value is not doubled or halved again.
• Position of the first downbeat in seconds. Anchors the grid when automatic detection starts off-beat.