How to match music to your edit's tempo and key

To match music to an edit, read the track's BPM and key, work out the tempo or key you need, and render a version that is time-stretched or pitch-shifted to hit it. In StemForge you load the track, run the analysis, set a target BPM or key, render, and import the result into your project, in either Premiere Pro or DaVinci Resolve Studio.

When you need it

• You want cuts to land on the beat, and the track's tempo is not the one you cut to.
• A piece of music has to fill an exact section length.
• You are layering two tracks and they need to share a tempo or sit in the same key.

Work out the tempo you need

Tempo is beats per minute. To fit a number of beats into a number of seconds, multiply the beats by 60 and divide by the seconds. Eight bars of 4/4 is 32 beats, so fitting that into 15 seconds needs 32 × 60 ÷ 15 = 128 BPM. If the track is at 120 BPM, you would render a version at 128.

Steps

1. Load the track into the StemForge panel. In Premiere Pro you can use the timeline selection. In DaVinci Resolve Studio use Media Pool Selection or Clip at Playhead.
2. Run the analysis to read the BPM and musical key.
3. Set a target BPM, a target key, or both.
4. Render. StemForge produces a time-stretched or pitch-shifted version as a new file.
5. Import the result into your project and place it on the timeline.

Getting a clean result

• Small changes sound cleaner than large ones. A few BPM either way is usually fine, and a large stretch is more likely to be audible.
• When you change the key, StemForge keeps the drums unshifted so they keep their punch.
• Two tracks in the same key, or in relative major and minor keys, usually sit together well.

What detection can and can't do

BPM detection works best on a steady tempo, and a live or drifting performance is harder to read. Key detection is built for tonal music, so it is much less meaningful on sound effects or noise. Treat the result as a strong starting point and check it by ear.

More detail

See BPM and key detection for Premiere Pro or BPM and key detection for DaVinci Resolve Studio. If you also want to rebalance the music itself, read what audio stems are.

Questions

Does changing the tempo change the pitch?

Not in StemForge. Time-stretching changes the speed and keeps the pitch, and pitch-shifting changes the key and keeps the speed.

Can I change tempo and key at once?

Yes. Set both targets and render one version.

Do I need to separate stems first?

No. The analysis and the render work on the whole track. Separating stems is an optional extra step.