Drop in a song and a handful of clips or photos: the editor finds the beats and cuts to the next clip exactly on the beat. Pick how often to cut, shuffle the order, preview it, then save a music-synced MP4. Everything happens in your browser, so nothing is uploaded.
Last updated:
Analyzing beats…beat cut
Recording…
Cut every
Clip order
Clips repeat in this order until the music ends. Each video clip continues where it left off the next time it appears.
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How to use the Beat Sync Video Editor
Add your music (MP3, WAV, M4A, OGG). A demo beat is loaded so you can try the tool right away.
Add clips and photos: select several videos and images at once. They replace the numbered demo cards.
Choose how often to cut: every 1 beat for a fast, energetic edit, every 2 or 4 beats for a calmer one. Set the music start and video length.
Arrange the order with the arrow buttons, or press Shuffle order for a random mix. Click the waveform to preview any moment.
Press Play preview to watch the montage with the music. If cuts feel early or late, move the beat offset slider.
Press Create video and keep the tab visible while it records in real time, then download the MP4.
How long each clip stays on screen
One beat lasts 60 ÷ BPM seconds. Multiply by the Cut every setting to get the length of each clip. This table shows common tempos:
Tempo
Typical styles
Every 1 beat
Every 2 beats
Every 4 beats
80 BPM
Hip-hop, R&B, ballads
0.75 s
1.5 s
3.0 s
100 BPM
Pop, reggaeton
0.60 s
1.2 s
2.4 s
120 BPM
Dance pop, house
0.50 s
1.0 s
2.0 s
128 BPM
EDM, house
0.47 s
0.94 s
1.88 s
140 BPM
Trap, dubstep (often felt as 70)
0.43 s
0.86 s
1.71 s
174 BPM
Drum and bass
0.34 s
0.69 s
1.38 s
Cuts shorter than about 0.4 seconds are hard to follow, so for fast songs cut every 2 or 4 beats and save single-beat cuts for the chorus or drop.
What happens behind the scenes
Onset strength. The music is split into overlapping 1,024-sample windows. A fast Fourier transform measures the energy in each frequency band, and the positive increases from one window to the next are summed. Drum hits and note starts produce sharp peaks.
Tempo. The onset curve is compared with shifted copies of itself (autocorrelation). The shift with the strongest match, gently weighted toward 120 BPM, gives the beat period.
Beat tracking. A dynamic-programming search chooses the chain of beats that lands on strong onsets while keeping each gap close to the period, so the beats follow small tempo changes in live recordings.
Cuts. Every Nth beat inside the selected part of the song becomes a cut, and the clips are assigned in order, repeating when the list runs out.
Recording. The preview canvas and the music are captured together with the browser's MediaRecorder and saved as MP4 or WebM.
Tips for a montage that feels on beat
Start the video on a strong moment, such as the first beat of the chorus. Set Music start to a few tenths of a second before it.
Use 8 to 20 clips for a 15 to 30 second video, so few of them repeat.
Pick clips with movement at the start: a cut lands better when something happens right away.
Mix wide shots and close-ups, and put your best clip right where the music builds.
For vertical videos, keep faces and text in the middle of the frame; Fill frame crops the edges.
Frequently asked questions
How does the beat detection work?
The tool computes an onset strength curve with spectral flux: for every 11.6 ms frame it measures how much the energy in each frequency band rose compared with the previous frame. Autocorrelation of that curve gives the tempo, weighted toward common tempos around 120 BPM, and a dynamic-programming beat tracker then places beats on strong onsets while keeping the spacing close to the tempo.
What does cut every 1, 2 or 4 beats mean?
It sets how many beats each clip stays on screen. At 120 BPM one beat lasts 0.5 seconds, so cutting every beat shows a new clip twice a second, every 2 beats gives 1 second per clip and every 4 beats (one bar in 4/4 time) gives 2 seconds per clip.
The cuts are slightly early or late. How do I fix it?
Use the beat offset slider to move every cut up to 200 ms earlier or later. If the detected beats drift on a song with a very steady tempo, switch Beat source to Steady grid and type the tempo; the grid is aligned to the strongest onsets automatically.
Why is the BPM half or double what I expected?
Tempo is ambiguous: a song at 140 BPM can feel like 70. The cut rate is what matters, so simply pick a different Cut every setting. You can also switch to Steady grid and type the exact BPM.
Can I use both videos and photos?
Yes. Photos get an optional slow zoom so they do not look static, and video clips play from where they stopped the last time they appeared, so repeated clips show new footage. The original sound of the video clips is replaced by your music.
Is the video really MP4?
In Chrome, Edge and Safari the recording is saved as MP4 with H.264 video and AAC audio. Browsers that cannot record MP4, such as some versions of Firefox, save WebM instead, which plays in most players and can be converted with a video converter.
Why does creating the video take as long as the music?
The montage is rendered and recorded in real time in your browser, which keeps everything on your device without any upload. Keep the tab visible while recording, because browsers slow down hidden tabs.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.