Video · 14
Video speed
0.5×, 0.75×, 1.5×, or 2×. The picture uses setpts. The audio uses atempo. Pitch follows the speed, the way a timeline speed change usually does.
How to use it
This is not a pitch-locked slow motion. At 2× the voice is higher and shorter. At 0.5× it is lower and longer. If you need the voice to stay in key, change the audio on the pitch and speed page and edit the picture separately.
The export is a new H.264 and AAC file. A 4 second clip at 2× comes back near 2 seconds. Duration scales with the speed you picked.
Very slow motion of a 24 fps clip looks stepped because there are no new frames, only repeated time. This page does not invent in-between frames.
Tips
- 2× is the useful speed for a screen recording that drags.
- 0.5× on a short action beat is enough. Slowing a whole minute is a long encode for a hard-to-watch result.
- Mute first if the sped-up audio is the part you do not want.
FAQ
Will the audio stay lined up?
Yes. Both streams are retimed by the same factor and written together.
Can I pick 1.1×?
Not here. The speeds are the ones that stay inside a single atempo stage and are easy to judge by ear.
Is the clip uploaded?
No. ffmpeg.wasm does the retiming locally.
License
Encoding uses the single-thread ffmpeg.wasm build shipped with Cutshed. The JavaScript wrapper (@ffmpeg/ffmpeg and @ffmpeg/util) is MIT. The core binary is GPL-2.0-or-later because the build enables GPL components, including libx264, libmp3lame, libvorbis, and native AAC and FLAC. That license covers the encoder, not your recording.