Change the speed of a video anywhere from 0.25× to 4×: a tutorial at 1.5×, a highlight at half speed, a long recording squeezed to a quarter of its length. Drag the slider in 0.05 steps, type an exact value, or tap a preset (0.25, 0.5, 1.5, 2 or 4). The picture is not re-encoded: each frame is copied unchanged and only its timing moves, so quality is untouched and the wait is far shorter than a full export. It works on MP4, MOV and WebM files. Audio is resampled to stay in sync, or dropped. The result is an MP4, made in your browser without uploading anything.
How it works
- Drop a video, or up to 20 that should all get the same speed.
- Set the speed with the slider, a preset or an exact number, then choose Keep audio or Drop audio.
- Press Process & download. The result line shows the new duration; a batch downloads as one ZIP.
Questions
- Does changing the speed change the pitch?
- Yes, when the audio is kept. It is resampled to the new speed, so it rises in pitch when sped up and drops when slowed, the way tape does, and stays in sync with the picture. Choose Drop audio for a silent result. If your browser cannot encode AAC, the audio is dropped automatically and the result says so.
- Can I set a custom speed such as 1.25× or 0.8×?
- Yes. Type any value from 0.25 to 4 into the number box, or drag the slider in 0.05 steps. A value outside that range is pulled to the nearest end rather than rejected. One speed applies to every clip in a batch, so clips that need different speeds go in separate runs.
- What format is the sped-up or slowed video?
- Always MP4. The video stream is moved into an MP4 container exactly as it was, so an H.264 clip stays H.264 and a VP9 WebM keeps its VP9 video inside the MP4. Kept audio is encoded fresh as AAC at 128 kbps.
- Does my file get uploaded?
- No. The models and all processing run inside your browser on your own device. You can verify this yourself: open your browser’s DevTools, watch the Network tab, and process a file: there are no uploads. After the first visit most tools also work fully offline.
- Does rotating re-encode the video?
- No. The rotation is written into the MP4’s orientation metadata and the frames are copied unchanged, so it is near instant and loses no quality. A few third-party players ignore that flag; browsers and phones honour it.
- What happens to the audio?
- Rotate keeps it untouched. Reverse always drops it, since reversed speech is rarely what anyone wants. Speed changes keep it in sync, or you can drop it with one switch.