About the Video Speed Changer
Speed up a long screen recording, turn a clip into a time-lapse, or slow footage down for a smooth slow-motion effect. This tool re-times both the video frames and the audio track, keeping the audio pitch natural so voices don't turn into chipmunks or drones. Processing happens on your own device with a WebAssembly build of FFmpeg — your video is never uploaded, so there are no size limits imposed by a server, no queue and no watermark.
How changing video speed works
A video's speed is defined by the timestamp attached to each frame. To speed up a clip by 2x, every frame's presentation timestamp is halved, so the same frames play in half the time; to slow down by 0.5x the timestamps are doubled. The audio is handled separately with a tempo filter that stretches or compresses the waveform while preserving pitch — the same technique podcast apps use for 1.5x playback.
Because frames are re-timed rather than dropped or duplicated, speeding up is lossless in terms of picture content, and the output is re-encoded once at a quality setting chosen to stay visually close to the source. Slowing down below the original frame rate will show the source frames for longer, which looks fine for moderate slow-motion (0.5x) but can appear stuttery at extreme values if the original was shot at 24–30 fps.
Choosing the right speed
- 1.25x – 1.5x: tutorials, lectures and screen recordings — faster without losing intelligibility.
- 2x – 4x: time-lapse style sequences, walk-throughs, unboxings and long process videos.
- 0.75x: subtle slow motion that keeps speech understandable.
- 0.5x – 0.25x: dramatic slow motion for sports, action shots or product reveals — best with source footage at 60 fps or higher.
Supported formats and limits
Upload MP4, MOV, WebM, MKV, AVI and most other common containers; the output is an MP4 (H.264 + AAC) that plays everywhere including social platforms and messaging apps. Because the work is done by your computer's CPU, very large files (multi-gigabyte 4K footage) will take longer than on a server farm — a rough guide is that a 1080p clip processes at around real-time on a modern laptop. Trimming the video first with the Video Trimmer keeps processing quick.
How to use the Video Speed Changer
- 1Select a video. Drop a video file onto the page or click to browse. Nothing is uploaded — the file stays in your browser's memory.
- 2Set the speed. Pick a preset (0.25x, 0.5x, 1.5x, 2x, 4x) or type a custom multiplier. Values above 1 speed the video up; values below 1 slow it down.
- 3Process. Click the speed-change button and wait for the progress bar. Longer or higher-resolution videos take proportionally longer.
- 4Preview and download. Play the result in the built-in player to check timing and audio, then download the MP4.
Frequently asked questions
- Does speeding up the video change the audio pitch?
- No. The audio is processed with a tempo filter that changes speed while preserving pitch, so voices sound natural rather than higher or lower. If you want the classic pitch-shifted effect instead, use the Speed & Pitch audio tool.
- Is there a file size or length limit?
- There is no server-imposed limit because nothing is uploaded. Practical limits come from your device's memory: files up to a few gigabytes work on most modern computers, and the process is faster on desktop than on phones.
- Will there be a watermark?
- No. The output is a clean MP4 with no watermark, no branding and no account required.
- Can I change the speed of just part of a video?
- Split the section out first with the Video Trimmer, change its speed here, then join the pieces back together with the Video Merger.
- What speed range is supported?
- Anything from 0.25x (four times slower) to 4x (four times faster). Extreme values are achieved by chaining tempo filters so audio quality is maintained across the whole range.
- Is my video private?
- Yes. The video is decoded, re-timed and re-encoded entirely on your device using FFmpeg compiled to WebAssembly. It is never transmitted to EverydayTab or any third party.