Video Speed Changer

Speed up or slow down MP4 video footage and automatically calculate complex pitch shifts entirely offline natively.

Change Video Playback Rate

Create fast-motion timelapses or slow-motion reels, instantly burning the new playback speed directly into the video file.

Motion Controls

Slower (0.5x)Faster (4.0x)
Note: We apply the highly complex atempo FFmpeg filter to stretch the audio stream pitch seamlessly corresponding to the video scale ratio without destroying audio semantics.

Client-Side Frame Rate Modification

Unlike simple browser preview playback controllers that artificially adjust the HTML5 media stream rate, this tool permanently burns your new defined framerate and timescale constraints instantly into the MP4 file.

How does Presentation Timestamp (PTS) calculation work?

Under the mathematical hood, our WebAssembly FFmpeg processor evaluates the -filter:v setpts=INVERSE_RATIO command logic to modify exactly when physical pixel frames trigger playback timing protocols in hardware. Additionally, utilizing the inverse atempo audio filter mapping, human vocal waves remain recognizable instead of being destroyed by brute-force algorithmic truncating.

About Video Speed Changer

This is a free, fast, and fully client-side video speed changer tool. All processing is done locally within your browser to ensure maximum privacy and security. No data is sent to our servers. Bookmark this page for quick access to ad-free, high-performance SEO and developer utilities.