Video Speed
FFmpeg PoweredSpeed up, slow down, or reverse playback
Drag & drop files here, or click to select
Supports MP4, WebM, AVI, MOV, MKV and other common formatsHow to Use
- Click the area above to select a file, or drag and drop a file onto the page
- Adjust parameters in the settings area
- Click the process button and download the result when ready
Frequently Asked Questions
How It Works
The Video Speed tool uses FFmpeg WebAssembly with the atempo audio filter and video setpts (Presentation Time Stamp) filter to modify playback speed. When speeding up, the PTS values are divided by the speed factor, causing frames to appear faster. When slowing down, PTS values are multiplied.
For pitch-preserving audio, the tool chains multiple atempo filters (each supporting 0.5x-2.0x) to achieve the desired speed. For example, 4x speed uses atempo=2.0,atempo=2.0. Without pitch preservation, the audio is simply resampled, which shifts the pitch proportionally to the speed change.
The video track uses the setpts filter to adjust frame timestamps. At higher speeds, frames are simply displayed faster with no frame dropping. At lower speeds, the original frames are held longer, creating a smooth slow-motion effect. The output is re-encoded with synchronized audio-video timestamps.
Tips & Best Practices
- Enable pitch preservation for videos with speech or music — without it, 2x speed makes voices sound like chipmunks.
- 2x speed is ideal for skipping through lectures or tutorials. 0.5x is perfect for detailed sports analysis or tutorial breakdowns.
- Watch file size: Speed changes don't significantly alter file size since the encoding parameters remain the same.
- Combine with trim: First trim the section you want to speed up, then apply speed adjustment for cleaner results.
- Check audio sync after processing at extreme speeds (above 4x) — some formats may have slight drift.
- For timelapse effects, combine 4x or 8x speed with a shorter trimmed segment for the best visual impact.
Use Cases
Sports analysts slowing down game footage frame-by-frame to study player movements and strategies in detail. Tutorial creators speeding up repetitive sections (like file copying or software installation) to keep viewers engaged.
Comedy content creators using fast-forward effects for humorous effect. Dance instructors slowing down choreography demonstrations so students can follow each movement. Product reviewers speeding through unboxing setup while keeping the important commentary at normal speed. Documentary editors creating time-lapse sequences from real-world footage by dramatically increasing playback speed.