How to Speed Up or Slow Down a Video — Time-Lapse and Slow Motion
Changing video speed is one of the most versatile editing techniques available. Speed up a long process into a satisfying time-lapse, slow down a fast action to reveal hidden detail, or simply shorten a clip by playing it at 1.5× to fit within a time limit. This guide covers when and how to use speed changes effectively.
Speed Up: Creating Time-Lapse Effects
Speeding up a video plays it faster than real time. A 2× speed multiplier plays 2 minutes of footage in 1 minute; 4× plays 4 minutes in 1 minute. The most dramatic application is a time-lapse — compressing hours of footage into seconds — which reveals patterns invisible at normal speed: clouds moving across a sky, a sunset, plant growth, or traffic flow.
For a strong time-lapse feel, use 4× or higher. For moderate acceleration like shortening a tutorial or talking-head video, 1.5× or 2× is typically sufficient. At high speed factors, audio becomes distorted regardless of pitch correction — muting and adding background music produces a much better result.
- 1.5× — natural pacing boost, works for tutorials and walkthroughs
- 2× — clearly accelerated, still legible for most spoken content
- 4× — strong time-lapse feel; use music instead of original audio
- 8× — extreme compression; suited for very slow processes like sunsets or cooking
Slow Down: Creating Slow Motion
Slowing a video plays it at a fraction of its original speed. A 0.5× factor plays 1 minute of footage over 2 minutes. A 0.25× factor creates a dreamy slow motion effect. The quality of the result depends heavily on the original frame rate.
A video shot at 60fps slowed to 0.5× plays at an effective 30fps — perfectly smooth. A video shot at 30fps slowed to 0.5× plays at 15fps — still smooth enough. But a video shot at 24fps slowed to 0.25× plays at 6fps — noticeably choppy. For best slow motion, start with footage shot at 60fps or higher.
- 0.75× — subtle slowdown, useful for emphasising a key moment
- 0.5× — clear slow motion; smooth with 60fps source
- 0.25× — dramatic slow motion; needs 60fps+ source for smooth playback
- Slow motion works best on action footage — fast movement, sport, nature
Audio and Speed Changes
When video speed changes, audio pitch shifts unless corrected — sped-up audio sounds like chipmunks, slowed audio sounds unnaturally deep. MediaFormatter adjusts audio pitch to compensate automatically, so the voices sound natural at the new speed.
At very high speed factors (4× and above), audio becomes too compressed to use regardless of pitch correction. For time-lapse videos, muting and adding royalty-free background music is almost always the right choice.