Video Speed Editor: Speed Ramp

Video speed editor for slow motion and fast motion: type an exact rate from 0.1× to 16× for the whole clip or for each section, shape a speed ramp on the curve, and see the predicted output length before you export an MP4.

▶ TYPE THE SPEED YOU WANT
• Enter 0.1×–16× with up to 2 decimal places, including rates such as 7.5×.
• Apply a rate to the Whole clip or give separate sections their own speeds.
• Move keyframes on the graph, or type a section's source time. Choose Constant, Linear ramp or Ease in/out for the section ahead.
• Scrub the preview and tap Add keyframe here at the playback position. Undo an edit or remove an interior keyframe.

▶ SEE THE OUTPUT LENGTH
• Source and Output lengths appear in the Speed editor. The prediction uses the same speed-step schedule sent to the renderer.
• After Export video, the result shows Expected and got lengths together. A warning appears if the measured length differs beyond the comparison tolerance.
• Save to gallery or Share the rendered MP4. Leaving an unsaved result asks whether to save it, discard it or keep it open.

▶ PREVIEW AND SOUND
• Use the source-time scrub bar and graph playhead to find the section you want to change.
• Preview is labeled Approximate preview. It lets you try the speed schedule before rendering.
• For a clip with sound, choose Keep pitch, Follow speed or Mute. Imported clips with sound start in Keep pitch; silent clips start in Mute.
• Ramps are made from small speed steps. Slow motion holds source frames longer, and a warning appears when effective frame rate falls below 15 fps.

▶ KEEP YOUR PROJECTS
• Pick video or Try sample to start. Recent projects let you reopen the Speed editor.
• Imported videos are copied into app storage, together with project edits. Deleting a project gives a 6-second Undo window before its app copy is removed; saved gallery copies remain.
• Create backup makes a manifest and media parts. Restore backup asks you to confirm a merge; select the manifest and every part together. Missing or unreadable parts are reported.

▶ GOOD TO KNOW
• A curve can use up to 120 speed steps. Larger speed changes or extra keyframes may need a simpler curve before export.
• There is no frame interpolation. Slowing footage does not create new motion detail.
• Export uses H.264 video in an SDR MP4, with AAC when sound is retained. Some source videos and HDR conversions may be unsupported on your device.
• The length comparison allows one output frame plus 50 ms; it is a check, not a promise that every rendered length will match.
• Keep the app open for reliable export completion. Brief app switches may continue while the process remains alive.