Video Speed Editor: Speed Ramp

Use this video speed editor to type an exact rate for each section, see the predicted output length, and compare it with the rendered length after export. Speed Ramp puts numeric speed controls and a source-time curve beside the video preview.

▶ 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.