Speed ramps: show what happens to clip time

Separate a constant speed from a curve

VideoShow places Standard and Curve in separate modes and shows an editable graph with several points. Funimate uses Normal and Curve and places a before-and-after duration readout above the graph. Both give a visible boundary between one constant setting and a changing rate across the clip.

Explain the mode through the selected control and its consequence, not only a different panel shape. A constant setting can have one multiplier, while a curve needs positions as well as values. When switching modes, define whether the app converts the curve, restores a previous setting or resets the edit. A person should not lose a carefully timed ramp through an apparently harmless tab change.

Keep a neutral baseline recognizable. A line at normal speed is not the same as an empty graph or a disabled feature. Make the baseline and supported bounds readable without requiring people to understand every preset name. If a curve currently leaves the total duration unchanged, say so without implying that every internal moment still occurs at its original project time.

Make each graph point an understandable edit

InShot provides a curve graph with control points, a filmstrip and a Smooth option. Dizzi separates Linear, Ramps and Auto Velocity and offers a Point control near the graph. These interfaces expose different editing policies; a shared graph aesthetic should not make them look interchangeable when the underlying controls behave differently.

Define the horizontal axis in terms the person can use. Does a point refer to a source moment or a position in the resulting timeline? Show enough frame context to identify the intended moment before moving it. Keep the selected point visibly distinct and expose its supported value. A tiny handle with no accompanying readout makes precise correction unnecessarily dependent on finger accuracy.

Provide discoverable point addition and removal, plus a recoverable way back. Do not rely on a hidden long press as the only path to a consequential graph operation if a named control can help. When points become very close, prevent accidental selection of a neighbor and preserve their ordering according to the actual editing model rather than allowing an unexplained jump.

Show original and resulting time together

Riveo displays two duration values near its speed graph and a Smooth Slo-Mo option. PowerDirector presents a duration comparison within its Curve preset workspace while retaining a separate project playback counter. That proximity helps only when labels make it clear which quantity belongs to the edited clip and which belongs to the whole project.

Keep source duration, resulting clip duration and current playback position separate. Updating the curve may move later clips or alter a project’s total length according to the editor’s rules. Show the resolved result promptly without letting a stale preview counter imply that the old timing still applies. If the calculation is pending, mark that state rather than presenting an old number as final.

A smoothing option also needs a bounded promise. It may invoke additional processing or a different playback treatment, depending on the product. The presence of a Smooth label does not prove that any source can become artifact-free slow motion. Show supported availability, progress and recovery, and let people judge the rendered result using their actual footage.

Keep retiming connected to the project

Winkit shows duration values beside a Montage curve, a Point action and Reset. Filmora HD shows the selected clip duration changing from 5.0 to 2.8 seconds while a music track and project timeline remain visible. Those views make the consequences of a local timing change easier to relate to the wider edit.

Preserve the intended source moment when the graph changes. A person slowing a gesture needs to inspect that gesture, not repeatedly hunt for it after every duration recalculation. If the playhead is represented in output time, keep its mapping understandable when the same source frame moves. Do not silently reinterpret a source-anchored marker as a fixed project-time marker.

Review dependent content such as captions, overlays, cuts and music according to the project’s actual attachment rules. Some elements may move with the source while others stay on the project timeline. Make those consequences visible where they matter. Avoid a universal promise that everything stays synchronized simply because the editor renders a new duration successfully.

Make presets inspectable and batch scope clear

Splice offers named speed patterns, Edit curve and an Apply to all hint. VN displays a Hero Time curve with a note about adding and removing points and a before-and-after duration readout. Named patterns can be useful starting points, but the person still needs to inspect the actual timing rather than infer it from an evocative label.

Show the selected pattern’s editable curve and explain whether subsequent changes create a custom version. Reset should have a clear baseline: the original normal-speed clip, the selected preset or the state at panel entry. These are different recovery actions. Keep their names and undo behavior consistent so exploration does not become destructive trial and error.

Apple’s iMovie speed controls illustrate product-specific speed ranges, reset behavior and an audio-pitch setting. The broader UI lesson is to expose the supported timing scope and related audio policy, not to assume every editor shares iMovie’s controls or processing behavior.

Model time mapping rather than a decorative line

Store the selected source range and the time-remapping definition independently from the graph’s screen coordinates. Keep graph points tied to the intended time domain and recompute the resulting duration from the supported mapping. A resize or orientation change should redraw the same edit, not change its timing because the points were stored as fitted pixel positions.

Define how trim, split, duplicate and replace operations affect the curve. A source replacement may need an explicit reset or review rather than inheriting arbitrary points from unrelated footage. Keep rendered preview jobs associated with an edit revision so an older result cannot overwrite a newer curve. Separate pending timing calculation, preview generation and final artifact export.

Provide an explicit audio policy where retiming affects sound. Pitch preservation, muting and separately timed music are not equivalent choices. Show the actual supported option without claiming a processing algorithm from its label. Accessible point selection, value adjustment and preset names should give people alternatives to delicate graph gestures, while preserving enough preview context to evaluate the edit.

Review a recognizable source moment

Choose footage with a recognizable action and ask a tester to slow only that moment while keeping the rest faster. Have them explain the source range and the resulting clip duration. Then reset, change a preset and cancel. Check whether the final curve matches their intention rather than whether they can merely produce a visually interesting graph.

Include short clips, closely spaced points, rapid changes, a source replacement and an interrupted preview. Test the actual audio policy and inspect the rendered artifact around each rate change. Lower-frame-rate source material and demanding edits may expose quality limits; report those limits honestly instead of treating a smooth preview control as evidence of perfect interpolation.

Measure wrong-moment edits, unexpected project-length changes, point-selection errors and mismatch between preview and final timing. Separate creative exploration from repeated repair. A person trying several presets is not necessarily struggling, while repeatedly restoring a lost action moment can reveal a genuine mapping problem. Use observation and artifact checks alongside coarse editing events.

Review source time and project time

Use these checks on a working build, not only on the polished reference state.

• ✓Constant speed and authored curves are distinct modes.
• ✓Point positions have a defined time domain.
• ✓Original, resulting and project durations are labelled.
• ✓Preset edits and reset have predictable baselines.
• ✓Captions, overlays and audio follow defined attachment rules.
• ✓Late previews cannot replace the current edit revision.
• ✓Rendered output is inspected for timing and quality limits.

Related design decisions

The AI video editor examples cover the larger creation workflow. Keep local retiming understandable without making people leave the project context.

Use the sharing and export examples when separating an interactive speed preview from a successfully created video artifact.