Speed Processing

The .speedUp() stage classifies every moment of the trace into activity types and applies different playback speeds to each. Idle time flies by while user actions play at normal speed.

Basic usage

await Recast
  .from('./traces')
  .parse()
  .speedUp({
    duringIdle: 4.0,
    duringUserAction: 1.0,
  })
  .render()
  .toFile('demo.mp4')

Activity classification

The speed processor analyzes the trace and classifies each segment:

Activity	Default Speed	Description
User Action	1.0x	Clicks, fills, keyboard input — plays at real-time
Navigation	2.0x	Page loads, redirects — slightly faster
Network Wait	2.0x	API calls in flight — compresses wait time
Idle	4.0x	Nothing happening — skips quickly

Configuration options

Option	Type	Default	Description
`duringIdle`	`number`	`4.0`	Speed multiplier for idle segments
`duringUserAction`	`number`	`1.0`	Speed multiplier for user interactions
`duringNetworkWait`	`number`	`2.0`	Speed multiplier for network activity
`duringNavigation`	`number`	`2.0`	Speed multiplier for page navigations
`minSegmentDuration`	`number`	`500`	Minimum segment length in ms (avoids jarring speed changes)
`maxSpeed`	`number`	`8.0`	Safety cap on speed multiplier

Full example

.speedUp({
  duringIdle: 4.0,
  duringUserAction: 1.0,
  duringNetworkWait: 2.0,
  duringNavigation: 2.0,
  minSegmentDuration: 500,
  maxSpeed: 8.0,
})

CLI equivalent

npx playwright-recast -i ./traces --speed-idle 4.0 --speed-action 1.0

Tips

Speed processing respects segment boundaries. Setting minSegmentDuration prevents rapid speed switching that can look jarring in the output.
When voiceover is active, segments where TTS audio is significantly shorter than the original timing trigger fast-forward automatically.
Click effect and cursor overlay timestamps are automatically remapped through speed processing, so visual effects appear at the correct video time.
Start with the defaults and adjust per-activity speeds based on your content. A product demo might use duringIdle: 6.0 to aggressively compress waits, while a tutorial might keep everything closer to 1.0x.