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ChangeSpeed

What is it?

The ChangeSpeed node allows you to change the playback speed of a video. It uses FFmpeg's setpts filter to adjust video timing and automatically adjusts audio speed to match, creating smooth speed changes while maintaining audio-video synchronization.

When would I use it?

Use the ChangeSpeed node when:

  • You want to create fast-motion effects (e.g., 2x, 3x faster)
  • You need to create slow-motion effects (e.g., 0.5x, 0.25x slower)
  • You want to speed up long videos for quick review
  • You need to slow down fast action for analysis
  • You're creating time-lapse or slow-motion content
  • You want to adjust video pacing for different audiences

How to use it

Basic Setup

  1. Add a ChangeSpeed node to your workflow
  2. Connect a video source to the "video" input
  3. Set your desired speed multiplier
  4. Run the workflow to change the video's playback speed

Parameters

  • video: The video content to change speed (supports VideoArtifact and VideoUrlArtifact)

  • speed: Playback speed multiplier (0.1-10.0x, default: 1.0)

    • 0.1 = 10x slower (very slow motion)
    • 0.5 = 2x slower (slow motion)
    • 1.0 = normal speed (default)
    • 2.0 = 2x faster (fast motion)
    • 5.0 = 5x faster (very fast motion)
    • 10.0 = 10x faster (maximum speed)

  • include_audio: When enabled, includes audio in the output file (default: true)

    • When enabled: Audio is speed-adjusted to match video speed
    • When disabled: Creates a silent video (no audio track)

  • processing_speed: Balance between processing speed and output quality (default: "balanced")

    • fast: Fastest processing, lower quality (ultrafast preset, CRF 30)
    • balanced: Good balance of speed and quality (medium preset, CRF 23)
    • quality: Highest quality, slower processing (slow preset, CRF 18)

Outputs

  • video: The video with changed playback speed, available as output to connect to other nodes

Example

Imagine you want to create a fast-motion effect by speeding up a video 3x:

  1. Add a ChangeSpeed node to your workflow
  2. Connect the video output from a LoadVideo node to the ChangeSpeed's "video" input
  3. Set "speed" to 3.0 for 3x faster playback
  4. Keep "include_audio" enabled (default) to include speed-adjusted audio
  5. Run the workflow - the video will play 3x faster with audio adjusted to match
  6. The output filename will be {original_filename}_speed3.0.{format}

Important Notes

  • The ChangeSpeed node uses FFmpeg's setpts filter for high-quality speed changes
  • Audio is automatically speed-adjusted using the atempo filter to maintain synchronization (when include_audio is enabled)
  • Speed changes affect both video and audio simultaneously
  • Processing time depends on video length and resolution
  • Extreme speed changes (very fast or very slow) may affect audio quality
  • When include_audio is disabled, the output video will be silent

Parameter Recommendations

  • For fast motion: Use 2.0-5.0 for sped-up effects
  • For slow motion: Use 0.25-0.75 for slow-motion effects
  • For time-lapse: Use 5.0-10.0 for very fast playback
  • For analysis: Use 0.5-0.75 to slow down fast action
  • For quick review: Use 2.0-3.0 to speed up long content

Common Issues

  • Processing Timeout: Large videos may take longer to process; the node has a 5-minute timeout
  • Audio Quality: Extreme speed changes may affect audio clarity
  • No Video Input: Make sure a video source is connected to the "video" input
  • FFmpeg Errors: Check the logs parameter for detailed error information if processing fails

Speed Examples

  • 0.25x: 4x slower - Good for analyzing fast action
  • 0.5x: 2x slower - Classic slow motion
  • 1.0x: Normal speed - No change
  • 2.0x: 2x faster - Fast motion
  • 3.0x: 3x faster - Very fast motion
  • 5.0x: 5x faster - Time-lapse effect