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Speed Up

Speeds up or slows down an audio segment by a given multiplier factor, changing playback speed without altering pitch quality.

Common Properties​

  • Name - The custom name of the node.
  • Color - The custom color of the node.
  • Delay Before (sec) - Waits in seconds before executing the node.
  • Delay After (sec) - Waits in seconds after executing node.
  • Continue On Error - Automation will continue regardless of any error. The default value is false.
info

If the ContinueOnError property is true, no error is caught when the project is executed, even if a Catch node is used.

Inputs​

  • Audio Segment ID - The ID of the audio segment to speed up or slow down.
  • Multiplier - Speed multiplier factor (default: 1.0)
    • 1.0 = Normal speed (no change)
    • 2.0 = Double speed (twice as fast)
    • 0.5 = Half speed (twice as slow)
    • 1.5 = 50% faster
    • 0.75 = 25% slower
  • Chunk Size - Chunk size in milliseconds for speed processing (default: 150). Smaller values provide smoother transitions but slower processing.

Options​

This node does not have configurable options. Configuration is done through inputs.

Output​

  • segment_id - The ID of the newly created speed-adjusted audio segment. If multiplier is 1.0 (no change), returns the original segment ID.

How It Works​

The Speed Up node uses advanced audio processing algorithms to change playback speed. When executed, the node:

  1. Validates the segment ID is not empty
  2. Retrieves the multiplier and chunk size values
  3. If multiplier equals 1.0, returns the original segment unchanged (optimization)
  4. Retrieves the audio segment from memory
  5. Processes the audio in chunks to adjust speed while maintaining quality
  6. Creates a new segment with the adjusted speed
  7. Establishes a dependency link in the processing graph
  8. Returns the ID of the speed-adjusted segment

Requirements​

  • Valid audio segment ID (from Create, Slice, Concatenate, etc.)
  • Segment must exist in memory
  • Multiplier must be a positive number (> 0)
  • Chunk size must be a positive number

Understanding Speed Multiplier​

Speed Increase (> 1.0)​

  • 1.25 = 25% faster (audio finishes in 80% of original time)
  • 1.5 = 50% faster (audio finishes in 67% of original time)
  • 2.0 = Double speed (audio finishes in 50% of original time)
  • 3.0 = Triple speed (audio finishes in 33% of original time)

Speed Decrease (< 1.0)​

  • 0.75 = 25% slower (audio takes 133% of original time)
  • 0.5 = Half speed (audio takes 200% of original time)
  • 0.25 = Quarter speed (audio takes 400% of original time)

No Change (= 1.0)​

  • 1.0 = Normal speed (no processing performed, returns original)

Understanding Chunk Size​

The chunk size parameter controls how audio is processed:

  • Smaller values (50-100 ms):

    • Smoother transitions
    • Better quality for complex audio
    • Slower processing
    • Higher CPU usage

  • Larger values (150-300 ms):

    • Faster processing
    • Lower CPU usage
    • May have slight artifacts in some cases
    • Good for voice/speech

  • Default (150 ms):

    • Balanced quality and performance
    • Suitable for most use cases

Duration Calculation​

New duration = Original duration ÷ Multiplier

Examples:

  • 60 seconds at 2.0x = 30 seconds
  • 60 seconds at 0.5x = 120 seconds
  • 60 seconds at 1.5x = 40 seconds
  • 60 seconds at 0.75x = 80 seconds

Error Handling​

The node will return specific errors in the following cases:

  • Audio segment ID is empty or null
  • Audio segment with the specified ID does not exist
  • Multiplier is zero or negative
  • Chunk size is zero or negative
  • Invalid numeric values

Usage Examples​

Example 1: Speed Up Podcast​

Create a faster version for time-saving:

  1. Create segment from podcast.mp3
  2. Use Speedup with Multiplier: 1.5 (50% faster)
  3. Export as podcast_fast.mp3
  4. Result: 60-minute podcast becomes 40 minutes

Example 2: Slow Down for Transcription​

Make audio easier to transcribe:

  1. Create segment from interview.wav
  2. Use Speedup with Multiplier: 0.75 (25% slower)
  3. Play back slowed version for accurate transcription

Example 3: Create Time-Lapse Audio​

Compress long recordings:

  1. Create segment from meeting.mp3 (2 hours)
  2. Use Speedup with Multiplier: 3.0 (triple speed)
  3. Export 40-minute summary version

Example 4: Batch Speed Processing​

Process multiple files to same speed:

  1. Loop through audio files
  2. Create segment for each
  3. Apply Speedup with consistent multiplier
  4. Export all processed files
  5. Delete segments

Example 5: Fine-Tune Speech Rate​

Adjust speaker pace slightly:

  1. Create segment from speech.mp3
  2. Use Speedup with Multiplier: 1.1 (10% faster)
  3. Subtle improvement in pacing
  4. Export adjusted speech

Example 6: Optimize for Platform​

Fit audio into time constraints:

  1. Get Metadata to find current duration (65 seconds)
  2. Target duration: 60 seconds
  3. Calculate multiplier: 65 / 60 = 1.083
  4. Apply Speedup with Multiplier: 1.083
  5. Export perfectly timed audio

Usage Notes​

  • Speed adjustment preserves audio quality using time-stretching algorithms
  • Pitch is maintained (doesn't create "chipmunk" effect)
  • Processing time increases with audio length
  • Very high multipliers (> 3.0) may cause quality degradation
  • Very low multipliers (< 0.25) may sound unnatural
  • Multiplier of 1.0 is optimized to skip processing entirely
  • The original segment remains unchanged in memory
  • Duration changes proportionally to multiplier

For Voice/Speech​

  • Speed up: 1.1 - 2.0 (optimal: 1.25 - 1.5)
  • Slow down: 0.5 - 0.9 (optimal: 0.75 - 0.85)

For Music​

  • Speed up: 1.05 - 1.25 (subtle changes)
  • Slow down: 0.75 - 0.95 (subtle changes)

For Audiobooks​

  • Speed up: 1.25 - 2.0 (common: 1.5)
  • Slow down: 0.75 - 0.9 (rare)

Extreme Processing​

  • Time-lapse: 2.0 - 5.0
  • Detailed analysis: 0.25 - 0.5

Performance Considerations​

  • Processing time is proportional to:
    • Audio duration
    • Multiplier distance from 1.0
    • Chunk size (smaller = slower)
  • Large files may take several seconds to process
  • Multiplier of 1.0 returns instantly (no processing)
  • Consider chunk size vs. quality tradeoff
  • Memory usage increases during processing

Common Use Cases​

  • Speeding up podcasts and audiobooks for faster listening
  • Slowing down audio for transcription or learning
  • Time-fitting audio to specific durations
  • Creating highlight reels with compressed content
  • Adjusting interview pacing
  • Making lectures more consumable
  • Creating time-lapse audio summaries
  • Meeting recording compression
  • Voice memo processing
  • Educational content speed adjustment
  • Accessibility (slower for comprehension)
  • Quick previews of long content

Best Practices​

  • Test with small multiplier changes first (1.1, 1.2)
  • Use Get Metadata to calculate exact multipliers for target durations
  • Adjust chunk size if you notice quality issues
  • Keep multipliers reasonable (0.5 - 2.0 range)
  • Listen to results before batch processing
  • Consider your audience's preferences
  • Document speed changes in file names (e.g., "podcast_1.5x.mp3")
  • Use variables for multipliers in batch operations
  • Delete original segments after confirming results

Quality Tips​

  • For speech, multipliers up to 2.0 are generally acceptable
  • For music, keep changes subtle (1.0 - 1.25)
  • Use smaller chunk sizes (75-100) for music
  • Use larger chunk sizes (150-200) for speech
  • Test different chunk sizes if quality is critical
  • Very high speeds may lose intelligibility
  • Very low speeds may sound robotic

Advanced Techniques​

Calculate Exact Multiplier for Target Duration​

1. Get Metadata (current duration in ms)
2. Define target_duration (in ms)
3. Calculate: multiplier = current_duration / target_duration
4. Apply Speedup with calculated multiplier
5. Result exactly matches target duration

Progressive Speed Adjustment​

1. Create segment
2. Try multiplier 1.5
3. If too fast, try 1.25
4. If too slow, try 1.75
5. Fine-tune until perfect

Batch Standardization​

For each audio file:
  1. Get Metadata
  2. If duration > 3600000 (1 hour):
     - Apply Speedup 1.5x
  3. Else:
     - Use normal speed
  4. Export

Time Calculation Examples​

Example 1: Podcast Episode​

  • Original: 45 minutes (2,700,000 ms)
  • Multiplier: 1.5
  • Result: 30 minutes (1,800,000 ms)

Example 2: Meeting Recording​

  • Original: 2 hours (7,200,000 ms)
  • Multiplier: 2.0
  • Result: 1 hour (3,600,000 ms)

Example 3: Audio Interview​

  • Original: 25 minutes (1,500,000 ms)
  • Multiplier: 0.75 (slow down)
  • Result: 33.33 minutes (2,000,000 ms)

Integration with Other Nodes​

Works seamlessly with:

  • Create - Speed up segments after creation
  • Slice - Speed up portions of audio
  • Concatenate - Combine segments with different speeds
  • Get Metadata - Check duration before/after speed change
  • Export - Save speed-adjusted audio
  • Delete - Clean up after processing

Troubleshooting​

Audio sounds robotic​

  • Multiplier is too extreme
  • Try value closer to 1.0
  • Adjust chunk size

Poor quality output​

  • Decrease chunk size for better quality
  • Reduce multiplier extremity
  • Check original audio quality

Processing is slow​

  • Increase chunk size (150-300)
  • Large audio file (expected)
  • Consider batch processing overnight

No change in audio​

  • Multiplier is exactly 1.0 (by design)
  • Check multiplier value
  • Verify correct segment ID

Example Workflow: Podcast Speed Versions​

1. Create segment from podcast.mp3
2. Export original (normal speed)
3. Speedup with multiplier 1.25
4. Export as podcast_1.25x.mp3
5. Speedup original with multiplier 1.5
6. Export as podcast_1.5x.mp3
7. Speedup original with multiplier 2.0
8. Export as podcast_2x.mp3
9. Delete segments

Example Workflow: Fit to Time Slot​

1. Create segment from speech.wav
2. Get Metadata (duration = 65000 ms)
3. Target: 60000 ms (1 minute)
4. Calculate: multiplier = 65000 / 60000 = 1.083
5. Speedup with multiplier 1.083
6. Export perfectly timed audio

Platform-Specific Recommendations​

Podcasts​

  • Common speeds: 1.25x, 1.5x, 2.0x
  • Listeners often prefer 1.5x

Audiobooks​

  • Common speeds: 1.0x, 1.25x, 1.5x
  • Some listeners use 2.0x

Educational Content​

  • Slow down: 0.75x - 0.85x for complex topics
  • Speed up: 1.25x - 1.5x for review

Meetings/Recordings​

  • Speed up: 1.5x - 2.0x for faster review
  • Rarely slow down

Music (Use Cautiously)​

  • Minimal changes: 1.0x - 1.1x
  • Quality degrades with higher multipliers