Editing Techniques

Lorenz Schwarz
Karlsruhe University of Arts and Design (HfG)
Winter Semester 2025/26
Course info

Slides marked include a live REAPER demonstration.

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Editing Techniques

Basic editing

Editing Techniques

Editing techniques

Core operations for processing and assembling audio material in a DAW.

  • Basic editing: cut, trim, split, and positioning operations
  • Transitions: fades, crossfades, and envelope control
  • Temporal manipulation: repetition, time-stretching, and pitch-shifting
  • Arrangement: layering and temporal structure
Editing Techniques

Cut, trim, and split

Basic editing operations remove, shorten, or divide material.

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Trimming in REAPER

Move the pointer to the left or right edge of a media item and drag to adjust its start or end.

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Editing Techniques

Auto trim and split

Auto trim/split detects passages below a threshold and divides the recording into separate items.

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Editing Techniques

Slip, slide, and ripple editing

Slip changes the source content inside an item; slide moves the complete item; ripple editing also moves later material.

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Editing Techniques
  • seek: jump to another playback position
  • scrub: move through the material while hearing the changing position
  • jog: move forward or backward in controlled increments

For locating transients, speech boundaries, and precise edit points.

Editing Techniques

Edit points and transitions

Related: Fundamentals of Sound · Wave Properties

Editing Techniques

Fades and crossfades

A fade changes the level at the beginning or end of a media item. A crossfade creates a transition between two overlapping items.

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Editing Techniques

Zero crossings

A zero crossing is an instant at which a waveform passes through zero amplitude while changing polarity.

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Editing Techniques

Edit boundaries

A split is inaudible while adjacent items remain unchanged. Clicks can occur when an edit creates an abrupt jump in the waveform.

  • check boundaries after rearranging items
  • zero-crossing alignment can help with exposed hard cuts
  • use a short fade or crossfade where needed

Abrupt edit compared with an edit aligned to nearby zero crossings

Editing Techniques

Signal combination in a crossfade

During a crossfade, the fade-out and fade-in occupy an overlapping time interval.

The two signals are summed sample by sample throughout the overlap. Its duration and curves determine the resulting transition.

Overlapping fade-out and fade-in signals and their combined result

Editing Techniques

Fade curves

The curve controls how quickly the level changes; terminology varies between DAWs.

  • equal gain: keeps the summed amplitudes constant
  • equal power: keeps the combined signal power approximately constant
  • linear: may refer to amplitude, gain, or decibels

Equal gain often suits correlated material; equal power often suits different sounds. Adjust by ear.

Comparison of fade and crossfade curves

Editing Techniques

Fades in REAPER

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Editing Techniques

Crossfades in REAPER


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Editing Techniques

Automation

Editing Techniques

Automation

Automation controls parameters over time for creative and technical purposes.

  • volume automation: changes gain across the timeline
  • pan automation: changes the relative level sent to output channels
  • effect parameter automation: changes processing parameters over time
Original waveform, volume-automation curve, and resulting waveform
Editing Techniques

Automation curves in REAPER


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Editing Techniques

Automation modes

  • read: plays existing automation without writing
  • write: continuously replaces automation during playback
  • touch: writes while a control is touched, then returns to the existing curve
  • latch: continues writing the last value after the control is released
  • trim/read: adjusts the result while preserving the underlying automation
Editing Techniques

Time-based editing

Editing Techniques

Coupled and independent time and pitch

Conventional tape playback couples speed, duration, and pitch.

  • at ⅔ playback rate, duration increases by 1.5 and pitch falls by a perfect fifth
  • digital processing provides separate time-stretching and pitch-shifting
  • in REAPER, Preserve pitch when changing rate determines whether a rate change also changes pitch
Editing Techniques

Time and pitch processing

  • playback-rate change or varispeed: changes pitch and duration together
  • time-stretching: changes duration while aiming to preserve pitch
  • pitch-shifting: changes pitch while aiming to preserve duration

Results depend on the algorithm, source material, and amount of transformation. Some modes provide formant control.

Comparison of time and pitch processing

Comparison of original, time-stretched, pitch-shifted, and playback-rate processed signals

Editing Techniques

Global, local, and automatic editing

  • global: changes the duration of the complete item
  • local: stretch or warp markers reposition selected moments within an item
  • automatic alignment: compares related recordings with a reference and adjusts timing—and sometimes pitch
  • automated results require checking for alignment and time-stretch artifacts

Example: Waves Sync Vx

Editing Techniques

Looping

Looping repeats a selected segment continuously.

  • similar levels and waveform phases help create a smooth boundary
  • a short crossfade can conceal clicks or discontinuities
  • loop length influences whether repetition is heard as texture, rhythm, or larger form
Editing Techniques

Reverse playback

Reverse playback changes temporal order: attacks become decays, and phrasing unfolds backward.

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Editing Techniques

Granular processing

Granular processing divides sound into short fragments called grains.

  • grains can overlap, repeat, reorder, or move through the source
  • grain duration and density shape rhythm and texture
  • time and pitch can be manipulated with some independence
  • dense grains may fuse into a continuous sound; sparse grains expose individual events
Editing Techniques

Granular processing

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Editing Techniques

Arrangement and layering

Layering on the timeline

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Layering combines sounds that overlap in time.
Editing Techniques

Arranging the montage

Arrangement organizes material across time.

  • order and group material into sections
  • use duration, silence, repetition, and contrast
  • vary density and energy over time
  • listen at the level of edits, phrases, sections, and complete form
Editing Techniques

Practical exercises

Editing Techniques

Editing study

Treat one short recording made with available equipment as the complete source for a 15–30-second study. Develop a coherent form using the editing methods introduced in this chapter, while keeping the original recording available for comparison.

Present the study and explain which intervention most strongly changed how the source is perceived.

Editing Techniques

Selected references

  • Roads, Curtis. Microsound. MIT Press, 2001.

Related: Fundamentals of Sound · Wave Properties · Spectral Analysis

© 2026 Lorenz Schwarz

Original text, diagrams, illustrations, photographs, audio, and video are licensed under CC BY 4.0, except where otherwise noted.

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