AUTOCHOPPER - Glitch Magic

AUTOCHOPPER by Glitch Magic is a VST/AU sampler plugin designed specifically for creating novel rhythmic sequences from nearly any audio file. Import an audio file and AUTOCHOPPER detects transients to create playable slices mapped to MIDI notes that can be triggered manually or automated with a unique arpeggiator section.

To further extend the possibilities, it features a filter section with ADSR, Amp ADSR, a mappable dual LFO + dual envelope modulation section to alter slice playback, an effects chain that can be completely different on each individual slice, as well as several user requested features such as MIDI drag out and sample transposition.

Table of Contents

• Quick Start
• Loading Samples
• Interface Overview
• Controls Reference
  • Header: Presets, A/B, Undo
  • Waveform Display
  • Instrument Tab
    • Slicing
    • Amp Envelope
    • Filter & Filter Envelope
    • Arpeggiator: Slice Length Mode
    • Arpeggiator
    • LFO 1 & LFO 2
    • Envelope 1 & Envelope 2 (Modulators)
    • Modulation Routing (Map)
  • Effects Tab
    • Per-slice playback modifiers
    • Effect chain
    • Randomize, Copy/Paste, Lock, Reset
• Signal Flow

Quick Start

1. Load the plugin in your DAW.
2. Load a sample: drag an audio file onto the waveform. Alternatively, use the Browse or Paste File Path function to import a sample.
3. Adjust Sensitivity to control how many slices are detected (higher = more slices). It will automatically place slice markers at transients.
4. Play MIDI notes starting from the root note (default C3) to trigger slices; each successive note plays the next slice.
5. Shape slices with the Amp Envelope, Filter, and Filter Envelope
6. Hit Map in the LFO and Mod Envelopes areas on the Instrument tab. Mappable parameters that can be modulated will blink. Click on the one you want to affect.
7. Open the Effects tab to add per-slice effects, reverse, time-stretch, and randomization. Each Slice can have a completely different effects chain. Use the Random functions to assign effects across the entire set of slices.
8. Enable the Arpeggiator to trigger slices rhythmically. The notes and rhythms the Arpeggiator triggers are stored in a cache and can be dragged out of the plugin into your DAW as a MIDI clip if you want to replicate playback exactly.

Loading Samples

Certain DAWs treat loading a sample into a 3rd party plugin differently. There are 3 ways to load a sample into AUTOCHOPPER:

• Drag-and-drop — drop an audio file onto the waveform area (or anywhere on the editor). Supported formats include .wav, .aif, .aiff, .flac, .mp3, .ogg, .m4a, .aac, .wma, and .caf.

Some DAWs (e.g. Ableton Live, Logic Pro) use proprietary compression or non-destructive region data for library content and timeline clips. Dragging those directly into AUTOCHOPPER may fail even though the DAW’s native plugins can play them. Flatten or consolidate the clip to a standard WAV/AIFF in your DAW first (Ableton: Consolidate; Logic: Flatten or Bounce), then drag it in. - Browse — opens a file picker where you can select an audio file to import from the system. - Paste — loads the file path currently on the system clipboard. Copy a path from your file manager or DAW, then click Paste.

If your DAW does not pass file paths when dragging from the arrangement (such as in Reaper DAW), use Browse or Paste instead.

Interface Overview

The window is organised top-to-bottom:

1. Header — logo, plugin name, Undo/Redo, A/B compare, and the preset menu.
2. Waveform display — the loaded sample with slice markers and MIDI note labels.
3. Tab bar — switch between the INSTRUMENT and EFFECTS panels.
4. Control panel — the controls for the active tab.

Controls Reference

Header: Presets, A/B, Undo

Waveform Display

Shows the sample, slice markers (numbered, with the mapped MIDI note name), the currently playing slice (green), and the slice selected for FX editing (purple).

Auditioning slices: Selecting a slice (by click or arrow keys) plays it through the full per-slice signal path — current effects chain, filter, and envelopes — at velocity 100, independent of the arpeggiator. This makes it easy to dial in effects across many slices using only the mouse. Playback follows the current Mode (Slice/Through) setting; auto note-off is timed from the slice region (start to next marker), capped at 5 seconds. | ⌘ + scroll or pinch | Zoom toward the cursor (zoom range 1×–64×). Windows: Ctrl + scroll or pinch. | | Scroll (when zoomed in) | Pan left/right through the sample. | | Drop an audio file | Load it as the new sample. | | Browse / Paste / Clear buttons | Load via picker, load from clipboard path, or unload the current sample. |

Instrument Tab

Slicing

Amp Envelope

Per-voice amplitude ADSR, drawn live in the envelope display (which can also show the actual output waveform — see WAVEFORMS toggle).

Filter & Filter Envelope

A per-voice state-variable filter with its own dedicated ADSR. The display shows the filter response curve and the post-filter spectrum.

Arpeggiator

Repeatedly triggers slices while a note is held. When enabled it consumes incoming note-ons and generates its own slice triggers (CCs and pitch-bend pass through). Generated notes use a fixed velocity of 100.

Timing modes:

• Sync — steps at a fixed tempo-locked division (Div). Swing alternates long/short steps on the grid.
• Free — steps at a fixed rate in Hz (Rate), independent of DAW tempo. Swing alternates long/short intervals.
• Slice Len — steps when each slice finishes playing, based on its audio length. This can optionally be quantized. See the dedicated Slice Length Mode section for a full explanation of Time, Quantize, and how they interact.

The Pattern and Mode menus show/hide the relevant controls — e.g. Rate only appears in Free, Div only in Sync, and Time/Quantize only in Slice Len.

Arpeggiator: Slice Length Mode

Slice Length is AUTOCHOPPER’s most distinctive and unique arpeggiator timing mode that allows you to generate syncopated rhythms based on slice length that you can further vary using the built in modulation sources.

Instead of constantly triggering notes at a fixed tempo division or a free-running rate, this mode advances through slices based on how long each slice actually takes to play and optionally quantizes playback to the nearest beat subdivision.

This allows you to generate interesting sequences from nearly any source audio extremely quickly and is one of AUTOCHOPPERS most powerful features.

How it works

When the arpeggiator is enabled and Mode is set to Slice Len, holding a note triggers the first slice immediately. The plugin then waits for the current slice to finish playing before moving to the next slice in the chosen Pattern (Forward, Reverse, Ping-Pong, or Random).

The wait duration is calculated from the slice’s natural length — the audio between its start marker and the next marker (using Slice playback mode, not Through). That length is then scaled by the Time control:

Because timing comes from the sample itself, the rhythm emerges from the audio rather than being imposed on it.

Alternatively, if you want to impose rhythm onto the output, you can quantize it.

In both cases, you can use the modulation sources to vary this and create rhythms that change in a periodic way to generate musical variations.

Unlike Sync and Free modes, Slice Length sends a note-off before each new slice trigger, so slices do not overlap unless you lengthen them with Time.

Quantize

With Quantize off, each step fires as soon as its calculated duration elapses. Sample-driven timing with no relationship to the DAW tempo.

Turning Quantize on snaps each step’s duration to the nearest grid value set by Quantize Div (1/1 through 1/16T, same divisions as the Sync arpeggiator). The duration is rounded to the closest multiple of that grid, with a minimum of one grid cell. This locks the sample-derived rhythm to your project tempo so AUTOCHOPPER stays in time with the rest of the track.

Swing becomes available when Quantize is on. It alternates long and short steps on the grid — the same shuffle behaviour as in Sync mode.

When to use it

• Quantize off — experimental, free-form sequencing where the sample’s internal rhythm drives the output. Good for glitch, texture, and unpredictable results. This is also useful for generating textures derived from noise sources like vinyl surface noise. It can also be used to generate moving drones using less rhythmic sources like ambient texture, especially when paired with reverbs and other time effects.
  
• Quantize on — tempo-locked rhythmic sequences that still respect the character of the source material. Good for drum loops, breakbeats, and any material where you want the chop to feel native to the sample but sit in the mix.

LFO 1 & LFO 2

Two identical, independent low-frequency oscillators used as modulation sources (route them with Map, more information on Mapping is at the end of this section). Each has a live animated waveform graph.

Envelope 1 & Envelope 2

Two independent ADSR modulation envelopes (separate from the amp/filter envelopes). By default each fires once per MIDI note-on, but each can loop or be driven by the arpeggiator. Each has a live ADSR display.

Modulation Routing (Map)

Each LFO and modulation Envelope has a Map button:

1. Click Map on a source (LFO 1/2 or Env 1/2). The UI enters mapping mode and highlights the controls you can target. Mappable controls will blink.
2. Click a target control on the Instrument panel to create a modulation route from that source to that parameter.
3. Right-click a modulated control to unmap the route from it.

Routes are saved with the preset/state.

Effects Tab

The Effects tab edits the currently selected slice. Select a slice on the waveform with the mouse or with the ← / → arrow keys.

Per-slice playback modifiers

These are applied at the sample-read stage, before the filter and effect chain.

Effect chain

Seven effects in a drag-to-reorder chain. Each row has an enable button, a header (click to expand/collapse), and a drag handle (the grip dots on the left). Effects are per slice — each slice has its own independent settings and order. Each effect runs only when its enable button is on.

Default order: Chorus → Ring Mod → Granular Delay → Distortion → Pitch Shift → Stereo Width → Vinyl.

Chorus / Flanger — The mode dropdown switches between Chorus (longer base delay) and Flanger (shorter base delay; feedback only takes effect in Flanger mode).

Ring Mod — multiplies the signal by an oscillator.

Granular Delay — grain-based delay/scatter.

This is the only effect with an audible tail after the slice ends (up to ~3 s depending on feedback).

Distortion — waveshaping with a tone (low-pass) control.

In Crush (bitcrusher) mode, Drive reduces bit depth rather than adding pre-gain.

Pitch Shift — time-domain (dual-head) pitch shifter; not formant-preserving.

Stereo Width — Haas-based widener plus equal-power pan. Always fully wet when enabled (no mix control).

Vinyl / Tape — wow/flutter pitch wobble, noise, and a “tape age” low-pass. Always fully wet when enabled (no mix control).

Randomize, Copy/Paste, Lock, Reset

You can edit the effects on a single slice individually as well as apply effects across all slices using a variety of functions.

Signal Flow

Per voice, for each played slice:

Sample read (+ Reverse / Time-Stretch)
        ↓
   State-variable Filter (+ Filter Envelope)
        ↓
   Per-slice Effect Chain (in the slice's chosen order)
        ↓
   Amp ADSR × Velocity × Crossfade × Sample Volume
        ↓
        Output

LFO 1/2 and Envelope 1/2 are modulation sources that can be routed (via Map) to Instrument-panel parameters; they are not in the audio path themselves.