MIDIopsy 101: A Beginner’s Guide to MIDI Analysis and Repair

MIDIopsy Workflow: Diagnose and Fix Common MIDI Problems Fast

Overview

A fast, repeatable workflow for inspecting MIDI files, identifying common issues, and applying targeted fixes so files play reliably across DAWs and instruments.

1) Preparation

• Backup: Save a copy of the original MIDI file.
• Tools: Use a MIDI inspector/editor (e.g., MIDI-OX, Sekaiju, DAW MIDI editor, or specialized scripts).

2) Quick automated checks

• File integrity: Load file to confirm no load errors.
• Tempo/Time signature scan: Verify declared tempo and time signature events.
• Track count & naming: Note track/channel assignments and any empty tracks.
• Channel map: Ensure channels 10/percussion usage is intended.

3) Note data diagnostics

• Out-of-range notes: Detect notes outside instrument ranges.
• Overlapping duplicates: Find overlapping identical notes that may cause stuck notes.
• Zero-length notes: Identify notes with zero or near-zero duration.
• Velocity anomalies: Spot inconsistent velocity distributions (e.g., all same velocity).

4) Controller & CC issues

• CC spikes: Find sudden large CC jumps (e.g., CC1, CC7, CC64).
• Unmapped CCs: List CC numbers that target no device parameter.
• Sustain behavior: Check CC64 placement and paired note-offs.

5) Program/change and patching problems

• Program changes: Ensure correct bank/program events precede notes.
• Bank select pairing: Confirm MSB/LSB bank selects are present if needed.
• Patch mismatches: Map GM vs. synth-specific patches.

6) Timing & quantization

• Swing/groove artifacts: Detect tempo grid misalignments.
• Humanization extremes: Identify excessive timing variance.
• PPQ/resolution issues: Compare file PPQ to project; resample if necessary.

7) Fixes (ordered, non-destructive)

• Normalize velocities: Apply a sensible velocity curve or scaling.
• Merge/split tracks: Reassign channels and consolidate instrument parts.
• Remove duplicates & zero-length notes: Delete or merge offending notes.
• Insert proper note-offs: Fix stuck notes by adding note-off events or CC64 resets.
• Correct program/bank events: Insert bank/program changes at track start.
• Flatten timing (optional): Quantize lightly or manually adjust problematic notes.
• Clean CC envelopes: Smooth spikes, filter unused CCs.

8) Validation

• Playback test: Listen in target DAW and with intended instruments.
• Cross-DAW check: Load in a second host to ensure compatibility.
• Edge-case test: Test percussion mapping, controller responsiveness, and fastest tempos.

9) Documentation & delivery

• Change log: Record fixes applied (e.g., “removed 12 duplicate notes; normalized velocities +10%”).
• Export versions: Save one cleaned file and keep the original.
• Notes for recipient: Briefly list any remaining limitations or required synth mappings.

10) Automation & scripting

• Batch scripts: Create scripts for recurring fixes (e.g., remove CCs, normalize velocities).
• Preset checks: Store inspection presets per target synth/format.

Quick checklist (use during cleanup)

• Backup ✓
• Load & scan ✓
• Fix duplicates/zero-length ✓
• Normalize velocities ✓
• Insert program/bank changes ✓
• Test playback in DAW(s) ✓
• Save cleaned copy + changelog ✓

Use this workflow to quickly triage MIDI files and produce consistent, playable results across setups.