Audio Concatenator

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First Run

Because the app is not signed with a platform certificate, each operating system will warn you before it runs for the first time. This is expected — the steps below take about 30 seconds and only need to be done once per downloaded copy.

chmod +x concat-linux-amd64.AppImage
./concat-linux-amd64.AppImage

Interface Overview

After opening the app, click Load Folder… to get started. The app accepts WAV, MP3, FLAC, AIFF, OGG, M4A, and MP4 files; everything is converted to WAV on output. No audio files need to be converted beforehand.

Simple Sort Mode

The Simple (GUI) radio button activates the standard sort controls. Choose a sort field and direction, then click Apply Sort.

Sorting only reorders what is already in the list. You can apply multiple sorts sequentially, or mix sorting with manual drag-and-drop.

Suffix Order (for Dekereke databases)

The Suffix Order panel lets you define a custom ordering for files that share a base name but differ by a suffix. This is designed for Dekereke databases, where a stimulus entry like 0001 produces files such as 0001-ynq-irt.wav, 0001-ans-irt.wav, etc.

How to use it:

1. Type each suffix substring (or regex pattern) into the input field and click Add, or press Enter. Add one entry per suffix variant.
2. Drag the entries to set their priority order — the file whose name contains the first matching entry in the list will sort first within its base group.
3. Click Apply Suffix Order.

Example — for files numbered 0001–0006, each with seven suffix variants:

Suffix list (in desired order):
  ynq-irt
  whq-irt
  ans-irt
  emphq-irt
  emph-ans-irt
  cntr-foc-irt
  cntr-top-irt

After clicking Apply Suffix Order, the file list becomes:

0001-ynq-irt.wav
0001-whq-irt.wav
0001-ans-irt.wav
0001-emphq-irt.wav
0001-emph-ans-irt.wav
0001-cntr-foc-irt.wav
0001-cntr-top-irt.wav
0002-ynq-irt.wav
0002-whq-irt.wav
…

Entries can be plain substrings or full Python regex patterns. If you type an invalid regex, the app auto-escapes it and treats it as a literal string.

Advanced Sort Mode (Regex)

Switch to Advanced (Regex) to sort by text extracted directly from filenames using regular expressions. This mode replaces the Simple sort entirely — use it when the GUI sort fields are not flexible enough for your naming convention.

What is a regex?

A regular expression (regex) is a pattern that describes text. The most useful concept here is the capture group: any text wrapped in ( ) parentheses is “captured” and used as the sort key.

Pattern:    ^(\d+)
Filename:   0042-ans-irt.wav
Captured:   0042   ← this value is used to sort the file

The layer system

Each row in the Advanced sort panel is a sort layer. Layers work like columns in a spreadsheet sort:

• Layer 1 (top) is the primary sort key — it has the highest priority.
• Layer 2 breaks ties within groups that are equal under Layer 1.
• Layer 3 breaks ties within groups equal under both Layer 1 and Layer 2, and so on.

Use ▲ / ▼ to reorder layers. Click + Add Layer to add a new one. The minimum is one layer.

The two-layer example above replicates the Suffix Order result: Layer 1 groups files by their leading number; Layer 2 sub-sorts them by suffix.

Controls per layer

Sort-as modes

Unmatched files

If a file’s name does not match a layer’s pattern, that file is sorted after all files that did match — but it still keeps its position relative to other unmatched files, and is still sorted correctly by any higher-priority layer it did match.

Regex Quick Reference

These are the building blocks you’ll use most often. Every example below is a complete pattern ready to paste into the Pattern field.

Regex syntax cheat sheet

Worked Example — Dekereke Database

Suppose your folder contains files named:

0001-ans-irt.wav      0002-ans-irt.wav      0003-ans-irt.wav
0001-ynq-irt.wav      0002-ynq-irt.wav      0003-ynq-irt.wav
0001-cntr-foc-irt.wav 0002-cntr-foc-irt.wav 0003-cntr-foc-irt.wav

You want the output order: all variants of 0001 first (ynq, ans, cntr-foc), then all of 0002, then 0003.

Option A — Suffix Order panel (Simple mode, recommended)

1. Open Simple (GUI) mode.
2. In the Suffix Order box, add entries in this order:

   ynq-irt
   ans-irt
   cntr-foc-irt

3. Click Apply Suffix Order.

Option B — Advanced (Regex) mode

1. Open Advanced (Regex) mode.
2. Set up two layers:
   Layer 1 ^(\d+) Numeric · Ascending — groups by base number

   Layer 2 -(\w+-irt)\. Alphabetical · Ascending — sub-sorts suffix

   Note: Alphabetical gives ans → cntr-foc → ynq. For a custom suffix order use Option A.

3. Click Apply Regex Sort.

Bit Depth

All input files are normalised to 44 100 Hz mono at the chosen bit depth before being joined. The click marker between each file is a 5 ms 2 kHz sine burst with 500 ms of silence on each side.

FAQ

What audio formats are supported as input?

WAV, MP3, FLAC, AIFF/AIF, OGG, M4A, MP4 — any format that ffmpeg can decode. The output is always WAV. The bundled ffmpeg binary handles all formats without any additional installation.

Do I need to install ffmpeg or Python?

No. The portable app bundles everything it needs — Python, ffmpeg, ffprobe, and all libraries — in a single download. Nothing else needs to be installed.

Can I manually reorder files after applying a sort?

Yes. Sort operations only rearrange the list — you can drag items freely before or after applying any sort. The list order at the moment you click Join Files is what gets used.

What if a file doesn’t match any suffix pattern?

In Suffix Order mode, unmatched files sort after all matched files within their base group, using natural filename order. In Advanced Regex mode, unmatched files sort after matched files for that layer.

My regex is marked ✓ but the sort looks wrong. Why?

The ✓ only confirms the pattern is syntactically valid, not that it matches your filenames. Check that your capture group ( ) is in the right place and that the Grp number matches the group you intend. Test patterns at regex101.com — choose “Python” flavour.

The join is slow for large folders. Is that normal?

Decoding, resampling, and writing audio is CPU-bound and scales with total audio duration. The join runs in the background so the UI stays responsive. A folder of 50 short WAV clips should finish in a few seconds; long MP3s decoded through ffmpeg take longer.

How do I save my sort settings to reuse them?

Click Save Settings… in the sort mode row to write a YAML file. Click Load Settings… to restore them in any future session. The YAML file is plain text and can be edited by hand or shared with colleagues; every field includes an inline comment listing the allowed values.

Is the macOS build Intel-compatible?

The current release is built for Apple Silicon (arm64) only. It will not run on older Intel Macs. Intel Mac support may be added in a future release. In the meantime, Intel Mac users can run the app from source — see the repository README.