I made a portable Windows audio converter — drag files in, get Opus/MP3/FLAC out, no install
I kept needing to batch-convert music and every tool I tried either wanted an
installer, bundled junk, or mangled the tags. So I built my own.
**What it does**
- Drag files or a folder onto the window, pick your output formats, hit Convert
- In: flac, mp3, m4a, aac, wav, ogg, opus, wma, aiff
- Out: Opus, MP3 and/or FLAC — all three in one pass if you want
- Tags and cover art carry over
- Converts in parallel, you set how many jobs
- Source files are never touched; output lands in opus\ / mp3\ / flac\ next to
the program
**Details I actually cared about**
- Opus encoding goes through an intermediate FLAC with ReplayGain/R128 tags
blanked, so opusenc doesn't silently attenuate your tracks to match old tags
- 16-bit FLAC output uses triangular dither instead of just truncating samples
- Lossy sources aren't padded out to 24-bit, which would bloat them 3-4x for
nothing
**Two ways to run it**
The download contains the program *and* its complete source, in the same folder:
- `AudioConverter.exe` — single file, double-click it
- `AudioConverter.bat` — runs the same program from `Converter.ps1`, the
plain-text PowerShell script sitting right next to it
Both open an identical window. The whole app is ~1650 lines of readable
PowerShell. You can open it in Notepad before you run anything.
**About the SmartScreen warning**
The exe isn't code-signed, and it unpacks its own components and launches
PowerShell — which is also what a malware dropper looks like, so SmartScreen and
some AV engines flag it. That's a reasonable reaction and I'm not going to ask
you to click through it on trust. What I can do is make the thing checkable:
- **Don't want to run an unsigned exe?** Then don't. Use `AudioConverter.bat` —
same program, and you can read every line of it first.
- **Want to know the exe isn't hiding anything?** Run it once, then hash what it
unpacked into `%LOCALAPPDATA%\AudioConverter\app` and compare against the
plain files in the download folder. They match — same script, same encoders,
so both launch paths are provably the same program. BUILD.txt has the exact
commands.
- **Want to build it yourself?** `Build-Exe.ps1` ships in the package and
compiles `Launcher.cs` (~100 lines) with the `csc.exe` that's already on
Windows. No SDK, no NuGet. It won't come out byte-identical — the in-box
compiler has no `/deterministic` switch — which is exactly why the check above
targets the payload instead of the exe's own hash.
- **The encoders aren't mine to vouch for.** FFmpeg and opusenc are unmodified
upstream builds; NOTICE.txt lists exact versions and SHA-256s so you can check
them against ffmpeg's and Xiph's own releases instead of against me.
No network access, no registry writes, no scheduled tasks, no installer. Delete
the folder and it's gone (plus `%LOCALAPPDATA%\AudioConverter` if you ran the
exe).
**Licenses**
Bundles FFmpeg (GPL v3) and opusenc from opus-tools (BSD), both unmodified. Full
license texts, exact versions and upstream source links ship in the package.
**Download:** https://filedn.eu/lwGY1UhAsUam9BITOnlFrzV/AudioConverterPortable.zip
Windows 10/11, nothing else to install, free.
This started as a personal tool, so the feature set is whatever I needed. Happy
to hear what's missing.