How it is built
The worst failure mode of a converter is telling you it succeeded when it did not. So every output is read back with ffprobe — codec, duration, lossless verdict — ten milliseconds of insurance.
Probe before you transcode: if the duration or sample rate cannot be read, it does not transcode. Empty files, random bytes and text files renamed to .mp3 are refused, with the reason spelled out.
The source file is read-only: output always goes to a separate directory, with a counter added for name clashes. There is no overwrite-the-source option, and there never will be.
Failures leave no trace: output is written as .part first and renamed only on success. A failed run leaves nothing behind — no half-written file, no temporary file.
No pointless work: lossless to lossless is skipped with a stated reason. Converting FLAC to WAV only changes the container and doubles the size for nothing.
Honest about DRM: KGM, VPR, QMC and NCM are recognised and filed separately. The file is fine, it just has DRM — this tool does not unpack anything and does not call it broken.
A single 33 MB exe. FFmpeg is yours to install and the project does not ship it. Fully offline: nothing about your files ever leaves it.
