Gnmidi 2.54 ((better)) -

: Converts MIDI files to readable text and back for manual editing.

If you have a library of thousands of MIDI files, modifying them one by one is impossible. GNMIDI 2.54 features a robust batch processing engine. You can apply operations—like renaming files based on internal title tags, transposing keys, or changing instruments—to entire directories instantly. Step-by-Step Guide: Common Tasks in GNMIDI 2.54 How to Transpose a MIDI File gnmidi 2.54