Free online OPUS to NBS converter

What the OPUS format is

OPUS is a lossy audio codec designed for speech, music, and real-time communication. Voice recorders, messaging applications, browsers, Discord, and other communication software commonly create .opus files, often inside an Ogg container.

OPUS stores an encoded waveform, not separate notes, instruments, tempo events, or MIDI-style timing data. A decoder can recover playable audio, but it cannot reliably identify every note, instrument, chord, or rhythmic event from the recording.

What the NBS format is

NBS generally means the Note Block Studio song format used for Minecraft note-block arrangements. An .nbs file records note pitches, timing, instrument assignments, layers, tempo, and song metadata so a compatible editor or Minecraft tool can reproduce the arrangement.

NBS is useful for editing note-block songs, changing instruments, adjusting timing, and importing arrangements into Minecraft-related tools. It is not a general-purpose audio container and cannot hold the original OPUS waveform as playable audio.

How to convert OPUS to NBS

There is no dependable one-click OPUS-to-NBS conversion because the source contains audio and the destination requires structured musical notes. Use an audio-to-MIDI step followed by an NBS import:

1. Decode the OPUS file to an uncompressed WAV file with FFmpeg:
   ffmpeg -i input.opus -ar 44100 -ac 2 intermediate.wav
2. Run an audio-to-MIDI transcription tool such as Spotify Basic Pitch against the WAV file. A typical command is:
   basic-pitch midi-output intermediate.wav
   This produces a MIDI file when the installation and input are supported.
3. Open the MIDI file in Open Note Block Studio using File → Import → MIDI or the equivalent MIDI-import command in your installed version.
4. Check the imported tempo, pitch range, instrument mapping, note lengths, and layer count. NBS instruments do not correspond exactly to every MIDI instrument.
5. Save the edited arrangement as song.nbs with File → Save As.

You can also try the free converter on 101convert.com, but an automatic service cannot infer a perfect note-block arrangement from arbitrary audio. If the service does not offer OPUS-to-NBS as a supported conversion, use the WAV, MIDI, and NBS workflow instead; renaming .opus to .nbs will not convert the data.

Quality and compatibility limitations

Audio-to-MIDI transcription works best with clean, monophonic recordings containing one clearly audible melody. Full mixes, vocals with effects, drums, reverb, overlapping chords, and background noise can produce missing notes, false notes, and incorrect timing.

Converting OPUS to WAV does not restore information removed by OPUS compression; it only creates a format that transcription software can process. The later MIDI-to-NBS step may also alter octave limits, note durations, tempo, polyphony, and instrument sounds. Review the result in Note Block Studio and correct it manually before using it in Minecraft.

If the goal is only to play or archive the recording, keep the original .opus file or convert it to WAV, FLAC, or another audio format. NBS is appropriate only when the desired result is an editable note-block sequence.