NukedOPL3Sharp

A C# port of nukeykt’s Nuked-OPL3 FM synth core, plus a small MIDI player application that demonstrates how to drive the chip from a Standard MIDI (.mid) file.

The output hash from Nuked-OPL3 was generated for several scenarios and embedded in tests to guarantee parity - it is bit by bit identical.

Projects

• NukedOPL3Sharp (chip/core library)
  • Implements the OPL3 chip as a register-driven synthesizer.
  • Main entry point: NukedOPL3Sharp.Opl3Chip (Reset, WriteRegister, GenerateStream, etc.).
• NukedOPL3Sharp.MidiPlayer (demo application)
  • Loads .mid / .midi files.
  • Loads instrument banks in .op2 and .wopl formats (user-selected; not bundled/autoloaded).
  • Renders audio by translating MIDI events into OPL3 register writes and then pulling PCM from Opl3Chip.
• NukedOPL3Sharp.Benchmarks (BenchmarkDotNet suite)
  • Separately measures dormant, 2-op, 4-op, rhythm, and dynamic buffered/resampled paths in nanoseconds per frame.

Benchmarks

Build before measuring so BenchmarkDotNet uses current Release binaries:

dotnet build NukedOPL3Sharp.Benchmarks\NukedOPL3Sharp.Benchmarks.csproj -c Release
dotnet run --project NukedOPL3Sharp.Benchmarks\NukedOPL3Sharp.Benchmarks.csproj -c Release --no-build -- --filter '*' --artifacts BenchmarkDotNet.Artifacts\current

How the MIDI demo wires up the chip

At a high level, the data flow is:

1. MidiFile parses the .mid file into events.
2. MidiSequence schedules events over time (ticks → samples) at a fixed sample rate.
3. OplMidiSynth receives MIDI events (note on/off, CC, program change, pitch bend), looks up patches from the loaded .op2/.wopl bank, and writes the corresponding OPL register values into an Opl3Chip.
4. MidiPlaybackEngine.Render(...) asks the chip for audio via Opl3Chip.GenerateStream(...) into an interleaved stereo buffer, then applies master gain and a light DC high-pass filter.
5. PlaybackService streams the generated audio to the sound device via OpenAL.

This is intentionally structured so the demo shows the minimum “glue” required to:

• convert MIDI timing to sample timing,
• map MIDI programs/drums to OPL patches,
• and drive Opl3Chip purely through register writes.

License

• NukedOPL3Sharp (chip/core library): GNU LGPL v2.1 — see LICENSE.
• NukedOPL3Sharp.MidiPlayer (application code): BSD 3-Clause — see NukedOPL3Sharp.MidiPlayer/LICENSE.txt.

Note: NukedOPL3Sharp.MidiPlayer depends on the LGPL-licensed NukedOPL3Sharp library, so redistributions must comply with both.

Third-party notices

See THIRD_PARTY_NOTICES.md.