Piano Reader is a Windows desktop application written in C# .NET 9 that converts piano roll videos (such as those rendered by Synthesia or similar software) into playable and editable MIDI files.

It analyzes video frames to detect pressed keys on a virtual piano keyboard, reconstructs the musical notes, and allows you to preview, configure, and export them as MIDI.

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✨ Features

• 📹 Input from video: Load MP4 videos (e.g., Synthesia renders).
• 🎼 Automatic note recognition: Detects key presses and reconstructs MIDI.
• 🎚 Configurable detection parameters: Adjust keyboard size, black/white key colors, deviation thresholds, and more.
• ⏱ Tempo control: Set custom BPM (40–220).
• 🔀 Transpose: Shift notes up or down (0–64 semitones).
• ▶ Preview playback: Play the detected MIDI before saving.
• 💾 Save / Load presets: Store and reload your recognition settings.
• ⊞ Windows only: Built with C# .NET 9, designed for Windows environments.

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📥 Installation

1. Ensure you have Windows 10/11 with .NET 9 Runtime installed.
2. Download the latest release from the Releases page.
3. Extract the archive and run PianoReader.exe.

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🖥 Usage

1. Open Piano Reader.
2. Load a piano-roll MP4 video (e.g., Synthesia render).
3. Adjust detection parameters on the right-hand panel until keys are recognized correctly.
4. Set start/stop frames, tempo, and transpose if needed.
5. Click Convert to generate the MIDI.
6. Preview with Play.
7. Save the final MIDI file with Save.

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⚙️ Parameters Explained

• Keyboard Top: Vertical position of the keyboard area (0–1000 px).
• Key Number: Number of keys (8–88).
• Start Key: Left-most key (C–B).
• Black Key Height / Width: Adjust black key dimensions for detection (1–300 / 1–100).
• Keyboard Height: Vertical height of the entire keyboard (1–300).
• White / Black Key Color: Base colors of unpressed keys. Configure pressed state for left/right separately.
• Color Deviation: Tolerance for detecting a pressed key (10–100).
• Start / Stop Frame: Video frame range to process.
• BPM: Tempo for MIDI playback (40–220).
• Transpose: Shift notes up/down by semitones (0–64).

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🎵 Example Workflow

1. Load a Synthesia MP4 (60 fps recommended for high accuracy).
2. Adjust Keyboard Top and Key Number to align with the on-screen keyboard.
3. Configure Color Deviation until pressed keys are detected correctly.
4. Set Start Frame and Stop Frame to trim silence.
5. Click Convert, then Play to preview.
6. Save the MIDI file.

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🚀 Development

• Language: C#
• Framework: .NET 9 (Windows only)
• GUI: WinForms

Build from source

1. Clone the repository:

   git clone https://github.com/manh9011/PianoReader.git
   cd PianoReader

   Open in Visual Studio 2022 or newer.

2. Restore NuGet dependencies.

3. Build and run.

📜 License

• This project is licensed under the MIT License

🙌 Credits

• Developed by manh9011.
• Inspired by Synthesia-style piano roll visualizations.
• Video decoder by OpenCvSharp.
• Midi writer by DryWetMidi.