chord-analyzer

# Chord Analyzer Skill Analyze music audio files to extract chord progressions, key signature, tempo, and song structure. ## When to Use ✅ **USE this skill when:** - User wants to analyze a song's chords and harmony - "What are the chords in this song?" - "Analyze this audio file" - "Extract the chord progression" - "What key is this song in?" - User provides an audio file path and asks for musical analysis ## When NOT to Use ❌ **DON'T use this skill when:** - Only wants general music info (lyrics, artist) → use web search - Wants to generate music → use music generation skills - Needs professional-grade transcription → recommend specialized software (Chordify, Hookpad) - Requires detailed instrument separation → use dedicated source separation tools ## Supported Formats - **Audio**: mp3, wav, m4a, flac, ogg - **Duration**: Works best for songs under 5 minutes ## Installation First time use requires installing dependencies: ```bash pip3 install librosa numpy scipy scikit-learn soundfile ``` ## Usage ### Basic Analysis ```bash # Analyze an audio file python3 chord_analyzer.py # Edit the script to change the audio path # Default: /Users/chentiewen/Music/网易云音乐/example.mp3 ``` ### Script Integration Copy the `chord_analyzer.py` script to your workspace and modify the `audio_path` variable: ```python audio_path = "/path/to/your/song.mp3" result = analyze_audio(audio_path) ``` ## Output The analyzer provides: 1. **Key Signature**: Detected musical key (e.g., C, F#m, G) 2. **Tempo**: Speed in BPM with rhythm classification 3. **Chord Progression**: Complete chord sequence with timestamps 4. **Chord Statistics**: Most frequently used chords 5. **Song Structure**: Intro/Verse/Outro segmentation (basic) ### Sample Output ``` 调性: F#m 速度: 123.0 BPM 节奏: 快板 (Allegro) 和弦走向: F#mdim → A → D → Bm → E → A → D → Bm → E ... 主要和弦: A: 15次 (20.3%) E: 14次 (18.9%) D: 12次 (16.2%) ``` ## How It Works 1. **Load Audio**: Uses `librosa.load()` to read audio at 22.05kHz 2. **Extract Chroma**: Computes chroma features (pitch class profiles) using STFT 3. **Detect Key**: Analyzes chroma energy across all 12 keys (major + minor) 4. **Track Tempo**: Uses `librosa.beat.beat_track()` for tempo detection 5. **Analyze Chords**: Samples chroma at measure boundaries and matches against chord templates 6. **Merge & Simplify**: Combines consecutive identical chords ## Limitations - **Accuracy**: Chord detection is approximated; not professional-grade - **Complexity**: Struggles with heavily layered or distorted music - **Structure**: Simple segmentation (not verse/chorus detection) - **Melody**: Does not extract melodic lines or instrument parts - **Chord Extensions**: Detects basic triads (major, minor, diminished), not 7th/9th chords ## For Complete Transcription For professional music transcription, recommend: - **Chordify**: https://chordify.net (online chord detection) - **Hookpad**: https://www.hooktheory.com/hookpad (theory + chords) - **MuseScore**: https://musescore.org (manual transcription) - **Capo**: https://capoapp.com (slow down + chord detection) ## Notes - Analysis takes ~10-30 seconds depending on song length - Best results with clear, non-distorted audio - Works best for pop/rock/folk styles with clear harmony - Not suitable for atonal, experimental, or heavily percussive music