beat_analysis.py

import librosa
import numpy as np
import pronouncing
import re
from functools import lru_cache
import string
from nltk.corpus import cmudict
import nltk

try:
    nltk.data.find('corpora/cmudict')
except LookupError:
    nltk.download('cmudict')

class BeatAnalyzer:
    def __init__(self):
        # Mapping for standard stress patterns by time signature
        # Simplified to only include 4/4, 3/4, 2/4, and 6/8
        self.stress_patterns = {
            # Format: Strong (1.0), Medium (0.5), Weak (0.0)
            "4/4": [1.0, 0.0, 0.5, 0.0],  # Strong, weak, medium, weak
            "3/4": [1.0, 0.0, 0.0],       # Strong, weak, weak
            "2/4": [1.0, 0.0],            # Strong, weak
            "6/8": [1.0, 0.0, 0.0, 0.5, 0.0, 0.0]   # Strong, weak, weak, medium, weak, weak
        }
        
        self.cmudict = None
        try:
            self.cmudict = cmudict.dict()
        except:
            pass  # Fall back to rule-based counting if cmudict is not available
            
        # Genre-specific syllable-to-beat ratio guidelines
        self.genre_syllable_ratios = {
            # Genre: (min_ratio, typical_ratio, max_ratio)
            'pop': (0.7, 1.5, 3.0),        # Pop tends to have more syllables per beat
            'rock': (0.7, 1.2, 2.5),       # Rock can vary widely
            'hiphop': (1.5, 3.0, 5.0),     # Hip hop often has many syllables per beat
            'rap': (2.0, 4.0, 7.0),        # Rap often has very high syllable counts
            'folk': (0.8, 1.0, 1.5),       # Folk often has close to 1:1 ratio
            'country': (0.7, 1.2, 2.0),    # Country tends to be moderate
            'jazz': (0.5, 1.0, 3.0),       # Jazz can be very flexible
            'reggae': (0.6, 1.0, 1.5),     # Reggae often emphasizes specific beats
            'soul': (0.7, 1.2, 2.0),       # Soul music tends to be expressive
            'r&b': (0.8, 1.5, 2.5),        # R&B can have melisma
            'electronic': (0.5, 1.0, 2.0), # Electronic music varies widely
            'disco': (1.0, 1.5, 2.5),      # Disco tends to have more syllables
            'classical': (0.5, 1.0, 2.0),  # Classical can vary by subgenre
            'metal': (0.8, 1.5, 3.0),      # Metal often has more syllables on strong beats
            'blues': (0.5, 0.8, 1.5),      # Blues often extends syllables
            'default': (0.7, 1.5, 3.0)     # Default for unknown genres
        }
        
    @lru_cache(maxsize=128)
    def count_syllables(self, word):
        """Count syllables in a word using CMU dictionary if available, otherwise use rule-based method."""
        word = word.lower().strip()
        word = re.sub(r'[^a-z]', '', word)  # Remove non-alphabetic characters
        
        if not word:
            return 0
            
        # Try using CMUDict first if available
        if self.cmudict and word in self.cmudict:
            return max([len(list(y for y in x if y[-1].isdigit())) for x in self.cmudict[word]])
            
        # Rule-based syllable counting as fallback
        # Modified version from NLTK's implementation
        vowels = "aeiouy"
        double_vowels = ['aa', 'ae', 'ai', 'ao', 'au', 'ay', 'ea', 'ee', 'ei', 'eo', 'eu', 'ey', 'ia', 'ie', 'ii', 'io', 'iu', 'oa', 'oe', 'oi', 'oo', 'ou', 'oy', 'ua', 'ue', 'ui', 'uo', 'uy']
        prev_was_vowel = False
        count = 0
        final_e = False
        
        if word.endswith('e') and not word.endswith('le'):
            final_e = True
            
        for i, char in enumerate(word):
            if char in vowels:
                # Check if current char and previous char form a dipthong
                if prev_was_vowel and i > 0 and (word[i-1:i+1] in double_vowels):
                    prev_was_vowel = True
                    continue
                
                if not prev_was_vowel:
                    count += 1
                prev_was_vowel = True
            else:
                prev_was_vowel = False
                
        # Handle edge cases
        if word.endswith('le') and len(word) > 2 and word[-3] not in vowels:
            count += 1
        elif final_e:
            count = max(count-1, 1)  # Remove last 'e', but ensure at least 1 syllable
        elif word.endswith('y') and not prev_was_vowel:
            count += 1
            
        # Ensure at least one syllable
        return max(count, 1)
    
    def analyze_beat_pattern(self, audio_path, sr=22050, time_signature="4/4"):
        """Analyze beat patterns and stresses in music using the provided time signature."""
        # Load audio
        y, sr = librosa.load(audio_path, sr=sr)
        
        # Get tempo and beat frames
        tempo, beat_frames = librosa.beat.beat_track(y=y, sr=sr)
        beat_times = librosa.frames_to_time(beat_frames, sr=sr)
        
        # Get beat strengths using onset envelope
        onset_env = librosa.onset.onset_strength(y=y, sr=sr)
        beat_strengths = onset_env[beat_frames]
        
        # Normalize beat strengths
        if len(beat_strengths) > 0 and np.max(beat_strengths) > np.min(beat_strengths):
            beat_strengths = (beat_strengths - np.min(beat_strengths)) / (np.max(beat_strengths) - np.min(beat_strengths))
        
        # Parse time signature
        if '/' in time_signature:
            num, denom = map(int, time_signature.split('/'))
        else:
            num, denom = 4, 4  # Default to 4/4
        
        # Group beats into bars (each bar is one phrase based on time signature)
        bars = []
        current_bar = []
        
        for i, (time, strength) in enumerate(zip(beat_times, beat_strengths)):
            # Determine metrical position and stress
            metrical_position = i % num
            
            # Define stress pattern according to time signature
            if time_signature == "4/4":
                if metrical_position == 0:  # First beat (strongest)
                    stress = "S"  # Strong
                elif metrical_position == 2:  # Third beat (medium)
                    stress = "M"  # Medium
                else:  # Second and fourth beats (weak)
                    stress = "W"  # Weak
            elif time_signature == "3/4":
                if metrical_position == 0:  # First beat (strongest)
                    stress = "S"  # Strong
                else:  # Other beats (weak)
                    stress = "W"  # Weak
            elif time_signature == "6/8":
                if metrical_position == 0:  # First beat (strongest)
                    stress = "S"  # Strong
                elif metrical_position == 3:  # Fourth beat (medium)
                    stress = "M"  # Medium
                else:  # Other beats (weak)
                    stress = "W"  # Weak
            elif time_signature == "2/4":
                if metrical_position == 0:  # First beat (strongest)
                    stress = "S"  # Strong
                else:  # Second beat (weak)
                    stress = "W"  # Weak
            else:
                # Default pattern for other time signatures
                if metrical_position == 0:
                    stress = "S"
                else:
                    stress = "W"
            
            # Add beat to current bar
            current_bar.append({
                'time': time,
                'strength': strength,
                'stress': stress,
                'metrical_position': metrical_position
            })
            
            # When we complete a bar, add it to our bars list
            if metrical_position == num - 1 or i == len(beat_times) - 1:
                if current_bar:
                    bars.append(current_bar)
                    current_bar = []
                    
        # If there's any remaining beats, add them as a partial bar
        if current_bar:
            bars.append(current_bar)
        
        # Organize beats into phrases (one phrase = one bar)
        phrases = []
        
        for i, bar in enumerate(bars):
            phrase_beats = bar
            
            if not phrase_beats:
                continue
                
            # Calculate the phrase information
            phrase = {
                'id': i,
                'num_beats': len(phrase_beats),
                'beats': phrase_beats,
                'stress_pattern': ''.join(beat['stress'] for beat in phrase_beats),
                'start_time': phrase_beats[0]['time'],
                'end_time': phrase_beats[-1]['time'] + (phrase_beats[-1]['time'] - phrase_beats[-2]['time'] if len(phrase_beats) > 1 else 0.5),
            }
            
            phrases.append(phrase)
        
        return {
            'tempo': tempo,
            'time_signature': time_signature,
            'num_beats': len(beat_times),
            'beat_times': beat_times.tolist(),
            'beat_strengths': beat_strengths.tolist(),
            'phrases': phrases
        }
    
    def create_lyric_template(self, beat_analysis):
        """Create templates for lyrics based on beat phrases."""
        templates = []
        
        if not beat_analysis or 'phrases' not in beat_analysis:
            return templates
            
        phrases = beat_analysis['phrases']
        
        for i, phrase in enumerate(phrases):
            duration = phrase['end_time'] - phrase['start_time']
            
            template = {
                'id': phrase['id'],
                'start_time': phrase['start_time'],
                'end_time': phrase['end_time'],
                'duration': duration,
                'num_beats': phrase['num_beats'],
                'stress_pattern': phrase['stress_pattern'],
                'syllable_guide': self.generate_phrase_guide(phrase)
            }
            
            templates.append(template)
            
        return templates
    
    def generate_phrase_guide(self, template, words_per_beat=0.5):
        """Generate a guide for each phrase to help the LLM."""
        num_beats = template['num_beats']
        stress_pattern = template['stress_pattern']
        
        # Create a visual representation of the stress pattern
        # S = Strong stress, M = Medium stress, W = Weak stress
        visual_pattern = ""
        for i, stress in enumerate(stress_pattern):
            if stress == "S":
                visual_pattern += "STRONG "
            elif stress == "M":
                visual_pattern += "medium "
            else:
                visual_pattern += "weak "
        
        # Estimate number of words based on beats (very rough estimate)
        est_words = max(1, int(num_beats * words_per_beat))
        
        # Estimate syllables - more flexible now, allowing for reasonable ranges
        # Typical song might have 1-3 syllables per beat
        min_syllables = num_beats
        max_syllables = num_beats * 3
        
        guide = f"~{est_words} words, ~{min_syllables}-{max_syllables} syllables | Pattern: {visual_pattern}"
        return guide

    def check_syllable_stress_match(self, text, template, genre="pop"):
        """Check if lyrics match the syllable and stress pattern with genre-specific flexibility."""
        # Split text into words and count syllables
        words = text.split()
        syllable_count = sum(self.count_syllables(word) for word in words)
        
        # Get expected syllable count based on number of beats
        expected_count = template['num_beats']
        
        # Get syllable-to-beat ratios based on genre
        genre_lower = genre.lower()
        if genre_lower in self.genre_syllable_ratios:
            min_ratio, typical_ratio, max_ratio = self.genre_syllable_ratios[genre_lower]
        else:
            min_ratio, typical_ratio, max_ratio = self.genre_syllable_ratios['default']
        
        # Calculate flexible min and max syllable expectations based on genre
        min_expected = max(1, int(expected_count * min_ratio))
        max_expected = int(expected_count * max_ratio)
        
        # Check if syllable count falls within genre-appropriate range
        within_range = min_expected <= syllable_count <= max_expected
        
        # Consider typical ratio - how close are we to the ideal for this genre?
        ideal_count = int(expected_count * typical_ratio)
        closeness_to_ideal = 1.0 - min(abs(syllable_count - ideal_count) / (max_expected - min_expected + 1), 1.0)
        
        # Get detailed syllable breakdown for stress analysis
        word_syllables = []
        for word in words:
            count = self.count_syllables(word)
            word_syllables.append(count)
        
        # Analyze stress pattern match using a more flexible approach
        stress_pattern = template['stress_pattern']
        
        # Simple stress matching algorithm (can be improved in future versions)
        # We need to map syllables to beats in a more flexible way
        syllable_to_beat_mapping = self._map_syllables_to_beats(word_syllables, stress_pattern)
        
        # Calculate stress match score based on alignment of stressed syllables with strong beats
        stress_match_percentage = self._calculate_stress_match(words, word_syllables, syllable_to_beat_mapping, stress_pattern)
        
        # Consider a stress match if the percentage is high enough
        stress_matches = stress_match_percentage >= 0.7
        
        return {
            'syllable_count': syllable_count,
            'expected_count': expected_count,
            'min_expected': min_expected,
            'max_expected': max_expected,
            'within_range': within_range,
            'matches_beat_count': syllable_count == expected_count,  # Exact match (strict)
            'close_match': within_range,  # Flexible match (based on genre)
            'stress_matches': stress_matches,
            'stress_match_percentage': stress_match_percentage,
            'closeness_to_ideal': closeness_to_ideal,
            'word_syllables': word_syllables,
            'ideal_syllable_count': ideal_count
        }
    
    def _map_syllables_to_beats(self, word_syllables, stress_pattern):
        """Map syllables to beats in a flexible way."""
        total_syllables = sum(word_syllables)
        total_beats = len(stress_pattern)
        
        # Simple mapping for now - this could be improved with more sophisticated algorithms
        if total_syllables <= total_beats:
            # Fewer syllables than beats - some beats have no syllables (prolongation)
            mapping = []
            syllable_index = 0
            for beat_index in range(total_beats):
                if syllable_index < total_syllables:
                    mapping.append((syllable_index, beat_index))
                    syllable_index += 1
            return mapping
        else:
            # More syllables than beats - some beats have multiple syllables (melisma/syncopation)
            mapping = []
            syllables_per_beat = total_syllables / total_beats
            for beat_index in range(total_beats):
                start_syllable = int(beat_index * syllables_per_beat)
                end_syllable = int((beat_index + 1) * syllables_per_beat)
                for syllable_index in range(start_syllable, end_syllable):
                    if syllable_index < total_syllables:
                        mapping.append((syllable_index, beat_index))
            return mapping
    
    def _calculate_stress_match(self, words, word_syllables, syllable_to_beat_mapping, stress_pattern):
        """Calculate how well syllable stresses match beat stresses."""
        # This is a simplified version - real stress analysis would be more complex
        # For now, we'll assume the first syllable of each word is stressed
        
        # First, create a flat list of all syllables with their stress (1 = stressed, 0 = unstressed)
        syllable_stresses = []
        for word, syllable_count in zip(words, word_syllables):
            # Simple assumption: first syllable is stressed, rest are unstressed
            for i in range(syllable_count):
                if i == 0:  # First syllable of word
                    syllable_stresses.append(1)  # Stressed
                else:
                    syllable_stresses.append(0)  # Unstressed
        
        # Count matches between syllable stress and beat stress
        matches = 0
        total_mapped = 0
        
        for syllable_index, beat_index in syllable_to_beat_mapping:
            if syllable_index < len(syllable_stresses):
                syllable_stress = syllable_stresses[syllable_index]
                beat_stress = 1 if stress_pattern[beat_index] == 'S' else (0.5 if stress_pattern[beat_index] == 'M' else 0)
                
                # Consider it a match if:
                # - Stressed syllable on Strong beat
                # - Unstressed syllable on Weak beat
                # - Some partial credit for other combinations
                if (syllable_stress == 1 and beat_stress > 0.5) or (syllable_stress == 0 and beat_stress < 0.5):
                    matches += 1
                elif syllable_stress == 1 and beat_stress == 0.5:  # Stressed syllable on Medium beat
                    matches += 0.7
                
                total_mapped += 1
        
        if total_mapped == 0:
            return 0
            
        return matches / total_mapped