File size: 4,351 Bytes
72f552e | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 | """Lyrics-to-beat mapping: group beats into segments and assign lyrics."""
import json
from pathlib import Path
from typing import Optional
def segment_lyrics(
beats: list[dict],
lyrics: list[dict],
beats_per_segment: int = 4,
) -> list[dict]:
"""Map timestamped lyrics onto beat-grouped segments.
Groups consecutive beats into segments (e.g. 4 beats = 1 bar in 4/4 time)
and assigns words to the segment where they start.
Args:
beats: List of beat dicts with "beat" and "time" keys.
lyrics: List of word dicts with "word", "start", "end" keys.
beats_per_segment: Number of beats per segment. 4 = one bar in 4/4 time.
Returns:
List of segment dicts with keys:
- segment: 1-indexed segment number
- start: start time in seconds
- end: end time in seconds
- duration: segment duration in seconds
- lyrics: raw lyrics text for this segment (may be empty)
- words: list of word dicts that fall in this segment
"""
beat_times = [b["time"] for b in beats]
# Build segment boundaries by grouping every N beats
segments = []
seg_num = 1
for i in range(0, len(beat_times) - 1, beats_per_segment):
start = beat_times[i]
# End is either N beats later or the last beat
end_idx = min(i + beats_per_segment, len(beat_times) - 1)
end = beat_times[end_idx]
# Store individual beat timestamps for this segment
seg_beat_times = [
round(beat_times[j], 3)
for j in range(i, min(i + beats_per_segment + 1, len(beat_times)))
]
segments.append({
"segment": seg_num,
"start": round(start, 3),
"end": round(end, 3),
"duration": round(end - start, 3),
"beats": seg_beat_times,
"lyrics": "",
"words": [],
})
seg_num += 1
# Assign words to segments based on where the word starts
for word in lyrics:
word_start = word["start"]
for seg in segments:
if seg["start"] <= word_start < seg["end"]:
seg["words"].append(word)
break
else:
# Word starts after last segment boundary — assign to last segment
if segments and word_start >= segments[-1]["start"]:
segments[-1]["words"].append(word)
# Build lyrics text per segment
for seg in segments:
seg["lyrics"] = " ".join(w["word"] for w in seg["words"])
return segments
def save_segments(
segments: list[dict],
output_path: str | Path,
) -> Path:
"""Save segments to a JSON file.
Args:
segments: List of segment dicts.
output_path: Path to save the JSON file.
Returns:
Path to the saved JSON file.
"""
output_path = Path(output_path)
output_path.parent.mkdir(parents=True, exist_ok=True)
with open(output_path, "w") as f:
json.dump(segments, f, indent=2)
return output_path
def run(
data_dir: str | Path,
beats_per_segment: int = 4,
) -> list[dict]:
"""Full segmentation pipeline: load beats + lyrics, segment, and save.
Args:
data_dir: Song data directory containing beats.json and lyrics.json
(e.g. data/Gone/).
beats_per_segment: Number of beats per segment (4 = one bar).
Returns:
List of segment dicts.
"""
data_dir = Path(data_dir)
with open(data_dir / "beats.json") as f:
beats = json.load(f)
with open(data_dir / "lyrics.json") as f:
lyrics = json.load(f)
segments = segment_lyrics(beats, lyrics, beats_per_segment=beats_per_segment)
save_segments(segments, data_dir / "segments.json")
return segments
if __name__ == "__main__":
import sys
if len(sys.argv) < 2:
print("Usage: python -m src.segmenter <data_dir>")
print(" e.g. python -m src.segmenter data/Gone")
sys.exit(1)
segments = run(sys.argv[1])
print(f"Created {len(segments)} segments:\n")
for seg in segments:
lyrics_display = f'"{seg["lyrics"]}"' if seg["lyrics"] else "(instrumental)"
print(f" Seg {seg['segment']}: {seg['start']:.3f}s - {seg['end']:.3f}s "
f"({seg['duration']:.3f}s) {lyrics_display}")
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