fix some bugs, add LRC synchronizer, text saver (if text not in LIBLRC, for upgrade library)

core/lrc.py

@@ -0,0 +1,195 @@
+"""LRC generation, parsing, embedding, and reading embedded lyrics.
+
+Reading embedded lyrics checks all tag locations for a given audio format:
+  - MP3       -> ID3 USLT / SYLT
+  - FLAC/OGG  -> LYRICS, UNSYNCEDLYRICS (Vorbis comments)
+  - M4A/MP4   -> `©lyr` atom
+"""
+from __future__ import annotations
+
+import re
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Optional
+
+
+_LRC_LINE_RE = re.compile(r"^\s*\[\d{1,3}:\d{2}(?:\.\d{1,3})?\]")
+_LRC_PARSE_RE = re.compile(r"\[(\d+):(\d+)\.(\d+)\](.*)$")
+
+
+@dataclass
+class LrcLine:
+    start: float
+    text: str
+
+
+def format_timestamp(seconds: float) -> str:
+    if seconds < 0:
+        seconds = 0.0
+    minutes = int(seconds // 60)
+    secs = seconds - minutes * 60
+    return f"[{minutes:02d}:{secs:05.2f}]"
+
+
+def segments_to_lrc(segments: list[dict]) -> str:
+    lines: list[str] = []
+    for seg in segments:
+        text = (seg.get("text") or "").strip()
+        if not text:
+            continue
+        start = float(seg.get("start", 0.0))
+        lines.append(f"{format_timestamp(start)}{text}")
+    return "\n".join(lines) + "\n"
+
+
+def parse_lrc(content: str) -> list[LrcLine]:
+    out: list[LrcLine] = []
+    for line in content.splitlines():
+        m = _LRC_PARSE_RE.match(line.strip())
+        if not m:
+            continue
+        mm, ss, frac, text = m.groups()
+        frac_sec = float(f"0.{frac}") if frac else 0.0
+        out.append(LrcLine(start=int(mm) * 60 + int(ss) + frac_sec, text=text.strip()))
+    return out
+
+
+def is_lrc(content: str) -> bool:
+    """True if content contains at least one LRC-style timestamp line."""
+    if not content:
+        return False
+    for line in content.splitlines():
+        if _LRC_LINE_RE.match(line):
+            return True
+    return False
+
+
+# ---------------------------------------------------------------- read embedded
+
+def read_embedded_lyrics(audio_path: Path) -> Optional[str]:
+    """Return lyrics stored in the file's tags, or None.
+
+    Order: prefer synced (LRC-like) -> plain. Never raises.
+    """
+    suffix = audio_path.suffix.lower()
+    try:
+        if suffix in (".mp3", ".mp2"):
+            return _read_mp3(audio_path)
+        if suffix in (".flac", ".ogg", ".opus"):
+            return _read_vorbis(audio_path)
+        if suffix in (".m4a", ".mp4", ".m4b", ".aac"):
+            return _read_mp4(audio_path)
+    except Exception:  # noqa: BLE001 — never break the pipeline on tag issues
+        return None
+    return None
+
+
+def _read_mp3(path: Path) -> Optional[str]:
+    from mutagen.id3 import ID3, ID3NoHeaderError
+    try:
+        tags = ID3(str(path))
+    except ID3NoHeaderError:
+        return None
+
+    # SYLT = synced lyrics (rare); USLT = unsynced (common, may contain LRC text)
+    sylt = tags.getall("SYLT")
+    for tag in sylt:
+        if tag.text:
+            try:
+                content = "\n".join(
+                    f"{format_timestamp(ms / 1000.0)}{txt}"
+                    for txt, ms in tag.text
+                )
+                if content.strip():
+                    return content
+            except Exception:  # noqa: BLE001
+                continue
+
+    uslt = tags.getall("USLT")
+    for tag in uslt:
+        if tag.text and str(tag.text).strip():
+            return str(tag.text)
+
+    return None
+
+
+def _read_vorbis(path: Path) -> Optional[str]:
+    suffix = path.suffix.lower()
+    if suffix == ".flac":
+        from mutagen.flac import FLAC as Audio
+    elif suffix == ".ogg":
+        from mutagen.oggvorbis import OggVorbis as Audio
+    else:
+        from mutagen.oggopus import OggOpus as Audio
+    audio = Audio(str(path))
+    for key in ("LYRICS", "UNSYNCEDLYRICS", "LYRIC", "SYNCEDLYRICS"):
+        if key in audio:
+            values = audio[key]
+            if isinstance(values, list) and values:
+                text = str(values[0])
+            else:
+                text = str(values)
+            if text.strip():
+                return text
+    return None
+
+
+def _read_mp4(path: Path) -> Optional[str]:
+    from mutagen.mp4 import MP4
+    audio = MP4(str(path))
+    for key in ("\xa9lyr", "©lyr"):
+        if key in audio:
+            values = audio[key]
+            if isinstance(values, list) and values:
+                text = str(values[0])
+            else:
+                text = str(values)
+            if text.strip():
+                return text
+    return None
+
+
+# ---------------------------------------------------------------- embedding
+
+def embed_lrc(audio_path: Path, lrc_content: str) -> None:
+    suffix = audio_path.suffix.lower()
+    if suffix in (".mp3", ".mp2"):
+        _embed_mp3(audio_path, lrc_content)
+    elif suffix in (".flac", ".ogg", ".opus"):
+        _embed_vorbis(audio_path, lrc_content)
+    elif suffix in (".m4a", ".mp4", ".m4b", ".aac"):
+        _embed_mp4(audio_path, lrc_content)
+    else:
+        raise ValueError(f"Unsupported format for LRC embedding: {suffix}")
+
+
+def _embed_mp3(path: Path, lrc_content: str) -> None:
+    from mutagen.id3 import ID3, USLT, ID3NoHeaderError
+    try:
+        tags = ID3(str(path))
+    except ID3NoHeaderError:
+        tags = ID3()
+    tags.delall("USLT")
+    tags.add(USLT(encoding=3, lang="rus", desc="", text=lrc_content))
+    tags.save(str(path), v2_version=3)
+
+
+def _embed_vorbis(path: Path, lrc_content: str) -> None:
+    suffix = path.suffix.lower()
+    if suffix == ".flac":
+        from mutagen.flac import FLAC as Audio
+    elif suffix == ".ogg":
+        from mutagen.oggvorbis import OggVorbis as Audio
+    else:
+        from mutagen.oggopus import OggOpus as Audio
+    audio = Audio(str(path))
+    audio["LYRICS"] = lrc_content
+    audio["UNSYNCEDLYRICS"] = lrc_content
+    audio.save()
+
+
+def _embed_mp4(path: Path, lrc_content: str) -> None:
+    from mutagen.mp4 import MP4
+    audio = MP4(str(path))
+    audio["\xa9lyr"] = [lrc_content]
+    audio.save()