Initial commit

backend/services/pianoplayer_svc.py

@@ -0,0 +1,76 @@
+"""
+pianoplayer service: annotate MusicXML with fingering (Parncutt algorithm).
+
+Note: defusedxml.defuse_stdlib() is called in main.py before this module
+is imported, so xml.etree (used by music21 internally) is already patched.
+"""
+import asyncio
+import os
+import tempfile
+from pathlib import Path
+
+# Configurable via env var; default 120 s is generous for complex scores.
+_FINGERING_TIMEOUT = int(os.environ.get("FINGERING_TIMEOUT_S", "120"))
+
+
+async def annotate_fingering(musicxml: str) -> str:
+    """Add finger annotations to MusicXML using the pianoplayer library."""
+    try:
+        return await asyncio.wait_for(
+            asyncio.get_running_loop().run_in_executor(None, _annotate, musicxml),
+            timeout=_FINGERING_TIMEOUT,
+        )
+    except asyncio.TimeoutError:
+        raise RuntimeError(
+            "Fingering generation timed out. "
+            "Try a shorter score or increase FINGERING_TIMEOUT_S."
+        )
+
+
+def _annotate(musicxml: str) -> str:
+    from pianoplayer.hand import RightHand, LeftHand
+    import music21
+
+    xml_path = None
+    out_tmp_name = None
+    try:
+        with tempfile.NamedTemporaryFile(
+            suffix=".xml", delete=False, mode="w", encoding="utf-8"
+        ) as f:
+            f.write(musicxml)
+            xml_path = f.name
+
+        score = music21.converter.parse(xml_path)
+
+        # pianoplayer works on individual parts
+        for part in score.parts:
+            notes = list(part.flatten().notes)
+            if not notes:
+                continue
+
+            # Determine left / right hand by average register
+            avg_pitch = sum(
+                n.pitch.midi for n in notes if hasattr(n, "pitch")
+            ) / max(len(notes), 1)
+            hand_cls = RightHand if avg_pitch >= 60 else LeftHand
+
+            try:
+                hand = hand_cls(score, 0)
+                hand.autodepth = False
+                hand.verbose = False
+                hand.generate(part=part.id if hasattr(part, "id") else 0)
+            except Exception:
+                pass  # pianoplayer can fail on complex scores; skip gracefully
+
+        out_tmp = tempfile.NamedTemporaryFile(suffix=".xml", delete=False)
+        out_tmp.close()
+        out_tmp_name = out_tmp.name
+        score.write("musicxml", fp=out_tmp_name)
+
+        return Path(out_tmp_name).read_text(encoding="utf-8")
+
+    finally:
+        if xml_path:
+            Path(xml_path).unlink(missing_ok=True)
+        if out_tmp_name:
+            Path(out_tmp_name).unlink(missing_ok=True)