Add a soprano recorder tab converter as a Linux AppImage.

The app turns a lead line into Baroque fingering tabs with rhythm kept, ships Twinkle and Ode to Joy, and reads photos locally with oemer when the bundled Python is present.

Co-authored-by: catpersonisme <catpersonisme@gmail.com>

scripts/build-appimage.sh

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+#!/usr/bin/env bash
+# One-command AppImage build. Needs network the first time (Python, models, Electron).
+set -euo pipefail
+cd "$(dirname "$0")/.."
+ROOT="$(pwd)"
+
+echo "== Install Node packages =="
+npm install
+
+PY="$ROOT/build/python/bin/python3"
+if ! "$PY" -c "import oemer.ete, onnxruntime" >/dev/null 2>&1; then
+  echo "== Download a relocatable Python and oemer =="
+  mkdir -p "$ROOT/build/cache"
+  TARBALL="$ROOT/build/cache/cpython.tar.gz"
+  URL="https://github.com/astral-sh/python-build-standalone/releases/download/20261003/cpython-3.12.15%2B20261003-x86_64-unknown-linux-gnu-install_only.tar.gz"
+  if [[ ! -f "$TARBALL" ]]; then
+    curl -fL --retry 3 -o "$TARBALL" "$URL"
+  fi
+  rm -rf "$ROOT/build/python"
+  tar -xzf "$TARBALL" -C "$ROOT/build"
+  "$PY" -m pip install --upgrade pip
+  "$PY" -m pip install \
+    "opencv-python-headless>=4.10,<5" \
+    "onnxruntime>=1.20" \
+    numpy scipy scikit-learn pillow matplotlib typing_extensions
+  "$PY" -m pip install --no-deps oemer
+fi
+
+SITE="$("$PY" -c "import oemer, pathlib; print(pathlib.Path(oemer.__file__).parent)")"
+mkdir -p "$SITE/checkpoints/unet_big" "$SITE/checkpoints/seg_net"
+if [[ ! -f "$SITE/checkpoints/unet_big/model.onnx" ]]; then
+  curl -fL --retry 3 -o "$SITE/checkpoints/unet_big/model.onnx" \
+    "https://github.com/BreezeWhite/oemer/releases/download/checkpoints/1st_model.onnx"
+fi
+if [[ ! -f "$SITE/checkpoints/seg_net/model.onnx" ]]; then
+  curl -fL --retry 3 -o "$SITE/checkpoints/seg_net/model.onnx" \
+    "https://github.com/BreezeWhite/oemer/releases/download/checkpoints/2nd_model.onnx"
+fi
+MPLBACKEND=Agg "$PY" -c "import oemer.ete, cv2; from cv2.typing import RotatedRect; print('oemer', cv2.__version__)"
+
+echo "== Trim the Python prefix =="
+rm -rf \
+  "$ROOT/build/python/lib/python3.12/test" \
+  "$ROOT/build/python/lib/python3.12/ensurepip" \
+  "$ROOT/build/python/lib/python3.12/idlelib" \
+  "$ROOT/build/python/lib/python3.12/turtledemo" \
+  "$ROOT/build/python/lib/python3.12/site-packages/pip" \
+  "$ROOT/build/python/lib/python3.12/site-packages/pip-"*.dist-info \
+  "$ROOT/build/python/lib/tcl9.0" \
+  "$ROOT/build/python/lib/tcl9" \
+  "$ROOT/build/python/lib/tk9.0" \
+  "$ROOT/build/python/lib/itcl4.3.8" \
+  "$ROOT/build/python/lib/libtcl9tk9.0.so" \
+  "$ROOT/build/python/lib/libtcl9.0.so" \
+  "$SITE/checkpoints/unet_big/weights.h5" \
+  "$SITE/checkpoints/seg_net/weights.h5" || true
+find "$ROOT/build/python" -type d -name __pycache__ -prune -exec rm -rf {} + || true
+find "$ROOT/build/python" -type d -name tests -path '*/site-packages/*' -prune -exec rm -rf {} + || true
+find "$ROOT/build/python" -name '*.a' -delete || true
+# Leave the CPython binary and libpython intact. Stripping those breaks the interpreter.
+find "$ROOT/build/python/lib/python3.12/site-packages" -type f -name '*.so' \
+  -exec strip --strip-unneeded {} + || true
+
+if [[ ! -f "$ROOT/electron/icon.png" ]]; then
+  "$PY" - <<'PY'
+from PIL import Image, ImageDraw
+image = Image.new("RGB", (512, 512), "#f3ecdf")
+draw = ImageDraw.Draw(image)
+draw.rounded_rectangle((206, 36, 306, 470), radius=48, fill="#e4cfae", outline="#6a4328", width=8)
+draw.ellipse((156, 92, 214, 150), outline="#6a4328", width=6)
+for y in (160, 210, 260, 330, 390, 450):
+    draw.ellipse((228, y, 284, y + 48), fill="#1c3830")
+image.save("electron/icon.png")
+PY
+fi
+
+echo "== Build the Next.js server =="
+npm run build
+rm -rf .next/standalone/public .next/standalone/.next/static .next/standalone/scripts
+mkdir -p .next/standalone/.next
+cp -a public .next/standalone/public
+cp -a .next/static .next/standalone/.next/static
+cp -a scripts .next/standalone/scripts
+
+echo "== Package the AppImage =="
+export CSC_IDENTITY_AUTO_DISCOVERY=false
+npx electron-builder --linux AppImage
+
+APPIMAGE="$(find dist -maxdepth 1 -name '*.AppImage' -printf '%T@ %p\n' | sort -nr | head -1 | cut -d' ' -f2-)"
+chmod +x "$APPIMAGE"
+SIZE="$(stat -c%s "$APPIMAGE")"
+echo "Built $APPIMAGE ($SIZE bytes)"
+LIMIT=$((600 * 1024 * 1024))
+if (( SIZE > LIMIT )); then
+  echo "AppImage is over 600MB." >&2
+  exit 1
+fi

scripts/run_oemer.py

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+#!/usr/bin/env python3
+"""Read one sheet-music image with oemer and print the MusicXML path.
+
+oemer asks ONNX Runtime for CUDA first. This wrapper forces the CPU provider
+so the AppImage does not need a GPU.
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+import traceback
+
+
+def force_cpu() -> None:
+    import onnxruntime as rt
+
+    original = rt.InferenceSession
+
+    def cpu_session(model, providers=None, **kwargs):  # type: ignore[no-untyped-def]
+        kwargs.pop("providers", None)
+        return original(model, providers=["CPUExecutionProvider"], **kwargs)
+
+    rt.InferenceSession = cpu_session  # type: ignore[method-assign]
+
+
+def prepare_png(src: str, dest: str) -> None:
+    from PIL import Image, ImageOps
+
+    with Image.open(src) as image:
+        rgb = ImageOps.exif_transpose(image).convert("RGB")
+        if min(rgb.size) < 80:
+            raise ValueError("This image is too small to read as sheet music.")
+        rgb.thumbnail((2200, 2200))
+        rgb.save(dest, "PNG")
+
+
+def recognize(png: str, out_dir: str) -> str:
+    from argparse import Namespace
+
+    from oemer.ete import clear_data, extract
+
+    def once(deskew: bool) -> str:
+        clear_data()
+        args = Namespace(
+            img_path=png,
+            output_path=out_dir,
+            use_tf=False,
+            save_cache=False,
+            without_deskew=not deskew,
+        )
+        return extract(args)
+
+    try:
+        return once(True)
+    except (Exception, SystemExit):
+        traceback.print_exc()
+        return once(False)
+
+
+def main() -> int:
+    if len(sys.argv) != 3:
+        print("usage: run_oemer.py IMAGE OUT_DIR", file=sys.stderr)
+        return 2
+    src, out_dir = sys.argv[1], sys.argv[2]
+    os.makedirs(out_dir, exist_ok=True)
+    png = os.path.join(out_dir, "page.png")
+    try:
+        prepare_png(src, png)
+        force_cpu()
+        musicxml = recognize(png, out_dir)
+    except Exception as exc:  # noqa: BLE001 — surface a single readable failure
+        print(f"{exc.__class__.__name__}: {exc}", file=sys.stderr)
+        traceback.print_exc()
+        return 1
+    if not musicxml or not os.path.isfile(musicxml):
+        print("oemer did not write MusicXML", file=sys.stderr)
+        return 1
+    print(f"MUSICXML={musicxml}")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())