warn user if ffmpeg is not available

matplotloom/__init__.py

@@ -1,3 +1,38 @@
+import subprocess
+import shutil
+import warnings
+
 from .loom import Loom
 
 __version__ = "0.8.1"
+__all__ = ["Loom"]
+
+
+def _check_ffmpeg_availability():
+    """Check if ffmpeg is available on the system."""
+    try:
+        # more reliable cross-platform
+        if shutil.which("ffmpeg") is not None:
+            return True
+
+        # Fallback: try running ffmpeg with subprocess
+        subprocess.run(
+            ["ffmpeg", "-version"],
+            capture_output=True,
+            check=True,
+            timeout=5
+        )
+        return True
+    except (subprocess.CalledProcessError, subprocess.TimeoutExpired, FileNotFoundError):
+        return False
+
+
+if not _check_ffmpeg_availability():
+    warnings.warn(
+        "ffmpeg is not available on your system. "
+        "matplotloom requires ffmpeg to create animations. "
+        "Please install ffmpeg to use this library. "
+        "Visit https://ffmpeg.org/download.html for installation instructions.",
+        UserWarning,
+        stacklevel=2
+    )