Finished with Phase 2.6

nonpacks/library/thumbnails.py

@@ -0,0 +1,60 @@
+"""ffmpeg thumbnail generation for gallery media (videos + gifs).
+
+Grid previews use a small cached JPEG extracted by ffmpeg; the browser only
+receives the real file when the full-screen modal opens.
+"""
+
+import shutil
+import subprocess
+from pathlib import Path
+
+from django.conf import settings
+
+FFMPEG = shutil.which('ffmpeg')
+
+MAX_WIDTH = 480
+
+
+def thumbnail_stored_path(file_index):
+    """Relative stored path of the cached thumbnail for an asset file."""
+    return f'thumbnails/{file_index.uuid}.jpg'
+
+
+def thumbnail_ready(file_index):
+    return (Path(settings.MEDIA_ROOT) / thumbnail_stored_path(file_index)).is_file()
+
+
+def generate_thumbnail(file_index):
+    """Generate (and cache) a JPEG thumbnail for a video/gif FileIndex.
+
+    Returns the relative stored path, or None when ffmpeg is unavailable or
+    extraction fails. Idempotent — a cached thumbnail is reused.
+    """
+    if not FFMPEG or not file_index.stored_path:
+        return None
+    src = (Path(settings.MEDIA_ROOT) / file_index.stored_path).resolve()
+    if not src.is_file():
+        return None
+
+    out_rel = thumbnail_stored_path(file_index)
+    out = (Path(settings.MEDIA_ROOT) / out_rel).resolve()
+    if out.is_file():
+        return out_rel
+
+    out.parent.mkdir(parents=True, exist_ok=True)
+    tmp = out.with_suffix('.tmp.jpg')
+    cmd = [
+        FFMPEG, '-y', '-i', str(src),
+        '-frames:v', '1',
+        '-vf', f"scale='min({MAX_WIDTH},iw)':-2",
+        '-q:v', '4',
+        str(tmp),
+    ]
+    try:
+        result = subprocess.run(cmd, capture_output=True, timeout=30)
+    except (subprocess.TimeoutExpired, OSError):
+        return None
+    if result.returncode != 0 or not tmp.is_file():
+        return None
+    tmp.replace(out)
+    return out_rel