kaledonya clips: a Discord-friendly clip site on top of Zipline

Co-Authored-By: Claude Opus 5.5 <[email protected]>

intake/app/media.py

@@ -0,0 +1,38 @@
+"""Size and a still frame of a clip, read straight from Zipline with ffprobe/ffmpeg, for Discord's link preview."""
+import json
+import subprocess
+import threading
+from functools import lru_cache
+
+# /v/ and /_site/thumb need no login: cap how many ffmpeg/ffprobe processes they can start at once
+SLOTS = threading.BoundedSemaphore(2)
+
+
+@lru_cache(maxsize=256)
+def video_size(url: str, length: str) -> tuple[int, int] | None:
+    """(width, height) of the first video stream; `length` is only part of the cache key (a reused name)."""
+    cmd = ["ffprobe", "-v", "error", "-select_streams", "v:0",
+           "-show_entries", "stream=width,height", "-of", "json", url]
+    try:
+        with SLOTS:
+            result = subprocess.run(cmd, capture_output=True, timeout=10)
+        stream = json.loads(result.stdout)["streams"][0]
+        return int(stream["width"]), int(stream["height"])
+    except (OSError, subprocess.TimeoutExpired, ValueError, KeyError, IndexError):
+        return None
+
+
+@lru_cache(maxsize=64)
+def still_jpeg(url: str, length: str) -> bytes | None:
+    """One frame (1 s in, or the first one for very short clips) as a JPEG at most 720 px tall."""
+    for seek in ("1", "0"):
+        cmd = ["ffmpeg", "-v", "error", "-ss", seek, "-i", url, "-frames:v", "1",
+               "-vf", "scale=-2:'min(720,ih)'", "-f", "image2", "-c:v", "mjpeg", "pipe:1"]
+        try:
+            with SLOTS:
+                result = subprocess.run(cmd, capture_output=True, timeout=30)
+        except (OSError, subprocess.TimeoutExpired):
+            return None
+        if result.returncode == 0 and result.stdout:
+            return result.stdout
+    return None