feat: massive cleanup, kctx cache

.local/bin/ffreduce

@@ -1,5 +1,10 @@
 #!/bin/bash -e
 
+if [ -z "$1" ] || [ -z "$2" ]; then
+    echo "USAGE: $(basename "${BASH_SOURCE[0]}") in out [smallside]" >&2
+    exit 1
+fi
+
 in="$1"; shift
 out="$1"; shift
 smallside="${1:-720}"; shift || true
@@ -9,10 +14,6 @@ if ! [ -r "$in" ]; then
     exit 1
 fi
 
-if [ -z "$out" ]; then
-    echo "error: output file name can't be empty" >&2
-    exit 1
-fi
 
 set -x
 #ffmpeg -i "$in" -r 24 -vcodec libx265 -vf "scale=-2:$smallside,setpts=0.5*PTS" "$@" "$out"