zshrc: Add shortcut to compress with ffmpeg

By default, ffmpeg uses crf 23 for h.264 encoding, but for screen
recordings, higher compression is usually fine too.

templates/_zshrc.j2

@@ -109,3 +109,17 @@ alias git-force-push='git push origin $(git rev-parse --abbrev-ref HEAD) --force
 
 # mpv
 alias mpv="mpv --autofit=70%"
+
+# stolen from: https://fem.social/@clerie/110275008064297220
+nmap-fast-ping='nmap -n --disable-arp-ping -sn $@'
+
+# ffmpeg shortcuts
+ffmpeg_compress() {
+  if [ -n "$1" ]; then
+    filename=$1:r
+    fileext=$1:e
+    ffmpeg -i $1 -c:v libx264 -preset slow -crf 28 $filename-comp.mp4
+  else
+    echo "ERROR: Please provide a file name"
+  fi
+}