extend flac2aac to consider most audio formats

modules/transcode.nix

@@ -6,14 +6,15 @@
   ];
 
   programs.zsh.initContent = ''
-    function flac2aac() {
+    function audio2aac() {
       local dir="''${1:-.}"
-      find "$dir" -name '*.flac' -type f -print0 | xargs -0 -P4 -n1 sh -c '
-        f="$1"
-        outfile="./transcode/''${f%.flac}.m4a"
-        mkdir -p "$(dirname "$outfile")"
-        ffmpeg -i "$f" -vn -c:a aac -b:a 256k -movflags +faststart "$outfile"
-      ' _
+      for f in "$dir"/**/*.(flac|mp3|wav|ogg|wma|aiff)(N); do
+        if [[ -f "$f" ]]; then
+          local outfile="./transcode/''${f%.*}.m4a"
+          mkdir -p "$(dirname "$outfile")"
+          ffmpeg -i "$f" -vn -c:a aac -b:a 256k -movflags +faststart "$outfile"
+        fi
+      done
     }
 
     function video2av1() {