Audio to video conversion works now, all bugs seems to be fixed.

usr/local/bin/convert-to-video.sh

@@ -56,6 +56,10 @@ build_video() {
   local audio_file="$1"
   local image_dir="$2"
   local container="$3"
+  local output_filename="$4"
+  local output_dir="$HOME/Videos"
+
+  mkdir -p "$output_dir"
 
   ffmpeg -y \
     -stream_loop -1 -framerate 1/35 -start_number 1 -i "$image_dir/stormux%d.png" \
@@ -64,7 +68,7 @@ build_video() {
     -c:v libx264 -crf 18 -preset veryfast -r 30 -pix_fmt yuv420p \
     -c:a copy \
     -shortest \
-    "$4"
+    "$output_dir/${output_filename##*/}"
 }
 
 [ "$#" -eq 1 ] || usage
@@ -82,4 +86,4 @@ output="${name}.${container}"
 
 build_video "$audio" "$image_dir" "$container" "$output"
 
-echo "Wrote $output"
+echo "Wrote $HOME/Videos/$output"