diff --git a/scripts/reencode_m4a.sh b/scripts/reencode_m4a.sh
index 8ddc742..cbe5726 100755
--- a/scripts/reencode_m4a.sh
+++ b/scripts/reencode_m4a.sh
@@ -6,15 +6,15 @@ map=
 vbr=
 while [[ $# > 0 ]]; do
    case $1 in
-      -map) map='-map 0:0';                          shift;;
-      -vbr) vbr='aac_at -profile:a aac_he -b:a 64k'; shift;;
+      -map) map='-map 0:a';                          shift;;
+      -vbr) vbr='aac -profile:a aac_he -b:a 64k';    shift;;
       *   )                                          break ;; # Anything else stops command line processing.
    esac
 done
 
 # if no variable bitrate, just copy audio
 if [[ -z $vbr ]]; then
-   map="$map copy"
+   vbr="copy"
 fi
 
 # ensure existence of destination folder