Fix audible m4a files

Based on https://rentry.co/n4ost

README.md

@@ -109,4 +109,5 @@ This lives in my `~/projects/scripts` directory and is added to my `$PATH`. Not
 | yubilock.sh             | Lock my screen when I remove my device. Runs using udev triggers                                                                                                                    |
 | ec | script to edit common configuration |
 | get-nav | Get NAV of a mutual fund from the Kuvera API |
-| audiobook2video | Generates a video for a music file, with a background |
+| audiobook2video | Generates a video for a music file, with a background |
+| fix-audible-m4a | Third-party. Fixes audible m4a fiels with incorrect Audio Object Type Specific Config bit. Source: https://rentry.co/n4ost | 

audible-strip-drm

@@ -4,3 +4,4 @@ IFS=$'\n\t'
 
 # PODMAN FTW!
 podman run -v $(pwd):/data ryanfb/inaudible@sha256:b66738d235be1007797e3a0a0ead115fa227e81e2ab5b7befb97d43f7712fac5
+for i in "*.m4a"; do fix-audible-m4a "$i";done

fix-audible-m4a

@@ -0,0 +1,30 @@
+#!/bin/bash
+# http://redsymbol.net/articles/unofficial-bash-strict-mode/
+set -euo pipefail
+
+# Source: https://rentry.co/n4ost
+
+f="$1"
+t=$(mktemp)
+mp4extract-bento4 moov/trak/mdia/minf/stbl/stsd/mp4a/esds \
+    "$f" /dev/stdout | xxd -p | tr -d '\n' > $t
+
+magic=$(sed -re 's/^.*0580808002(....).*$/\1/' $t)
+
+if [ "$magic" != "1212" ]; then
+    echo "no need to fix"
+    rm "$t"
+    exit 0
+fi
+
+t2=`mktemp`
+new=$(sed -re 's/05808080021212/05808080021210/' $t | xxd -r -p >$t2)
+rm $t
+old="${f}.pre-fix"
+mv -v "$f" "$old"
+mp4edit --replace \
+    moov/trak/mdia/minf/stbl/stsd/mp4a/esds:"$t2" \
+    "$old" \
+    "$f"
+
+rm "$old"