Splits an audio file in chapters, according to file metadata. Tested with Privacy and Utopia from Escape the Technocracy

split-chapters.sh

#! /usr/bin/env bash

# Splits an audio file into chapters
# Usage: ./split-chapters.sh input_file

if [ "$#" -ne 1 ]; then
  echo "Usage: $0 input_file" >&2
  exit 1
fi

audio="$1"
output_format="mp3" # or ogg etc

if ! command -v ffprobe >/dev/null; then
  echo "ffprobe is required but not installed. Please install the ffmpeg package" >&2
  exit 1
fi

tmp_file="$(mktemp)"
ffprobe -print_format json -show_chapters -i "$audio" 2>/dev/null | jq -c '.chapters[]' >"$tmp_file"
readarray -t chapters <"$tmp_file"
rm "$tmp_file"

count=${#chapters[@]}
echo "$count chapters found"
pad=$((1 + count / 10))

for chap in "${chapters[@]}"; do
  id=$(echo "$chap" | jq -r '.id')
  chap_num=$(printf "%0${pad}d" "$id")

  tags=$(echo "$chap" | jq -r '.tags')
  title=$(echo "$tags" | jq -r '.title' | cut -f2 -d':' | tr -s ' ' '-' | tr -cd '[:alnum:]-' | tr '[:upper:]' '[:lower:]')
  output=$(echo "$chap_num-$title.$output_format" | tr -s '-')
  start_time=$(echo "$chap" | jq -r '.start_time')
  end_time=$(echo "$chap" | jq -r '.end_time')

  echo "$chap_num: [$start_time:$end_time] $output"
  ffmpeg -ss "$start_time" -to "$end_time" -i "$audio" -map 0:a -c:a libmp3lame -b:a 192k "$output"
  echo "wrote $output"
done

echo
echo "Done"