ringtonemaker

#!/bin/bash

readonly program="$(basename "${0}")"

# Default values
readonly max_duration='40' # Maxium allowed duration for iPhone ringtones
duration="${max_duration}"
cut_start='00:00:00'
fade_duration='1'

function depends_on {
  local -r all_deps=("${@}")
  local missing_deps=()

  for dep in "${all_deps[@]}"; do
    hash "${dep}" 2> /dev/null || missing_deps+=("${dep}")
  done

  if [[ "${#missing_deps[@]}" -gt 0 ]]; then
    echo 'Missing required tools:' >&2
    printf '  %s\n' "${missing_deps[@]}" >&2
    exit 1
  fi
}

function get_output_path {
  local -r ext="${1}"
  local -r input_path="${2}"
  local -r init_output_path="${3}"

  if [[ -n "${init_output_path}" ]]; then
    [[ "${init_output_path##*.}" == "${ext##*.}" ]] && echo "${init_output_path}" || echo "${init_output_path}${ext}"
  else
    echo "$(pwd -P)/$(basename "${input_path%.*}${ext}")"
  fi
}

function try_overwrite {
  local -r force="${1}"
  local -r input_path="${2}"

  if [[ "${force}" == 'true' ]]; then
    mkdir -p "$(dirname "${input_path}")"
    return 0
  fi

  if [[ ! -d "$(dirname "${input_path}")" ]]; then
    echo "Cannot create '${input_path}'. Parent directory does not exist." >&2
    exit 1
  fi

  if [[ -e "${input_path}" ]]; then
    echo "Cannot write to '${input_path}'. Already exists." >&2
    exit 1
  fi
}

function usage {
  echo "
    Usage:
      ${program} [-d <duration>] [-s <time>] [-o <output_file>] <input_file>

    Options:
      -d <number>, --duration <number>   Duration (in seconds) of the output file. Maximum is "${max_duration}".
      -f, --fade-out <number>            Duration of audio fade out at the end. Default is ${fade_duration}.
      -o <file>, --output-file <file>    File to output to. Default is with same name on current directory.
      -O, --overwrite                    Create intermediary directories and overwrite output.
      -s <time>, --start <time>          Start time from when to start cutting, in the form xx:xx:xx
      -h, --help                         Show this help.
  " | sed -E 's/^ {4}//'
}

# Options
args=()
while [[ "${1}" ]]; do
  case "${1}" in
    -h | --help)
      usage
      exit 0
      ;;
    -d | --duration)
      duration="${2}"
      shift
      ;;
    -f | --fade-out)
      fade_duration="${2}";
      shift
      ;;
    -o | --output-file)
      given_output_path="${2}"
      shift
      ;;
    -O | --overwrite)
      readonly overwrite='true'
      ;;
    -s | --start)
      cut_start="${2}"
      shift
      ;;
    --)
      shift
      args+=("${@}")
      break
      ;;
    -*)
      echo "Unrecognised option: ${1}"
      exit 1
      ;;
    *)
      args+=("${1}")
      ;;
  esac
  shift
done
set -- "${args[@]}"

depends_on 'ffmpeg'

readonly input_file="${1}"
readonly output_file="$(get_output_path '.m4r' "${input_file}" "${given_output_path}")"
try_overwrite "${overwrite:-false}" "${output_file}"

if [[ "${#}" -ne 1 || ! -f "${input_file}" ]]; then
  usage
  exit 1
fi

[[ "${duration}" -gt "${max_duration}" ]] && duration="${max_duration}"

ffmpeg -i "${input_file}" -af "afade=t=out:st=$(bc <<< "${duration} - ${fade_duration}"):d=${fade_duration}" -vn -acodec aac -f mp4 -ss "${cut_start}" -t "${duration}" "${output_file}"