Cut out a part of a media file within the given time stamps (without converting or reencoding!)

ffmpeg-cut

#!/bin/bash
#
# Author: Riyad Preukschas <riyad@informatik.uni-bremen.de>
# License: Mozilla Public License 2.0
#
# Cuts out a part of a media file within the given time stamps (without converting or reencoding!).


set -o nounset  # complain when reading unset vars
# set -o xtrace  # print every command as it's executed


usage() {
  echo "Error: wrong number of arguments"
  echo "Usage: $0 [--from <from_time>] [--to <to_time>] <input_file> [<output_file>]"
  echo "       will cut out a part of a media file within the given time stamps"
  echo "       (without converting or reencoding!)."
  echo ""
  echo "OPTIONS"
  echo " --from <from_time>"
  echo " --to   <to_time>"
  echo "        specify the times from/to the file should be cut."
  echo "        (e.g. \"00:01:25\")"
}


parse_command_line_args() {
  OPT_FROM_TIME=''
  OPT_TO_TIME=''
  OPT_INPUT_FILE=''
  OPT_OUTPUT_FILE=''

  if [[ $# -lt 3 || $# -gt 6 ]]; then
    usage
    exit 1
  fi

  while [[ $# -gt 2 ]]
  do
    case "$1" in
      --from)
        readonly OPT_FROM_TIME="$2"
        shift
        ;;
      --to)
        readonly OPT_TO_TIME="$2"
        shift
        ;;
      *)
        echo "Error: unknown argument \"$1\""
        usage
        exit 1
      ;;
    esac
    shift
  done

  readonly OPT_INPUT_FILE="$1"
  shift
  # if the input file doesn't exists ffmpeg will complain anyway

  if [[ $# -gt 0 ]]; then
    readonly OPT_OUTPUT_FILE="$1"
    shift
  else
    local filename
    filename=$(basename -- "$OPT_INPUT_FILE")
    readonly OPT_OUTPUT_FILE="$(dirname "${OPT_INPUT_FILE}")/${filename%.*}.ffmpeg-cut.${filename##*.}"
  fi
  # if the output file exists ffmpeg will ask whether it should be overwritten
}


main() {
  parse_command_line_args "$@"

  local ffmpeg_options=()
  if [[ ${OPT_FROM_TIME} ]]; then
    ffmpeg_options+=(-ss "${OPT_FROM_TIME}")
  fi
  if [[ ${OPT_TO_TIME} ]]; then
    ffmpeg_options+=(-to "${OPT_TO_TIME}")
  fi

  ffmpeg -i "${OPT_INPUT_FILE}" -c copy "${ffmpeg_options[@]}" "${OPT_OUTPUT_FILE}"
}


main "$@"