Generate bash commands to cut and concatenate a video based on time periods (using ffmpeg)

ffmpeg-cut-concatenate.js

/*

1. Open http://majestic-geese.surge.sh
2. Insert time periods e.g.:
  5:49 - 7:24
  10:11 - 11:22
  11:58- 12:45
  13:04- 13:34
  13:48 - 13:58
  17:08- 18:08

3. Open debug bar
4. Insert code below
5. run: copy(makeCommands('v.avi', 'mp4', 480))
6. Insert and run clipboard into Terminal

*/


function getPeriods(){
  var data = document.getElementsByTagName('textarea')[0].value.trim();
  return data.split(/\n/).map(function(str){
    str = str.trim();
    var period = str.split(/\s?\-\s?/);
    var duration = makePeriodString(period[0], period[1]);
    var startStr = period[0];
    if (startStr.split(':')[0].length === 1) {
      startStr = '0' + startStr;
    }
    return [startStr, duration];
  });
}

function makePeriodString(a, b){
  a = a.split(':');
  b = b.split(':');
  var minDiff = b[0] - a[0];
  var secDiff = b[1] - a[1];
  var durationSec = minDiff * 60 + secDiff;
  var durationOnlySec = (durationSec % 60).toString();
  if (durationOnlySec < 10) {
    durationOnlySec = '0' + durationOnlySec;
  }
  return Math.floor(durationSec / 60) + ':' + durationOnlySec;
}

function makeConvertCommands(videoPath, periods, ext){
  return periods.map(function(item, i){
    return `ffmpeg -i ${videoPath} -ss 00:${item[0]} -c copy -t 00:0${item[1]} part${i}.${ext}`;
  });
}

function makeFileListCommand(periods, ext){
  var content = periods.map(function(item, i){
    return `file part${i}.${ext}`
  }).join(' \\n');
  return `echo -e "${content}" >> vlist_${ext}.txt`;
}

function makeCommands(videoPath, ext, res){

  var MOVIE_NAME = 'mentopship_movie';
  var periods = getPeriods();

  var convertC = makeConvertCommands(videoPath, periods, ext).join(' && ');
  var fileListC = makeFileListCommand(periods, ext);
  var glueC = `ffmpeg -f concat -i vlist_${ext}.txt -c copy ${MOVIE_NAME}.${ext}`;

  var resizeC = '';
  if (res) {
    resizeC = `ffmpeg -i ${MOVIE_NAME}.${ext} -s 480x320 -c:a copy ${MOVIE_NAME}_480.${ext}`;
  }
  var cleanUpCommand = `rm part*.${ext} && rm vlist_*.txt`;

  return [
    convertC,
    fileListC,
    glueC,
    resizeC,
    cleanUpCommand,
  ].join(' && ');
}