loop.js

for(var i = 0, startFrame = 0, endFrame = 0; i < s; i++) {
  startFrame = ((framecount/parts)*i|0);
  endFrame = ((framecount/parts)*(i+1)|0) - 1;
  trimPoints = trimPoints.concat([startFrame,endFrame]);
  console.log(endFrame - startFrame + 1);
}

// sb - startBytes
// eb - endBytes
// parts - number of parts
// ranges - byte ranges array
// 
for(var i = 0, sb = 0, eb = 0; i < parts; i++) {
  sb = ((dlen/parts)*i|0);
  eb = ((dlen/parts)*(i+1)|0) - 1;
  ranges = ranges.concat([sb,eb]);
  console.log(eb - sb + 1);
}