sp-streams/dist/pts-normalizer-stream.js

Streamplace Streams for Piping Video Around and Stuff

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = ptsNormalizerStream;

var _mpegMungerStream = require("./mpeg-munger-stream");

var _mpegMungerStream2 = _interopRequireDefault(_mpegMungerStream);

var _debug = require("debug");

var _debug2 = _interopRequireDefault(_debug);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/**
 * Whatever mpegts streams you pipe to it, the output will consistently increase in the way you'd
 * expect it to. Neato! For now assumes a 60/90000 timebase, which from my basic experimentation
 * seems like a pretty reasonable assumption.
 *
 * You should usually call me with source.pipe(ptsNormalizer, {end: false})
 */

var log = (0, _debug2.default)("sp:pts-normalizer-stream");
var TBN = 60;
var TBD = 90000;
var oneFramePts = TBD / TBN;

function ptsNormalizerStream() {
  var mpegMunger = (0, _mpegMungerStream2.default)();
  var ptsOut = 0;
  var offset = 0;
  var renormalize = false;
  mpegMunger.on("pipe", function (source) {
    log("New stream provided, renormalizing");
    source.on("end", function () {
      return mpegMunger.unpipe(source);
    });
    // A new stream! Okay cool. When we first see a video pts, let's adjust everything to that.
    renormalize = true;
  });
  mpegMunger.on("end", function () {
    throw new Error("MAYDAY: mpegmunger ended somehow");
  });
  mpegMunger.transformPTS = function (pts) {
    if (renormalize === true) {
      offset = ptsOut - pts + oneFramePts;
      renormalize = false;
    }
    return pts + offset;
  };
  mpegMunger.transformDTS = function (dts) {
    return dts + offset;
  };
  return mpegMunger;
}