@sqhead/mux.js/lib/rawH264/transmuxer.js

A collection of lightweight utilities for inspecting and manipulating video container formats.

var Stream = require('../utils/stream.js');
var H264Stream = require('../codecs/h264').H264Stream;
var VideoSegmentStream = require('../mp4/transmuxer').VideoSegmentStream;
var CoalesceStream = require('./coalesce-stream.js');


// object types
var Transmuxer;

var TIMESCALE = 90000; // Hz
var ACCESS_UNIT_DELIMITER = new Uint8Array([0, 0, 0, 1, 9]);

/**
 * A Stream that takes raw H264 frames as binary data as input and produces
 * corresponding media segments, suitable for use with Media Source
 * Extension (MSE) implementations that support the ISO BMFF byte
 * stream format, like Chrome.
 */
Transmuxer = function(options) {

  Transmuxer.prototype.init.call(this);

  options = options || {};
  this.baseMediaDecodeTime = options.baseMediaDecodeTime || 0;
  this.transmuxPipeline_;

  this.setupPipeline = function() {
    var pipeline = {};
    this.transmuxPipeline_ = pipeline;

    pipeline.type = 'rawh264';

    var videoTrack = {
      timelineStartInfo: {
        baseMediaDecodeTime: 0
      },
      id: 0,
      codec: 'avc',
      type: 'video'
    };

    // Setup pipelines
    pipeline.h264Stream = new H264Stream();
    pipeline.videoSegmentStream = new VideoSegmentStream(videoTrack, options);
    pipeline.coalesceStream = new CoalesceStream(options);
    pipeline.coalesceStream.numberOfTracks++;

    pipeline.h264Stream
      .pipe(pipeline.videoSegmentStream)
      .pipe(pipeline.coalesceStream);

    // Re-emit any data coming from the coalesce stream to the outside world
    pipeline.coalesceStream.on('data', this.trigger.bind(this, 'data'));
    // Let the consumer know we have finished flushing the entire pipeline
    pipeline.coalesceStream.on('done', this.trigger.bind(this, 'done'));

    // Set head of pipeline
    pipeline.headOfPipeline = pipeline.h264Stream;
  };
  this.setupPipeline();

  // feed incoming data to the front of the parsing pipeline
  // data must be object with `data` and `timestamp` fields
  this.push = function(data) {
    // Set correct pts/dts values
    pts = dts = data.timestamp * TIMESCALE;

    // Prepend Access Unit Delimiter
    packetData = new Uint8Array(data.data.byteLength + ACCESS_UNIT_DELIMITER.byteLength);
    packetData.set(ACCESS_UNIT_DELIMITER);
    packetData.set(data.data, ACCESS_UNIT_DELIMITER.byteLength);

    var packet = {
      type: 'video',
      trackId: 0,
      pts: pts,
      dts: dts,
      data: packetData
    };
    this.transmuxPipeline_.headOfPipeline.push(packet);
  };

  // flush any buffered data
  this.flush = function() {
    // Start at the top of the pipeline and flush all pending work
    this.transmuxPipeline_.headOfPipeline.flush();
  };

};
Transmuxer.prototype = new Stream();

module.exports = {
  Transmuxer: Transmuxer
};