Tracking de l'application VApp (IHM du jeu)

VApp/node_modules/mux.js/lib/partial/audio-segment-stream.js

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+'use strict';
+
+var Stream = require('../utils/stream.js');
+var mp4 = require('../mp4/mp4-generator.js');
+var audioFrameUtils = require('../mp4/audio-frame-utils');
+var trackInfo = require('../mp4/track-decode-info.js');
+var ONE_SECOND_IN_TS = require('../utils/clock').ONE_SECOND_IN_TS;
+var AUDIO_PROPERTIES = require('../constants/audio-properties.js');
+
+/**
+ * Constructs a single-track, ISO BMFF media segment from AAC data
+ * events. The output of this stream can be fed to a SourceBuffer
+ * configured with a suitable initialization segment.
+ */
+var AudioSegmentStream = function(track, options) {
+  var
+    adtsFrames = [],
+    sequenceNumber = 0,
+    earliestAllowedDts = 0,
+    audioAppendStartTs = 0,
+    videoBaseMediaDecodeTime = Infinity,
+    segmentStartPts = null,
+    segmentEndPts = null;
+
+  options = options || {};
+
+  AudioSegmentStream.prototype.init.call(this);
+
+  this.push = function(data) {
+    trackInfo.collectDtsInfo(track, data);
+
+    if (track) {
+      AUDIO_PROPERTIES.forEach(function(prop) {
+        track[prop] = data[prop];
+      });
+    }
+
+    // buffer audio data until end() is called
+    adtsFrames.push(data);
+  };
+
+  this.setEarliestDts = function(earliestDts) {
+    earliestAllowedDts = earliestDts;
+  };
+
+  this.setVideoBaseMediaDecodeTime = function(baseMediaDecodeTime) {
+    videoBaseMediaDecodeTime = baseMediaDecodeTime;
+  };
+
+  this.setAudioAppendStart = function(timestamp) {
+    audioAppendStartTs = timestamp;
+  };
+
+  this.processFrames_ = function() {
+    var
+      frames,
+      moof,
+      mdat,
+      boxes,
+      timingInfo;
+
+    // return early if no audio data has been observed
+    if (adtsFrames.length === 0) {
+      return;
+    }
+
+    frames = audioFrameUtils.trimAdtsFramesByEarliestDts(
+      adtsFrames, track, earliestAllowedDts);
+    if (frames.length === 0) {
+      // return early if the frames are all after the earliest allowed DTS
+      // TODO should we clear the adtsFrames?
+      return;
+    }
+
+    track.baseMediaDecodeTime = trackInfo.calculateTrackBaseMediaDecodeTime(
+      track, options.keepOriginalTimestamps);
+
+    audioFrameUtils.prefixWithSilence(
+      track, frames, audioAppendStartTs, videoBaseMediaDecodeTime);
+
+    // we have to build the index from byte locations to
+    // samples (that is, adts frames) in the audio data
+    track.samples = audioFrameUtils.generateSampleTable(frames);
+
+    // concatenate the audio data to constuct the mdat
+    mdat = mp4.mdat(audioFrameUtils.concatenateFrameData(frames));
+
+    adtsFrames = [];
+
+    moof = mp4.moof(sequenceNumber, [track]);
+
+    // bump the sequence number for next time
+    sequenceNumber++;
+
+    track.initSegment = mp4.initSegment([track]);
+
+    // it would be great to allocate this array up front instead of
+    // throwing away hundreds of media segment fragments
+    boxes = new Uint8Array(moof.byteLength + mdat.byteLength);
+
+    boxes.set(moof);
+    boxes.set(mdat, moof.byteLength);
+
+    trackInfo.clearDtsInfo(track);
+
+    if (segmentStartPts === null) {
+      segmentEndPts = segmentStartPts = frames[0].pts;
+    }
+
+    segmentEndPts += frames.length * (ONE_SECOND_IN_TS * 1024 / track.samplerate);
+
+    timingInfo = { start: segmentStartPts };
+
+    this.trigger('timingInfo', timingInfo);
+    this.trigger('data', {track: track, boxes: boxes});
+  };
+
+  this.flush = function() {
+    this.processFrames_();
+    // trigger final timing info
+    this.trigger('timingInfo', {
+      start: segmentStartPts,
+      end: segmentEndPts
+    });
+    this.resetTiming_();
+    this.trigger('done', 'AudioSegmentStream');
+  };
+
+  this.partialFlush = function() {
+    this.processFrames_();
+    this.trigger('partialdone', 'AudioSegmentStream');
+  };
+
+  this.endTimeline = function() {
+    this.flush();
+    this.trigger('endedtimeline', 'AudioSegmentStream');
+  };
+
+  this.resetTiming_ = function() {
+    trackInfo.clearDtsInfo(track);
+    segmentStartPts = null;
+    segmentEndPts = null;
+  };
+
+  this.reset = function() {
+    this.resetTiming_();
+    adtsFrames = [];
+    this.trigger('reset');
+  };
+};
+
+AudioSegmentStream.prototype = new Stream();
+
+module.exports = AudioSegmentStream;