First release

node_modules/mux.js/cjs/mp4/audio-frame-utils.js

@@ -0,0 +1,148 @@
+"use strict";
+
+/**
+ * mux.js
+ *
+ * Copyright (c) Brightcove
+ * Licensed Apache-2.0 https://github.com/videojs/mux.js/blob/master/LICENSE
+ */
+var coneOfSilence = require('../data/silence');
+
+var clock = require('../utils/clock');
+/**
+ * Sum the `byteLength` properties of the data in each AAC frame
+ */
+
+
+var sumFrameByteLengths = function sumFrameByteLengths(array) {
+  var i,
+      currentObj,
+      sum = 0; // sum the byteLength's all each nal unit in the frame
+
+  for (i = 0; i < array.length; i++) {
+    currentObj = array[i];
+    sum += currentObj.data.byteLength;
+  }
+
+  return sum;
+}; // Possibly pad (prefix) the audio track with silence if appending this track
+// would lead to the introduction of a gap in the audio buffer
+
+
+var prefixWithSilence = function prefixWithSilence(track, frames, audioAppendStartTs, videoBaseMediaDecodeTime) {
+  var baseMediaDecodeTimeTs,
+      frameDuration = 0,
+      audioGapDuration = 0,
+      audioFillFrameCount = 0,
+      audioFillDuration = 0,
+      silentFrame,
+      i,
+      firstFrame;
+
+  if (!frames.length) {
+    return;
+  }
+
+  baseMediaDecodeTimeTs = clock.audioTsToVideoTs(track.baseMediaDecodeTime, track.samplerate); // determine frame clock duration based on sample rate, round up to avoid overfills
+
+  frameDuration = Math.ceil(clock.ONE_SECOND_IN_TS / (track.samplerate / 1024));
+
+  if (audioAppendStartTs && videoBaseMediaDecodeTime) {
+    // insert the shortest possible amount (audio gap or audio to video gap)
+    audioGapDuration = baseMediaDecodeTimeTs - Math.max(audioAppendStartTs, videoBaseMediaDecodeTime); // number of full frames in the audio gap
+
+    audioFillFrameCount = Math.floor(audioGapDuration / frameDuration);
+    audioFillDuration = audioFillFrameCount * frameDuration;
+  } // don't attempt to fill gaps smaller than a single frame or larger
+  // than a half second
+
+
+  if (audioFillFrameCount < 1 || audioFillDuration > clock.ONE_SECOND_IN_TS / 2) {
+    return;
+  }
+
+  silentFrame = coneOfSilence()[track.samplerate];
+
+  if (!silentFrame) {
+    // we don't have a silent frame pregenerated for the sample rate, so use a frame
+    // from the content instead
+    silentFrame = frames[0].data;
+  }
+
+  for (i = 0; i < audioFillFrameCount; i++) {
+    firstFrame = frames[0];
+    frames.splice(0, 0, {
+      data: silentFrame,
+      dts: firstFrame.dts - frameDuration,
+      pts: firstFrame.pts - frameDuration
+    });
+  }
+
+  track.baseMediaDecodeTime -= Math.floor(clock.videoTsToAudioTs(audioFillDuration, track.samplerate));
+  return audioFillDuration;
+}; // If the audio segment extends before the earliest allowed dts
+// value, remove AAC frames until starts at or after the earliest
+// allowed DTS so that we don't end up with a negative baseMedia-
+// DecodeTime for the audio track
+
+
+var trimAdtsFramesByEarliestDts = function trimAdtsFramesByEarliestDts(adtsFrames, track, earliestAllowedDts) {
+  if (track.minSegmentDts >= earliestAllowedDts) {
+    return adtsFrames;
+  } // We will need to recalculate the earliest segment Dts
+
+
+  track.minSegmentDts = Infinity;
+  return adtsFrames.filter(function (currentFrame) {
+    // If this is an allowed frame, keep it and record it's Dts
+    if (currentFrame.dts >= earliestAllowedDts) {
+      track.minSegmentDts = Math.min(track.minSegmentDts, currentFrame.dts);
+      track.minSegmentPts = track.minSegmentDts;
+      return true;
+    } // Otherwise, discard it
+
+
+    return false;
+  });
+}; // generate the track's raw mdat data from an array of frames
+
+
+var generateSampleTable = function generateSampleTable(frames) {
+  var i,
+      currentFrame,
+      samples = [];
+
+  for (i = 0; i < frames.length; i++) {
+    currentFrame = frames[i];
+    samples.push({
+      size: currentFrame.data.byteLength,
+      duration: 1024 // For AAC audio, all samples contain 1024 samples
+
+    });
+  }
+
+  return samples;
+}; // generate the track's sample table from an array of frames
+
+
+var concatenateFrameData = function concatenateFrameData(frames) {
+  var i,
+      currentFrame,
+      dataOffset = 0,
+      data = new Uint8Array(sumFrameByteLengths(frames));
+
+  for (i = 0; i < frames.length; i++) {
+    currentFrame = frames[i];
+    data.set(currentFrame.data, dataOffset);
+    dataOffset += currentFrame.data.byteLength;
+  }
+
+  return data;
+};
+
+module.exports = {
+  prefixWithSilence: prefixWithSilence,
+  trimAdtsFramesByEarliestDts: trimAdtsFramesByEarliestDts,
+  generateSampleTable: generateSampleTable,
+  concatenateFrameData: concatenateFrameData
+};