First release

node_modules/mux.js/lib/codecs/adts.js

@@ -0,0 +1,156 @@
+/**
+ * mux.js
+ *
+ * Copyright (c) Brightcove
+ * Licensed Apache-2.0 https://github.com/videojs/mux.js/blob/master/LICENSE
+ */
+'use strict';
+
+var Stream = require('../utils/stream.js');
+var ONE_SECOND_IN_TS = require('../utils/clock').ONE_SECOND_IN_TS;
+
+var AdtsStream;
+
+var
+  ADTS_SAMPLING_FREQUENCIES = [
+    96000,
+    88200,
+    64000,
+    48000,
+    44100,
+    32000,
+    24000,
+    22050,
+    16000,
+    12000,
+    11025,
+    8000,
+    7350
+  ];
+
+/*
+ * Accepts a ElementaryStream and emits data events with parsed
+ * AAC Audio Frames of the individual packets. Input audio in ADTS
+ * format is unpacked and re-emitted as AAC frames.
+ *
+ * @see http://wiki.multimedia.cx/index.php?title=ADTS
+ * @see http://wiki.multimedia.cx/?title=Understanding_AAC
+ */
+AdtsStream = function(handlePartialSegments) {
+  var
+    buffer,
+    frameNum = 0;
+
+  AdtsStream.prototype.init.call(this);
+
+  this.push = function(packet) {
+    var
+      i = 0,
+      frameLength,
+      protectionSkipBytes,
+      frameEnd,
+      oldBuffer,
+      sampleCount,
+      adtsFrameDuration;
+
+    if (!handlePartialSegments) {
+      frameNum = 0;
+    }
+
+    if (packet.type !== 'audio') {
+      // ignore non-audio data
+      return;
+    }
+
+    // Prepend any data in the buffer to the input data so that we can parse
+    // aac frames the cross a PES packet boundary
+    if (buffer) {
+      oldBuffer = buffer;
+      buffer = new Uint8Array(oldBuffer.byteLength + packet.data.byteLength);
+      buffer.set(oldBuffer);
+      buffer.set(packet.data, oldBuffer.byteLength);
+    } else {
+      buffer = packet.data;
+    }
+
+    // unpack any ADTS frames which have been fully received
+    // for details on the ADTS header, see http://wiki.multimedia.cx/index.php?title=ADTS
+    while (i + 5 < buffer.length) {
+
+      // Look for the start of an ADTS header..
+      if ((buffer[i] !== 0xFF) || (buffer[i + 1] & 0xF6) !== 0xF0) {
+        // If a valid header was not found,  jump one forward and attempt to
+        // find a valid ADTS header starting at the next byte
+        i++;
+        continue;
+      }
+
+      // The protection skip bit tells us if we have 2 bytes of CRC data at the
+      // end of the ADTS header
+      protectionSkipBytes = (~buffer[i + 1] & 0x01) * 2;
+
+      // Frame length is a 13 bit integer starting 16 bits from the
+      // end of the sync sequence
+      frameLength = ((buffer[i + 3] & 0x03) << 11) |
+        (buffer[i + 4] << 3) |
+        ((buffer[i + 5] & 0xe0) >> 5);
+
+      sampleCount = ((buffer[i + 6] & 0x03) + 1) * 1024;
+      adtsFrameDuration = (sampleCount * ONE_SECOND_IN_TS) /
+        ADTS_SAMPLING_FREQUENCIES[(buffer[i + 2] & 0x3c) >>> 2];
+
+      frameEnd = i + frameLength;
+
+      // If we don't have enough data to actually finish this ADTS frame, return
+      // and wait for more data
+      if (buffer.byteLength < frameEnd) {
+        return;
+      }
+
+      // Otherwise, deliver the complete AAC frame
+      this.trigger('data', {
+        pts: packet.pts + (frameNum * adtsFrameDuration),
+        dts: packet.dts + (frameNum * adtsFrameDuration),
+        sampleCount: sampleCount,
+        audioobjecttype: ((buffer[i + 2] >>> 6) & 0x03) + 1,
+        channelcount: ((buffer[i + 2] & 1) << 2) |
+          ((buffer[i + 3] & 0xc0) >>> 6),
+        samplerate: ADTS_SAMPLING_FREQUENCIES[(buffer[i + 2] & 0x3c) >>> 2],
+        samplingfrequencyindex: (buffer[i + 2] & 0x3c) >>> 2,
+        // assume ISO/IEC 14496-12 AudioSampleEntry default of 16
+        samplesize: 16,
+        data: buffer.subarray(i + 7 + protectionSkipBytes, frameEnd)
+      });
+
+      frameNum++;
+
+      // If the buffer is empty, clear it and return
+      if (buffer.byteLength === frameEnd) {
+        buffer = undefined;
+        return;
+      }
+
+      // Remove the finished frame from the buffer and start the process again
+      buffer = buffer.subarray(frameEnd);
+    }
+  };
+
+  this.flush = function() {
+    frameNum = 0;
+    this.trigger('done');
+  };
+
+  this.reset = function() {
+    buffer = void 0;
+    this.trigger('reset');
+  };
+
+  this.endTimeline = function() {
+    buffer = void 0;
+    this.trigger('endedtimeline');
+  };
+};
+
+AdtsStream.prototype = new Stream();
+
+module.exports = AdtsStream;