silence.js
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/**
* mux.js
*
* Copyright (c) Brightcove
* Licensed Apache-2.0 https://github.com/videojs/mux.js/blob/master/LICENSE
*/
var highPrefix = [33, 16, 5, 32, 164, 27];
var lowPrefix = [33, 65, 108, 84, 1, 2, 4, 8, 168, 2, 4, 8, 17, 191, 252];
var zeroFill = function(count) {
var a = [];
while (count--) {
a.push(0);
}
return a;
};
var makeTable = function(metaTable) {
return Object.keys(metaTable).reduce(function(obj, key) {
obj[key] = new Uint8Array(metaTable[key].reduce(function(arr, part) {
return arr.concat(part);
}, []));
return obj;
}, {});
};
var silence;
module.exports = function() {
if (!silence) {
// Frames-of-silence to use for filling in missing AAC frames
var coneOfSilence = {
96000: [highPrefix, [227, 64], zeroFill(154), [56]],
88200: [highPrefix, [231], zeroFill(170), [56]],
64000: [highPrefix, [248, 192], zeroFill(240), [56]],
48000: [highPrefix, [255, 192], zeroFill(268), [55, 148, 128], zeroFill(54), [112]],
44100: [highPrefix, [255, 192], zeroFill(268), [55, 163, 128], zeroFill(84), [112]],
32000: [highPrefix, [255, 192], zeroFill(268), [55, 234], zeroFill(226), [112]],
24000: [highPrefix, [255, 192], zeroFill(268), [55, 255, 128], zeroFill(268), [111, 112], zeroFill(126), [224]],
16000: [highPrefix, [255, 192], zeroFill(268), [55, 255, 128], zeroFill(268), [111, 255], zeroFill(269), [223, 108], zeroFill(195), [1, 192]],
12000: [lowPrefix, zeroFill(268), [3, 127, 248], zeroFill(268), [6, 255, 240], zeroFill(268), [13, 255, 224], zeroFill(268), [27, 253, 128], zeroFill(259), [56]],
11025: [lowPrefix, zeroFill(268), [3, 127, 248], zeroFill(268), [6, 255, 240], zeroFill(268), [13, 255, 224], zeroFill(268), [27, 255, 192], zeroFill(268), [55, 175, 128], zeroFill(108), [112]],
8000: [lowPrefix, zeroFill(268), [3, 121, 16], zeroFill(47), [7]]
};
silence = makeTable(coneOfSilence);
}
return silence;
};