2a09d1a4
 liuqimichale
添加宜春 天水 宣化
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
|
/**
* mux.js
*
* Copyright (c) 2016 Brightcove
* All rights reserved.
*
* Accepts program elementary stream (PES) data events and corrects
* decode and presentation time stamps to account for a rollover
* of the 33 bit value.
*/
'use strict';
var Stream = require('../utils/stream');
var MAX_TS = 8589934592;
var RO_THRESH = 4294967296;
var handleRollover = function(value, reference) {
var direction = 1;
if (value > reference) {
// If the current timestamp value is greater than our reference timestamp and we detect a
// timestamp rollover, this means the roll over is happening in the opposite direction.
// Example scenario: Enter a long stream/video just after a rollover occurred. The reference
// point will be set to a small number, e.g. 1. The user then seeks backwards over the
// rollover point. In loading this segment, the timestamp values will be very large,
// e.g. 2^33 - 1. Since this comes before the data we loaded previously, we want to adjust
// the time stamp to be `value - 2^33`.
direction = -1;
}
// Note: A seek forwards or back that is greater than the RO_THRESH (2^32, ~13 hours) will
// cause an incorrect adjustment.
while (Math.abs(reference - value) > RO_THRESH) {
value += (direction * MAX_TS);
}
return value;
};
var TimestampRolloverStream = function(type) {
var lastDTS, referenceDTS;
TimestampRolloverStream.prototype.init.call(this);
this.type_ = type;
this.push = function(data) {
if (data.type !== this.type_) {
return;
}
if (referenceDTS === undefined) {
referenceDTS = data.dts;
}
data.dts = handleRollover(data.dts, referenceDTS);
data.pts = handleRollover(data.pts, referenceDTS);
lastDTS = data.dts;
this.trigger('data', data);
};
this.flush = function() {
referenceDTS = lastDTS;
this.trigger('done');
};
this.discontinuity = function() {
referenceDTS = void 0;
lastDTS = void 0;
};
};
TimestampRolloverStream.prototype = new Stream();
module.exports = {
TimestampRolloverStream: TimestampRolloverStream,
handleRollover: handleRollover
};
|
