Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 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 85 86 87 88 89 90 91 92 93 94 95 | 3x 3x 5x 5x 1x 1x 3x 7x 7x 4x 3x 7x 5x 5x 5x 2x 2x 3x 3x 2x 2x 1x 2x 6x 6x 6x 6x 2x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x | import BinarySearch from './binary-search';
import { logger } from '../utils/logger';
export function findFirstFragWithCC (fragments, cc) {
let firstFrag = null;
for (let i = 0; i < fragments.length; i += 1) {
const currentFrag = fragments[i];
if (currentFrag && currentFrag.cc === cc) {
firstFrag = currentFrag;
break;
}
}
return firstFrag;
}
export function findFragWithCC (fragments, CC) {
return BinarySearch.search(fragments, (candidate) => {
if (candidate.cc < CC)
return 1;
else if (candidate.cc > CC)
return -1;
else
return 0;
});
}
export function shouldAlignOnDiscontinuities (lastFrag, lastLevel, details) {
let shouldAlign = false;
if (lastLevel && lastLevel.details && details) {
if (details.endCC > details.startCC || (lastFrag && lastFrag.cc < details.startCC))
shouldAlign = true;
}
return shouldAlign;
}
// Find the first frag in the previous level which matches the CC of the first frag of the new level
export function findDiscontinuousReferenceFrag (prevDetails, curDetails) {
const prevFrags = prevDetails.fragments;
const curFrags = curDetails.fragments;
if (!curFrags.length || !prevFrags.length) {
logger.log('No fragments to align');
return;
}
const prevStartFrag = findFirstFragWithCC(prevFrags, curFrags[0].cc);
if (!prevStartFrag || (prevStartFrag && !prevStartFrag.startPTS)) {
logger.log('No frag in previous level to align on');
return;
}
return prevStartFrag;
}
export function adjustPts (sliding, details) {
details.fragments.forEach((frag) => {
Eif (frag) {
let start = frag.start + sliding;
frag.start = frag.startPTS = start;
frag.endPTS = start + frag.duration;
}
});
details.PTSKnown = true;
}
// If a change in CC is detected, the PTS can no longer be relied upon
// Attempt to align the level by using the last level - find the last frag matching the current CC and use it's PTS
// as a reference
export function alignDiscontinuities (lastFrag, lastLevel, details) {
Eif (shouldAlignOnDiscontinuities(lastFrag, lastLevel, details)) {
const referenceFrag = findDiscontinuousReferenceFrag(lastLevel.details, details);
Iif (referenceFrag) {
logger.log('Adjusting PTS using last level due to CC increase within current level');
adjustPts(referenceFrag.start, details);
}
}
// try to align using programDateTime attribute (if available)
Eif (details.PTSKnown === false && lastLevel && lastLevel.details && lastLevel.details.fragments && lastLevel.details.fragments.length) {
// if last level sliding is 1000 and its first frag PROGRAM-DATE-TIME is 2017-08-20 1:10:00 AM
// and if new details first frag PROGRAM DATE-TIME is 2017-08-20 1:10:08 AM
// then we can deduce that playlist B sliding is 1000+8 = 1008s
let lastPDT = lastLevel.details.programDateTime;
let newPDT = details.programDateTime;
// date diff is in ms. frag.start is in seconds
let sliding = (newPDT - lastPDT) / 1000 + lastLevel.details.fragments[0].start;
Eif (!isNaN(sliding)) {
logger.log(`adjusting PTS using programDateTime delta, sliding:${sliding.toFixed(3)}`);
adjustPts(sliding, details);
}
}
}
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