88 lines
2.6 KiB
JavaScript
88 lines
2.6 KiB
JavaScript
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const { parseTrun } = require("../tools/mp4-inspector");
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const { findBox } = require("./probe");
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var window = require('global/window');
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/**
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* Utility function for parsing data from mdat boxes.
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* @param {Array<Uint8Array>} segment the segment data to create mdat/traf pairs from.
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* @returns mdat and traf boxes paired up for easier parsing.
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*/
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var getMdatTrafPairs = function(segment) {
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var trafs = findBox(segment, ['moof', 'traf']);
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var mdats = findBox(segment, ['mdat']);
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var mdatTrafPairs = [];
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// Pair up each traf with a mdat as moofs and mdats are in pairs
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mdats.forEach(function(mdat, index) {
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var matchingTraf = trafs[index];
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mdatTrafPairs.push({
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mdat: mdat,
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traf: matchingTraf
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});
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});
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return mdatTrafPairs;
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};
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/**
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* Parses sample information out of Track Run Boxes and calculates
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* the absolute presentation and decode timestamps of each sample.
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*
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* @param {Array<Uint8Array>} truns - The Trun Run boxes to be parsed
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* @param {Number|BigInt} baseMediaDecodeTime - base media decode time from tfdt
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@see ISO-BMFF-12/2015, Section 8.8.12
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* @param {Object} tfhd - The parsed Track Fragment Header
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* @see inspect.parseTfhd
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* @return {Object[]} the parsed samples
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*
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* @see ISO-BMFF-12/2015, Section 8.8.8
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**/
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var parseSamples = function(truns, baseMediaDecodeTime, tfhd) {
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var currentDts = baseMediaDecodeTime;
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var defaultSampleDuration = tfhd.defaultSampleDuration || 0;
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var defaultSampleSize = tfhd.defaultSampleSize || 0;
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var trackId = tfhd.trackId;
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var allSamples = [];
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truns.forEach(function(trun) {
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// Note: We currently do not parse the sample table as well
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// as the trun. It's possible some sources will require this.
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// moov > trak > mdia > minf > stbl
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var trackRun = parseTrun(trun);
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var samples = trackRun.samples;
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samples.forEach(function(sample) {
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if (sample.duration === undefined) {
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sample.duration = defaultSampleDuration;
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}
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if (sample.size === undefined) {
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sample.size = defaultSampleSize;
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}
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sample.trackId = trackId;
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sample.dts = currentDts;
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if (sample.compositionTimeOffset === undefined) {
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sample.compositionTimeOffset = 0;
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}
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if (typeof currentDts === 'bigint') {
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sample.pts = currentDts + window.BigInt(sample.compositionTimeOffset);
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currentDts += window.BigInt(sample.duration);
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} else {
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sample.pts = currentDts + sample.compositionTimeOffset;
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currentDts += sample.duration;
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}
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});
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allSamples = allSamples.concat(samples);
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});
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return allSamples;
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};
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module.exports = {
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getMdatTrafPairs,
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parseSamples
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};
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