501 lines
14 KiB
JavaScript
501 lines
14 KiB
JavaScript
/**
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* @file m3u8/parse-stream.js
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*/
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import Stream from '@videojs/vhs-utils/dist/stream.js';
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/**
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* "forgiving" attribute list psuedo-grammar:
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* attributes -> keyvalue (',' keyvalue)*
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* keyvalue -> key '=' value
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* key -> [^=]*
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* value -> '"' [^"]* '"' | [^,]*
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*/
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const attributeSeparator = function() {
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const key = '[^=]*';
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const value = '"[^"]*"|[^,]*';
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const keyvalue = '(?:' + key + ')=(?:' + value + ')';
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return new RegExp('(?:^|,)(' + keyvalue + ')');
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};
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/**
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* Parse attributes from a line given the separator
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*
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* @param {string} attributes the attribute line to parse
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*/
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const parseAttributes = function(attributes) {
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// split the string using attributes as the separator
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const attrs = attributes.split(attributeSeparator());
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const result = {};
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let i = attrs.length;
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let attr;
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while (i--) {
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// filter out unmatched portions of the string
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if (attrs[i] === '') {
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continue;
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}
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// split the key and value
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attr = (/([^=]*)=(.*)/).exec(attrs[i]).slice(1);
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// trim whitespace and remove optional quotes around the value
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attr[0] = attr[0].replace(/^\s+|\s+$/g, '');
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attr[1] = attr[1].replace(/^\s+|\s+$/g, '');
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attr[1] = attr[1].replace(/^['"](.*)['"]$/g, '$1');
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result[attr[0]] = attr[1];
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}
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return result;
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};
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/**
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* A line-level M3U8 parser event stream. It expects to receive input one
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* line at a time and performs a context-free parse of its contents. A stream
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* interpretation of a manifest can be useful if the manifest is expected to
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* be too large to fit comfortably into memory or the entirety of the input
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* is not immediately available. Otherwise, it's probably much easier to work
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* with a regular `Parser` object.
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*
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* Produces `data` events with an object that captures the parser's
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* interpretation of the input. That object has a property `tag` that is one
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* of `uri`, `comment`, or `tag`. URIs only have a single additional
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* property, `line`, which captures the entirety of the input without
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* interpretation. Comments similarly have a single additional property
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* `text` which is the input without the leading `#`.
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*
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* Tags always have a property `tagType` which is the lower-cased version of
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* the M3U8 directive without the `#EXT` or `#EXT-X-` prefix. For instance,
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* `#EXT-X-MEDIA-SEQUENCE` becomes `media-sequence` when parsed. Unrecognized
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* tags are given the tag type `unknown` and a single additional property
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* `data` with the remainder of the input.
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*
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* @class ParseStream
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* @extends Stream
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*/
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export default class ParseStream extends Stream {
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constructor() {
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super();
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this.customParsers = [];
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this.tagMappers = [];
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}
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/**
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* Parses an additional line of input.
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*
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* @param {string} line a single line of an M3U8 file to parse
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*/
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push(line) {
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let match;
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let event;
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// strip whitespace
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line = line.trim();
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if (line.length === 0) {
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// ignore empty lines
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return;
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}
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// URIs
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if (line[0] !== '#') {
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this.trigger('data', {
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type: 'uri',
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uri: line
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});
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return;
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}
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// map tags
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const newLines = this.tagMappers.reduce((acc, mapper) => {
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const mappedLine = mapper(line);
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// skip if unchanged
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if (mappedLine === line) {
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return acc;
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}
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return acc.concat([mappedLine]);
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}, [line]);
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newLines.forEach(newLine => {
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for (let i = 0; i < this.customParsers.length; i++) {
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if (this.customParsers[i].call(this, newLine)) {
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return;
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}
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}
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// Comments
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if (newLine.indexOf('#EXT') !== 0) {
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this.trigger('data', {
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type: 'comment',
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text: newLine.slice(1)
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});
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return;
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}
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// strip off any carriage returns here so the regex matching
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// doesn't have to account for them.
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newLine = newLine.replace('\r', '');
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// Tags
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match = (/^#EXTM3U/).exec(newLine);
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if (match) {
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this.trigger('data', {
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type: 'tag',
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tagType: 'm3u'
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});
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return;
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}
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match = (/^#EXTINF:?([0-9\.]*)?,?(.*)?$/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'inf'
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};
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if (match[1]) {
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event.duration = parseFloat(match[1]);
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}
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if (match[2]) {
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event.title = match[2];
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-TARGETDURATION:?([0-9.]*)?/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'targetduration'
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};
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if (match[1]) {
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event.duration = parseInt(match[1], 10);
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#ZEN-TOTAL-DURATION:?([0-9.]*)?/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'totalduration'
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};
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if (match[1]) {
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event.duration = parseInt(match[1], 10);
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-VERSION:?([0-9.]*)?/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'version'
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};
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if (match[1]) {
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event.version = parseInt(match[1], 10);
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-MEDIA-SEQUENCE:?(\-?[0-9.]*)?/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'media-sequence'
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};
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if (match[1]) {
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event.number = parseInt(match[1], 10);
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-DISCONTINUITY-SEQUENCE:?(\-?[0-9.]*)?/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'discontinuity-sequence'
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};
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if (match[1]) {
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event.number = parseInt(match[1], 10);
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-PLAYLIST-TYPE:?(.*)?$/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'playlist-type'
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};
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if (match[1]) {
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event.playlistType = match[1];
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-BYTERANGE:?([0-9.]*)?@?([0-9.]*)?/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'byterange'
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};
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if (match[1]) {
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event.length = parseInt(match[1], 10);
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}
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if (match[2]) {
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event.offset = parseInt(match[2], 10);
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-ALLOW-CACHE:?(YES|NO)?/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'allow-cache'
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};
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if (match[1]) {
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event.allowed = !(/NO/).test(match[1]);
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-MAP:?(.*)$/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'map'
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};
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if (match[1]) {
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const attributes = parseAttributes(match[1]);
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if (attributes.URI) {
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event.uri = attributes.URI;
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}
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if (attributes.BYTERANGE) {
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const [length, offset] = attributes.BYTERANGE.split('@');
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event.byterange = {};
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if (length) {
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event.byterange.length = parseInt(length, 10);
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}
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if (offset) {
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event.byterange.offset = parseInt(offset, 10);
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}
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}
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-STREAM-INF:?(.*)$/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'stream-inf'
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};
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if (match[1]) {
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event.attributes = parseAttributes(match[1]);
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if (event.attributes.RESOLUTION) {
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const split = event.attributes.RESOLUTION.split('x');
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const resolution = {};
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if (split[0]) {
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resolution.width = parseInt(split[0], 10);
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}
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if (split[1]) {
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resolution.height = parseInt(split[1], 10);
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}
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event.attributes.RESOLUTION = resolution;
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}
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if (event.attributes.BANDWIDTH) {
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event.attributes.BANDWIDTH = parseInt(event.attributes.BANDWIDTH, 10);
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}
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if (event.attributes['PROGRAM-ID']) {
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event.attributes['PROGRAM-ID'] = parseInt(event.attributes['PROGRAM-ID'], 10);
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}
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-MEDIA:?(.*)$/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'media'
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};
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if (match[1]) {
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event.attributes = parseAttributes(match[1]);
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-ENDLIST/).exec(newLine);
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if (match) {
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this.trigger('data', {
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type: 'tag',
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tagType: 'endlist'
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});
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return;
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}
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match = (/^#EXT-X-DISCONTINUITY/).exec(newLine);
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if (match) {
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this.trigger('data', {
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type: 'tag',
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tagType: 'discontinuity'
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});
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return;
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}
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match = (/^#EXT-X-PROGRAM-DATE-TIME:?(.*)$/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'program-date-time'
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};
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if (match[1]) {
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event.dateTimeString = match[1];
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event.dateTimeObject = new Date(match[1]);
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-KEY:?(.*)$/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'key'
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};
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if (match[1]) {
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event.attributes = parseAttributes(match[1]);
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// parse the IV string into a Uint32Array
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if (event.attributes.IV) {
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if (event.attributes.IV.substring(0, 2).toLowerCase() === '0x') {
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event.attributes.IV = event.attributes.IV.substring(2);
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}
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event.attributes.IV = event.attributes.IV.match(/.{8}/g);
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event.attributes.IV[0] = parseInt(event.attributes.IV[0], 16);
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event.attributes.IV[1] = parseInt(event.attributes.IV[1], 16);
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event.attributes.IV[2] = parseInt(event.attributes.IV[2], 16);
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event.attributes.IV[3] = parseInt(event.attributes.IV[3], 16);
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event.attributes.IV = new Uint32Array(event.attributes.IV);
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}
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-START:?(.*)$/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'start'
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};
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if (match[1]) {
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event.attributes = parseAttributes(match[1]);
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event.attributes['TIME-OFFSET'] = parseFloat(event.attributes['TIME-OFFSET']);
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event.attributes.PRECISE = (/YES/).test(event.attributes.PRECISE);
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-CUE-OUT-CONT:?(.*)?$/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'cue-out-cont'
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};
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if (match[1]) {
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event.data = match[1];
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} else {
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event.data = '';
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-CUE-OUT:?(.*)?$/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'cue-out'
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};
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if (match[1]) {
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event.data = match[1];
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} else {
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event.data = '';
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}
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this.trigger('data', event);
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return;
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}
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match = (/^#EXT-X-CUE-IN:?(.*)?$/).exec(newLine);
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if (match) {
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event = {
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type: 'tag',
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tagType: 'cue-in'
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};
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if (match[1]) {
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event.data = match[1];
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} else {
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event.data = '';
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}
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this.trigger('data', event);
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return;
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}
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// unknown tag type
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this.trigger('data', {
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type: 'tag',
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data: newLine.slice(4)
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});
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});
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}
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/**
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* Add a parser for custom headers
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*
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* @param {Object} options a map of options for the added parser
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* @param {RegExp} options.expression a regular expression to match the custom header
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* @param {string} options.customType the custom type to register to the output
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* @param {Function} [options.dataParser] function to parse the line into an object
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* @param {boolean} [options.segment] should tag data be attached to the segment object
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*/
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addParser({expression, customType, dataParser, segment}) {
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if (typeof dataParser !== 'function') {
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dataParser = (line) => line;
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}
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this.customParsers.push(line => {
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const match = expression.exec(line);
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if (match) {
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this.trigger('data', {
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type: 'custom',
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data: dataParser(line),
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customType,
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segment
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});
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return true;
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}
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});
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}
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/**
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* Add a custom header mapper
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*
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* @param {Object} options
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* @param {RegExp} options.expression a regular expression to match the custom header
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* @param {Function} options.map function to translate tag into a different tag
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*/
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addTagMapper({expression, map}) {
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const mapFn = line => {
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if (expression.test(line)) {
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return map(line);
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}
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return line;
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};
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this.tagMappers.push(mapFn);
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}
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}
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