shaka-player
Version:
DASH/EME video player library
285 lines (248 loc) • 8.48 kB
JavaScript
/**
* @license
* Copyright 2016 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
goog.provide('shaka.hls.ManifestTextParser');
goog.require('shaka.hls.Attribute');
goog.require('shaka.hls.Playlist');
goog.require('shaka.hls.PlaylistType');
goog.require('shaka.hls.Segment');
goog.require('shaka.hls.Tag');
goog.require('shaka.hls.Utils');
goog.require('shaka.util.Error');
goog.require('shaka.util.StringUtils');
goog.require('shaka.util.TextParser');
/**
* Creates a new ManifestTextParser.
*
* @constructor
* @struct
*/
shaka.hls.ManifestTextParser = function() {
/** @private {number} */
this.globalId_ = 0;
};
/**
* @param {ArrayBuffer} data
* @param {string} absolutePlaylistUri An absolute, final URI after redirects.
* @return {!shaka.hls.Playlist}
* @throws {shaka.util.Error}
*/
shaka.hls.ManifestTextParser.prototype.parsePlaylist =
function(data, absolutePlaylistUri) {
const MEDIA_PLAYLIST_TAGS = shaka.hls.ManifestTextParser.MEDIA_PLAYLIST_TAGS;
const SEGMENT_TAGS = shaka.hls.ManifestTextParser.SEGMENT_TAGS;
// Get the input as a string. Normalize newlines to \n.
let str = shaka.util.StringUtils.fromUTF8(data);
str = str.replace(/\r\n|\r(?=[^\n]|$)/gm, '\n').trim();
const lines = str.split(/\n+/m);
if (!/^#EXTM3U($|[ \t\n])/m.test(lines[0])) {
throw new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.MANIFEST,
shaka.util.Error.Code.HLS_PLAYLIST_HEADER_MISSING);
}
/** shaka.hls.PlaylistType */
let playlistType = shaka.hls.PlaylistType.MASTER;
// First, look for media playlist tags, so that we know what the playlist
// type really is before we start parsing.
for (let i = 1; i < lines.length; i++) {
// Ignore comments.
if (!shaka.hls.Utils.isComment(lines[i])) {
const tag = this.parseTag_(lines[i]);
// These tags won't actually be used, so don't increment the global id.
this.globalId_ -= 1;
if (MEDIA_PLAYLIST_TAGS.includes(tag.name)) {
playlistType = shaka.hls.PlaylistType.MEDIA;
break;
} else if (tag.name == 'EXT-X-STREAM-INF') {
i += 1;
}
}
}
/** {Array.<shaka.hls.Tag>} */
const tags = [];
for (let i = 1; i < lines.length;) {
// Skip comments
if (shaka.hls.Utils.isComment(lines[i])) {
i += 1;
continue;
}
const tag = this.parseTag_(lines[i]);
if (SEGMENT_TAGS.includes(tag.name)) {
if (playlistType != shaka.hls.PlaylistType.MEDIA) {
// Only media playlists should contain segment tags
throw new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.MANIFEST,
shaka.util.Error.Code.HLS_INVALID_PLAYLIST_HIERARCHY);
}
const segmentsData = lines.splice(i, lines.length - i);
const segments = this.parseSegments_(
absolutePlaylistUri, segmentsData, tags);
return new shaka.hls.Playlist(
absolutePlaylistUri, playlistType, tags, segments);
}
tags.push(tag);
i += 1;
// An EXT-X-STREAM-INF tag is followed by a URI of a media playlist.
// Add the URI to the tag object.
if (tag.name == 'EXT-X-STREAM-INF') {
const tagUri = new shaka.hls.Attribute('URI', lines[i]);
tag.addAttribute(tagUri);
i += 1;
}
}
return new shaka.hls.Playlist(absolutePlaylistUri, playlistType, tags);
};
/**
* Parses an array of strings into an array of HLS Segment objects.
*
* @param {string} absoluteMediaPlaylistUri
* @param {!Array.<string>} lines
* @param {!Array.<!shaka.hls.Tag>} playlistTags
* @return {!Array.<shaka.hls.Segment>}
* @private
* @throws {shaka.util.Error}
*/
shaka.hls.ManifestTextParser.prototype.parseSegments_ =
function(absoluteMediaPlaylistUri, lines, playlistTags) {
/** @type {!Array.<shaka.hls.Segment>} */
let segments = [];
/** @type {!Array.<shaka.hls.Tag>} */
let segmentTags = [];
lines.forEach((line) => {
if (/^(#EXT)/.test(line)) {
let tag = this.parseTag_(line);
if (shaka.hls.ManifestTextParser.MEDIA_PLAYLIST_TAGS.includes(tag.name)) {
playlistTags.push(tag);
} else {
segmentTags.push(tag);
}
} else if (shaka.hls.Utils.isComment(line)) {
// Skip comments.
return [];
} else {
const verbatimSegmentUri = line.trim();
const absoluteSegmentUri = shaka.hls.Utils.constructAbsoluteUri(
absoluteMediaPlaylistUri, verbatimSegmentUri);
// The URI appears after all of the tags describing the segment.
const segment = new shaka.hls.Segment(absoluteSegmentUri, segmentTags);
segments.push(segment);
segmentTags = [];
}
});
return segments;
};
/**
* Parses a string into an HLS Tag object while tracking what id to use next.
*
* @param {string} word
* @return {!shaka.hls.Tag}
* @throws {shaka.util.Error}
* @private
*/
shaka.hls.ManifestTextParser.prototype.parseTag_ = function(word) {
return shaka.hls.ManifestTextParser.parseTag(this.globalId_++, word);
};
/**
* Parses a string into an HLS Tag object.
*
* @param {number} id
* @param {string} word
* @return {!shaka.hls.Tag}
* @throws {shaka.util.Error}
*/
shaka.hls.ManifestTextParser.parseTag = function(id, word) {
/* HLS tags start with '#EXT'. A tag can have a set of attributes
(#EXT-<tagname>:<attribute list>) and/or a value (#EXT-<tagname>:<value>).
An attribute's format is 'AttributeName=AttributeValue'.
The parsing logic goes like this:
1. Everything before ':' is a name (we ignore '#').
2. Everything after ':' is a list of comma-seprated items,
2a. The first item might be a value, if it does not contain '='.
2b. Otherwise, items are attributes.
3. If there is no ":", it's a simple tag with no attributes and no value */
const blocks = word.match(/^#(EXT[^:]*)(?::(.*))?$/);
if (!blocks) {
throw new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.MANIFEST,
shaka.util.Error.Code.INVALID_HLS_TAG,
word);
}
const name = blocks[1];
const data = blocks[2];
const attributes = [];
let value;
if (data) {
const parser = new shaka.util.TextParser(data);
let blockAttrs;
// Regex: any number of non-equals-sign characters at the beginning
// terminated by comma or end of line
const valueRegex = /^([^,=]+)(?:,|$)/g;
const blockValue = parser.readRegex(valueRegex);
if (blockValue) {
value = blockValue[1];
}
// Regex:
// 1. Key name ([1])
// 2. Equals sign
// 3. Either:
// a. A quoted string (everything up to the next quote, [2])
// b. An unquoted string
// (everything up to the next comma or end of line, [3])
// 4. Either:
// a. A comma
// b. End of line
const attributeRegex = /([^=]+)=(?:"([^"]*)"|([^",]*))(?:,|$)/g;
while ((blockAttrs = parser.readRegex(attributeRegex))) {
const attrName = blockAttrs[1];
const attrValue = blockAttrs[2] || blockAttrs[3];
const attribute = new shaka.hls.Attribute(attrName, attrValue);
attributes.push(attribute);
}
}
return new shaka.hls.Tag(id, name, attributes, value);
};
/**
* HLS tags that only appear on Media Playlists.
* Used to determine a playlist type.
*
* @const {!Array.<string>}
*/
shaka.hls.ManifestTextParser.MEDIA_PLAYLIST_TAGS = [
'EXT-X-TARGETDURATION',
'EXT-X-MEDIA-SEQUENCE',
'EXT-X-DISCONTINUITY-SEQUENCE',
'EXT-X-PLAYLIST-TYPE',
'EXT-X-MAP',
'EXT-X-I-FRAMES-ONLY',
'EXT-X-ENDLIST',
];
/**
* HLS tags that only appear on Segments in a Media Playlists.
* Used to determine the start of the segments info.
*
* @const {!Array.<string>}
*/
shaka.hls.ManifestTextParser.SEGMENT_TAGS = [
'EXTINF',
'EXT-X-BYTERANGE',
'EXT-X-DISCONTINUITY',
'EXT-X-PROGRAM-DATE-TIME',
'EXT-X-KEY',
'EXT-X-DATERANGE',
];