shaka-player
Version:
DASH/EME video player library
253 lines (222 loc) • 7.32 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} uri
* @return {!shaka.hls.Playlist}
* @throws {shaka.util.Error}
*/
shaka.hls.ManifestTextParser.prototype.parsePlaylist = function(data, uri) {
// Get the input as a string. Normalize newlines to \n.
var str = shaka.util.StringUtils.fromUTF8(data);
str = str.replace(/\r\n|\r(?=[^\n]|$)/gm, '\n').trim();
var lines = str.split(/\n+/m);
if (!/^#EXTM3U($|[ \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 */
var playlistType = shaka.hls.PlaylistType.MASTER;
/** {Array.<shaka.hls.Tag>} */
var tags = [];
var i = 1;
while (i < lines.length) {
// Skip comments
if (shaka.hls.Utils.isComment(lines[i])) {
i += 1;
continue;
}
var tag = this.parseTag_(lines[i]);
if (shaka.hls.ManifestTextParser.MEDIA_PLAYLIST_TAGS
.indexOf(tag.name) >= 0) {
playlistType = shaka.hls.PlaylistType.MEDIA;
} else if (shaka.hls.ManifestTextParser.SEGMENT_TAGS
.indexOf(tag.name) >= 0) {
if (playlistType != shaka.hls.PlaylistType.MEDIA) {
// Only media playlist 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);
}
var segmentsData = lines.splice(i, lines.length - i);
var segments = this.parseSegments_(segmentsData, tags);
return new shaka.hls.Playlist(uri, playlistType, tags, segments);
}
tags.push(tag);
i += 1;
// EXT-X-STREAM-INF tag is followed by a uri of a media playlist.
// Add uri to the tag object.
if (tag.name == 'EXT-X-STREAM-INF') {
var tagUri = new shaka.hls.Attribute('URI', lines[i]);
tag.addAttribute(tagUri);
i += 1;
}
}
return new shaka.hls.Playlist(uri, playlistType, tags);
};
/**
* Parses an array of strings into an HLS Segment objects.
*
* @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(lines, playlistTags) {
/** @type {!Array.<shaka.hls.Segment>} */
var segments = [];
/** @type {!Array.<shaka.hls.Tag>} */
var segmentTags = [];
lines.forEach(function(line) {
if (/^(#EXT)/.test(line)) {
var tag = this.parseTag_(line);
if (shaka.hls.ManifestTextParser.MEDIA_PLAYLIST_TAGS
.indexOf(tag.name) >= 0) {
playlistTags.push(tag);
} else {
segmentTags.push(tag);
}
} else if (shaka.hls.Utils.isComment(line)) {
// Skip comments
return;
} else {
var uri = line.trim();
// Uri appears after all the tags describing the segment.
var segment = new shaka.hls.Segment(uri, segmentTags);
segments.push(segment);
segmentTags = [];
}
}.bind(this));
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>) or a value (#EXT-<tagname>:<value>).
Attributes' format is 'AttributeName=AttributeValue'.
The parsing logic goes like this:
1) Everything before ':' is a name (we ignore '#').
2) Everything after should be parsed as attributes if it contains '='.
3) Otherwise, this is a value.
4) If there is no ":", it's a simple tag with no attributes and no value */
var blocks = word.match(/^#(EXT[^:]*)(?::(.*))?$/);
if (!blocks) {
throw new shaka.util.Error(
shaka.util.Error.Severity.CRITICAL,
shaka.util.Error.Category.MANIFEST,
shaka.util.Error.Code.INVALID_HLS_TAG);
}
var name = blocks[1];
var data = blocks[2];
var attributes = [];
if (data && data.indexOf('=') >= 0) {
var parser = new shaka.util.TextParser(data);
var blockAttrs;
// Regex:
// 1. Key name ([1])
// 2. Equals sign
// 3. Either:
// a. A quoted string (everything up to the next quote, [2])
// b. An unquoted string
// (everything up to the next comma or end of line, [3])
// 4. Either:
// a. A comma
// b. End of line
var regex = /([^=]+)=(?:"([^"]*)"|([^",]*))(?:,|$)/g;
while (blockAttrs = parser.readRegex(regex)) {
var attrName = blockAttrs[1];
var attrValue = blockAttrs[2] || blockAttrs[3];
var attribute = new shaka.hls.Attribute(attrName, attrValue);
attributes.push(attribute);
}
} else if (data) {
return new shaka.hls.Tag(id, name, attributes, data);
}
return new shaka.hls.Tag(id, name, attributes);
};
/**
* 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'
];