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Merge remote-tracking branch 'origin/main' into fix/better-segment-ch…
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…oice
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@brandonocasey
brandonocasey committed May 26, 2021
2 parents 2bd3f53 + 458be2c commit dd29591
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Showing 5 changed files with 2,199 additions and 1,659 deletions.
13 changes: 13 additions & 0 deletions src/manifest.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ import videojs from 'video.js';
import window from 'global/window';
import { Parser as M3u8Parser } from 'm3u8-parser';
import { resolveUrl } from './resolve-url';
import { getLastParts } from './playlist.js';

const { log } = videojs;

Expand Down Expand Up @@ -92,6 +93,18 @@ export const parseManifest = ({
manifest.targetDuration = targetDuration;
}

const parts = getLastParts(manifest);

if (parts.length && !manifest.partTargetDuration) {
const partTargetDuration = parts.reduce((acc, p) => Math.max(acc, p.duration), 0);

if (onwarn) {
onwarn(`manifest has no partTargetDuration defaulting to ${partTargetDuration}`);
log.error('LL-HLS manifest has parts but lacks required #EXT-X-PART-INF:PART-TARGET value. See https://datatracker.ietf.org/doc/html/draft-pantos-hls-rfc8216bis-09#section-4.4.3.7. Playback is not guaranteed.');
}
manifest.partTargetDuration = partTargetDuration;
}

return manifest;
};

Expand Down
246 changes: 191 additions & 55 deletions src/playlist-loader.js
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Original file line number Diff line number Diff line change
Expand Up @@ -16,9 +16,69 @@ import {
setupMediaPlaylist,
forEachMediaGroup
} from './manifest';
import {getKnownPartCount} from './playlist.js';

const { mergeOptions, EventTarget } = videojs;

const addLLHLSQueryDirectives = (uri, media) => {
if (media.endList) {
return uri;
}
const query = [];

if (media.serverControl && media.serverControl.canBlockReload) {
const {preloadSegment} = media;
// next msn is a zero based value, length is not.
let nextMSN = media.mediaSequence + media.segments.length;

// If preload segment has parts then it is likely
// that we are going to request a part of that preload segment.
// the logic below is used to determine that.
if (preloadSegment) {
const parts = preloadSegment.parts || [];
// _HLS_part is a zero based index
const nextPart = getKnownPartCount(media) - 1;

// if nextPart is > -1 and not equal to just the
// length of parts, then we know we had part preload hints
// and we need to add the _HLS_part= query
if (nextPart > -1 && nextPart !== (parts.length - 1)) {
// add existing parts to our preload hints
query.push(`_HLS_part=${nextPart}`);
}

// this if statement makes sure that we request the msn
// of the preload segment if:
// 1. the preload segment had parts (and was not yet a full segment)
// but was added to our segments array
// 2. the preload segment had preload hints for parts that are not in
// the manifest yet.
// in all other cases we want the segment after the preload segment
// which will be given by using media.segments.length because it is 1 based
// rather than 0 based.
if (nextPart > -1 || parts.length) {
nextMSN--;
}
}

// add _HLS_msn= in front of any _HLS_part query
query.unshift(`_HLS_msn=${nextMSN}`);
}

if (media.serverControl && media.serverControl.canSkipUntil) {
// add _HLS_skip= infront of all other queries.
query.unshift('_HLS_skip=' + (media.serverControl.canSkipDateranges ? 'v2' : 'YES'));
}

query.forEach(function(str, i) {
const symbol = i === 0 ? '?' : '&';

uri += `${symbol}${str}`;
});

return uri;
};

/**
* Returns a new segment object with properties and
* the parts array merged.
Expand All @@ -35,6 +95,12 @@ export const updateSegment = (a, b) => {

const result = mergeOptions(a, b);

// if only the old segment has preload hints
// and the new one does not, remove preload hints.
if (a.preloadHints && !b.preloadHints) {
delete result.preloadHints;
}

// if only the old segment has parts
// then the parts are no longer valid
if (a.parts && !b.parts) {
Expand All @@ -50,6 +116,18 @@ export const updateSegment = (a, b) => {
}
}

// set skipped to false for segments that have
// have had information merged from the old segment.
if (!a.skipped && b.skipped) {
result.skipped = false;
}

// set preload to false for segments that have
// had information added in the new segment.
if (a.preload && !b.preload) {
result.preload = false;
}

return result;
};

Expand All @@ -70,15 +148,30 @@ export const updateSegment = (a, b) => {
*/
export const updateSegments = (original, update, offset) => {
const oldSegments = original.slice();
const result = update.slice();
const newSegments = update.slice();

offset = offset || 0;
const length = Math.min(original.length, update.length + offset);
const result = [];

let currentMap;

for (let newIndex = 0; newIndex < newSegments.length; newIndex++) {
const oldSegment = oldSegments[newIndex + offset];
const newSegment = newSegments[newIndex];

if (oldSegment) {
currentMap = oldSegment.map || currentMap;

result.push(updateSegment(oldSegment, newSegment));
} else {
// carry over map to new segment if it is missing
if (currentMap && !newSegment.map) {
newSegment.map = currentMap;
}

for (let i = offset; i < length; i++) {
const newIndex = i - offset;
result.push(newSegment);

result[newIndex] = updateSegment(oldSegments[i], result[newIndex]);
}
}
return result;
};
Expand Down Expand Up @@ -116,12 +209,27 @@ export const resolveSegmentUris = (segment, baseUri) => {

const getAllSegments = function(media) {
const segments = media.segments || [];
const preloadSegment = media.preloadSegment;

// a preloadSegment with only preloadHints is not currently
// a usable segment, only include a preloadSegment that has
// parts.
if (media.preloadSegment && media.preloadSegment.parts) {
segments.push(media.preloadSegment);
if (preloadSegment && preloadSegment.parts && preloadSegment.parts.length) {
// if preloadHints has a MAP that means that the
// init segment is going to change. We cannot use any of the parts
// from this preload segment.
if (preloadSegment.preloadHints) {
for (let i = 0; i < preloadSegment.preloadHints.length; i++) {
if (preloadSegment.preloadHints[i].type === 'MAP') {
return segments;
}
}
}
// set the duration for our preload segment to target duration.
preloadSegment.duration = media.targetDuration;
preloadSegment.preload = true;

segments.push(preloadSegment);
}

return segments;
Expand All @@ -147,28 +255,41 @@ export const isPlaylistUnchanged = (a, b) => a === b ||
* master playlist with the updated media playlist merged in, or
* null if the merge produced no change.
*/
export const updateMaster = (master, media, unchangedCheck = isPlaylistUnchanged) => {
export const updateMaster = (master, newMedia, unchangedCheck = isPlaylistUnchanged) => {
const result = mergeOptions(master, {});
const playlist = result.playlists[media.id];
const oldMedia = result.playlists[newMedia.id];

if (!playlist) {
if (!oldMedia) {
return null;
}

if (unchangedCheck(playlist, media)) {
if (unchangedCheck(oldMedia, newMedia)) {
return null;
}

const mergedPlaylist = mergeOptions(playlist, media);
newMedia.segments = getAllSegments(newMedia);

const mergedPlaylist = mergeOptions(oldMedia, newMedia);

media.segments = getAllSegments(media);
// always use the new media's preload segment
if (mergedPlaylist.preloadSegment && !newMedia.preloadSegment) {
delete mergedPlaylist.preloadSegment;
}

// if the update could overlap existing segment information, merge the two segment lists
if (playlist.segments) {
if (oldMedia.segments) {
if (newMedia.skip) {
newMedia.segments = newMedia.segments || [];
// add back in objects for skipped segments, so that we merge
// old properties into the new segments
for (let i = 0; i < newMedia.skip.skippedSegments; i++) {
newMedia.segments.unshift({skipped: true});
}
}
mergedPlaylist.segments = updateSegments(
playlist.segments,
media.segments,
media.mediaSequence - playlist.mediaSequence
oldMedia.segments,
newMedia.segments,
newMedia.mediaSequence - oldMedia.mediaSequence
);
}

Expand All @@ -181,22 +302,22 @@ export const updateMaster = (master, media, unchangedCheck = isPlaylistUnchanged
// that is referenced by index, and one by URI. The index reference may no longer be
// necessary.
for (let i = 0; i < result.playlists.length; i++) {
if (result.playlists[i].id === media.id) {
if (result.playlists[i].id === newMedia.id) {
result.playlists[i] = mergedPlaylist;
}
}
result.playlists[media.id] = mergedPlaylist;
result.playlists[newMedia.id] = mergedPlaylist;
// URI reference added for backwards compatibility
result.playlists[media.uri] = mergedPlaylist;
result.playlists[newMedia.uri] = mergedPlaylist;

// update media group playlist references.
forEachMediaGroup(master, (properties, mediaType, groupKey, labelKey) => {
if (!properties.playlists) {
return;
}
for (let i = 0; i < properties.playlists.length; i++) {
if (media.id === properties.playlists[i].id) {
properties.playlists[i] = media;
if (newMedia.id === properties.playlists[i].id) {
properties.playlists[i] = newMedia;
}
}
});
Expand Down Expand Up @@ -263,34 +384,44 @@ export default class PlaylistLoader extends EventTarget {
this.state = 'HAVE_NOTHING';

// live playlist staleness timeout
this.on('mediaupdatetimeout', () => {
if (this.state !== 'HAVE_METADATA') {
// only refresh the media playlist if no other activity is going on
return;
}
this.handleMediaupdatetimeout_ = this.handleMediaupdatetimeout_.bind(this);
this.on('mediaupdatetimeout', this.handleMediaupdatetimeout_);
}

this.state = 'HAVE_CURRENT_METADATA';
handleMediaupdatetimeout_() {
if (this.state !== 'HAVE_METADATA') {
// only refresh the media playlist if no other activity is going on
return;
}
const media = this.media();

this.request = this.vhs_.xhr({
uri: resolveUrl(this.master.uri, this.media().uri),
withCredentials: this.withCredentials
}, (error, req) => {
// disposed
if (!this.request) {
return;
}
let uri = resolveUrl(this.master.uri, media.uri);

if (error) {
return this.playlistRequestError(this.request, this.media(), 'HAVE_METADATA');
}
if (this.experimentalLLHLS) {
uri = addLLHLSQueryDirectives(uri, media);
}
this.state = 'HAVE_CURRENT_METADATA';

this.haveMetadata({
playlistString: this.request.responseText,
url: this.media().uri,
id: this.media().id
});
this.request = this.vhs_.xhr({
uri,
withCredentials: this.withCredentials
}, (error, req) => {
// disposed
if (!this.request) {
return;
}

if (error) {
return this.playlistRequestError(this.request, this.media(), 'HAVE_METADATA');
}

this.haveMetadata({
playlistString: this.request.responseText,
url: this.media().uri,
id: this.media().id
});
});

}

playlistRequestError(xhr, playlist, startingState) {
Expand All @@ -317,6 +448,17 @@ export default class PlaylistLoader extends EventTarget {
this.trigger('error');
}

parseManifest_({url, manifestString}) {
return parseManifest({
onwarn: ({message}) => this.logger_(`m3u8-parser warn for ${url}: ${message}`),
oninfo: ({message}) => this.logger_(`m3u8-parser info for ${url}: ${message}`),
manifestString,
customTagParsers: this.customTagParsers,
customTagMappers: this.customTagMappers,
experimentalLLHLS: this.experimentalLLHLS
});
}

/**
* Update the playlist loader's state in response to a new or updated playlist.
*
Expand All @@ -334,13 +476,9 @@ export default class PlaylistLoader extends EventTarget {
this.request = null;
this.state = 'HAVE_METADATA';

const playlist = playlistObject || parseManifest({
onwarn: ({message}) => this.logger_(`m3u8-parser warn for ${id}: ${message}`),
oninfo: ({message}) => this.logger_(`m3u8-parser info for ${id}: ${message}`),
manifestString: playlistString,
customTagParsers: this.customTagParsers,
customTagMappers: this.customTagMappers,
experimentalLLHLS: this.experimentalLLHLS
const playlist = playlistObject || this.parseManifest_({
url,
manifestString: playlistString
});

playlist.lastRequest = Date.now();
Expand Down Expand Up @@ -647,11 +785,9 @@ export default class PlaylistLoader extends EventTarget {

this.src = resolveManifestRedirect(this.handleManifestRedirects, this.src, req);

const manifest = parseManifest({
const manifest = this.parseManifest_({
manifestString: req.responseText,
customTagParsers: this.customTagParsers,
customTagMappers: this.customTagMappers,
experimentalLLHLS: this.experimentalLLHLS
url: this.src
});

this.setupInitialPlaylist(manifest);
Expand Down
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