feat(playback watcher): Configurable live seekable window (#997)

README.md

@@ -55,6 +55,7 @@ Video.js Compatibility: 6.0, 7.0
  - [customTagMappers](#customtagmappers)
  - [cacheEncryptionKeys](#cacheencryptionkeys)
  - [handlePartialData](#handlepartialdata)
+ - [liveRangeSafeTimeDelta](#liverangesafetimedelta)
  - [Runtime Properties](#runtime-properties)
  - [vhs.playlists.master](#vhsplaylistsmaster)
  - [vhs.playlists.media](#vhsplaylistsmedia)
@@ -451,6 +452,11 @@ This option defaults to `false`.
 * Default: `false`
 * Use partial appends in the transmuxer and segment loader
 
+##### liveRangeSafeTimeDelta
+* Type: `number`,
+* Default: [`SAFE_TIME_DELTA`](https://github.com/videojs/http-streaming/blob/e7cb63af010779108336eddb5c8fd138d6390e95/src/ranges.js#L17)
+* Allow to re-define length (in seconds) of time delta when you compare current time and the end of the buffered range.
+
 ### Runtime Properties
 Runtime properties are attached to the tech object when HLS is in
 use. You can get a reference to the VHS source handler like this:

src/playback-watcher.js

@@ -75,6 +75,7 @@ export default class PlaybackWatcher {
  this.tech_ = options.tech;
  this.seekable = options.seekable;
  this.allowSeeksWithinUnsafeLiveWindow = options.allowSeeksWithinUnsafeLiveWindow;
+ this.liveRangeSafeTimeDelta = options.liveRangeSafeTimeDelta;
  this.media = options.media;
 
  this.consecutiveUpdates = 0;
@@ -502,7 +503,7 @@ export default class PlaybackWatcher {
  if (seekable.length &&
  // can't fall before 0 and 0 seekable start identifies VOD stream
  seekable.start(0) > 0 &&
- currentTime < seekable.start(0) - Ranges.SAFE_TIME_DELTA) {
+ currentTime < seekable.start(0) - this.liveRangeSafeTimeDelta) {
  return true;
  }
 

src/videojs-http-streaming.js

@@ -32,6 +32,7 @@ import {
 } from './playlist-selectors.js';
 import {isAudioCodec, isVideoCodec, browserSupportsCodec} from '@videojs/vhs-utils/dist/codecs.js';
 import logger from './util/logger';
+import {SAFE_TIME_DELTA} from './ranges';
 
 // IMPORTANT:
 // keep these at the bottom they are replaced at build time
@@ -673,7 +674,8 @@ class VhsHandler extends Component {
  'handlePartialData',
  'playlistSelector',
  'initialPlaylistSelector',
- 'experimentalBufferBasedABR'
+ 'experimentalBufferBasedABR',
+ 'liveRangeSafeTimeDelta'
  ].forEach((option) => {
  if (typeof this.source_[option] !== 'undefined') {
  this.options_[option] = this.source_[option];
@@ -706,11 +708,20 @@ class VhsHandler extends Component {
  };
 
  this.masterPlaylistController_ = new MasterPlaylistController(this.options_);
- this.playbackWatcher_ = new PlaybackWatcher(videojs.mergeOptions(this.options_, {
- seekable: () => this.seekable(),
- media: () => this.masterPlaylistController_.media(),
- masterPlaylistController: this.masterPlaylistController_
- }));
+
+ const playbackWatcherOptions = videojs.mergeOptions(
+ {
+ liveRangeSafeTimeDelta: SAFE_TIME_DELTA
+ },
+ this.options_,
+ {
+ seekable: () => this.seekable(),
+ media: () => this.masterPlaylistController_.media(),
+ masterPlaylistController: this.masterPlaylistController_
+ }
+ );
+
+ this.playbackWatcher_ = new PlaybackWatcher(playbackWatcherOptions);
 
  this.masterPlaylistController_.on('error', () => {
  const player = videojs.players[this.tech_.options_.playerId];

test/playback-watcher.test.js

@@ -13,6 +13,7 @@ import {
 } from '../src/playback-watcher';
 // needed for plugin registration
 import '../src/videojs-http-streaming';
+import { SAFE_TIME_DELTA } from '../src/ranges';
 
 let monitorCurrentTime_;
 
@@ -1184,6 +1185,8 @@ QUnit.test('skips gap from muxed video underflow', function(assert) {
 });
 
 QUnit.test('detects live window falloff', function(assert) {
+ this.playbackWatcher.liveRangeSafeTimeDelta = SAFE_TIME_DELTA;
+
  const beforeSeekableWindow_ =
  this.playbackWatcher.beforeSeekableWindow_.bind(this.playbackWatcher);
 
@@ -1222,6 +1225,23 @@ QUnit.test('detects live window falloff', function(assert) {
  );
 });
 
+QUnit.test('respects liveRangeSafeTimeDelta flag', function(assert) {
+ this.playbackWatcher.liveRangeSafeTimeDelta = 1;
+
+ const beforeSeekableWindow_ =
+ this.playbackWatcher.beforeSeekableWindow_.bind(this.playbackWatcher);
+
+ assert.ok(
+ beforeSeekableWindow_(videojs.createTimeRanges([[12, 20]]), 10),
+ 'true if playlist live and current time before seekable'
+ );
+
+ assert.ok(
+ !beforeSeekableWindow_(videojs.createTimeRanges([]), 10),
+ 'false if no seekable range'
+ );
+});
+
 QUnit.test('detects beyond seekable window for VOD', function(assert) {
  const playlist = {
  endList: true,