Fix: In-manifest VTT iOS MSE issue (#1360)

* fix: Add exception guard for VTT parsing state if vtt.js is not loaded for any reasons. * fix: Do not override native for all iOS/iPadOS browsers * fix: Add guard for vtt-segment-loader to actually load vtt.js in case we do not have it loaded * chore: fix eslit errors * chore: Add loadVttJs test * chore: Add test for parse exception if no vtt.js is loaded for any reason Co-authored-by: Dzianis Dashkevich <ddashkevich@brightcove.com>
videojs · Jan 24, 2023 · 6ba70e0 · 6ba70e0
1 parent d7e8713
commit 6ba70e0
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Showing 6 changed files with 165 additions and 70 deletions.
diff --git a/src/playlist-controller.js b/src/playlist-controller.js
@@ -283,7 +283,24 @@ export class PlaylistController extends videojs.EventTarget {
     this.subtitleSegmentLoader_ =
       new VTTSegmentLoader(merge(segmentLoaderSettings, {
         loaderType: 'vtt',
-        featuresNativeTextTracks: this.tech_.featuresNativeTextTracks
+        featuresNativeTextTracks: this.tech_.featuresNativeTextTracks,
+        loadVttJs: () => new Promise((resolve, reject) => {
+          function onLoad() {
+            tech.off('vttjserror', onError);
+            resolve();
+          }
+
+          function onError() {
+            tech.off('vttjsloaded', onLoad);
+            reject();
+          }
+
+          tech.one('vttjsloaded', onLoad);
+          tech.one('vttjserror', onError);
+
+          // safe to call multiple times, script will be loaded only once:
+          tech.addWebVttScript_();
+        })
       }), options);
 
     this.setupSegmentLoaderListeners_();

diff --git a/src/videojs-http-streaming.js b/src/videojs-http-streaming.js
@@ -1223,16 +1223,25 @@ const VhsSourceHandler = {
     tech.vhs.src(source.src, source.type);
     return tech.vhs;
   },
-  canPlayType(type, options = {}) {
-    const {
-      vhs: { overrideNative = !videojs.browser.IS_ANY_SAFARI } = {}
-    } = merge(videojs.options, options);
+  canPlayType(type, options) {
+    const simpleType = simpleTypeFromSourceType(type);
 
-    const supportedType = simpleTypeFromSourceType(type);
-    const canUseMsePlayback = supportedType &&
-      (!Vhs.supportsTypeNatively(supportedType) || overrideNative);
+    if (!simpleType) {
+      return '';
+    }
+
+    const overrideNative = VhsSourceHandler.getOverrideNative(options);
+    const supportsTypeNatively = Vhs.supportsTypeNatively(simpleType);
+    const canUseMsePlayback = !supportsTypeNatively || overrideNative;
 
     return canUseMsePlayback ? 'maybe' : '';
+  },
+  getOverrideNative(options = {}) {
+    const { vhs = {} } = options;
+    const defaultOverrideNative = !(videojs.browser.IS_ANY_SAFARI || videojs.browser.IS_IOS);
+    const { overrideNative = defaultOverrideNative } = vhs;
+
+    return overrideNative;
   }
 };
 

diff --git a/src/vtt-segment-loader.js b/src/vtt-segment-loader.js
@@ -14,6 +14,12 @@ import {createTimeRanges} from './util/vjs-compat';
 const VTT_LINE_TERMINATORS =
   new Uint8Array('\n\n'.split('').map(char => char.charCodeAt(0)));
 
+class NoVttJsError extends Error {
+  constructor() {
+    super('Trying to parse received VTT cues, but there is no WebVTT. Make sure vtt.js is loaded.');
+  }
+}
+
 /**
  * An object that manages segment loading and appending.
  *
@@ -35,6 +41,8 @@ export default class VTTSegmentLoader extends SegmentLoader {
 
     this.featuresNativeTextTracks_ = settings.featuresNativeTextTracks;
 
+    this.loadVttJs = settings.loadVttJs;
+
     // The VTT segment will have its own time mappings. Saving VTT segment timing info in
     // the sync controller leads to improper behavior.
     this.shouldSaveSegmentTimingInfo_ = false;
@@ -298,29 +306,16 @@ export default class VTTSegmentLoader extends SegmentLoader {
     }
     segmentInfo.bytes = simpleSegment.bytes;
 
-    // Make sure that vttjs has loaded, otherwise, wait till it finished loading
-    if (typeof window.WebVTT !== 'function' &&
-        this.subtitlesTrack_ &&
-        this.subtitlesTrack_.tech_) {
-
-      let loadHandler;
-      const errorHandler = () => {
-        this.subtitlesTrack_.tech_.off('vttjsloaded', loadHandler);
-        this.stopForError({
-          message: 'Error loading vtt.js'
-        });
-        return;
-      };
-
-      loadHandler = () => {
-        this.subtitlesTrack_.tech_.off('vttjserror', errorHandler);
-        this.segmentRequestFinished_(error, simpleSegment, result);
-      };
-
+    // Make sure that vttjs has loaded, otherwise, load it and wait till it finished loading
+    if (typeof window.WebVTT !== 'function' && typeof this.loadVttJs === 'function') {
       this.state = 'WAITING_ON_VTTJS';
-      this.subtitlesTrack_.tech_.one('vttjsloaded', loadHandler);
-      this.subtitlesTrack_.tech_.one('vttjserror', errorHandler);
-
+      // should be fine to call multiple times
+      // script will be loaded once but multiple listeners will be added to the queue, which is expected.
+      this.loadVttJs()
+        .then(
+          () => this.segmentRequestFinished_(error, simpleSegment, result),
+          () => this.stopForError({ message: 'Error loading vtt.js' })
+        );
       return;
     }
 
@@ -392,6 +387,8 @@ export default class VTTSegmentLoader extends SegmentLoader {
   /**
    * Uses the WebVTT parser to parse the segment response
    *
+   * @throws NoVttJsError
+   *
    * @param {Object} segmentInfo
    *        a segment info object that describes the current segment
    * @private
@@ -400,6 +397,11 @@ export default class VTTSegmentLoader extends SegmentLoader {
     let decoder;
     let decodeBytesToString = false;
 
+    if (typeof window.WebVTT !== 'function') {
+      // caller is responsible for exception handling.
+      throw new NoVttJsError();
+    }
+
     if (typeof window.TextDecoder === 'function') {
       decoder = new window.TextDecoder('utf8');
     } else {

diff --git a/test/playlist-controller.test.js b/test/playlist-controller.test.js
@@ -1,4 +1,5 @@
 import QUnit from 'qunit';
+import sinon from 'sinon';
 import videojs from 'video.js';
 import window from 'global/window';
 import {
@@ -591,6 +592,24 @@ QUnit.test('resets everything for a fast quality change', function(assert) {
   assert.deepEqual(removeFuncArgs, {start: 0, end: 60}, 'remove() called with correct arguments if media is changed');
 });
 
+QUnit.test('loadVttJs should be passed to the vttSegmentLoader and resolved on vttjsloaded', function(assert) {
+  const stub = sinon.stub(this.player.tech_, 'addWebVttScript_').callsFake(() => this.player.tech_.trigger('vttjsloaded'));
+  const controller = new PlaylistController({ src: 'test', tech: this.player.tech_});
+
+  controller.subtitleSegmentLoader_.loadVttJs().then(() => {
+    assert.equal(stub.callCount, 1, 'tech addWebVttScript called once');
+  });
+});
+
+QUnit.test('loadVttJs should be passed to the vttSegmentLoader and rejected on vttjserror', function(assert) {
+  const stub = sinon.stub(this.player.tech_, 'addWebVttScript_').callsFake(() => this.player.tech_.trigger('vttjserror'));
+  const controller = new PlaylistController({ src: 'test', tech: this.player.tech_});
+
+  controller.subtitleSegmentLoader_.loadVttJs().catch(() => {
+    assert.equal(stub.callCount, 1, 'tech addWebVttScript called once');
+  });
+});
+
 QUnit.test('seeks in place for fast quality switch on non-IE/Edge browsers', function(assert) {
   let seeks = 0;
 

diff --git a/test/videojs-http-streaming.test.js b/test/videojs-http-streaming.test.js
@@ -2980,12 +2980,14 @@ QUnit.test('has no effect if native HLS is available and browser is Safari', fun
   videojs.browser.IS_ANY_SAFARI = origIsAnySafari;
 });
 
-QUnit.test('loads if native HLS is available but browser is not Safari', function(assert) {
+QUnit.test('has no effect if native HLS is available and browser is any non-safari browser on ios', function(assert) {
   const Html5 = videojs.getTech('Html5');
   const oldHtml5CanPlaySource = Html5.canPlaySource;
   const origIsAnySafari = videojs.browser.IS_ANY_SAFARI;
+  const originalIsIos = videojs.browser.IS_IOS;
 
   videojs.browser.IS_ANY_SAFARI = false;
+  videojs.browser.IS_IOS = true;
   Html5.canPlaySource = () => true;
   Vhs.supportsNativeHls = true;
   const player = createPlayer();
@@ -2997,10 +2999,11 @@ QUnit.test('loads if native HLS is available but browser is not Safari', functio
 
   this.clock.tick(1);
 
-  assert.ok(player.tech_.vhs, 'loaded VHS tech');
+  assert.ok(!player.tech_.vhs, 'did not load vhs tech');
   player.dispose();
   Html5.canPlaySource = oldHtml5CanPlaySource;
   videojs.browser.IS_ANY_SAFARI = origIsAnySafari;
+  videojs.browser.IS_IOS = originalIsIos;
 });
 
 QUnit.test(

diff --git a/test/vtt-segment-loader.test.js b/test/vtt-segment-loader.test.js
@@ -12,6 +12,7 @@ import {
 } from './loader-common.js';
 import { encryptionKey, subtitlesEncrypted } from 'create-test-data!segments';
 import {merge, createTimeRanges} from '../src/util/vjs-compat';
+import sinon from 'sinon';
 
 const oldVTT = window.WebVTT;
 
@@ -308,6 +309,19 @@ QUnit.module('VTTSegmentLoader', function(hooks) {
     QUnit.test(
       'waits for vtt.js to be loaded before attempting to parse cues',
       function(assert) {
+        let promiseLoadVttJs; let resolveLoadVttJs;
+
+        loader = new VTTSegmentLoader(LoaderCommonSettings.call(this, {
+          loaderType: 'vtt',
+          loadVttJs: () => {
+            promiseLoadVttJs = new Promise((resolve) => {
+              resolveLoadVttJs = resolve;
+            });
+
+            return promiseLoadVttJs;
+          }
+        }), {});
+
         const vttjs = window.WebVTT;
         const playlist = playlistWithDuration(40);
         let parsedCues = false;
@@ -319,22 +333,6 @@ QUnit.module('VTTSegmentLoader', function(hooks) {
           loader.state = 'READY';
         };
 
-        let vttjsCallback = () => {};
-
-        this.track.tech_ = {
-          one(event, callback) {
-            if (event === 'vttjsloaded') {
-              vttjsCallback = callback;
-            }
-          },
-          trigger(event) {
-            if (event === 'vttjsloaded') {
-              vttjsCallback();
-            }
-          },
-          off() {}
-        };
-
         loader.playlist(playlist);
         loader.track(this.track);
         loader.load();
@@ -361,10 +359,58 @@ QUnit.module('VTTSegmentLoader', function(hooks) {
 
         window.WebVTT = vttjs;
 
-        loader.subtitlesTrack_.tech_.trigger('vttjsloaded');
+        promiseLoadVttJs.then(() => {
+          assert.equal(loader.state, 'READY', 'loader is ready to load next segment');
+          assert.ok(parsedCues, 'parsed cues');
+        });
 
-        assert.equal(loader.state, 'READY', 'loader is ready to load next segment');
-        assert.ok(parsedCues, 'parsed cues');
+        resolveLoadVttJs();
+      }
+    );
+
+    QUnit.test(
+      'parse should throw if no vtt.js is loaded for any reason',
+      function(assert) {
+        const vttjs = window.WebVTT;
+        const playlist = playlistWithDuration(40);
+        let errors = 0;
+
+        const originalParse = loader.parseVTTCues_.bind(loader);
+
+        loader.parseVTTCues_ = (...args) => {
+          delete window.WebVTT;
+          return originalParse(...args);
+        };
+
+        const spy = sinon.spy(loader, 'error');
+
+        loader.on('error', () => errors++);
+
+        loader.playlist(playlist);
+        loader.track(this.track);
+        loader.load();
+
+        assert.equal(errors, 0, 'no error at loader start');
+
+        this.clock.tick(1);
+
+        // state WAITING for segment response
+        this.requests[0].responseType = 'arraybuffer';
+        this.requests.shift().respond(200, null, new Uint8Array(10).buffer);
+
+        this.clock.tick(1);
+
+        assert.equal(errors, 1, 'triggered error when parser emmitts fatal error');
+        assert.ok(loader.paused(), 'loader paused when encountering fatal error');
+        assert.equal(loader.state, 'READY', 'loader reset after error');
+        assert.ok(
+          spy.withArgs(sinon.match({
+            message: 'Trying to parse received VTT cues, but there is no WebVTT. Make sure vtt.js is loaded.'
+          })).calledOnce,
+          'error method called once with instance of NoVttJsError'
+        );
+
+        window.WebVTT = vttjs;
       }
     );
 
@@ -748,25 +794,22 @@ QUnit.module('VTTSegmentLoader', function(hooks) {
     });
 
     QUnit.test('loader triggers error event when vtt.js fails to load', function(assert) {
+      let promiseLoadVttJs; let rejectLoadVttJs;
+
+      loader = new VTTSegmentLoader(LoaderCommonSettings.call(this, {
+        loaderType: 'vtt',
+        loadVttJs: () => {
+          promiseLoadVttJs = new Promise((resolve, reject) => {
+            rejectLoadVttJs = reject;
+          });
+
+          return promiseLoadVttJs;
+        }
+      }), {});
       const playlist = playlistWithDuration(40);
       let errors = 0;
 
       delete window.WebVTT;
-      let vttjsCallback = () => {};
-
-      this.track.tech_ = {
-        one(event, callback) {
-          if (event === 'vttjserror') {
-            vttjsCallback = callback;
-          }
-        },
-        trigger(event) {
-          if (event === 'vttjserror') {
-            vttjsCallback();
-          }
-        },
-        off() {}
-      };
 
       loader.on('error', () => errors++);
 
@@ -794,11 +837,13 @@ QUnit.module('VTTSegmentLoader', function(hooks) {
       );
       assert.equal(errors, 0, 'no errors yet');
 
-      loader.subtitlesTrack_.tech_.trigger('vttjserror');
+      promiseLoadVttJs.catch(() => {
+        assert.equal(loader.state, 'READY', 'loader is reset to ready');
+        assert.ok(loader.paused(), 'loader is paused after error');
+        assert.equal(errors, 1, 'loader triggered error when vtt.js load triggers error');
+      });
 
-      assert.equal(loader.state, 'READY', 'loader is reset to ready');
-      assert.ok(loader.paused(), 'loader is paused after error');
-      assert.equal(errors, 1, 'loader triggered error when vtt.js load triggers error');
+      rejectLoadVttJs();
     });
 
     QUnit.test('does not save segment timing info', function(assert) {