From 85b6d5fd4c11a4949a6e7e813cabe185b464ab6a Mon Sep 17 00:00:00 2001
From: Alvaro Velad Galvan <ladvan91@hotmail.com>
Date: Tue, 18 Apr 2023 19:27:19 +0200
Subject: [PATCH] fix(HLS): Fix support of fragmented WebVTT

---
 lib/hls/hls_parser.js         | 13 +++++++---
 lib/media/streaming_engine.js |  9 ++++++-
 test/hls/hls_parser_unit.js   | 45 +++++++++++++++++++++++++++++++++++
 3 files changed, 63 insertions(+), 4 deletions(-)

diff --git a/lib/hls/hls_parser.js b/lib/hls/hls_parser.js
index 33dd090c99..26a86b6492 100644
--- a/lib/hls/hls_parser.js
+++ b/lib/hls/hls_parser.js
@@ -1729,9 +1729,9 @@ shaka.hls.HlsParser = class {
     let codecs = '';
     /** @type {string} */
     const type = this.getType_(tag);
-    // Text does not require a codec.
-    if (type != shaka.util.ManifestParserUtils.ContentType.TEXT && groupId &&
-        this.groupIdToCodecsMap_.has(groupId)) {
+    if (type == shaka.util.ManifestParserUtils.ContentType.TEXT) {
+      codecs = tag.getAttributeValue('CODECS') || '';
+    } else if (groupId && this.groupIdToCodecsMap_.has(groupId)) {
       codecs = this.groupIdToCodecsMap_.get(groupId);
     }
 
@@ -2007,6 +2007,13 @@ shaka.hls.HlsParser = class {
         }
       }
 
+      if (type == ContentType.TEXT) {
+        const firstSegment = realStream.segmentIndex.get(0);
+        if (firstSegment && firstSegment.initSegmentReference) {
+          stream.mimeType = 'application/mp4';
+        }
+      }
+
       // Add finishing touches to the stream that can only be done once we have
       // more full context on the media as a whole.
       if (this.hasEnoughInfoToFinalizeStreams_()) {
diff --git a/lib/media/streaming_engine.js b/lib/media/streaming_engine.js
index a8bf25a448..832ab9c3b2 100644
--- a/lib/media/streaming_engine.js
+++ b/lib/media/streaming_engine.js
@@ -378,7 +378,7 @@ shaka.media.StreamingEngine = class {
   /**
    * @param {shaka.extern.Stream} textStream
    */
-  switchTextStream(textStream) {
+  async switchTextStream(textStream) {
     this.currentTextStream_ = textStream;
 
     if (!this.startupComplete_) {
@@ -390,6 +390,13 @@ shaka.media.StreamingEngine = class {
     goog.asserts.assert(textStream && textStream.type == ContentType.TEXT,
         'Wrong stream type passed to switchTextStream!');
 
+    // In HLS it is possible that the mimetype changes when the media
+    // playlist is downloaded, so it is necessary to have the updated data
+    // here.
+    if (!textStream.segmentIndex) {
+      await textStream.createSegmentIndex();
+    }
+
     this.switchInternal_(
         textStream, /* clearBuffer= */ true,
         /* safeMargin= */ 0, /* force= */ false);
diff --git a/test/hls/hls_parser_unit.js b/test/hls/hls_parser_unit.js
index f8a0974181..3eab6a30d8 100644
--- a/test/hls/hls_parser_unit.js
+++ b/test/hls/hls_parser_unit.js
@@ -2263,6 +2263,51 @@ describe('HlsParser', () => {
     expect(actual).toEqual(manifest);
   });
 
+  it('parses manifest with MP4+WEBVTT streams', async () => {
+    const master = [
+      '#EXTM3U\n',
+      '#EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="sub1",LANGUAGE="eng",',
+      'CODECS="wvtt",URI="text"\n',
+      '#EXT-X-STREAM-INF:BANDWIDTH=200,CODECS="avc1",',
+      'RESOLUTION=960x540,FRAME-RATE=60,SUBTITLES="sub1"\n',
+      'video\n',
+    ].join('');
+
+    const media = [
+      '#EXTM3U\n',
+      '#EXT-X-PLAYLIST-TYPE:VOD\n',
+      '#EXT-X-MAP:URI="init.mp4",BYTERANGE="616@0"\n',
+      '#EXTINF:5,\n',
+      '#EXT-X-BYTERANGE:121090@616\n',
+      'main.mp4',
+    ].join('');
+
+    const manifest = shaka.test.ManifestGenerator.generate((manifest) => {
+      manifest.anyTimeline();
+      manifest.addPartialVariant((variant) => {
+        variant.addPartialStream(ContentType.VIDEO);
+      });
+      manifest.addPartialTextStream((stream) => {
+        stream.language = 'en';
+        stream.mime('application/mp4', 'wvtt');
+      });
+      manifest.sequenceMode = sequenceMode;
+      manifest.type = shaka.media.ManifestParser.HLS;
+    });
+
+    fakeNetEngine
+        .setResponseText('test:/master', master)
+        .setResponseText('test:/audio', media)
+        .setResponseText('test:/video', media)
+        .setResponseText('test:/text', media)
+        .setResponseValue('test:/init.mp4', initSegmentData)
+        .setResponseValue('test:/main.mp4', segmentData);
+
+    const actual = await parser.start('test:/master', playerInterface);
+    await loadAllStreamsFor(actual);
+    expect(actual).toEqual(manifest);
+  });
+
   it('detects VTT streams by codec', async () => {
     const master = [
       '#EXTM3U\n',