From 77140991f10885b0169495c29300ea35b04ad511 Mon Sep 17 00:00:00 2001
From: "Suraj kumar (sk)" <71056993+surajkumar-sk@users.noreply.github.com>
Date: Wed, 14 Apr 2021 02:26:02 +0530
Subject: [PATCH] fix(hls): Assume MP4 if MIME type can't be deduced (#3325)

Fixes #3142
---
 lib/hls/hls_parser.js       |  9 +++---
 lib/util/error.js           |  6 +---
 test/hls/hls_parser_unit.js | 64 ++++++++++++++++++++++---------------
 3 files changed, 43 insertions(+), 36 deletions(-)

diff --git a/lib/hls/hls_parser.js b/lib/hls/hls_parser.js
index 11f212ef40..8cdc1c955f 100644
--- a/lib/hls/hls_parser.js
+++ b/lib/hls/hls_parser.js
@@ -2414,11 +2414,10 @@ shaka.hls.HlsParser = class {
     const contentMimeType = response.headers['content-type'];
 
     if (!contentMimeType) {
-      throw new shaka.util.Error(
-          shaka.util.Error.Severity.CRITICAL,
-          shaka.util.Error.Category.MANIFEST,
-          shaka.util.Error.Code.HLS_COULD_NOT_GUESS_MIME_TYPE,
-          extension);
+      // if the HLS content is lacking in both MIME type metadata and
+      // segment file extensions we fall back to assuming its MP4.
+      const fallbackMimeType = map['mp4'];
+      return fallbackMimeType;
     }
 
     // Split the MIME type in case the server sent additional parameters.
diff --git a/lib/util/error.js b/lib/util/error.js
index 37d4b2b5e0..1624c16d02 100644
--- a/lib/util/error.js
+++ b/lib/util/error.js
@@ -582,11 +582,7 @@ shaka.util.Error.Code = {
    */
   'HLS_MULTIPLE_MEDIA_INIT_SECTIONS_FOUND': 4020,
 
-  /**
-   * HLS parser was unable to guess mime type of a stream.
-   * <br> error.data[0] is the stream file's extension.
-   */
-  'HLS_COULD_NOT_GUESS_MIME_TYPE': 4021,
+  // RETIRED: 'HLS_COULD_NOT_GUESS_MIME_TYPE': 4021,
 
   /**
    * No Master Playlist has been provided. Master playlist provides
diff --git a/test/hls/hls_parser_unit.js b/test/hls/hls_parser_unit.js
index dddec76d3c..43c6cd46fc 100644
--- a/test/hls/hls_parser_unit.js
+++ b/test/hls/hls_parser_unit.js
@@ -1935,6 +1935,44 @@ describe('HlsParser', () => {
     await testHlsParser(master, media, manifest);
   });
 
+  it('falls back to mp4 if HEAD request fails', async () => {
+    const master = [
+      '#EXTM3U\n',
+      '#EXT-X-STREAM-INF:BANDWIDTH=200,CODECS="avc1,mp4a",',
+      'RESOLUTION=960x540,FRAME-RATE=60,VIDEO="vid"\n',
+      'audio\n',
+      '#EXT-X-MEDIA:TYPE=VIDEO,GROUP-ID="vid",URI="video"',
+    ].join('');
+
+    const media = [
+      '#EXTM3U\n',
+      '#EXT-X-MAP:URI="init.mp4",BYTERANGE="616@0"\n',
+      '#EXT-X-PLAYLIST-TYPE:VOD\n',
+      '#EXTINF:5,\n',
+      '#EXT-X-BYTERANGE:121090@616\n',
+      'main.test',
+    ].join('');
+
+    const manifest = shaka.test.ManifestGenerator.generate((manifest) => {
+      manifest.anyTimeline();
+      manifest.addPartialVariant((variant) => {
+        variant.addPartialStream(ContentType.VIDEO, (stream) => {
+          stream.mime('video/mp4', 'avc1');
+        });
+        variant.addPartialStream(ContentType.AUDIO, (stream) => {
+          stream.mime('audio/mp4', 'mp4a');
+        });
+      });
+    });
+
+    fakeNetEngine.setHeaders(
+        'test:/main.test', {
+          'content-type': '',
+        });
+
+    await testHlsParser(master, media, manifest);
+  });
+
   describe('Errors out', () => {
     const Code = shaka.util.Error.Code;
 
@@ -1956,32 +1994,6 @@ describe('HlsParser', () => {
           .toBeRejectedWith(Util.jasmineError(error));
     }
 
-    it('if unable to guess mime type', async () => {
-      const master = [
-        '#EXTM3U\n',
-        '#EXT-X-STREAM-INF:BANDWIDTH=200,CODECS="avc1,mp4a",',
-        'RESOLUTION=960x540,FRAME-RATE=60,VIDEO="vid"\n',
-        'audio\n',
-        '#EXT-X-MEDIA:TYPE=VIDEO,GROUP-ID="vid",URI="video"',
-      ].join('');
-
-      const media = [
-        '#EXTM3U\n',
-        '#EXT-X-MAP:URI="init.mp4",BYTERANGE="616@0"\n',
-        '#EXT-X-PLAYLIST-TYPE:VOD\n',
-        '#EXTINF:5,\n',
-        '#EXT-X-BYTERANGE:121090@616\n',
-        'main.exe',
-      ].join('');
-
-      const error = new shaka.util.Error(
-          shaka.util.Error.Severity.CRITICAL,
-          shaka.util.Error.Category.MANIFEST,
-          Code.HLS_COULD_NOT_GUESS_MIME_TYPE, 'exe');
-
-      await verifyError(master, media, error);
-    });
-
     it('if unable to guess codecs', async () => {
       const master = [
         '#EXTM3U\n',