Ignore duplicate CODECS in HLS.

In HLS, the CODECS attribute may contain duplicate of the same codec
with different profiles.

Closes #1817

Change-Id: I0d59c1ade6c8387a2e6b3ca00c0287e15c943ea3

lib/hls/hls_parser.js

@@ -596,7 +596,8 @@ shaka.hls.HlsParser.prototype.createVariantsForTag_ =
   const codecsString = tag.getAttributeValue('CODECS', defaultCodecs);
   // Strip out internal whitespace while splitting on commas:
   /** @type {!Array.<string>} */
-  let codecs = codecsString.split(/\s*,\s*/);
+  let codecs =
+      shaka.hls.HlsParser.filterDuplicateCodecs_(codecsString.split(/\s*,\s*/));
   let resolutionAttr = tag.getAttribute('RESOLUTION');
   let width = null;
   let height = null;
@@ -1891,6 +1892,33 @@ shaka.hls.HlsParser.prototype.getStartTimeFromTextSegment_ =
 };
 
 
+/**
+ * Filters out duplicate codecs from the codec list.
+ * @param {!Array.<string>} codecs
+ * @return {!Array.<string>}
+ * @private
+ */
+shaka.hls.HlsParser.filterDuplicateCodecs_ = function(codecs) {
+  const seen = new Set();
+  const ret = [];
+  for (const codec of codecs) {
+    // HLS says the CODECS field needs to include all codecs that appear in the
+    // content.  This means that if the content changes profiles, it should
+    // include both.  Since all known browsers support changing profiles without
+    // any other work, just ignore them  See also:
+    // https://github.com/google/shaka-player/issues/1817
+    const shortCodec = shaka.util.MimeUtils.getCodecBase(codec);
+    if (!seen.has(shortCodec)) {
+      ret.push(codec);
+      seen.add(shortCodec);
+    } else {
+      shaka.log.debug('Ignoring duplicate codec');
+    }
+  }
+  return ret;
+};
+
+
 /**
  * Attempts to guess which codecs from the codecs list belong to a given content
  * type.  Does not assume a single codec is anything special, and does not throw

test/hls/hls_parser_unit.js

@@ -199,6 +199,34 @@ describe('HlsParser', function() {
         .catch(fail).then(done);
   });
 
+  it('ignores duplicate CODECS', async function() {
+    let master = [
+      '#EXTM3U\n',
+      '#EXT-X-STREAM-INF:BANDWIDTH=200,CODECS="avc1.4d001e,avc1.42000d",',
+      'RESOLUTION=960x540,FRAME-RATE=60\n',
+      'video',
+    ].join('');
+
+    let 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('');
+
+    let manifest = new shaka.test.ManifestGenerator()
+            .anyTimeline()
+            .addPeriod(0)
+              .addPartialVariant()
+                .addPartialStream(ContentType.VIDEO)
+                  .mime('video/mp4', 'avc1.4d001e')
+          .build();
+
+    await testHlsParser(master, media, manifest);
+  });
+
   it('parses video-only variant', async function() {
     let master = [
       '#EXTM3U\n',