feat(MediaCap): Support multiplex content with MediaCap

If we have a multiplexd content with audio and video, we combine
the audio and video codecs in the manifest parser.
For example, a multiplexed stream would be with:
mimeType="video/mp4", codecs="avc1.64001e,mp4a.40.2".

When sending the request to MediaCapabilities.decodingInfo(), we
need to have the config for both audio and video to get the result
as "supported".
The video config would be:
contentType='video/mp4, codecs="avc1.64001e"'.
The audio config would be:
contentType='audio/mp4, codecs="mp4a.40.2"'.

Issue shaka-project#1391

Change-Id: I74a8580c07228e9600dc40c611ebd5d34f8cd7ee

lib/util/stream_utils.js

@@ -374,8 +374,25 @@ shaka.util.StreamUtils = class {
     };
 
     if (video) {
+      let audioCodec;
+      let videoCodec = video.codecs;
+
+      // For multiplexed streams with audio+video codecs, the config should have
+      // AudioConfiguration and VideoConfiguration.
+      if (video.codecs.includes(',')) {
+        [videoCodec, audioCodec] = video.codecs.split(',');
+        const audioFullType = shaka.util.MimeUtils.getFullOrConvertedType(
+            video.mimeType, audioCodec, ContentType.AUDIO);
+        mediaDecodingConfig['audio'] = {
+          contentType: audioFullType,
+          channels: 2,
+          bitrate: variant.bandwidth || 1,
+          samplerate: 1,
+          spatialRendering: false,
+        };
+      }
       const fullType = shaka.util.MimeUtils.getFullOrConvertedType(
-          video.mimeType, video.codecs, ContentType.VIDEO);
+          video.mimeType, videoCodec, ContentType.VIDEO);
       // VideoConfiguration
       mediaDecodingConfig['video'] = {
         contentType: fullType,

test/util/stream_utils_unit.js

@@ -464,6 +464,24 @@ describe('StreamUtils', () => {
     });
   });
 
+  describe('getDecodingInfosForVariants', () => {
+    it('for multiplexd content', async () => {
+      manifest = shaka.test.ManifestGenerator.generate((manifest) => {
+        manifest.addVariant(0, (variant) => {
+          variant.addVideo(1, (stream) => {
+            stream.mime('video/mp2t', 'avc1.4d400d,mp4a.40.2');
+          });
+        });
+      });
+
+      await shaka.util.StreamUtils.getDecodingInfosForVariants(
+          manifest.variants);
+      expect(manifest.variants.length).toBeTruthy();
+      expect(manifest.variants[0].decodingInfos.length).toBe(1);
+      expect(manifest.variants[0].decodingInfos[0].supported).toBeTruthy();
+    });
+  });
+
   describe('filterManifest', () => {
     let fakeDrmEngine;