feat(DASH): Expose accessibility purpose in track (#5216)

Closes #5211

externs/shaka/manifest.js

@@ -326,6 +326,7 @@ shaka.extern.FetchCryptoKeysFunction;
  *   trickModeVideo: ?shaka.extern.Stream,
  *   emsgSchemeIdUris: ?Array.<string>,
  *   roles: !Array.<string>,
+ *   accessibilityPurpose: ?shaka.dash.DashParser.AccessibilityPurpose,
  *   forced: boolean,
  *   channelsCount: ?number,
  *   audioSamplingRate: ?number,
@@ -424,6 +425,8 @@ shaka.extern.FetchCryptoKeysFunction;
  * @property {!Array.<string>} roles
  *   The roles of the stream as they appear on the manifest,
  *   e.g. 'main', 'caption', or 'commentary'.
+ * @property {?shaka.dash.DashParser.AccessibilityPurpose} accessibilityPurpose
+ *   The DASH accessibility descriptor, if one was provided for this stream.
  * @property {boolean} forced
  *   <i>Defaults to false.</i> <br>
  *   Whether the stream set was forced

externs/shaka/player.js

@@ -225,6 +225,7 @@ shaka.extern.BufferedInfo;
  *   primary: boolean,
  *   roles: !Array.<string>,
  *   audioRoles: Array.<string>,
+ *   accessibilityPurpose: ?shaka.dash.DashParser.AccessibilityPurpose,
  *   forced: boolean,
  *   videoId: ?number,
  *   audioId: ?number,
@@ -301,6 +302,9 @@ shaka.extern.BufferedInfo;
  *   The roles of the audio in the track, e.g. <code>'main'</code> or
  *   <code>'commentary'</code>. Will be null for text tracks or variant tracks
  *   without audio.
+ * @property {?shaka.dash.DashParser.AccessibilityPurpose} accessibilityPurpose
+ *   The DASH accessibility descriptor, if one was provided for this track.
+ *   For text tracks, this describes the text; otherwise, this is for the audio.
  * @property {boolean} forced
  *   True indicates that this in the forced text language for the content.
  *   This flag is based on signals from the manifest.

lib/dash/dash_parser.js

@@ -933,6 +933,8 @@ shaka.dash.DashParser = class {
     const accessibilities = XmlUtils.findChildren(elem, 'Accessibility');
     const LanguageUtils = shaka.util.LanguageUtils;
     const closedCaptions = new Map();
+    /** @type {?shaka.dash.DashParser.AccessibilityPurpose} */
+    let accessibilityPurpose;
     for (const prop of accessibilities) {
       const schemeId = prop.getAttribute('schemeIdUri');
       const value = prop.getAttribute('value');
@@ -1015,6 +1017,15 @@ shaka.dash.DashParser = class {
             kind = ManifestParserUtils.TextStreamKind.CLOSED_CAPTION;
           }
         }
+      } else if (schemeId == 'urn:tva:metadata:cs:AudioPurposeCS:2007') {
+        // See DASH DVB Document A168 Rev.6 Table 5.
+        if (value == '1') {
+          accessibilityPurpose =
+              shaka.dash.DashParser.AccessibilityPurpose.VISUALLY_IMPAIRED;
+        } else if (value == '2') {
+          accessibilityPurpose =
+              shaka.dash.DashParser.AccessibilityPurpose.HARD_OF_HEARING;
+        }
       }
     }
 
@@ -1057,7 +1068,7 @@ shaka.dash.DashParser = class {
     const streams = representations.map((representation) => {
       const parsedRepresentation = this.parseRepresentation_(context,
           contentProtection, kind, language, label, main, roleValues,
-          closedCaptions, representation);
+          closedCaptions, representation, accessibilityPurpose);
       if (parsedRepresentation) {
         parsedRepresentation.hdr = parsedRepresentation.hdr || videoRange;
       }
@@ -1133,12 +1144,14 @@ shaka.dash.DashParser = class {
    * @param {!Array.<string>} roles
    * @param {Map.<string, string>} closedCaptions
    * @param {!Element} node
+   * @param {?shaka.dash.DashParser.AccessibilityPurpose} accessibilityPurpose
+   *
    * @return {?shaka.extern.Stream} The Stream, or null when there is a
    *   non-critical parsing error.
    * @private
    */
   parseRepresentation_(context, contentProtection, kind, language, label,
-      isPrimary, roles, closedCaptions, node) {
+      isPrimary, roles, closedCaptions, node, accessibilityPurpose) {
     const XmlUtils = shaka.util.XmlUtils;
     const ContentType = shaka.util.ManifestParserUtils.ContentType;
 
@@ -1320,6 +1333,7 @@ shaka.dash.DashParser = class {
         hdr,
         tilesLayout,
         matchedStreams: [],
+        accessibilityPurpose,
       };
     }
 
@@ -2072,6 +2086,16 @@ shaka.dash.DashParser.AdaptationInfo;
 shaka.dash.DashParser.GenerateSegmentIndexFunction;
 
 
+/**
+ * @enum {string}
+ * @export
+ */
+shaka.dash.DashParser.AccessibilityPurpose = {
+  VISUALLY_IMPAIRED: 'visually impaired',
+  HARD_OF_HEARING: 'hard of hearing',
+};
+
+
 /**
  * @typedef {{
  *   generateSegmentIndex: shaka.dash.DashParser.GenerateSegmentIndexFunction

lib/hls/hls_parser.js

@@ -2321,6 +2321,7 @@ shaka.hls.HlsParser = class {
       closedCaptions,
       hdr: undefined,
       tilesLayout: undefined,
+      accessibilityPurpose: null,
     };
   }
 

lib/mss/mss_parser.js

@@ -532,6 +532,7 @@ shaka.mss.MssParser = class {
         timescale: context.timescale,
         codecPrivateData: null,
       },
+      accessibilityPurpose: null,
     };
 
     // This is specifically for text tracks.

lib/offline/manifest_converter.js

@@ -205,6 +205,7 @@ shaka.offline.ManifestConverter = class {
       spatialAudio: streamDB.spatialAudio,
       closedCaptions: streamDB.closedCaptions,
       tilesLayout: streamDB.tilesLayout,
+      accessibilityPurpose: null,
     };
 
     return stream;

lib/player.js

@@ -2384,6 +2384,7 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
         audioSamplingRate: null,
         spatialAudio: false,
         closedCaptions: null,
+        accessibilityPurpose: null,
       },
       bandwidth: 100,
       allowedByApplication: true,
@@ -4860,6 +4861,7 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
       audioSamplingRate: null,
       spatialAudio: false,
       closedCaptions: null,
+      accessibilityPurpose: null,
     };
 
     const fullMimeType = shaka.util.MimeUtils.getFullType(
@@ -5011,6 +5013,7 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
       spatialAudio: false,
       closedCaptions: null,
       tilesLayout: '1x1',
+      accessibilityPurpose: null,
     };
 
     this.manifest_.imageStreams.push(stream);
@@ -5430,6 +5433,7 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
               audioSamplingRate: null,
               spatialAudio: false,
               closedCaptions: null,
+              accessibilityPurpose: null,
             };
             manifest.textStreams.push(textStream);
             closedCaptionsSet.add(id);

lib/util/periods.js

@@ -1529,6 +1529,7 @@ shaka.util.PeriodCombiner = class {
       audioSamplingRate: null,
       spatialAudio: false,
       closedCaptions: null,
+      accessibilityPurpose: null,
     };
   }
 

lib/util/stream_utils.js

@@ -1109,6 +1109,7 @@ shaka.util.StreamUtils = class {
       originalAudioId: null,
       originalTextId: null,
       originalImageId: null,
+      accessibilityPurpose: null,
     };
 
     if (video) {
@@ -1130,6 +1131,7 @@ shaka.util.StreamUtils = class {
       track.spatialAudio = audio.spatialAudio;
       track.label = audio.label;
       track.audioRoles = audio.roles;
+      track.accessibilityPurpose = audio.accessibilityPurpose;
     }
 
     return track;
@@ -1179,6 +1181,7 @@ shaka.util.StreamUtils = class {
       originalAudioId: null,
       originalTextId: stream.originalId,
       originalImageId: null,
+      accessibilityPurpose: stream.accessibilityPurpose,
     };
 
     return track;
@@ -1253,6 +1256,7 @@ shaka.util.StreamUtils = class {
       originalAudioId: null,
       originalTextId: null,
       originalImageId: stream.originalId,
+      accessibilityPurpose: null,
     };
 
     return track;
@@ -1373,6 +1377,7 @@ shaka.util.StreamUtils = class {
       originalAudioId: null,
       originalTextId: null,
       originalImageId: null,
+      accessibilityPurpose: null,
     };
 
     return track;

test/dash/dash_parser_manifest_unit.js

@@ -1864,6 +1864,49 @@ describe('DashParser Manifest', () => {
     expect(stream).toBeUndefined();
   });
 
+  it('reads accessibility purpose elements', async () => {
+    const manifestText = [
+      '<MPD minBufferTime="PT75S">',
+      '  <Period id="1" duration="PT30S">',
+      '    <AdaptationSet id="1" contentType="text">',
+      '      <Accessibility ',
+      '          schemeIdUri="urn:tva:metadata:cs:AudioPurposeCS:2007"',
+      '          value="2" />',
+      '      <Representation id="text-en" mimeType="text/webvtt">',
+      '        <BaseURL>t-en.vtt</BaseURL>',
+      '      </Representation>',
+      '    </AdaptationSet>',
+      '    <AdaptationSet id="1" mimeType="video/mp4">',
+      '      <Representation id="video-sd" width="640" height="480">',
+      '        <BaseURL>v-sd.mp4</BaseURL>',
+      '        <SegmentBase indexRange="100-200" />',
+      '      </Representation>',
+      '    </AdaptationSet>',
+      '    <AdaptationSet id="1" mimeType="audio/mp4">',
+      '      <Accessibility ',
+      '          schemeIdUri="urn:tva:metadata:cs:AudioPurposeCS:2007"',
+      '          value="1" />',
+      '      <Representation id="audio-sd" width="640" height="480">',
+      '        <BaseURL>v-sd.mp4</BaseURL>',
+      '        <SegmentBase indexRange="100-200" />',
+      '      </Representation>',
+      '    </AdaptationSet>',
+      '  </Period>',
+      '</MPD>',
+    ].join('\n');
+
+    fakeNetEngine.setResponseText('dummy://foo', manifestText);
+    /** @type {shaka.extern.Manifest} */
+    const manifest = await parser.start('dummy://foo', playerInterface);
+    const textStream = manifest.textStreams[0];
+    expect(textStream.accessibilityPurpose)
+        .toBe(shaka.dash.DashParser.AccessibilityPurpose.HARD_OF_HEARING);
+    const variant = manifest.variants[0];
+    expect(variant.video.accessibilityPurpose).toBeUndefined();
+    expect(variant.audio.accessibilityPurpose)
+        .toBe(shaka.dash.DashParser.AccessibilityPurpose.VISUALLY_IMPAIRED);
+  });
+
   it('converts Accessibility element to "kind"', async () => {
     const manifestText = [
       '<MPD minBufferTime="PT75S">',

test/media/adaptation_set_unit.js

@@ -218,6 +218,7 @@ describe('AdaptationSet', () => {
       forced: false,
       trickModeVideo: null,
       type: '',
+      accessibilityPurpose: null,
     };
   }
 });

test/offline/manifest_convert_unit.js

@@ -389,6 +389,7 @@ describe('ManifestConverter', () => {
       spatialAudio: false,
       closedCaptions: null,
       tilesLayout: undefined,
+      accessibilityPurpose: null,
     };
   }
 
@@ -438,6 +439,7 @@ describe('ManifestConverter', () => {
       spatialAudio: false,
       closedCaptions: null,
       tilesLayout: undefined,
+      accessibilityPurpose: null,
     };
   }
 
@@ -486,6 +488,7 @@ describe('ManifestConverter', () => {
       spatialAudio: false,
       closedCaptions: null,
       tilesLayout: undefined,
+      accessibilityPurpose: null,
     };
   }
 
@@ -531,6 +534,7 @@ describe('ManifestConverter', () => {
       spatialAudio: streamDb.spatialAudio,
       closedCaptions: streamDb.closedCaptions,
       tilesLayout: streamDb.tilesLayout,
+      accessibilityPurpose: null,
     };
 
     expect(stream).toEqual(expectedStream);

test/offline/storage_integration.js

@@ -1403,6 +1403,7 @@ filterDescribe('Storage', storageSupport, () => {
       originalAudioId: audioId.toString(),
       originalTextId: null,
       originalImageId: null,
+      accessibilityPurpose: null,
     };
   }
 
@@ -1447,6 +1448,7 @@ filterDescribe('Storage', storageSupport, () => {
       originalAudioId: null,
       originalTextId: id.toString(),
       originalImageId: null,
+      accessibilityPurpose: null,
     };
   }