Pass any CHARACTERISTICS value of a track with the track object

[OwenEdwards]

If an #EXT-X-MEDIA for a track has a CHARACTERISTICS value, include that with the information about the track for use by HLS playlist playback. (possible values of CHARACTERISTICS include public.accessibility.transcribes-spoken-dialog, public.accessibility.describes-music-and-sound, and public.accessibility.describes-video).

[gkatsev]

this and below need to be dot-notation.

[OwenEdwards]

I was just trying to be consistent with the pattern used for INSTREAM-ID already. Are you saying you want me to fix that, as well as what I added?

[gkatsev]

that's why the build is failing. INSTREAM-ID requires the bracket notation because of the hyphen; if you take a look at other things, they use dot-notation.

[gesinger]

Hey @OwenEdwards , looks nice and simple, but any reason we don't just leave CHARACTERISTICS as part of attributes?

[OwenEdwards]

@gesinger this seems like the only way to pass the characteristics over to the HLS player (videojs-contrib-hls), so that it could process them (see videojs/videojs-contrib-hls#1019). I don't think the attributes get passed over, do they? If you want to pass over all the attributes, that would work, I guess - this was just targeted at adding the specific new feature of videojs-contrib-hls that I was looking for.

[gesinger]

Sorry @OwenEdwards , you are right, it definitely wasn't passed before this change.

The only thing I'd add to this PR is a test, maybe something like:

QUnit.test('parses characteristics attribute', function() {
  const parser = new Parser();
  const manifest = [
    '#EXTM3U',
    '#EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID=subs,CHARACTERISTICS=char,NAME=test',
    '#EXT-X-STREAM-INF:BANDWIDTH=1,CODECS="mp4a.40.2, avc1.4d400d",SUBTITLES="subs"',
    'index.m3u8'
  ].join('\n');

  parser.push(manifest);

  QUnit.equal(parser.manifest.mediaGroups.SUBTITLES.subs.test.characteristics,
              'char',
              'parsed CHARACTERISTICS attribute');
});

EDIT: updated a bug in test (thanks @mjneil )

[OwenEdwards]

@gesinger - I added that test. I think this should do it; thanks for making it so easy!

[gesinger]

No problem @OwenEdwards . Thanks for the contribution!