Alternate Audio Language ShakaUI

[stuartflanagan]

Have you read the Tutorials?
Yes

Have you read the FAQ and checked for duplicate open issues?
Yes

What version of Shaka Player are you using?
4.3.4

Please ask your question
I have a manifest with multiple audio of the same Language.

The Audio is Alternate Audio Described.
The current Shaka UI displays the Language of English for both

The markup for the manifest is as follows

 <AdaptationSet mimeType="audio/mp4" startWithSAP="1" segmentAlignment="true" lang="en" label="English Audio Description" subsegmentAlignment="true" subsegmentStartsWithSAP="1">
      <Role schemeIdUri="urn:mpeg:dash:role:2011" value="alternate"/>
      <Accessibility schemeIdUri="urn:tva:metadata:cs:AudioPurposeCS:2007" value="1"/>
      <!-- MPEG Common Encryption -->
...
</AdaptationSet>

My question is should I expect this to use the label property so that the user can distinguish between the Alternative Audio track?

[stuartflanagan]

Could this be a bug?

[joeyparrish]

The player API lets you see both languages and roles, and to select by language and role together if you wish. The UI is configurable to show roles IIRC. Let me find the config for you.

[joeyparrish]

Here it is. Configure the UI's trackLabelFormat field:

• https://shaka-player-demo.appspot.com/docs/api/shaka.extern.html#.UIConfiguration
• https://shaka-player-demo.appspot.com/docs/api/shaka.ui.Overlay.html#.TrackLabelFormat

Quoting the docs:

field	type	description
trackLabelFormat	shaka.ui.Overlay.TrackLabelFormat	An enum that determines what is shown in the labels for text track and audio variant selection. LANGUAGE means that only the language of the item is shown. ROLE means that only the role of the item is shown. LANGUAGE_ROLE means both language and role are shown, or just language if there is no role. LABEL means the non-standard DASH "label" attribute or the HLS "NAME" attribute are shown. Defaults to LANGUAGE.

Here's a snippet, assuming video is a reference to your video element:

video.ui.configure(
    'trackLabelFormat',
    shaka.ui.Overlay.TrackLabelFormat.LANGUAGE_ROLE);

[stuartflanagan]

That is great thank you for that information @joeyparrish !

[absidue]

@joeyparrish Is there a reason shaka uses the non-standard label attribute instead of the Label element that is in the DASH specification (Section 5.3.10)?
Link to the specification: https://standards.iso.org/ittf/PubliclyAvailableStandards/c083314_ISO_IEC%2023009-1_2022(en).zip

[avelad]

Shaka supports both forms. See https://github.com/shaka-project/shaka-player/blob/main/lib/dash/dash_parser.js#L1114-L1125

[absidue]

@avelad Would probably be a good idea to update the docs to say that, as they currently only say that it supports the non-standard label attribute.

[avelad]

@absidue Can you tell me where you have seen it? I'll try to do a PR to fix it.

[absidue]

In the description for the trackLabelFormat option in the UIConfiguration interface:

[...] LABEL means the non-standard DASH "label" attribute or the HLS "NAME" attribute are shown. [...]

https://shaka-player-demo.appspot.com/docs/api/shaka.extern.html#.UIConfiguration