Selecting Audio language auto switches the text track(using selectAudioLanguage, selectTextTrack API)

[shanmugapriyaEK]

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

What version of Shaka Player are you using?:2.3.3

Can you reproduce the issue with our latest release version?:yes

Can you reproduce the issue with the latest code from master?:yes

Are you using the demo app or your own custom app?:both

If custom app, can you reproduce the issue using our demo app?:yes

What browser and OS are you using?:Chrome MAV

What are the manifest and license server URIs?:Demo asset- 'Angel One (multicodec, multilingual)

What did you do? Using selectTextTrack (with all the tracks listed), setting selectAudioLanguage auto switches the text track.
Reproduce in sample app by doing

1. Text track does not list all the texttracks. Hence made changes to list all the tracks without any language or role
2. Switched audio language using selectAudioLanguage resulted in track change
3. Observed that in streaming_engine.js assertions fails.
   if (!mediaState && stream.type == ContentType.TEXT &&
   this.config_.ignoreTextStreamFailures) {//this was set to false
   this.loadNewTextStream(stream);
   return;
   }
   goog.asserts.assert(mediaState, 'switch: expected mediaState to exist');

What did you expect to happen? It should not switch text track

What actually happened? changes text track

[michellezhuogg]

Not able to reproduce the assertion fail, however, both switchVariant_() and switchTextStream_() are called when switching audio language.

[shanmugapriyaEK]

I made changes in sample to reproduce it. Shaka demo application does not list all the track. It does a filter for language and role. I removed that piece of code in order to list all the tracks.
Removed the below code in info_section.js
// Split language and role
var res = languageAndRole.split(':');
var language = res[0];
var role = res[1] || '';

tracks = tracks.filter(function(track) {
var langMatch = track.language == language;
var roleMatch = role == '' || track.roles.indexOf(role) > -1;
return langMatch && roleMatch;
});

[shanmugapriyaEK]

By setting the ignoreTextStreamFailures flag to true , I was able to resolve this issue in my sample Application.
Also I tried removing this check in steaming_Engine.js switchInternal_ as below
if (!mediaState && stream.type == ContentType.TEXT ) {
this.loadNewTextStream(stream);
return;
}
Can you please explain me more in detail about this ?
Is there a possibility for fix in 2.3?

[ismena]

Hi @shanmugapriyaEK,

Could you clarify why you wanted all the text track listed at the same time? The way we intended for this to work was that you would choose a language first (selectTextLanguage()) and then select a track from in this language from a track list.

Do you think you could follow that path?

I'm pretty sure what you're seeing happens because you go around selectTextLanguage().
Here's how it works:
We have an internal variable that stores current text language. It's set to your preferred text language when the playback starts or to English(I think) by default if no preference has been provided.
This variable gets updated when you call selectTextLanguage(). If a different language has been selected, we switch to a new track in the newly selected language.
Because you go around this logic when you choose from all the text tracks regardless of language this variable doesn't get updated. When selectAudioLanguage() is called and we refresh the state your current text language is the old language (from before you switched the track), hence we update accordingly.

We might be able to work with you to accommodate your use case if there is a reason you can't call selectTextLanguage() first, but I want to check if the intended approach might work for you first.

[shanmugapriyaEK]

We have exposed this API to our clients.
Consider the scenario where they wanted to switch based on bandwidth or kind. By this way I am forcing the clients to use two API (first selectTextLanguage and then set selectTextTrack )for switching. Also they had do the filtering in their application for listing the text tracks.