CEA-608 Closed Captions end up in the same media group

[adadukin-dolby]

Version

Media3 1.9.2

More version details

No response

Devices that reproduce the issue

Android Emulator (sdk_gphone64_arm64) with Android 16
Emulator version (36.4.9-14788078)

Devices that do not reproduce the issue

No response

Reproducible in the demo app?

Yes

Reproduction steps

1. Update media.exolist.json asset under demos/main/src/main/asset with the entry below

      {
        "name": "DASH with CEA-608 tracks",
        "uri": "https://livesim2.dashif.org/vod/testpic_2s/cea608.mpd"
      },

2. Put a breakpoint (or log track groups) in PlayerControlView#gatherSupportedTrackInfosOfType

3. Build and run sample app. Find newly added entry and play it

4. While the caption list seem correct from the UI side, the debugger should produce something similar to the screenshot below

Expected result

According to the TrackGroup documentation,

Note that audio tracks whose languages differ are not grouped, because content in different
languages is not considered to be the same. Conversely, audio tracks in the same language that
only differ in properties such as bitrate, sampling rate, channel count and so on can be grouped.
This also applies to text tracks.

It seems that the text tracks in different languages should end up in different track groups. The issue has also been discussed in a separate bug report which confirms our suspicion that this is not an intended behaviour.

I agree that merging the english and spanish tracks into a single track group seems wrong

Sample app seem to handle it correctly though, because it iterates over all available Formats across all track groups in here.

Actual result

en and sv closed captions end up in the same TrackGroup.

Media

https://livesim2.dashif.org/vod/testpic_2s/cea608.mpd

Bug Report

• You will email the zip file produced by adb bugreport to android-media-github@google.com after filing this issue.

[adadukin-dolby]

Can you, please, confirm whether closed captions ending up in the same TrackGroup is intended behaviour or an actual bug?

If the later, we identified where the issue comes from and can raise a PR with the changes.

You will email the zip file produced by adb bugreport to android-media-github@google.com after filing this issue.

It seems there is not much to send just yet. Please, do let me know if you still require the bugreport.

[icbaker]

Yeah, I agree these tracks should be in separate track groups. If you have a PR with a fix, we can take a look.

[adadukin-dolby]

@icbaker sure, we will be back with a PR in the next few weeks then.

[adadukin-dolby]

@icbaker the changes are now ready: #3205