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

Is your feature request related to a problem? Please describe.

Our organization has DASH H265 assets containing CEA708 captions with the same start/end times of other captions, where each said caption is encoded into a different cue window. We would like the Shaka Player to extract all captions from such assets.

Describe the solution you'd like

While Shaka's CEA708 parser currently creates each simultaneous subtitle cue window individually via defineWindow_(), Shaka emits the simultaneous captions all at once via deleteWindows_(). Only the last cue with the same start/end time is saved. The others are overwritten by deleteWindows_().

I will open a PR to address the above asymmetry by saving all cues on windows with the same start/end time when deleting/clearing windows.

Describe alternatives you've considered

Additional context

Are you planning to send a PR to add it?
Yes