This change allows you to enable/disable tracks within which
all samples are key-frames without any re-buffering (e.g. audio,
text and metadata). This effectively reverts V2 back to the
behavior in V1, only this time we're doing it properly. []ly
disabling/enabling, or disabling/enabling whilst paused, no longer
cause samples to get "lost" between the source and renderers.
Note it also becomes really easy to support a few other things,
although support is not exposed in this change:
- Enable/disable video tracks without any re-buffering, by
changing the toKeyframe argument passed to discardTo to true.
- Retain media in the buffer for some time after it's been played
(e.g. to support a single back-5s-seek efficiently), by
subtracting the desired back-buffer time from the value that's
passed to discardTo.
Issue: #2956
Issue: #2926
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=160128586
1b71e3b40d