Allow text tracks to purge cues outside of the buffered range

• Component: Media
• Status: RESOLVED FIXED

[Eric Carlson]

TextTrackCues associated in-band tracks live "forever" - until the video element is deleted or reloaded. This is fine for relatively short files, but not so good for long lived files (eg. a very long live stream), or for timed metadata where the "cue" size can be much larger than a text sample. 

Allow text tracks to opt in to purging cues who's time range does not intersect with the `buffered` range, where audio and video data is also not available. Only AVFoundation backed in-band tracks opt in at this time, because AVFoundation will redeliver cues if a time range is played again.

[Eric Carlson]

Created attachment 425882 [details]
Patch

[Eric Carlson]

rdar://14913419

[Jer Noble]

Comment on attachment 425882 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=425882&action=review

r=me with nit:

> Source/WebCore/html/track/InbandDataTextTrack.h:48
> +    bool purgesCuesFromUnbufferedRanges() const final { return true; }

Nit: This confused me on initial reading, which I parsed as "purge cues from unbuffered ranges". Maybe "shouldPurgeCuesFromUnbufferedRanges()"?

[Eric Carlson]

Created attachment 425895 [details]
Patch for landing

[Eric Carlson]

Created attachment 425921 [details]
Patch for landing

[Eric Carlson]

Created attachment 425982 [details]
Patch for landing

[EWS]

Committed r275949 (236509@main): <https://commits.webkit.org/236509@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 425982 [details].