BD-J applets seek their player and restart playlists without any event
reaching the read loop, menu loop points do this constantly. Compare
bd_tell against the end of the previous read and treat a mismatch as a
jump. Checking before the read keeps the new position's head out of
the old slave demuxer, the forward-only stream cannot re-read it. A
read delivered together with a jump event can already carry data of
the new position, the same check drops it.
Kacper Michajłow
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