The CMAF path passed duration_secs: 0 into play_streaming_dynamic, and
the streaming position timer clamps current_position to the duration
it was given — so elapsed, remaining, progress and auto-advance all
froze at zero. Duration is now derived from the CMAF segment table's
per-segment sample counts.
PlaybackEvent also gained buffer_progress (the streaming buffer fill
the audio thread already tracked but never surfaced); the poll loop
feeds it to the seek-bar cache overlay.
cc
vicrodh
655a90f400