When a clip has video audio and subtitle, if need send gap event
to audio and subtitle, we should make sure all has been sent, so
need every stream keep one send_gap_event.
https://bugzilla.gnome.org/show_bug.cgi?id=780429
Wait in the event function when EOS is received until all pads are EOS
and then forward the EOS event from each pads own event function.
Also send a new GAP event for EOS pads from the event function whenever
going from PLAYING->PAUSED by shortly waking up the GCond. This is needed
to allow sinks to pre-roll again, as they did not receive EOS yet because
we blocked that, but also will never get data again.
https://bugzilla.gnome.org/show_bug.cgi?id=736655
* Update outgoing segment.base with accumulated time, ensuring all
streams are synchronized.
* Only consider streams as "new" is they have a STREAM_START event
with a different seqnum.
* Use GstStream segment.base instead of separate variable to store
the past running time.
* Disable passthrough
* Switch to glib 2.32 GMutex/GCond
* Avoid getting pad parent the expensive way
* Minor other fixes
Before gapless playback failed when switching between audio-only,
video-only and audio-video files, when choosing different clocks
and when the different streams had different durations.
This is now handled by a helper element, which keeps track of the
running times of all streams and synchronizes them.
Fixes bug #602437.
