When we have nested timelines, we need to make sure the underlying
formatted file is reloaded when commiting the main composition to
take into account the new timeline.
In other to make the implementation as simple as possible we make
sure that whenever the toplevel composition is commited, the decodebin
holding the gesdemux is torn down so that a new demuxer is created
with the new content of the timeline.
To do that a we do a NleCompositionQueryNeedsTearDown query to which
gesdemux answers leading to a full nlecomposition stack
deactivation/activation cycle.
First marshilling it to the main thread is dangerous as it is a blocking
operation and it should never happen there.
The asset cache is MT safe now so it is possible to load the timeline
from that thread directly
Making sure to have 1 GstDiscoverer per thread.
Use that new feature in gesdemux by loading the timeline directly from
the streaming thread. Modifying the timeline is not supported allowed
anyway.
/usr/bin/ld: .libs/libgstges_la-gesdemux.o: in function `ges_timeline_new_from_uri_from_main_thread':
./plugins/ges/gesdemux.c:279: undefined reference to `gst_discoverer_new'
/usr/bin/ld: ./plugins/ges/gesdemux.c:288: undefined reference to `gst_discoverer_start'
