A TrackElement is a TimelineElement that specifically belongs to a single Track of its timeline.
Its start and
duration specify its temporal extent in the track. Specifically, a track
element wraps some nleobject, such as an nlesource or nleoperation, which can be retrieved with
get_nleobject, and its
start, duration
, in_point,
priority and
active properties expose the corresponding nleobject properties. When a track element is added to a track, its nleobject is added to
the corresponding nlecomposition that the track wraps.
Most users will not have to work directly with track elements since a Clip will automatically create track elements for its timeline's tracks and take responsibility for updating them. The only track elements that are not automatically created by clips, but a user is likely to want to create, are Effect-s.
You can set up control bindings for a track element child property using
set_control_source. A GstTimedValueControlSource should
specify the timed values using the internal source coordinates (see
TimelineElement). By default, these will be updated to lie between the
in_point and out-point of the element. This can be switched off by setting
auto_clamp_control_sources to
false.