Avoids dereferencing dead objects
What happens in the autovideosink case is that context 1 is created and
destroyed before all the async operations hae executed on the associated
window. When the delayed operations execute, they then reference dead
objects and crash.
We fix this by keeping refs over all async operations so the object
cannot be deleted while async operations are in flight.
https://bugzilla.gnome.org/show_bug.cgi?id=782379
Execute GL calls without marshalling them to the context thread. In the cocoa
and eagl backends calling gst_gl_context_activate is cheap and therefore calling
it on the current thread and serializing GL calls with a per-context lock is
more efficient (faster and has less overhead) than marshalling everything to the
context thread.
This optimization cuts a large overhead in g_poll (continuously waking up the
context thread) and in g_mutex_*/g_cond_* (waiting for results from the context
thread).
Otherwise the pipeline stalls when running
more than one glimagesink with gst-launch.
Also only register the custom nsapp loop
when setting up the nsapp from gstgl.
Depending on the platform, it was only ever implemented to 1) set a
default surface size, 2) resize based on the video frame or 3) nothing.
Instead, provide a set_preferred_size () that elements/applications
can use to request a certain size which may be ignored for
videooverlay/other cases.
Removes the use of NSOpenGL* variety and functions. Any Cocoa
specific functions that took/returned a NSOpenGL* object now
take/return the CGL equivalents.
