Don't use the duration in the segment for calculating clipping values.
The duration is expressed in stream time and clipping is done on unrelated
timestamp values.
This used to be interesting for elements that used the segment structure to
implement seeking because then they would use stream-time for the segment
start/stop values and the duration could be used as a fallback when the stop
position was not set. Now that the complete segment event is passed between
elements we cannot do this anymore because some elements might store the
duration and start/stop values with different time bases in the segment.
When we have no chain function or when we are operating the pad in the wrong
mode, emit a critical instead of posting an error message. This is certainly a
programming error and we cannot always post a message (like when the pad has no
parent)
Use a frame flag to signal to subclass it should reset any retained
state w.r.t. frame parsing since the frame being passed is 'new',
i.e. not related to previously passed and processed data.
Make the pad activation code look more like other activation code.
Only start the sinkpad task when we decide to activate in pull mode, when we
later add srcpad pullmode this will be needed.
... so as to allow the push-mode case to provide data to subclass
on a buffer by buffer basis (as in regular forward case), rather
than all buffers of a fragment chucked together.
Also refactor buffer handling some more, and add some debug.
Rename _is_writable() with _is_exclusive because the writability does not depend
on the amount of references to the memory object anymore.
Add accessor macros for the memory flags.
Rename the GstBuffer _peek_memory() method to _get_memory() and return a
reference to the memory now that we can do this without affecting writability
of the memory object. Make it possible to also make this function merge the
buffer memory.
Add methods to replace memory in a buffer. Make some convience macros for the
buffer memory functions.
Fix unit tests.
Make an _init method where the parent mini-object and other fields are
initialized.
Check that the passed structure doesn't already have a parent.
Use the _new_custom () constructors
... since that is already handled by _update_duration, or should not be done
altogether if the duration is determined by non-estimated means.
Fixes#669502.
