gst_buffer_take_memory -> gst_buffer_insert_memory because insert is what the
method does.
Make all methods deal with ranges so that we can replace, merge, remove and map
a certain subset of the memory in a buffer. With the new methods we can make
some code nicer and reuse more code. Being able to deal with a subset of the
buffer memory allows us to optimize more cases later (most notably RTP headers
and payload that could be in different memory objects).
Make some more convenient macros that call the more generic range methods.
We reset all the waiting streams, let them push another buffer to
see if they're now active again. This allows faster switching
between streams and prevents deadlocks if downstream does any
waiting too.
Also improve locking a bit, srcresult must be protected by the
multiqueue lock too because it's used/set from random threads.
Otherwise we might block forever because upstream (e.g. multiqueue) is waiting
for the previously active stream to return forever (which is waiting here
in inputselector) before pushing something on the newly selected stream.
Add gst_buffer_append() which appends the memory blocks from one buffer to
another. Remove the old inefficient _merge() and _join() methods which forced a
premature memcpy in most cases.
Remove the _is_span() and _span() methods they are not needed anymore now that
we can _append(). Merging and spanning will be delayed until mapping or maybe
not at all when the element can deal with the different memory blocks.
Remove the const from the GstCaps in get/set_param. set_param modifies
the refcount of the caps.
Don't increment the refcount of the caps result of get_param like we
do with other objects.
Update some annotiations.
... which controls how to (forcibly) deal with (non-)writable data and
is not necessarily related to identical caps.
In particular, it is also not so helpful anymore with a more advanced
GstVideoFilter subclass which always has a transform_ip method currently,
even though its subclass may not have a corresponding _ip method.
