gst_buffer_make_writable() requires exclusive reference to the
GstMemory so the _make_writable() for the msdk buffer will result
to fallback system memory copy, because the msdk memory were initialized
with GST_MEMORY_FLAG_NO_SHARE flag.
Note that, disable sharing GstMemory brings high overhead but actually
the msdk memory objects can be shared over multiple buffers.
If the memory is not shareable, newly added GstAllocator::mem_copy will
create copied msdk memory.
../subprojects/gst-plugins-bad/sys/msdk/msdk.c(61): error C2065: 'MFX_FOURCC_RGB565'
The minimum required version for the format seems to MFX_VERSION >= 1028
Implements 2 memory allocators:
1\ GstMsdkSystemAllocator: This will allocate system memory.
2\ GstMsdkVideoAllocator: This will allocate device memory depending
on the platform. (eg. VASurface)
Currently GstMsdkBufferPool uses video allocator currently by default
only on linux. On Windows, we should use system memory until d3d
allocator
is implemented.
https://bugzilla.gnome.org/show_bug.cgi?id=790752
