The video decoders tried calling gst_buffer_add_*meta() on non-writable
buffer resulting in warnings of this kind:
gstamcvideodec.c:921 (_gl_sync_render_unlocked): WARNING: amcvideodec
Failed to create the transformation meta for the gl_sync 0xabc03848
buffer 0xabb01b40 (0)
https://bugzilla.gnome.org/show_bug.cgi?id=758694