Get the total size of the memory blocks in b.
When not NULL, offset will contain the offset of the data in the
first memory block in buffer and maxsize will contain the sum of
the size and offset and the amount of extra padding on the last
memory block. offset and maxsize can be used to resize the
buffer memory blocks with gst_buffer_resize().
Get the total size of the memory blocks in b. When not NULL, offset will contain the offset of the data in the first memory block in buffer and maxsize will contain the sum of the size and offset and the amount of extra padding on the last memory block. offset and maxsize can be used to resize the buffer memory blocks with gst_buffer_resize().