Get the total size of length memory blocks stating from idx in buffer.
When not NULL, offset will contain the offset of the data in the
memory block in buffer at idx and maxsize will contain the sum of the size
and offset and the amount of extra padding on the memory block at idx +
length -1.
offset and maxsize can be used to resize the buffer memory blocks with
gst_buffer_resize_range().
Get the total size of length memory blocks stating from idx in buffer. When not NULL, offset will contain the offset of the data in the memory block in buffer at idx and maxsize will contain the sum of the size and offset and the amount of extra padding on the memory block at idx + length -1. offset and maxsize can be used to resize the buffer memory blocks with gst_buffer_resize_range().