TIVidResize puts the input of the resizer into DMAI buffers. If the upstream
element already generates DMAI buffers (e.g. if it is a TIViddec), they are
reused. However, if the upstream element is something else, a memcpy is done in
a DMAI buffer. This memcpy can be avoided by adding a bufferalloc function to
TIVidResize's sink pad, allowing the upstream element to put its data directly
into the DMAI buffer.