Propose buffer allocation parameters for upstream elements.
This function must be implemented if the element reads or
writes the buffer content. The query that was passed to
the decide_allocation is passed in this method (or null
when the element is in passthrough mode). The default
implementation will pass the query downstream when in
passthrough mode and will copy all the filtered metadata
API in non-passthrough mode.
Propose buffer allocation parameters for upstream elements. This function must be implemented if the element reads or writes the buffer content. The query that was passed to the decide_allocation is passed in this method (or null when the element is in passthrough mode). The default implementation will pass the query downstream when in passthrough mode and will copy all the filtered metadata API in non-passthrough mode.