This callback will be called only once during the filter lifetime, after
all the options have been set, but before links between filters are
established and format negotiation is done.
Basic filter initialization should be done here. Filters with dynamic
inputs and/or outputs should create those inputs/outputs here based on
provided options. No more changes to this filter's inputs/outputs can be
done after this callback.
This callback must not assume that the filter links exist or frame
parameters are known.
@ref AVFilter.uninit "uninit" is guaranteed to be called even if
initialization fails, so this callback does not have to clean up on
failure.
@return 0 on success, a negative AVERROR on failure
Filter initialization function.
This callback will be called only once during the filter lifetime, after all the options have been set, but before links between filters are established and format negotiation is done.
Basic filter initialization should be done here. Filters with dynamic inputs and/or outputs should create those inputs/outputs here based on provided options. No more changes to this filter's inputs/outputs can be done after this callback.
This callback must not assume that the filter links exist or frame parameters are known.
@ref AVFilter.uninit "uninit" is guaranteed to be called even if initialization fails, so this callback does not have to clean up on failure.
@return 0 on success, a negative AVERROR on failure