input buffer size for H 264 decoder main profile

[Database4]

Hi, I want to allocate static memory for H264 main profile decoder input buffer, which should be able to contain 1 NAL unit of data.
is there any way of allocatiing less memory other than based on max bitrate which can support?
currently i allocated buffer which can fit for 1 picture data for a worst case resolution.
I should able to support byte stream format and also other RTP formats.

Thanks in advance.