I am looking for A simple cost effective, non OS based solution to encode h.264 on to a sd card for a toy application.
You use to be able to buy chips that did the h.264 encoding. Most Corex-M processors will not have enough SRAM to cache video buffers and thus you are better of using an application processor where you can external DRAM or off loading to external chip. There you can find ones with H.264 encoders, for example the TI Davinci processors.