According to the data sheet for the 7850:
Double Data Rate 2 (DDR2)
The ADV7850 can use DDR2 external memory to simultaneously
provide 3D comb and frame TBC operation.
It requires a minimum memory of 128 Mb with a speed grade of
200 MHz at CAS latency (CL) 3.
The recommended DDR2 memory compatible with the
ADV7850 include the MT47H32M16HR-25E:G from Micron
What are the implications if we lower the memory down to 128 Mb or 256 Mb? Is there any performance degradations to the 3D comb/frame TBC? We originally went by what the EVAL board had, but it sounds like its overkill and we can get away with a smaller value.