how to use drc metadata?

[wumaster]

Hi, I'm using fdk v2.0.1. I set the drc_TargetRefLevel, prog_ref_level param in encoder side, and then I set the AAC_DRC_BOOST_FACTOR and AAC_DRC_ATTENUATION_FACTOR param to 127 in decoder side, but the output level did not match the drc_TargetRefLevel. The drc function seems to have a lot of params. Can you please give a reference file about the fdkaac drc function?