DA7217 DAI setting

Now, I'm using DA7217 to drive two differential headphone, mcu provide MCLK is 4.096M, sample rate is 16K, 16bit,

I generate a 1K sin wave and send to da7217 by I2S,but,its output is 8K, I don't now why ,could you give me the setting of registor about pll

and make it work correctly

thanks .