Mp4 format vs IPad sync

[xin_li97]

i have two MP4 files. One has 16bits ( Bit rate) which can sync to my IPad, another has 31bits which can't sync to IPad. I got file's bit rate from "Get Infor " on Itune.

How could I change MP4 bit rate?

I compare my MP4 file's property with IPad spec, everything meets the spec. but the file with 16bit can sync, 31bits can't sync