tips needed: aac encode on android using ffmpeg-neon optimization

there I am trying to do some performance improvement about libfaac/libx264 encoder using ffmpeg and neon.seems successfully开发者_Python百科 compiled ffmpeg with neon support,and video encode performance indeed has some improvement,however when it comes to aac encode, it barely can run...Do I have to do some code change about aac specificly? Does this have something to do with neon`s fft stuff?Totally clueless, any tips would be greatly appreciated!Thanks