Convert H264 frame byte array to yuv420 NDK ffmpeg

Hi developers,
I am developing and android app to display input h264 streams from camera and show them on the screen .
I need to convert H264 streams to yuv420 format. I searched google for this requirement and I think the better way is to use ffmpeg library and NDK native classes.

So all I need is to implement this native method that can be called from android studio code:
int nRet = WF_VCodec.WFVC_Decode(
/*input byte[]*/ pAVData,
/*input int*/ DataLen,
/*out byte[]*/ out_yuv420,
/*out int*/ out_yuv420ByteSize,
/*out int*/ out_picture_width,
/*out int*/ out_picture_heigh);