Change resolution of a video using FFmpeg

Change resolution of a video using FFmpeg

I need to decrease the resolution of a file programatically in Android,
but there isn´t any class to do that. So I found that I could do it using
FFmpeg with this code:
ffmpeg -y -i /sdcard/in.mp4 -vf transpose=3 -s 320x240 -r 15 -aspect 3:4
-ab 12288 -vcodec mpeg4 -b 2097152 -sample_fmt s16 /sdcard/out.mp4
How could I execute this code in my app?? I know there are a version of
FFmpeg adapted to Android but I don´t know anything about native code in
Android.
Thanks for help!!