encoder 'aac' not enable exception while processing video for slowing

While chaging playback speed of video (making video slow) following exception occurs using FFMPEG android java library.

[aac @ 0x416c26f0] The encoder 'aac' is experimental but experimental codecs are not enabled, add '-strict -2' if you want to use it.

Here is a command to change playback of the speed

 VideoIn = getInternalDirectoryPath() + "/Download/input.mp4";
 VideoOut = getInternalDirectoryPath() + "/Download/output.mp4";
 cmd = "-i "+VideoIn+" -vf setpts=2*PTS -strict -2 "+VideoOut;

adding -strict in command avoid encoder 'aac' not enable exception. You can follow this link to implement ffmpeg video commands.

Here is the complete sample code

   public class TestFFMpegActivity {
        private static String cmd,
        private static FFmpeg ffmpeg;
        private static Context mContext;


        public static String getInternalDirectoryPath() {
            return Environment.getExternalStorageDirectory().getAbsolutePath();
        }

        public static void initiateFFmpeg(Context context, String path) {
            mContext = context;
            ffmpeg = FFmpeg.getInstance(context);   
            VideoIn = getInternalDirectoryPath() + "/Download/input.mp4";
            VideoOut = getInternalDirectoryPath() + "/Download/output.mp4";
            cmd = "-i "+VideoIn+" -vf setpts=2*PTS -strict -2 "+VideoOut;
            try {
                ffmpeg.loadBinary(new LoadBinaryResponseHandler() {

                    @Override
                    public void onStart() {
                    }

                    @Override
                    public void onFailure() {
                    }

                    @Override
                    public void onSuccess() {
                    }

                    @Override
                    public void onFinish() {
                        processVideo();
                    }
                });
            } catch (FFmpegNotSupportedException e) {
                // Handle if FFmpeg is not supported by device
            }
        } 
        private static void processVideo(){
        try {
            ffmpeg.execute(cmd ,
                    new ExecuteBinaryResponseHandler() {

                        @Override
                        public void onStart() {
                            //for logcat
                            Log.w(null,"processing started");
                        }

                        @Override
                public void onProgress(String message) {
                    //for logcat
                    Log.w(null, "onProgress");
                }

                @Override
                public void onFailure(String message) {
                    Log.w(null, message.toString());
                }

                @Override
                public void onSuccess(String message) {
                    Log.w(null, message.toString());
                }

                @Override
                public void onFinish() {

                }
            });
        } catch (FFmpegCommandAlreadyRunningException e) {
            Toast.makeText(mContext, "Video processing failed due to exception", Toast.LENGTH_LONG).show();

            // Handle if FFmpeg is already running
            e.printStackTrace();
            Log.w(null, e.toString());
        }
    }
}