PCM to AAC conversion using mediacodec

I am using a media codec class in Android (Jelly Bean) to encode PCM format to AAC. The file was encoded but no music player is able to play that file. I was not able to find any working code or proper documentation on the net.

This is my code:

public void doConvert()
{

    new AsyncTask<Void, Void, Void>()
    {

        @Override
        protected Void doInBackground(Void... params) 
        {
            try
            {
                int codecCount = MediaCodecList.getCodecCount();

                for ( int i=0; i < codecCount; i++)
                {
                    MediaCodecInfo info = MediaCodecList.getCodecInfoAt(i);
                    Logger.getLogger(MainActivity.class.getSimpleName()).log(Level.INFO, info.getName());
                    for ( String type : info.getSupportedTypes() )
                    {
                        Logger.getLogger(MainActivity.class.getSimpleName()).log(Level.INFO, type);
                    }

                }

                File inputFile = new File( Environment.getExternalStorageDirectory().getAbsolutePath()+"/Download/Ghajini27_Mono_8Khz.wav");
                //File inputFile = new File( sampleFD.get);
                Log.e("File", String.valueOf(inputFile.length()));
                FileInputStream fis = new FileInputStream(inputFile);
                fis.skip(44);//remove wav header

                File outputFile = new File( Environment.getExternalStorageDirectory().getAbsolutePath()+"/Download/out.m4a");
                if ( outputFile.exists()) outputFile.delete();

                FileOutputStream fos = new FileOutputStream(outputFile);

                //BufferedOutputStream bos=new BufferedOutputStream(new FileOutputStream(outputFile));
                MediaCodec codec = MediaCodec.createEncoderByType("audio/mp4a-latm");
                MediaFormat outputFormat = MediaFormat.createAudioFormat("audio/mp4a-latm", 22050, 1);
                outputFormat.setInteger(M