Converting real audio into mp3 format through a Java Program is very easy, for this I am going to perform two step process and two encoder libraries(Mencoder and Lame). I am going to use encoder libraries which they can convert a file data format from rm to mp3 with command line option. To convert rm into mp3 we need to covert rm file into wav file and then, from wav file to mp3 format. So the first step describes how to convert rm to wav.

First Step:
To convert rm to wav file format we need Mencoder codec, it has command line option to convert the rm input format to wav output format. This is the command for that conversion
command: mplayer d:\films\rm1.rm -ao pcm:file=rm1.wav -vc dummy -vo null
Download link for mplayer codecs. At this stage we can get the .wav file as the output, from now we can convert this file into any format.

Second Step:
This is the last step to convert Real media into mp3 format. The lame Encoder is the powerful encoder to do this process.
Command:

lame -h prefix-of-music-file_01.wav  song.mp3 High Quality
To download the Lame
there only we can find some more options like -h(this is for High Quality).
Till now we know how to convert the rm into mp3 format, use this information write a
Java program, by using java's command exec we can run mplayer and lame commands through
a java program.
The Lame and Mplayer provides libraries for windows and Linux so you can run the Java
program on any platform with these libraries. Mplayer is the most powerful tool for media
if you want to use some more options find, can here

the JAVA Program is:
//Give the file name with absolute path
//Executing this program install both the exe files
class converter{
public static void main(String args[])throws IOException{
String command1="mplayer "+args[0]+" -ao pcm:file=rm1.wav -vc dummy -vo null";
String command2= "lame -hProcess "+rm1.wav+" "+rm1.mp3;
Process child = Runtime.getRuntime().exec(command1);
child = Runtime.getRuntime().exec(command2);
}
}