Please follow these steps to convert your MP4 files to MP3 format.
1. Open RealPlayer.
2. Go to Library.
3. Right on the MP4 video and click on Edit --> Convert or click More (shown in the bottom of RealPlayer) and choose Convert.
4. Choose the "Convert to:" and select MP3 as your format.
5. You can choose where the converted MP3 files should be saved by selecting your destination in the "Save in:" section.
Please let us know if you have additional questions.