感謝葳蕤, Thanks a ton, it works. But still can't understand...

The convertor works. I also checked out that converting is is a RealPlayer Plus Premium Feature.

Now the problem is that I have to convert so many mp4 songs to iPod format. So I don't understand how come some of 長工's songs don't need to be converted, but many need? I guess he used Avidemux to edit these songs. Is the software giving the different quality of MP4 file when 長工 was making them?

Thanks again!