MP3 is covered by a patent. That means if your app implements the MP3 algorithm, you owe Fraunhofer some money.
However, "if you use directshow or quicktime to import the mp3 into your application... then you would not require licenses since 'they' have already paid [Fraunhofer].", is this true?
In short what are the ways a developer can be clear of MP3 patent infringement in an app they are selling when they only need to load (decode) an mp3 file for playback?
For me, by using library such as Lame, you can use MP3 algorithm for free.
Actually,
You can not distribute library or application which encodes or decodes mp3. as that requires per deployment mp3 licence fee.
But
It is free, If user downloads it from his own machine. that means If you dont distribute mp3 encode-decode code with your app and force user to download it when he want to use your software is free.
In short It is free for personal use, not for commercial use.
From mp3 wikipedia,
Additionally, patent holders declined to enforce license fees on free and open source decoders, which allows many free MP3 decoders to develop
Note: I made a very fast mp3 decoder for ARM 9.