I noticed a lot of different questions about the subject MP3 in the legal website (https://law.stackexchange.com/search?q=mp3). But none of them answer my question really.

First of all, I'm thinking about including features in a technical service that should be compatible with MP3 files. This means I would like to know if it is legal for me decode and use a user-uploaded MP3 file. For example; converting it into another audio format. Or make an image of the frequency waves within that MP3 file. Is it I allowed to work with the MP3 format without paying a license fees?

Secondly, is it also allowed to encode an audio file into the MP3 format. For example a text-to-speech tool that outputs the audio in an MP3 encoded file.

So shortly; Can I legally use (read/encode to/decode from) the MP3 format without paying a license fee?

2 Answers 2


Some MP3 technologies are still under patent in the US: you can read the wiki page on that matter to see if it is applicable to what you intend to do. This assumes you write your own code – if you use someone else's conversion software, that would depend on the licensing terms for the software.

  • 1
    So basically, everyone is allowed now to decode it since no pattents currently apply on that process. So legally it won't matter if the code is written by myself or used from a third party? Encoding will be "illigal" in some US states till 31 december 2017? If so, will it be enough to ask the user to supply a residential address and based on that don't deliver encoding services in US?
    – Bob Ortiz
    Commented Apr 29, 2016 at 20:36
  • If you use somebody else's software, you have to abide by the terms of the EULA, irrespective of patent. You can check mp3licensing.com: LAME seems to claim to be free.
    – user6726
    Commented Apr 29, 2016 at 21:52
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    Also: a patent would prohibit you from implementing a protected technology, if that technology is patented in the US and you are in the US. Customers using your software would not be violating patent law by using your (hypothetically illegal) product, so it would not matter if the customer is in the US or in Belgium.
    – user6726
    Commented Apr 29, 2016 at 22:33
  • 1
    Copyright in the actual recorded material is an issue too
    – Dale M
    Commented Apr 30, 2016 at 7:14

Notwithstanding any patents on the format, the content of the actual recording is almost certainly copyright. To legally make a copy (including translating to another format) you need the permission of the copyright holder or a fair use/fair dealing exemption.

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