Have you ever received a file with the extension .M4b and not been able to open it even though people keep telling you that you can? Or have you received an email from a customer telling you that they’re not able to open your audio book to listen on their computer or windows phone?

Here are some simple steps to explain how you can open the file quite easily.

First of all, what is a .M4b file?

.m4b is the file extension for MPEG-4 files, commonly used for audio books. It can be read by any media player or audio book player with the ability to open these type of files and is a common file type for audio books downloaded from iTunes or Audible.

Very often .M4b files are protected by DRM, meaning that they’re protected and can only be played on authorised devices, and this may be a reason why you are unable to open the file in a usual media player, such as Windows Media Player.

However, if it isn’t protected by DRM then the steps below will allow you to open an .M4b file on a Windows computer.

Sometimes, Windows users will receive a message saying they can’t open such a file because it doesn’t recognise the file extension. This is very often not a problem with the file, but simply an issue with the way your computer interprets it, and might actually be a bit of a false response.

Most computers will be able to open the file if you have media player software, and on a Windows computer, Windows Media Player is able to read .M4b files.Sometimes, however, your computer doesn’t recognise that this is the case and so you need to force your media player to try and open the file.

Opening the file

You can force your computer to open the file with a program that you suggest.

To do this right click on the file and select ‘open with‘, you’ll then get a list of available programs that your computer suggests may be able to play the file. If Windows Media Player isn’t there, select ‘choose default progam

Browse to Windows Media Player, select it and click ‘ok


You may get a message saying that the file extension might not be recognised, ignore this message and click ‘yes’ to try and play the content.
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The file should then play.You can equally try this method with any other available media player on your computer or device to force it to try and open the file.