# Libraries Preferences

### From Audacity Manual

Both the optional MP3 Export Library and the optional FFmpeg Import/Export Library allow Audacity to import and/or export many additional audio formats such as AC3, AMR(NB), M4A and WMA, and to import audio from video files.

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## MP3 Export Library

- MP3 Export Library Version: This shows the current version of the LAME MP3 encoding library being used by Audacity for MP3 export. If a suitable version of LAME is not accessible to Audacity, the message will instead state that the library is "not found". In that case, use the provided buttons to either locate LAME on your computer or download a free copy of it, following the instructions on the FAQ:Installation and Plug-Ins page.
- Locate: If you already have the LAME library on disk and Audacity can't find it, use this button to tell Audacity where it is.
- Download: Use this to fetch a copy of the LAME library.

## FFmpeg Import/Export Library

- FFmpeg Library Version: This shows the current version of the FFmpeg library being used by Audacity for custom export. If a suitable version of FFmpeg is not accessible to Audacity, the message will instead state that the library is "not found". In that case, use the provided buttons to either locate the FFmpeg library on your computer or download a free copy of it, following the instructions on this page.
- Locate: If you already have the FFmpeg library on disk and Audacity can't find it, use this button to tell Audacity where it is.
- Download: Use this to fetch a copy of the FFmpeg library.
- Allow background on-demand loading: Check this box for somewhat quicker access to the audio when importing using the optional FFmpeg library. If the box is checked, there will be no progress dialog while the audio imports and is copied into the project. The waveform will start to be drawn from left to right almost immediately. Audio may be played and edited wherever the sequence of patterned blocks (representing the as yet uncomputed waveform) has been replaced by the blue peaks and troughs of the normal Audacity waveform.

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