<p>What is a good free library for editing MP3s/FLACs. </p>

<p>By editing I mean:</p>

<ul>
<li>Cutting audio file into multiple parts</li>
<li>Joining multiple audio files together</li>
<li>Increase playback speed of file without affecting the pitch (eg. podcasts up to 1.3x)</li>
<li>Re-encoding audio file from Flac -> MP3 or vice versa</li>
</ul>

<p>I don't mean software, I mean a library that I can use within another application. Programming language agnostic.</p>

I use
Audacity
for all my editing needs
Audacity is a free, easy-to-use audio
  editor and recorder for Windows, Mac
  OS X, GNU/Linux and other operating
  systems. You can use Audacity to:
```
```
* Record live audio.
* Convert tapes and records into digital recordings or CDs.
* Edit Ogg Vorbis, MP3, WAV or AIFF sound files.
* Cut, copy, splice or mix sounds together.
* Change the speed or pitch of a recording.
```
```