I want to cut a portion of audio file and render in mp3 or aac, but in render tab i can not find any settings for this. i also went through this thread: http://blenderartists.org/forum/showthread.php?247012-Render-Audio-Only-in-Blender
But i can not see any button called "mixdown" in the scene tab. I am using version 2.74. so is it possible to render only audio?