Free App that allows you to easily and quickly extract the audio from any video format .mp4, .mpg, .avi, mkv, .3gp. It also has other functions such as:

Reduce audio noise in any format
Increase or decrease the volume of an Audio
Any audio format allowed .mp3, .mav, .aac, .ogg, .alac, .flac, .aiff, .dsd
Standardize or normalize the volume of an Audio
Partially or totally remove the voices from an Audio file