A free program for Android, by rierie501.

AudioVideo Converter app for Android is an audio and video converter. This tool can convert between various audio and video formats. It supports a wide range of input and output formats such as mp4, flv, m4v, mpeg, ogg, wmv, mkv, and more. 

It can convert between MP3, WAV, WMA, M4A, AAC, OGG, and other formats. It has a simple and intuitive interface. It is very easy to use. You just need to select the audio or video file, select the output format, and click the convert button. It will convert the audio file to the desired output format.