A free program for Android, by Napplics.

“Audio Video MP3 Converter” is an audio and video converter, which allows you to convert all popular audio and video formats to MP3, even though the output quality may not be the best. You can choose between two output formats, one with a bit-rate of 128kbps and the other one with a bit-rate of 192kbps. The default setting is the one with 128kbps, but you can also set it to the one with the higher quality. The converter supports many popular video formats, such as AVI, MOV, MP4, WMV, MKV, MPG, MPEG, FLV, WMV, RMVB, TS, etc. It also supports MP3 formats, even though the output quality is not the best.