I use this video converter:
http://www.video-dvd-ripper.com/video-converter/
It supports the mutual conversion between almost all video/audio formats, and HD videos.
Input Formats: MPG, MPEG, MPEG2, VOB, MP4, M4V, RM, RMVB, WMV, ASF, TS, MKV, AVI, 3GP, FLV, MPV, MOD, TOD, MP3, MP2, AAC, AC3, WAV, MID, MIDI, WMA, M4A, RA, RAM .
Output Formats: MP4, H.264, AVI, MP3, WMV, WMA, FLV, MKV, MPEG-1, MPEG-2, 3GP, 3GPP, VOB, DivX, Mov, RM, RMVB, M4A, AAC, WAV, OGG, RA.
It is easy to operate. Just few clicks are OK. The conversion will be finished in short while and with lossless quality.
May be you can try it. Hope it helpful for you.