You can use the Video Converter. It supports the mutual conversion between all the video formats.
Input Formats: MPG, MPEG, MPEG2, VOB, MP4, M4V, RM, SWF, RMVB, WMV, ASF, TS, MKV, AVI, 3GP, FLV, MPV, MOD, TOD, MP3, MP2, AAC, AC3, WAV, MID, MIDI, WMA, M4A, RA, RAM etc..
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 etc..
It also has strong editing functions of video effecting, video word and picture watermark, video trimming, video cropping, video joinning.
For more informaion and free download from:
It is easy to operate. Just few clicks are OK.
Here is the specific guide for you to follow:
Hope it useful for you.