This video editor allows you to cut/crop the video, audio and encode it in different formats.
This app create a ffmpeg command line for encoding, or encode directly in the browser using the web ffmpeg. 
Load a video/audio, adjust the start/end time, and click & drag on the screen to crop into a rectangle.
You can convert a video, audio to different format such as mp4, avi, mov, wmv, flv, m4a, aac, ogg, wma, gif animation. Supports merging video and audio.
This app only works locally without going through the server. You don't need to upload a video to any server.

Readable media formats for encoding: 
webm,mp4,swf,avi,flv,m4v,mkv,mov,mpe,mpeg,wmv
aac,ac3,aiff,aif,amr,ape,au,flac,m4a,mka,mp3,mpc,ogg,ra,rm,wave
wma,asf,3ga,3gp,caf,gsm,m4p,m4r,mp2,mpa,mpga,oma,qcp,ram,aifc,oga,voc,vqf..