c# - Video conversion too long -

I use NRECO. But this process is too long I tried to convert 200m videos, but it took more than an hour. The code I use:

  var ffMpeg = new FFMpegConverter (); Command = string.format ("- I \" {0} \ "-C: Vi Libthora-C: a livvarbis-parset altfst \" {1} \ "", inputfile, outputfile); FfMpeg.Invoke (order);  

Can someone suggest me how to improve the performance of the conversion? thank you in advanced.

Try this code:

  ffmpeg -i movie.mp4 -VF "Crop = 640: 256: 0: 400" -Heads 5 -Prase Atphast -City-2 Your CroppyMovy.MP4