transcoding using nvenc ffmpeg

./ffmpeg -i /mnt/file.avi -c:v nvenc_h264 -preset slow -b:v 2000k -c:a libmp3lame testnvenc.mp4
ffmpeg version 3.0.2 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 5.3.1 (Ubuntu 5.3.1-14ubuntu2.1) 20160413
  configuration: --enable-opencl --enable-opengl --enable-nvenc --enable-nonfree --prefix=/home/y/ --extra-cflags='-I /home/y/nvidia_video_sdk_6.0.1/Samples/common/inc' --enable-libmp3lame