$ ffmpeg -h encoder=nvenc
ffmpeg version 2.6.3 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.7 (SUSE Linux)
  configuration: --shlibdir=/usr/lib64 --prefix=/usr --mandir=/usr/share/man --libdir=/usr/lib64 --enable-shared --disable-static --enable-debug --disable-stripping --extra-cflags='-O2 -g -m64 -fmessage-length=0 -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -I./cudautils_and_nvenc_include_files' --extra-ldflags=-L./cudautils_and_nvenc_include_files --enable-pic --optflags='-O2 -g -m64 -fmessage-length=0 -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables -fasynchronous-unwind-tables' --enable-gpl --enable-x11grab --enable-version3 --enable-pthreads --datadir=/usr/share/ffmpeg --enable-libfaac --enable-libaacplus --enable-nonfree --enable-nvenc --enable-libopenjpeg --enable-avfilter --enable-libpulse --enable-libwebp --enable-libvpx --enable-libopus --enable-libmp3lame --enable-libvorbis --enable-libtheora --enable-libspeex --enable-libxvid --enable-libx264 --enable-libx265 --enable-libschroedinger --enable-libgsm --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-postproc --enable-libdc1394 --enable-librtmp --enable-libfreetype --enable-avresample --enable-libtwolame --enable-libvo-aacenc --enable-gnutls --enable-libass --disable-libwebp --enable-frei0r --enable-libcelt --enable-libcdio --enable-ladspa
  libavutil      54. 20.100 / 54. 20.100
  libavcodec     56. 26.100 / 56. 26.100
  libavformat    56. 25.101 / 56. 25.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 11.102 /  5. 11.102
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Encoder nvenc [Nvidia NVENC h264 encoder]:
    Threading capabilities: no
    Supported pixel formats: nv12
nvenc AVOptions:
  -preset            <string>     E..V.... Set the encoding preset (one of hq, hp, bd, ll, llhq, llhp, default) (default "hq")
  -cbr               <int>        E..V.... Use cbr encoding mode (from 0 to 1) (default 0)
  -2pass             <int>        E..V.... Use 2pass cbr encoding mode (low latency mode only) (from -1 to 1) (default -1)
  -gpu               <int>        E..V.... Selects which NVENC capable GPU to use. First GPU is 0, second is 1, and so on. (from 0 to INT_MAX) (default 0)