ffmpeg -y -i bbb.mp4 -c:v libx265 -frames:v 1 -x265-params preset=slower:tune=psnr -f mp4 /dev/null
ffmpeg version 3.4.2 Copyright (c) 2000-2018 the FFmpeg developers
  built with Apple LLVM version 9.0.0 (clang-900.0.39.2)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.4.2 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --disable-jack --enable-gpl --enable-ffplay --enable-frei0r --enable-libass --enable-libfdk-aac --enable-libfontconfig --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopus --enable-librtmp --enable-librubberband --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtesseract --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzimg --enable-libzmq --enable-opencl --enable-videotoolbox --enable-openssl --enable-lzma --enable-libopenjpeg --disable-decoder=jpeg2000 --extra-cflags=-I/usr/local/Cellar/openjpeg/2.3.0/include/openjpeg-2.3 --enable-nonfree
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'bbb.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: isomavc1
    creation_time   : 2013-12-16T17:59:32.000000Z
    title           : Big Buck Bunny, Sunflower version
    artist          : Blender Foundation 2008, Janus Bager Kristensen 2013
    comment         : Creative Commons Attribution 3.0 - http://bbb3d.renderfarming.net
    genre           : Animation
    composer        : Sacha Goedegebure
  Duration: 00:10:34.53, start: 0.000000, bitrate: 4486 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 4001 kb/s, 60 fps, 60 tbr, 60k tbn, 120 tbc (default)
    Metadata:
      creation_time   : 2013-12-16T17:59:32.000000Z
      handler_name    : GPAC ISO Video Handler
    Stream #0:1(und): Audio: mp3 (mp4a / 0x6134706D), 48000 Hz, stereo, s16p, 160 kb/s (default)
    Metadata:
      creation_time   : 2013-12-16T17:59:37.000000Z
      handler_name    : GPAC ISO Audio Handler
    Stream #0:2(und): Audio: ac3 (ac-3 / 0x332D6361), 48000 Hz, 5.1(side), fltp, 320 kb/s (default)
    Metadata:
      creation_time   : 2013-12-16T17:59:37.000000Z
      handler_name    : GPAC ISO Audio Handler
    Side data:
      audio service type: main
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> hevc (libx265))
  Stream #0:2 -> #0:1 (ac3 (native) -> aac (native))
Press [q] to stop, [?] for help
[libx265 @ 0x7fe49d805400] Unknown option: preset.
[libx265 @ 0x7fe49d805400] Unknown option: tune.
x265 [info]: HEVC encoder version 2.7
x265 [info]: build info [Mac OS X][clang 9.0.0][64 bit] 8bit+10bit+12bit
x265 [info]: using cpu capabilities: MMX2 SSE2Fast LZCNT SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
x265 [info]: Main profile, Level-4.1 (Main tier)
x265 [info]: Thread pool created using 8 threads
x265 [info]: Slices                              : 1
x265 [info]: frame threads / pool features       : 3 / wpp(17 rows)
x265 [info]: Coding QT: max CU size, min CU size : 64 / 8
x265 [info]: Residual QT: max TU size, max depth : 32 / 1 inter / 1 intra
x265 [info]: ME / range / subpel / merge         : hex / 57 / 2 / 2
x265 [info]: Keyframe min / max / scenecut / bias: 25 / 250 / 40 / 5.00
x265 [info]: Lookahead / bframes / badapt        : 20 / 4 / 2
x265 [info]: b-pyramid / weightp / weightb       : 1 / 1 / 0
x265 [info]: References / ref-limit  cu / depth  : 3 / on / on
x265 [info]: AQ: mode / str / qg-size / cu-tree  : 1 / 1.0 / 32 / 1
x265 [info]: Rate Control / qCompress            : CRF-28.0 / 0.60
x265 [info]: tools: rd=3 psy-rd=2.00 rskip signhide tmvp strong-intra-smoothing
x265 [info]: tools: lslices=6 deblock sao
Finishing stream 0:1 without any data written to it.
Output #0, mp4, to '/dev/null':
  Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: isomavc1
    composer        : Sacha Goedegebure
    title           : Big Buck Bunny, Sunflower version
    artist          : Blender Foundation 2008, Janus Bager Kristensen 2013
    comment         : Creative Commons Attribution 3.0 - http://bbb3d.renderfarming.net
    genre           : Animation
    encoder         : Lavf57.83.100
    Stream #0:0(und): Video: hevc (libx265) (hev1 / 0x31766568), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 60 fps, 15360 tbn, 60 tbc (default)
    Metadata:
      creation_time   : 2013-12-16T17:59:32.000000Z
      handler_name    : GPAC ISO Video Handler
      encoder         : Lavc57.107.100 libx265
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1(side), fltp, 341 kb/s (default)
    Metadata:
      creation_time   : 2013-12-16T17:59:37.000000Z
      handler_name    : GPAC ISO Audio Handler
      encoder         : Lavc57.107.100 aac
    Side data:
      audio service type: main
frame=    1 fps=0.0 q=-0.0 Lsize=       4kB time=00:00:00.00 bitrate=454276.9kbits/s dup=1 drop=1 speed=0.000305x
video:1kB audio:0kB subtitle:0kB other streams:0kB global headers:2kB muxing overhead: 509.075897%
x265 [info]: frame I:      1, Avg QP:35.12  kb/s: 288.96
x265 [info]: consecutive B-frames: 100.0% 0.0% 0.0% 0.0% 0.0%

encoded 1 frames in 0.17s (5.83 fps), 288.96 kb/s, Avg QP:35.12
[aac @ 0x7fe49d806600] Qavg: nan