avconv -i 2.mp4 -vf palettegen palette.png
avconv version 9.20-6:9.20-0ubuntu0.14.04.1, Copyright (c) 2000-2014 the Libav developers
  built on Dec  7 2016 21:22:31 with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '2.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 0
    compatible_brands: isom3gp4
    creation_time   : 2018-04-24 00:25:41
  Duration: 00:00:38.89, start: 0.000000, bitrate: 17076 kb/s
    Stream #0.0(eng): Video: h264 (High), yuv420p, 1920x1080, 17026 kb/s, PAR 1:1 DAR 16:9, 30.04 fps, 90k tbn
    Metadata:
      creation_time   : 2018-04-24 00:25:41
    Stream #0.1(eng): Audio: aac, 48000 Hz, stereo, fltp, 122 kb/s
    Metadata:
      creation_time   : 2018-04-24 00:25:41
[AVFilterGraph @ 0xaa5b80] No such filter: 'palettegen'
Error opening filters!