ffmpeg推流异常报错

使用ffmpeg推流：

ffmpeg -i dy.mp4 -vcodec libx264 -acodec aac -f flv rtmp://test.domain/live/test

出现如下报错：

Unknown encoder 'libx264'

ffmpeg version 3.4.1 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-28)
  configuration: --prefix=/usr/local/ffmpeg
  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
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'dy.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42avc1
    creation_time   : 2018-10-08T12:59:18.000000Z
  Duration: 00:43:13.80, start: 0.000000, bitrate: 1090 kb/s
    Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv), 1280x720 [SAR 1:1 DAR 16:9], 1025 kb/s, 25 fps, 25 tbr, 25k tbn, 50 tbc (default)
    Metadata:
      creation_time   : 2018-10-08T12:59:18.000000Z
      handler_name    : VideoHandler
    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 61 kb/s (default)
    Metadata:
      creation_time   : 2018-10-08T12:59:18.000000Z
      handler_name    : SoundHandler
Unknown encoder 'libx264'

如上报错，缺少libx264库，需要安装该库：