# ffmpeg -ss 30.5 -i tmp.flv -vframes 1 out1.png
ffmpeg version N-85962-g164e277 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-11)
  configuration: --enable-gpl --enable-libx264 --enable-nonfree --enable-libfdk_aac --enable-libmp3lame --enable-libass
  libavutil      55. 62.100 / 55. 62.100
  libavcodec     57. 95.100 / 57. 95.100
  libavformat    57. 72.101 / 57. 72.101
  libavdevice    57.  7.100 / 57.  7.100
  libavfilter     6. 88.100 /  6. 88.100
  libswscale      4.  7.101 /  4.  7.101
  libswresample   2.  8.100 /  2.  8.100
  libpostproc    54.  6.100 / 54.  6.100
Input #0, flv, from 'tmp.flv':
  Duration: 00:42:59.94, start: 1258.836000, bitrate: 1430 kb/s
    Stream #0:0: Video: h264 (High), yuvj420p(pc, bt709, progressive), 1920x1080, 30.30 fps, 30 tbr, 1k tbn, 60 tbc
    Stream #0:1: Audio: aac, 44100 Hz, stereo, fltp
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> png (native))
Press [q] to stop, [?] for help
[swscaler @ 0x2427e80] deprecated pixel format used, make sure you did set range correctly
Output #0, image2, to 'out1.png':
  Metadata:
    encoder         : Lavf57.72.101
    Stream #0:0: Video: png, rgb24, 1920x1080, q=2-31, 200 kb/s, 30 fps, 30 tbn, 30 tbc
    Metadata:
      encoder         : Lavc57.95.100 png
frame=    1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.03 bitrate=N/A speed=0.187x
video:911kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown