三分钟带你学会用ffmpeg解帧合帧

1. 解帧，把视频变为图片

ffmpeg -i "input.mp4" -r 5 output_dir/frame%04d.jpg

      参数说明：-i 输入

                       -r 帧率

                       output_dir里面存放解帧好的图片

ffmpeg version 2.8.15-0ubuntu0.16.04.1 Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.10) 20160609
  configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
  libavutil      54. 31.100 / 54. 31.100
  libavcodec     56. 60.100 / 56. 60.100
  libavformat    56. 40.101 / 56. 40.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 40.101 /  5. 40.101
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.101 /  1.  2.101
  libpostproc    53.  3.100 / 53.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf56.40.101
  Duration: 00:01:00.19, start: 0.000000, bitrate: 40041 kb/s
    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuvj420p(pc), 3840x2160 [SAR 1:1 DAR 16:9], 39839 kb/s, 16.48 fps, 30 tbr, 30k tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 195 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Output #0, image2, to 'output_dir/frame%04d.jpg':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf56.40.101
    Stream #0:0(und): Video: mjpeg, yuvj420p(pc), 3840x2160 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 5 fps, 5 tbn, 5 tbc (default)
    Metadata:
      handler_name    : VideoHandler
      encoder         : Lavc56.60.100 mjpeg
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> mjpeg (native))
Press [q] to stop, [?] for help
frame=  303 fps= 15 q=24.8 Lsize=N/A time=00:01:00.60 bitrate=N/A dup=0 drop=689    
video:80883kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

2. 合帧，把图片合成视频 

ffmpeg -r 5 -start_number 123 -i input_dir/frame%04d.jpg  -vf fps=5  video.mp4

  参数说明：-r 帧率

                    -i 输入图片

                    -start_number 起始帧号

   在当前路径下合成了video.mp4的视频。