FFmpeg命令行练习（4）

ffmpeg工具

ffmpeg -i 1111.avi -vcodec mpeg4 -b:v 200k -r 15 -an 2222.mp4

ffmpeg version 4.1 Copyright (c) 2000-2018 the FFmpeg developers
  built with Apple LLVM version 10.0.0 (clang-1000.11.45.5)
  configuration: 
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
Input #0, avi, from '1111.avi':
  Metadata:
    encoder         : Lavf56.19.100
  Duration: 00:00:39.16, start: 0.000000, bitrate: 656 kb/s
    Stream #0:0: Video: h264 (High) (H264 / 0x34363248), yuv420p(progressive), 800x368 [SAR 1:1 DAR 50:23], 579 kb/s, 24 fps, 24 tbr, 24 tbn, 48 tbc
    Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 44100 Hz, stereo, fltp, 64 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> mpeg4 (native))
Press [q] to stop, [?] for help
Output #0, mp4, to '2222.mp4':
  Metadata:
    encoder         : Lavf58.20.100
    Stream #0:0: Video: mpeg4 (mp4v / 0x7634706D), yuv420p, 800x368 [SAR 1:1 DAR 50:23], q=2-31, 200 kb/s, 15 fps, 15360 tbn, 15 tbc
    Metadata:
      encoder         : Lavc58.35.100 mpeg4
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
frame=  291 fps=0.0 q=10.8 size=     512kB time=00:00:19.33 bitrate= 217.0kbits/frame=  513 fps=511 q=31.0 size=    1024kB time=00:00:34.13 bitrate= 245.8kbits/frame=  588 fps=507 q=22.8 Lsize=    1187kB time=00:00:39.13 bitrate= 248.4kbits/s dup=1 drop=349 speed=33.7x    
video:1183kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.284331%

参数具体说明：

• 转封装格式从AVI格式转换为MP4格式
• 视频编码从AVC转换为MPEG4格式
• 视频码率从原来的579kbit/s转换为200kbit/s
• 视频帧率从原来的24fps转换为15fps
• 转码后的文件中不包括音频（-an参数）