FFMPEG命令参数

命令解析

进入bin目录,输入ffmpeg -help可以查看相关命令参数,如下:

Getting help:
    -h      -- print basic options 
    -h long -- print more options
    -h full -- print all options (including all format and codec specific options, very long)
    -h type=name -- print all options for the named decoder/encoder/demuxer/muxer/filter
    See man ffmpeg for detailed description of the options.

Print help / information / capabilities:

显示许可证,执照,版本信息
-L                  show license    
-h topic            show help      
-? topic            show help
-help topic         show help
--help topic        show help
-version            show version

显示配置命令参数
-buildconf          show build configuration

显示可用的格式(编码,协议相关的)
-formats            show available formats
-devices            show available devices

显示支持的编解码格式
-codecs             show available codecs
-decoders           show available decoders
-encoders           show available encoders

显示支持的bit流过滤协议
-bsfs               show available bit stream filters
显示支持的协议
-protocols          show available protocols
-filters            show available filters

显示支持的像素格式(rgb,yuv,nv...)
-pix_fmts           show available pixel formats
显示standard声道布局
-layouts            show standard channel layouts
显示音频采样的格式(8位,16,32位...)
-sample_fmts        show available audio sample formats

-colors             show available color names
-sources device     list sources of the input device
-sinks device       list sinks of the output device

硬件加速方法
-hwaccels           show available HW acceleration methods

Global options (affect whole program instead of just one file:

日志相关
-loglevel loglevel  set logging level
-v loglevel         set logging level
-report             generate a report

设置缓冲区
-max_alloc bytes    set maximum size of a single allocated block

覆盖输出文件
-y                  overwrite output files
-n                  never overwrite output files

-ignore_unknown     Ignore unknown stream types
-stats              print progress report during encoding
-max_error_rate ratio of errors (0.0: no errors, 1.0: 100% error  maximum error rate
-bits_per_raw_sample number  set the number of bits per raw sample
-vol volume         change audio volume (256=normal)


Per-file main options:

强制采用格式fmt
-f fmt              force format
 编解码名称
-c codec            codec name
-codec codec        codec name

-pre preset         preset name

设置outfile metadata  from infile
-map_metadata outfile[,metadata]:infile[,metadata]  set metadata information of outfile from infile

设置纪录时间
-t duration         record or transcode "duration" seconds of audio/video
-to time_stop       record or transcode stop time


-fs limit_size      set the limit file size in bytes
-ss time_off        set the start time offset
-sseof time_off     set the start time offset relative to EOF
-seek_timestamp     enable/disable seeking by timestamp with -ss
-timestamp time     set the recording timestamp ('now' to set the current time)
-metadata string=string  add metadata
-program title=string:st=number...  add program with specified streams
-target type        specify target file type ("vcd", "svcd", "dvd", "dv" or "dv50" with optional prefixes "pal-", "ntsc-
" or "film-")
-apad               audio pad
-frames number      set the number of frames to output
-filter filter_graph  set stream filtergraph
-filter_script filename  read stream filtergraph description from a file
-reinit_filter      reinit filtergraph on input parameter changes
-discard            discard
-disposition        disposition



视频参数
Video options:
设置视频帧的数量
-vframes number     set the number of video frames to output
设置帧率
-r rate             set frame rate (Hz value, fraction or abbreviation)
设置帧的大小(格式为宽X高,如1080X720)
-s size             set frame size (WxH or abbreviation)
设置横纵比
-aspect aspect      set aspect ratio (4:3, 16:9 or 1.3333, 1.7777)
设置的文件比特数量
-bits_per_raw_sample number  set the number of bits per raw sample
不做视频记录
-vn                 disable video
强制使用codec编解码方式
-vcodec codec       force video codec ('copy' to copy stream)
-timecode hh:mm:ss[:;.]ff  set initial TimeCode value.

处理的遍数
-pass n             select the pass number (1 to 3)

音视频码率
-vf filter_graph    set video filters
-ab bitrate         audio bitrate (please use -b:a)
-b bitrate          video bitrate (please use -b:v)
-dn                 disable data


音频参数
Audio options:

设置音频帧的数量
-aframes number     set the number of audio frames to output
设置音频的质量
-aq quality         set audio quality (codec-specific)
设置音频的采样率
-ar rate            set audio sampling rate (in Hz)
设置音频的通道
-ac channels        set number of audio channels
不做音频记录
-an                 disable audio
强制使用编码
-acodec codec       force audio codec ('copy' to copy stream)
设置音频音量
-vol volume         change audio volume (256=normal)
-af filter_graph    set audio filters


Subtitle options:
-s size             set frame size (WxH or abbreviation)
-sn                 disable subtitle
-scodec codec       force subtitle codec ('copy' to copy stream)
-stag fourcc/tag    force subtitle tag/fourcc
-fix_sub_duration   fix subtitles duration
-canvas_size size   set canvas size (WxH or abbreviation)
-spre preset        set the subtitle options to the indicated preset

命令使用

常用参数如下:

主要参数： 
-i 设定输入流 
-f 设定输出格式 
-ss 开始时间 

视频参数： 
-b 设定视频流量，默认为200Kbit/s 
-r 设定帧速率，默认为25 
-s 设定画面的宽与高 
-aspect 设定画面的比例 
-vn 不处理视频 
-vcodec 设定视频编解码器，未设定时则使用与输入流相同的编解码器 

音频参数： 
-ar 设定采样率 
-ac 设定声音的Channel数 
-acodec 设定声音编解码器，未设定时则使用与输入流相同的编解码器 
-an 不处理音频

1.分离视频音频流

ffmpeg -i test.mp4 -an -vcodec copy video
ffmpeg -i test.mp4 -vn -acodec copy audeo

2.合并音视频流

ffmpeg -i video -i audio -vcodec copy -acodec copy video.mp4

3.视频转码

ffmpeg –i test.mp4 –vcodec h264 –s 352*278 –an –f m4v test.264