FFmpeg三大工具--ffmpeg

一、前言

FFmpeg的Static版本的bin文件夹中只有三个.exe文件，分别是： ffmpeg.exe、ffplay.exe、ffprobe.exe，这三个是FFmpeg源代码编译后生成的可执行文件，也就是FFmpeg的三大工具，本文章主要介绍ffmpeg。

ffmpeg工具主要用于编解码，ffmpeg的主要工作流程相对比较简单，如下所示：

读取输入源
进行音视频的解封装
解码每一帧音视频数据
编码每一帧音视频数据
进行音视频的重写封装
输出到目标

如上图示：

ffmpeg首先读取输入源，然后通过Demuxer将音视频包进行解封装，这个动作通过调用libavformat中的接口即可实现；
接下来通过Decoder进行解码，将音视频通过Decoder解包称为YUV或者PCM这样的数据，Decoder通过libavcodec中的接口即可实现；
然后通过Encoder将对应的数据进行编码，编码可以通过libavcodec中的接口来实现；
接下来将编码后的音视频数据包通过Muxer进行封装，Muxer封装通过libavformat中的接口即可实现，输出成为输出流；

二、ffmpeg命令查询解析

通过ffmpeg --help可以看到ffmpeg常见的命令，大概分为6个部分：

ffmpeg信息查询部分
公共操作参数部分
文件主要操作参数部分
视频操作参数部分
音频操作参数部分
字幕操作参数部分

C:\Users\wangjichuan>ffmpeg --help	//输入命令
ffmpeg version 3.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 7.2.0 (GCC)
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-cuda --enable-cuvid --enable-d3d11va --enable-nvenc --enable-dxva2 --enable-avisynth --enable-libmfx
  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
  libpostproc    54.  7.100 / 54.  7.100
Hyper fast Audio and Video encoder
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...

Getting help:
    -h      -- print basic options	//打印基本参数
    -h long -- print more options	//打印更多参数
    -h full -- print all options (including all format and codec specific options, very long)	//打印全部参数
    -h type=name -- print all options for the named decoder/encoder/demuxer/muxer/filter	//打印指定模块参数，模块包括解码器、编码器、解封装、封装、滤镜
    See man ffmpeg for detailed description of the options.

Print help / information / capabilities:	//ffmpeg信息查询部分
-L                  show license	//查询ffmpeg目前所支持的license协议
-h topic            show help	//查询help		
-? topic            show help	//查询help
-help topic         show help	//查询help
--help topic        show help	//查询help
-version            show version	//查询ffmpeg的版本
-buildconf          show build configuration
-formats            show available formats	//查询ffmpeg支持的文件格式
-muxers             show available muxers	//查询ffmpeg支持的封装
-demuxers           show available demuxers	//查询ffmpeg支持的解封装
-devices            show available devices	//查询ffmpeg支持的
-codecs             show available codecs	//查询ffmpeg支持的编码格式
-decoders           show available decoders	//查询ffmpeg支持的解码器
-encoders           show available encoders	//查询ffmpeg支持的编码器
-bsfs               show available bit stream filters	
-protocols          show available protocols
-filters            show available filters	//查询ffmpeg支持的滤镜
-pix_fmts           show available pixel formats
-layouts            show standard channel layouts
-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
-hwaccels           show available HW acceleration methods

Global options (affect whole program instead of just one file:	//公共操作参数部分
-loglevel loglevel  set logging level
-v loglevel         set logging level
-report             generate a report
-max_alloc bytes    set maximum size of a single allocated block
-y                  overwrite output files
-n                  never overwrite output files
-ignore_unknown     Ignore unknown stream types
-filter_threads     number of non-complex filter threads
-filter_complex_threads  number of threads for -filter_complex
-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:	//文件主要操作参数部分
-f fmt              force format
-c codec            codec name
-codec codec        codec name
-pre preset         preset name
-map_metadata outfile[,metadata]:infile[,metadata]  set metadata information of outfile from infile
-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

Video options:	//视频操作参数部分
-vframes number     set the number of video frames to output
-r rate             set frame rate (Hz value, fraction or abbreviation)
-s size             set frame size (WxH or abbreviation)
-aspect aspect      set aspect ratio (4:3, 16:9 or 1.3333, 1.7777)
-bits_per_raw_sample number  set the number of bits per raw sample
-vn                 disable video
-vcodec codec       force video codec ('copy' to copy stream)
-timecode hh:mm:ss[:;.]ff  set initial TimeCode value.
-pass n             select the pass number (1 to 3)
-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

Audio options:	//音频操作参数部分
-aframes number     set the number of audio frames to output
-aq quality         set audio quality (codec-specific)
-ar rate            set audio sampling rate (in Hz)
-ac channels        set number of audio channels
-an                 disable audio
-acodec codec       force audio codec ('copy' to copy stream)
-vol volume         change audio volume (256=normal)
-af filter_graph    set audio filters

Subtitle options:	//字幕操作参数部分
-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

三、命令查询示例

ffmpeg -formats

C:\Users\wangjichuan>ffmpeg -formats	//输入命令
ffmpeg version 3.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 7.2.0 (GCC)
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-cuda --enable-cuvid --enable-d3d11va --enable-nvenc --enable-dxva2 --enable-avisynth --enable-libmfx
  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
  libpostproc    54.  7.100 / 54.  7.100
File formats:
 D. = Demuxing supported
 .E = Muxing supported
 --
 D  3dostr          3DO STR
  E 3g2             3GP2 (3GPP2 file format)
  E 3gp             3GP (3GPP file format)
 ......
 ......
 ......

第一列是多媒体文件封装格式的Demuxing支持与Muxing支持；
第二列是多媒体文件格式；
第三列是文件格式的详细说明；

ffmpeg -decoders

C:\Users\wangjichuan>ffmpeg -decoders	//输入命令
ffmpeg version 3.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 7.2.0 (GCC)
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-cuda --enable-cuvid --enable-d3d11va --enable-nvenc --enable-dxva2 --enable-avisynth --enable-libmfx
  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
  libpostproc    54.  7.100 / 54.  7.100
Decoders:
 V..... = Video
 A..... = Audio
 S..... = Subtitle
 .F.... = Frame-level multithreading
 ..S... = Slice-level multithreading
 ...X.. = Codec is experimental
 ....B. = Supports draw_horiz_band
 .....D = Supports direct rendering method 1
 ------
 V....D 012v                 Uncompressed 4:2:2 10-bit
 V....D 4xm                  4X Movie
 V....D 8bps                 QuickTime 8BPS video
 ......
 ......
 ......

第一列包含6个字段：第一个字段用来表示此编码器为音频、视频还是字幕；第二个字段表示帧级别的多线程支持；第三个字段表示分片级别的多线程；第四个字段表示该编码为试验版本；第五个字段吧小时draw horiz band模式支持；第六个字段表示直接渲染模式支持；

第二列是编码格式；

第三列是编码格式的详细说明；

ffmpeg -filters

C:\Users\wangjichuan>ffmpeg -filters
ffmpeg version 3.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 7.2.0 (GCC)
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-cuda --enable-cuvid --enable-d3d11va --enable-nvenc --enable-dxva2 --enable-avisynth --enable-libmfx
  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
  libpostproc    54.  7.100 / 54.  7.100
Filters:
  T.. = Timeline support
  .S. = Slice threading
  ..C = Command support
  A = Audio input/output
  V = Video input/output
  N = Dynamic number and/or type of input/output
  | = Source or sink filter
 ... abench            A->A       Benchmark part of a filtergraph.
 ... acompressor       A->A       Audio compressor.
 ... acopy             A->A       Copy the input audio unchanged to the output.
 ... acrossfade        AA->A      Cross fade two input audio streams.
 ... acrusher          A->A       Reduce audio bit resolution.
 T.. adelay            A->A       Delay one or more audio channels.
 ... aecho             A->A       Add echoing to the audio.
 ... aemphasis         A->A       Audio emphasis.
 ... aeval             A->A       Filter audio signal according to a specified expression.
 T.. afade             A->A       Fade in/out input audio.
 ... afftfilt          A->A       Apply arbitrary expressions to samples in frequency domain.
 .S. afir              AA->A      Apply Finite Impulse Response filter with supplied coefficients in 2nd stream.
 ... aformat           A->A       Convert the input audio to one of the specified formats.
 ......
 ......
 ......