FFmpeg命令行工具-实用命令

help命令使用
流选择选项
视频封装解封装

3.1 视频格式转换
3.2 分离/合并视频音频流
3.3 截取视频片段
3.4 视频转换为m3u8格式
3.5 把视频文件推送到rtmp服务器
3.6 对视频进行切片

视频解码编码

4.1 视频截图
4.2 视频/图片尺寸修改
4.3 分离视频的YUV通道分量
4.4 图片序列与视频的互相转换

视频filter

5.1 视频加水印overlay
5.2 视频旋转transpose
5.3 调色3DLutFilter
5.4 图像/视频转换成黑白的hue
5.5 裁剪视频crop
5.6 视频尺寸缩放scale
5.7 视频中去水印delogo
5.8 给视频或图像加上黑边pad
5.9 计算psnr/ssim
5.10 视频按时间拼接
5.11 视频左右拼接
5.12 打印视频帧的一些信息showinfo
5.13 生成纯色的图片
5.14 打印帧序号/pts到视频帧水印drawtext

音频解码编码

6.1 PCM原始数据和WAV格式转换

音频filter

7.1 倍速atempo

字幕相关

8.1 字幕文件转换
8.2 集成字幕到视频文件

ffplay命

9.1 ffplay播放yuv视频数据
9.2 ffplay播放PCM音频数据
9.3 ffplay播放音频并显示波形图
9.4 ffplay指定显示宽高

ffprobe命令

10.1 ffprobe查看媒体文件的信息
10.2 ffprobe查看时间戳

其他

11.1 ffmpeg或ffplay 打开 DEBUG 日志输出
11.2 FFmpeg命令日志输出到文件
11.3 打印支持DirectShow的设备列表

参考

[1] ffmpeg.org/ffmpeg-all

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1. help命令使用

首先我们要学会使用ffmpeg工具提供的最最基本的一个命令：ffmpeg -help。

有了他我们就可以更加愉快地学习使用ffmpeg的各种功能了。

执行ffmpeg -help后，在终端会打印下面的帮助信息：

ffmpeg version 3.4.2-1~16.04.york0 Copyright (c) 2000-2018 the FFmpeg developersbuilt with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.6) 20160609configuration: --prefix=/usr --extra-version='1~16.04.york0' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --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-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --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-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-sharedlibavutil      55. 78.100 / 55. 78.100libavcodec     57.107.100 / 57.107.100libavformat    57. 83.100 / 57. 83.100libavdevice    57. 10.100 / 57. 10.100libavfilter     6.107.100 /  6.107.100libavresample   3.  7.  0 /  3.  7.  0libswscale      4.  8.100 /  4.  8.100libswresample   2.  9.100 /  2.  9.100libpostproc    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-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/filterSee man ffmpeg for detailed description of the options.Print help / information / capabilities:
-L                  show license
-h topic            show help
-? topic            show help
-help topic         show help
--help topic        show help
-version            show version
-buildconf          show build configuration
-formats            show available formats
-muxers             show available muxers
-demuxers           show available demuxers
-devices            show available devices
-codecs             show available codecs
-decoders           show available decoders
-encoders           show available encoders
-bsfs               show available bit stream filters
-protocols          show available protocols
-filters            show available filters
-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 methodsGlobal options (affect whole program instead of just one file:
-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:
-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        dispositionVideo options:
-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 dataAudio options:
-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 filtersSubtitle 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

最上面部分是ffmpeg的版本信息和各模块的版本信息。

1.1 ffmpeg命令的语法结构

usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...

语法结构很简单。
中括号中的参数是可选项。
options是对输入和输出都有影响的选项。
[[infile options] -i infile]...指定输入选项和输入文件，...表示可以包含多个输入。
{[outfile options] outfile}...指定输出选项和输出文件，...表示可以包含多个输出。

1.2 获取详细的help信息

ffmpeg -help给出了基本的帮助信息，其中下面的信息说明了如何获得更全面的帮助信息。

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/filterSee man ffmpeg for detailed description of the options.

-h long: 打印更多的选项参数。
-h full: 打印所有的选项参数，包括所有针对于format和codec的选项，信息特别的长。
-h type=name: 打印打印指定名称的decoder/encoder/demuxer/muxer/filter的所有选项信息。
man ffmpeg: 查看ffmpeg的帮助手册。

特别强调一下-h type=name这个命令，要经常去使用这个命令。比如查看libx264支持的参数，执行ffmpeg -h encoder=libx264，会打印libx264 encoder的使用说明：

Encoder libx264 [libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10]:General capabilities: delay threads Threading capabilities: autoSupported pixel formats: yuv420p yuvj420p yuv422p yuvj422p yuv444p yuvj444p nv12 nv16 nv21
libx264 AVOptions:-preset            <string>     E..V.... Set the encoding preset (cf. x264 --fullhelp) (default "medium")-tune              <string>     E..V.... Tune the encoding params (cf. x264 --fullhelp)-profile           <string>     E..V.... Set profile restrictions (cf. x264 --fullhelp) -fastfirstpass     <boolean>    E..V.... Use fast settings when encoding first pass (default true)-level             <string>     E..V.... Specify level (as defined by Annex A)-passlogfile       <string>     E..V.... Filename for 2 pass stats-wpredp            <string>     E..V.... Weighted prediction for P-frames-a53cc             <boolean>    E..V.... Use A53 Closed Captions (if available) (default true)-x264opts          <string>     E..V.... x264 options-crf               <float>      E..V.... Select the quality for constant quality mode (from -1 to FLT_MAX) (default -1)-crf_max           <float>      E..V.... In CRF mode, prevents VBV from lowering quality beyond this point. (from -1 to FLT_MAX) (default -1)-qp                <int>        E..V.... Constant quantization parameter rate control method (from -1 to INT_MAX) (default -1)-aq-mode           <int>        E..V.... AQ method (from -1 to INT_MAX) (default -1)none                         E..V....variance                     E..V.... Variance AQ (complexity mask)autovariance                 E..V.... Auto-variance AQautovariance-biased              E..V.... Auto-variance AQ with bias to dark scenes-aq-strength       <float>      E..V.... AQ strength. Reduces blocking and blurring in flat and textured areas. (from -1 to FLT_MAX) (default -1)-psy               <boolean>    E..V.... Use psychovisual optimizations. (default auto)-psy-rd            <string>     E..V.... Strength of psychovisual optimization, in <psy-rd>:<psy-trellis> format.-rc-lookahead      <int>        E..V.... Number of frames to look ahead for frametype and ratecontrol (from -1 to INT_MAX) (default -1)-weightb           <boolean>    E..V.... Weighted prediction for B-frames. (default auto)-weightp           <int>        E..V.... Weighted prediction analysis method. (from -1 to INT_MAX) (default -1)none                         E..V....simple                       E..V....smart                        E..V....-ssim              <boolean>    E..V.... Calculate and print SSIM stats. (default auto)-intra-refresh     <boolean>    E..V.... Use Periodic Intra Refresh instead of IDR frames. (default auto)-bluray-compat     <boolean>    E..V.... Bluray compatibility workarounds. (default auto)-b-bias            <int>        E..V.... Influences how often B-frames are used (from INT_MIN to INT_MAX) (default INT_MIN)-b-pyramid         <int>        E..V.... Keep some B-frames as references. (from -1 to INT_MAX) (default -1)none                         E..V....strict                       E..V.... Strictly hierarchical pyramidnormal                       E..V.... Non-strict (not Blu-ray compatible)-mixed-refs        <boolean>    E..V.... One reference per partition, as opposed to one reference per macroblock (default auto)-8x8dct            <boolean>    E..V.... High profile 8x8 transform. (default auto)-fast-pskip        <boolean>    E..V.... (default auto)-aud               <boolean>    E..V.... Use access unit delimiters. (default auto)-mbtree            <boolean>    E..V.... Use macroblock tree ratecontrol. (default auto)-deblock           <string>     E..V.... Loop filter parameters, in <alpha:beta> form.-cplxblur          <float>      E..V.... Reduce fluctuations in QP (before curve compression) (from -1 to FLT_MAX) (default -1)-partitions        <string>     E..V.... A comma-separated list of partitions to consider. Possible values: p8x8, p4x4, b8x8, i8x8, i4x4, none, all-direct-pred       <int>        E..V.... Direct MV prediction mode (from -1 to INT_MAX) (default -1)none                         E..V....spatial                      E..V....temporal                     E..V....auto                         E..V....-slice-max-size    <int>        E..V.... Limit the size of each slice in bytes (from -1 to INT_MAX) (default -1)-stats             <string>     E..V.... Filename for 2 pass stats-nal-hrd           <int>        E..V.... Signal HRD information (requires vbv-bufsize; cbr not allowed in .mp4) (from -1 to INT_MAX) (default -1)none                         E..V....vbr                          E..V....cbr                          E..V....-avcintra-class    <int>        E..V.... AVC-Intra class 50/100/200 (from -1 to 200) (default -1)-motion-est        <int>        E..V.... Set motion estimation method (from -1 to 4) (default -1)dia                          E..V....hex                          E..V....umh                          E..V....esa                          E..V....tesa                         E..V....-forced-idr        <boolean>    E..V.... If forcing keyframes, force them as IDR frames. (default false)-coder             <int>        E..V.... Coder type (from -1 to 1) (default default)default                      E..V....cavlc                        E..V....cabac                        E..V....vlc                          E..V....ac                           E..V....-b_strategy        <int>        E..V.... Strategy to choose between I/P/B-frames (from -1 to 2) (default -1)-chromaoffset      <int>        E..V.... QP difference between chroma and luma (from INT_MIN to INT_MAX) (default -1)-sc_threshold      <int>        E..V.... Scene change threshold (from INT_MIN to INT_MAX) (default -1)-noise_reduction   <int>        E..V.... Noise reduction (from INT_MIN to INT_MAX) (default -1)-x264-params       <string>     E..V.... Override the x264 configuration using a :-separated list of key=value parameters

1.3 打印帮助或支持能力的信息

ffmpeg -help打印的下面部分的信息说明了如何获取一些help信息和各种格式支持的能力。

Print help / information / capabilities:
-L                  show license
-h topic            show help
-? topic            show help
-help topic         show help
--help topic        show help
-version            show version
-buildconf          show build configuration
-formats            show available formats
-muxers             show available muxers
-demuxers           show available demuxers
-devices            show available devices
-codecs             show available codecs
-decoders           show available decoders
-encoders           show available encoders
-bsfs               show available bit stream filters
-protocols          show available protocols
-filters            show available filters
-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

1.4 全局选项

帮助信息的下面部分是全局选项的说明。

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

很多选项都经常使用，比如-v, -y。

1.5 文件选项

帮助信息的下面部分是针对每个文件可以指定的选项。

Per-file main options:
-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

比如-f fmt指定文件的格式。
-c, -t, -to, -ss这几个选项都比较常用。

1.6 视频/音频/字幕相关的选项

帮助信息的下面部分是针对视频/音频/字幕相关的选项。

Video options:
-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 dataAudio options:
-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 filtersSubtitle 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

上面列出的选项大多数都是经常会用到的。

2. 流选择选项

一些媒体格式如Mp4、AVI等可以包含多种类型的流。
FFmpeg可以识别5种流类型：音频audio (a), 附件attachment (t), 数据data (d), 字幕subtitle (s) 和视频video (v)。
可以通过-map选项来选择需要的流，语法格式如下：

file_number:stream_type[:stream_number]

file_number和stream_number分别表示文件索引和流索引。
有一些特别的流选择指令：
-map 0 ：选择所有的流类型和其中所有的流。
-map i:v ：选择文件i中的所有视频流； -map i:a 选择所有的音频流；-map i:s
选择所有的字幕流。

3. 视频封装解封装

3.1 视频格式转换

ffmpeg -i input.avi c:a copy c:v copy output.mp4
ffmpeg -i input.mp4 output.ts

3.2 分离/合并视频音频流

ffmpeg -i input-video -vn -c:a copy output-audio //分离音频流
//-vn is no video.
//-acodec copy says use the same audio stream that's already in there.ffmpeg -i input-video -c:v copy -an output-video //分离视频流
//-an is no audio.
//-vcodec copy says use the same video stream that's already in there.ffmpeg -i input-video -c:v copy -an output-video -c:a -vn output-audio //同时分离音频和视频流ffmpeg -i video_file -i audio_file -c:v copy -c:a copy output_file //合并视频音频流

3.3 截取视频片段

ffmpeg -ss 5 -i input.mp4 -t 10 -c:v copy -c:a copy output.mp4
//-ss 5指定从输入视频第5秒开始截取，-t 10指明最多截取10秒。
//而-c:v copy -c:a copy标示视频与音频的编码不发生改变，而是直接复制，这样会大大提升速度，因为这样就不需要完全解码视频。

截取10s到20s

ffmpeg -i input.mp4 -c:v libx264 -filter:v select="between(t\, 10\, 20)" out.mp4

从头截取前10帧

ffmpeg -i input.mp4 -c:v libx264 -filter:v select="gt(n\, -1)" -vframes 10 out.mp4
ffmpeg -i input.mp4 -c:v libx264 -filter:v select="between(n\, 0\, 9)" out.mp4

中间截取 (10-20帧)

ffmpeg -i input.mp4 -c:v libx264 -filter:v select="between(n\, 10\, 20)" out.mp4

3.4 视频转换为m3u8格式

ffmpeg -i yoona.mp4 -c copy -map 0 -f segment -segment_list yoona.m3u8 -segment_time 10 yoona-%04d.ts

Set segment duration to time, the value must be a duration specification. Default value is "2".
Note that splitting may not be accurate, unless you force the reference stream key-frames at the given time. See the introductory notice and the examples below.

3.5 把视频文件推送到rtmp服务器

ffmpeg -re -i jack.mp4 -c copy -f flv rtmp://host/live/test

3.6 对视频进行切片

均匀切片

ffmpeg -i input.mp4 -c copy -f segment -segment_format mp4 -segment_time 300 -reset_timestamps 1 test_output-%d.mp4

以上命令把input.mp4切分为5分钟时长的视频片段。
segment muxer的参数可以使用ffmpeg -h muxer=segment查看

按照时间点进行剪切

ffmpeg -i input.mp4 -c copy -f segment -segment_format mp4 -segment_times 60,120,150 -reset_timestamps 1 test_output-%d.mp4

在第60秒、第120秒和第150秒这三个时间点进行切片。

4. 视频解码编码

4.1 视频截图

获取视频时间点01:23:45的截图

ffmpeg -ss 01:23:45 -i input -vframes 1 -q:v 2 output.jpg-i input file           the path to the input file
-ss 01:23:45            seek the position to the specified timestamp
-vframes 1              only handle one video frame
-q:v 2                  to control output quality. Full range is a linear scale of 1-31 where a lower value results in a higher quality. 2-5 is a good range to try.
output.jpg              output filename, should have a well-known extension

截取视频帧序号34的图像，帧序号从0开始。

ffmpeg -i <input> -vf "select=eq(n\,34)" -vframes 1 out.png

4.2 视频/图片尺寸修改

ffmpeg -i sample.jpg -s w*h out.jpg

4.3 分离视频的YUV通道分量

ffmpeg -i jack.mp4 -filter_complex "extractplanes=y+u+v[y][u][v]" -map "[y]" jack_y.mp4 -map "[u]" jack_u.mp4 -map "[v]" jack_v.mp4

4.4 图片序列与视频的互相转换

ffmpeg -i %04d.jpg output.mp4
ffmpeg -i input.mp4 %04d.jpg
\\第一行命令是把0001.jpg、0002.jpg、0003.jpg等编码成output.mp4，
\\第二行则是相反把input.mp4变成0001.jpg……。
\\%04d.jpg表示从1开始用0补全的4位整数为文件名的jpg文件序列。

5. 视频filter

5.1 视频加水印

ffmpeg -i xizong.mp4 -i fleight.jpg -filter_complex "overlay=W-w-5:5" -codec:a copy xizong_fleight.mp4
//在右上角加水印，边距为5像素。

5.2 视频旋转transpose

顺时针翻转90度

ffmpeg -i input -vf transpose=1 output

翻转180度

ffmpeg -i in.mp4 -vf "transpose=1,transpose=1" out.mp4

5.3 调色3DLutFilter

应用颜色查找表Lut，有‘nearest’、‘trilinear’、‘tetrahedral’三种插值算法，命令行调用如下：

ffmpeg -i log.mp4 -vf lut3d="file=DK79.cube"  out.mp4

5.4 图像/视频转换成黑白的

图像转换成黑白的

ffmpeg -i sample.png -vf hue=s=0 output.png

//把视频转换为黑白的
ffmpeg -i julin_5s.mp4 -vf hue=s=0 -c:a copy julin_monochrome.mp4

5.5 裁剪视频crop

使用-crop选项，语法如下：

crop=ow[:oh[:x[:y[:keep_aspect]]]]

ow、oh表示裁减之后输出视频的宽和高，
x、y表示在输入视频上开始裁减的横坐标和纵坐标，
keep_aspect: 1表示保持裁剪后输出的纵横比与输入一致，0表示不保持。

裁剪输入视频的左三分之一，中间三分之一，右三分之一:
ffmpeg -i input -vf crop=iw/3:ih :0:0 output
ffmpeg -i input -vf crop=iw/3:ih :iw/3:0 output
ffmpeg -i input -vf crop=iw/3:ih :iw/3*2:0 output

裁剪中间一半区域：
ffmpeg -i input -vf crop=iw/2:ih/2 output

5.6 视频尺寸缩放scale

将输入的1920x1080缩小到960x540输出

ffmpeg -i input.mp4 -vf scale=960:540 output.mp4
//ps: 如果540不写，写成-1，即scale=960:-1, 那也是可以的，ffmpeg会通知缩放滤镜在输出时保持原始的宽高比。

5.7 视频中去水印delogo

使用delogo filter
它对logo周围像素的简单插值来实现。只需设置一个覆盖logo的矩形。在每个方向上，紧靠矩形外的下一个像素的值将用于计算矩形内的插值像素值。

语法：-vf delogo=x:y:w:h[:t[:show]]
x:y 离左上角的坐标
w:h logo的宽和高
show：默认值0，若设置为1，指定区域的边界会绘制一个绿色的矩形框用于找到合适的x、y、w、h参数。

示例

ffmpeg -i input.mp4 -vf delogo=x=0:y=0:w=100:h=60 output.mp4

5.8 给视频或图像加上黑边pad

比如一个输入视频尺寸是1280x534的源，想要加上黑边变成1280x720，使用下面的命令可以实现。

ffmpeg -i input.mp4 -vf pad=1280:720:0:93:black output.mp4

按照从左到右的顺序依次为：“宽”、“高”、“X坐标”和“Y坐标”，宽和高指的是输入视频尺寸（包含加黑边的尺寸），X、Y指的是视频所在位置。
默认是加黑色的边，black可以不写。
上面的命令中93是根据(720-534) / 2计算得到。

如果视频原始1920x800的话，完整的语法应该是：

   -vf 'scale=1280:534,pad=1280:720:0:93:black'

先将视频缩小到1280x534，然后在加入黑边变成1280x720，将1280x534的视频放置在x=0，y=93的地方。

5.9 计算psnr/ssim

分析 psnr 主要是针对转码前的视频和转码后的视频的对比；如果转码是降分辨率，对比的时候，还需要对源视频加 -s widthxhigh;保证分辨率一致再做 psnr 和 ssim 的计算；

psnr

ffmpeg -i src.mp4  -i dst.mp4  -lavfi psnr="stats_file=psnr.log" -f null -

ssim

ffmpeg -i src.mp4  -i dst.mp4  -lavfi ssim="stats_file=ssim.log" -f null -

同时计算psnr和ssim

ffmpeg -i main.mpg -i ref.mpg -lavfi  "ssim;[0:v][1:v]psnr" -f null -

5.10 视频按时间拼接

使用 FFmpeg 的concat 工具。

先创建一个文本文件，包含需要拼接的文件的列表。

filelist.txt：

file 'input1.mp4'
file 'input2.mp4'
file 'input3.mp4'

命令

ffmpeg -f concat -i filelist.txt -c copy output.mp4

5.11 视频左右拼接

ffmpeg -ss 00:05:00 -i v1.mp4 -ss -ss 00:05:00 -i v2.mp4 -filter_complex "[0:v]crop=iw/2:ih:0:0[v1];[1:v]crop=iw/2:ih:iw/2:0[v2];[v1][v2]hstack[v3];[v3]drawbox=iw/2-1:0:2:ih[v4]" -map [v4] -map 0:a -c:a copy -c:v libx264 -t 00:01:00 -y out.mp4

5.12 打印视频帧的一些信息showinfo

ffmpeg -hide_banner  -i  v.mp4 -vf showinfo -frames:v 1 -f null /dev/null

打印的信息类似

[Parsed_showinfo_0 @ 0x74f2d40] config out time_base: 0/0, frame_rate: 0/0
[Parsed_showinfo_0 @ 0x74f2d40] n:   0 pts:      0 pts_time:0       pos:    55743 fmt:yuv420p sar:1395/1394 s:656x360 i:P iskey:1 type:I checksum:81726064 plane_checksum:[C119CB7C 5DDE813C 3A76139D] mean:[106 126 142] stdev:[52.5 8.3 18.8]
[Parsed_showinfo_0 @ 0x74f2d40]   side data - User Data Unregistered:
[Parsed_showinfo_0 @ 0x74f2d40] UUID=dc45e9bd-e6d9-48b7-962c-d820d923eeef
[Parsed_showinfo_0 @ 0x74f2d40] color_range:unknown color_space:unknown color_primaries:unknown color_trc:unknown
[Parsed_showinfo_0 @ 0x74f2d40] n:   1 pts:   1024 pts_time:0.0666667 pos:    69559 fmt:yuv420p sar:1395/1394 s:656x360 i:P iskey:0 type:B checksum:3AB39554 plane_checksum:[C775F70F 3E19845B DFD819DB] mean:[107 126 142] stdev:[52.5 8.3 18.8]
[Parsed_showinfo_0 @ 0x74f2d40] color_range:unknown color_space:unknown color_primaries:unknown color_trc:unknown

5.13 生成纯色的图片

生成黑色的图片

ffmpeg -f lavfi -i color=Black:640x480 -frames:v 1 -y black.jpg

详细参数介绍见ffmpeg文档

5.14 打印帧序号/pts到视频帧水印drawtext

打印帧序号

ffmpeg -i test.mp4 -vf drawtext=fontcolor=red:fontsize=40:fontfile=msyh.ttf:line_spacing=7:text=%{n}:x=50:y=50 -vsync 0  -y out.mp4

打印帧pts

ffmpeg -i test.mp4 -vf drawtext=fontcolor=red:fontsize=30:fontfile=msyh.ttf:line_spacing=7:text=%{pts}:x=50:y=50  -vsync 0  -y out.mp4

打印帧类型

 ffmpeg -i test.mp4 -vf drawtext=fontcolor=red:fontsize=20:fontfile=msyh.ttf:line_spacing=7:text=%{pict_type}:x=50:y=50 -vsync 0 -y out.mp4

把视频的pts[时间戳]添加为视频水印，精度到毫秒

ffmpeg -i test.mp4 -vf “drawtext=fontsize=60:text=’%{pts:hms}’” -c:v libx264 -c copy -f mp4 output.mp4 -y

6. 音频解码编码

6.1 PCM原始数据和WAV格式转换

wav格式转换为PCM裸流

ffmpeg -i xizong.wav -f f32le -ar 44100 -acodec pcm_f32le output_f32le.raw

参数说明：
-f f32le … 浮点数32为小字端的采样格式
-ar 44100 … 采样频率
-ac 2 … 声道数量

PCM裸流转wav格式

ffmpeg -f f32le -ar 44100 -ac 2 -acodec pcm_f32le -i xizong_f32le.raw xizong_f32le.wav

说明需要先使用ffprobe查看wav中音频的采样格式，以上例子是使用的f32le采样格式的数据。

7. 音频filter

7.1 倍速atempo

速度减半

ffmpeg -i input.mp3 -af atempo=0.5 output.mp3

2倍速率

ffmpeg -i input.mp3 -af atempo=2 output.mp3

8. 字幕相关

8.1 字幕文件转换

字幕文件有很多种，常见的有 .srt , .ass 文件等。

//将.srt文件转换成.ass文件
ffmpeg -i subtitle.srt subtitle.ass将.ass文件转换成.srt文件
ffmpeg -i subtitle.ass subtitle.srt

8.2 集成字幕到视频文件

ffmpeg -i input.mp4 -i subtitles.srt -c:s mov_text -c:v copy -c:a copy output.mp4

9. ffplay命令

9.1 ffplay播放yuv视频数据

ffplay -f <文件格式> -pix_fmt <像素格式> -video_size <视频尺寸> <文件名>
示例：
ffplay -f rawvideo -pix_fmt yuv420p -video_size 848x480 yuv_video

9.2 ffplay播放PCM音频数据

ffplay -f <格式名> -ac <声道数> -ar <采样率> <文件名>
示例：
ffplay -f f32le -ac 1 -ar 48000 pcm_audio

9.3 ffplay播放音频并显示波形图

ffplay -showmode 1 simple.mp4

9.4 ffplay指定显示的宽高

ffplay -x 1208 -y 720 sample.mp4

10. ffprobe命令

10.1 ffprobe查看媒体文件的信息

ffprobe target.mp4 -show_format -show_streams -print_format json -loglevel fatal

示例输出：

root@smallest:/home/video# ffprobe jack.mp4 -show_format -show_streams -print_format json -loglevel fatal
{"streams": [{"index": 0,"codec_name": "h264","codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10","profile": "High","codec_type": "video","codec_time_base": "1/50","codec_tag_string": "avc1","codec_tag": "0x31637661","width": 848,"height": 480,"coded_width": 848,"coded_height": 480,"has_b_frames": 1,"sample_aspect_ratio": "1:1","display_aspect_ratio": "53:30","pix_fmt": "yuv420p","level": 30,"chroma_location": "left","refs": 1,"is_avc": "true","nal_length_size": "4","r_frame_rate": "25/1","avg_frame_rate": "25/1","time_base": "1/25000","start_pts": 0,"start_time": "0.000000","duration_ts": 39754000,"duration": "1590.160000","bit_rate": "449785","bits_per_raw_sample": "8","nb_frames": "7499","disposition": {"default": 1,"dub": 0,"original": 0,"comment": 0,"lyrics": 0,"karaoke": 0,"forced": 0,"hearing_impaired": 0,"visual_impaired": 0,"clean_effects": 0,"attached_pic": 0,"timed_thumbnails": 0},"tags": {"creation_time": "2016-09-14T08:14:35.000000Z","language": "und","handler_name": "TrackHandler"}},{"index": 1,"codec_name": "aac","codec_long_name": "AAC (Advanced Audio Coding)","profile": "HE-AAC","codec_type": "audio","codec_time_base": "1/48000","codec_tag_string": "mp4a","codec_tag": "0x6134706d","sample_fmt": "fltp","sample_rate": "48000","channels": 2,"channel_layout": "stereo","bits_per_sample": 0,"r_frame_rate": "0/0","avg_frame_rate": "0/0","time_base": "1/24000","start_pts": 0,"start_time": "0.000000","duration_ts": 7199744,"duration": "299.989333","bit_rate": "48030","max_bit_rate": "56888","nb_frames": "7031","disposition": {"default": 1,"dub": 0,"original": 0,"comment": 0,"lyrics": 0,"karaoke": 0,"forced": 0,"hearing_impaired": 0,"visual_impaired": 0,"clean_effects": 0,"attached_pic": 0,"timed_thumbnails": 0},"tags": {"creation_time": "2016-09-14T08:11:52.000000Z","language": "und","handler_name": "Sound Media Handler"}}],"format": {"filename": "jack.mp4","nb_streams": 2,"nb_programs": 0,"format_name": "mov,mp4,m4a,3gp,3g2,mj2","format_long_name": "QuickTime / MOV","start_time": "0.000000","duration": "299.988333","size": "18813764","bit_rate": "501719","probe_score": 100,"tags": {"major_brand": "mp42","minor_version": "0","compatible_brands": "isomavc1mp42","creation_time": "2016-09-14T08:14:35.000000Z"}}
}

-print_format json: 结果以json格式呈现
-show_format: 打印封装格式信息，在format节点中。
-show_streams: 打印流信息，在streams节点中。

10.2 ffprobe查看时间戳

查看视频dts

ffprobe -show_packets -select_streams v 1.ts | grep dts_time

查看视频pts

ffprobe -show_packets -select_streams v 1.ts | grep pts_time

查看视频流前几帧的pts

ffprobe -v error -of compact -read_intervals  %+#10 -show_packets -select_streams v 1.ts

查看关键帧的pts

ffprobe -v error -select_streams v:0 -show_entries packet=pts_time,flags -of csv=print_section=0 input.mp4 | awk -F',' '/K/ {print $1}'

查看关键帧帧间的间隔

./ffprobe -of compact -select_streams v -show_packets  'test.mp4'| grep K_ | awk 'BEGIN{FS="|";last=-1}{split($5,a,"="); if(last != -1) {print "Keframe pos: " a[2] ", Interval: " a[2]-last " seconds"} else {print "Keyframe: " a[2]}; last=a[2]}'

11. 其他

11.1 ffmpeg或ffplay 打开 DEBUG 日志输出。

$ ffplay -v debug $URL

API中开启debug日志

av_log_set_level(AV_LOG_DEBUG);

11.2 FFmpeg命令日志输出到文件

执行ffmpeg或者ffprobe输出重定向到文件的时候发现文件是空的。
可以采用下面的方式。

ffprobe xxx > file 2>&1

shell输出分好多种，0表示键盘输出，1表示屏幕输出，2表示错误输出。 cmd > file，只是把屏幕输出重定向到文件中。
调用ffmpeg相关命令，打印信息都被终端认为是错误输出，但是一般情况下这种信息也会输出到屏幕上,所以我们可以在屏幕上看到它。但是，当我们想重定向到文件中，却被系统认为是错误输出而忽略。
2>&1表示错误输出重定向到屏幕输出。&标明其后面跟的是一个文件描述符，而不是一个文件名。

11.3 打印支持DirectShow的设备列表

打印支持DirectShow的设备列表

ffmpeg -list_devices true -f dshow -i dummy

打开名称为“Lenovo EasyCamera”的摄像头

ffmpeg -f dshow -i video="Lenovo EasyCamera"