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FFmpegAndroid/doc/FFmpeg_command_line.md

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# 前言
FFmpeg多媒体库支持的命令行调用分为三个模块:ffmpeg、ffprobe、ffplay。<br>
其中ffmpeg命令行常用于音视频剪切、转码、滤镜、拼接、混音、截图等;<br>
ffprobe用于检测多媒体流格式;ffplay用于播放视频,包括本地与网络视频。<br>
详情可查阅FFmpeg官方文档:[ffmpeg Documentation](https://ffmpeg.org/documentation.html)<br>
# 一、ffmpeg命令行
## 1、命令行参数介绍
Print help / information / capabilities:<br>
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-help&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show help<br>
-version&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show version<br>
-formats&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available formats<br>
-muxers&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available muxers<br>
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-demuxers&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available demuxers<br>
-devices&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available devices<br>
-codecs&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available codecs<br>
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-decoders&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available decoders<br>
-encoders&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available encoders<br>
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-bsfs&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available bit stream filters<br>
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-protocols&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available protocols<br>
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-filters&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available filters<br>
-pix_fmts&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available pixel formats<br>
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-sample_fmts&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available audio sample formats<br>
-hwaccels&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;show available HW acceleration methods<br>
Global options (affect whole program instead of just one file:<br>
-v loglevel&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;set logging level<br>
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-y&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;overwrite output files<br>
-n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;never overwrite output files<br>
-filter_threads&nbsp;&nbsp;&nbsp;number of non-complex filter threads<br>
-stats&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;print progress report during encoding<br>
-vol volume&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;change audio volume (256=normal)<br>
Per-file main options:<br>
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-f fmt&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;force format<br>
-c codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;codec name<br>
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-codec codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;codec name<br>
-t duration&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;record or transcode "duration" seconds of audio/video<br>
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-to time_stop&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;record or transcode stop time<br>
-fs limit_size&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;set the limit file size in bytes<br>
-ss time_off&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;set the start time offset<br>
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-sseof time_off&nbsp;&nbsp;&nbsp;set the start time offset relative to EOF<br>
-frames number&nbsp;&nbsp;&nbsp;set the number of frames to output<br>
Video options:<br>
-vframes number&nbsp;&nbsp;&nbsp;&nbsp;set the number of video frames to output<br>
-r rate&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;set frame rate (Hz value, fraction or abbreviation)<br>
-s size&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;set frame size (WxH or abbreviation)<br>
-aspect aspect&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;set aspect ratio (4:3, 16:9 or 1.3333, 1.7777)<br>
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-vn&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;disable video<br>
-vcodec codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;force video codec ('copy' to copy stream)<br>
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-vf filter_graph&nbsp;&nbsp;&nbsp;&nbsp;set video filters<br>
-ab bitrate&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;audio bitrate (please use -b:a)<br>
-b bitrate&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;video bitrate (please use -b:v)<br>
Audio options:<br>
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-aframes number&nbsp;&nbsp;&nbsp;set the number of audio frames to output<br>
-aq quality&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;set audio quality (codec-specific)<br>
-ar rate&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;set audio sampling rate (in Hz)<br>
-ac channels&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;set number of audio channels<br>
-an&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;disable audio<br>
-acodec codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;force audio codec ('copy' to copy stream)<br>
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-vol volume&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;change audio volume (256=normal)<br>
-af filter_graph&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;set audio filters<br>
Subtitle options:<br>
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-s size&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;set frame size<br>
-sn&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;disable subtitle<br>
-scodec codec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;force subtitle codec ('copy' to copy stream)<br>
命令行整体格式:以ffmpeg开头,参数之间用空格隔开,每个参数key以"-"开头,后面跟着参数value,输出文件放在命令行最后。<br>
## 2、音频常见操作
### 2.1 音频转码
直接转码:<br>
ffmpeg -i input.mp3 output.m4a<br>
指定编码器、采样率、声道数转码:<br>
ffmpeg -i input.mp3 -acodec aac -ac 2 -ar 44100 output.m4a<br>
### 2.2 音频剪切
-ss 10指定从第10秒开始,-t 20代表剪切20秒<br>
ffmpeg -i input.mp3 -ss 10 -t 20 cut.mp3<br>
### 2.3 音频拼接
ffmpeg -i concat:"hello.mp3|world.mp3" -acodec copy -vn concat.mp3<br>
### 2.4 音频混音
使用amix,参数inputs代表输入流个数,duration有longest、shortest、first三种模式,weights设置每条流音量权重占比:<br>
ffmpeg -i hello.mp3 -i world.mp3 -filter_complex amix=inputs=2:duration=first -vn mix.mp3<br>
使用amerge,合并成多声道输出:<br>
ffmpeg -i hello.mp3 -i world.mp3 -filter_complex [0:a][1:a]amerge=inputs=2[aout] -map [aout] merge.mp3<br>
### 2.5 空灵音效
aecho接收4个参数:in_gain (0, 1];out_gain (0, 1];delays (0 - 90000];decays (0 - 1.0]<br>
ffmpeg -i input.mp3 -af aecho=0.8:0.8:1000:0.5 echo.mp3<br>
### 2.6 惊悚音效
tremolo接收2个参数:frequency [0.1, 20000.0];depth (0, 1]<br>
ffmpeg -i input.mp3 -af tremolo=5:0.9 tremolo.mp3<br>
### 2.7 搞笑音效
搞笑音效通过调节音速实现,使用atempo:<br>
ffmpeg -i input.mp3 -filter_complex atempo=0.5 atempo.mp3<br>
### 2.8 静音检测
ffmpeg -i input.mp3 -af silencedetect=noise=0.0001 -f null -<br>
### 2.9 修改音量
ffmpeg -i input.mp3 -af volume=0.5 volume.mp3<br>
### 2.10 抽取音频
从视频抽取音频,也就是disable视频流、拷贝音频流:<br>
ffmpeg -i input.mp4 -acodec copy -vn out.mp3<br>
## 3、视频常见操作
### 3.1 视频剪切
基本剪切,指定起始时间、剪切时长:<br>
ffmpeg -i input.mp4 -ss 10 -t 20 -codec copy cut.mp4<br>
精确剪切,包含多音轨,-map 0代表所有track流进行剪切,-accurate_seek代表精确seek:<br>
ffmpeg -i input.mp4 -ss 10 -accurate_seek -t 20 -map 0 -codec copy cut.mp4<br>
### 3.2 视频转码
使用-vcodec指定视频编码,-acodec指定音频编码,-s 640x480指定视频分辨率,<br>
-b 200k指定码率,-r 20指定帧率,这样达到视频压缩效果:<br>
ffmpeg -i input.mp4 -vcodec libx264 -acodec aac -s 640x480 -b 200k -r 20 transcode.mp4<br>
### 3.3 视频截图
使用-vframes指定截图数量,-ss指定起始时间放在-i前面,这样保证先seek到指定位置再截图。<br>
如果是先-i指定输入文件再-ss,是从时间0开始解码,直到指定时间再截图,这样效率太低:<br>
ffmpeg -ss 10 -i input.mp4 -f image2 -vframes 1 -an screenshot.jpg<br>
### 3.4 图片水印
使用-filter_complex指定位置overlay=x:y,如下所示:<br>
ffmpeg -i input.mp4 -i logo.png -filter_complex overlay=10:20 pic_watermark.mp4<br>
如果要灵活设置左上角、右上角、左下角、右下角位置,可以使用case语句,其中main_w代表视频宽度,<br>
main_h代表视频高度,overlay_w代表水印宽度,overlay_h代表水印高度:<br>
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```
public static String obtainOverlay(int offsetX, int offsetY, int location) {
switch (location) {
case 2:
return "overlay='(main_w-overlay_w)-" + offsetX + ":" + offsetY + "'";
case 3:
return "overlay='" + offsetX + ":(main_h-overlay_h)-" + offsetY + "'";
case 4:
return "overlay='(main_w-overlay_w)-" + offsetX + ":(main_h-overlay_h)-" + offsetY + "'";
case 1:
default:
return "overlay=" + offsetX + ":" + offsetY;
}
}
public static String[] addWaterMarkImg(String inputPath, String imgPath, int location,
int offsetXY, String outputPath) {
String overlay = obtainOverlay(offsetXY, offsetXY, location);
String waterMarkCmd = "ffmpeg -i %s -i %s -filter_complex %s -preset:v superfast %s";
waterMarkCmd = String.format(waterMarkCmd, inputPath, imgPath, overlay, outputPath);
return waterMarkCmd.split(" ");
}
```
### 3.5 GIF水印
使用-ignore_loop 0代表GIF循环显示,其他操作与图片水印一致:<br>
ffmpeg -i input.mp4 -ignore_loop 0 -i logo.gif -filter_complex overlay=10:20 gif_mark.mp4<br>
### 3.6 去除水印
使用delogo命令,然后指定水印位置:<br>
ffmpeg -i input.mp4 -filter_complex delogo=x=10:y=20:w=90:h=30 delogo.mp4<br>
### 3.7 视频拼接
视频拼接分为垂直拼接、水平拼接,还有前后拼接,这里主要介绍垂直与水平拼接,其中使用hstack做水平拼接,vstack做垂直拼接:<br>
ffmpeg -i input1.mp4 -i input2.mp4 -filter_complex hstack out.mp4<br>
### 3.8 视频翻转
使用reverse实现视频翻转,但是处理比较耗时:<br>
ffmpeg -i input.mp4 -vf reverse -an output.mp4<br>
### 3.9 视频降噪
使用-nr代表noise reduction,进行视频降噪:<br>
ffmpeg -i in.mp4 -nr 500 out.mp4<br>
### 3.10 视频抽帧
ffmpeg -ss 20 -accurate_seek -t 10 -i input.mp4 -an -r 5 %3d.jpg<br>
### 3.11 播放速度
使用setpts设置视频速度,atempo设置音频速度:<br>
ffmpeg -i in.mp4 -filter_complex [0:v]setpts=%.2f*PTS[v];[0:a]atempo=%.2f[a] -map [v] -map [a] out.mp4<br>
# 二、ffplay命令行
ffplay主要用于播放视频,也可以播放网络流,示例如下:<br>
ffplay -i beyond.mp4<br>
# 三、ffprobe命令行
ffprobe主要用于检测多媒体信息,包括时长、视频分辨率、帧率、音频采样率、声道数、每个stream流信息等等。<br>
支持显示形式包括:json和xml,例如-print_format json<br>
ffprobe -i input.mp4 -show_streams -show_format -print_format json<br>
如果要显示每帧数据信息,使用-show_frames可以显示pts、packet_size、duration、frame_type等信息:<br>
ffprobe -i input.mp4 -show_frames<br>
如果只要显示视频流,使用-select_streams v。其中v代表video,a代表audio,s代表subtitle。<br>
ffprobe -i input.mp4 -show_frames -select_streams v<br>