> For the complete documentation index, see [llms.txt](https://wtifs.gitbook.io/diva-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wtifs.gitbook.io/diva-notes/work/ffmpeg.md).

# Ffmpeg

**安装**

```
brew install ffmpeg
```

**基础用法**

```bash
ffmpeg -i 源文件         // 查看源文件信息
ffmpeg -i 源文件 目标文件 // 格式转换
```

**常用参数**

```bash
-fs 15MB // file size 指定输出文件大小，不好使
-preset  // 压缩预设参数，可选 ultrafast / fast / medium / slow 等
```

**视频压缩**

```bash
ffmpeg -i xxx.mp4 -c:v libx265 -preset ultrafast xxx2.mp4
```

**批量从视频中提取音频**

```bash
for s in *.mp4;do ffmpeg -i $s ${s}.mp3;done
```