了解

FFmpeg是一个音视频处理库，提供了如 ffmpeg, ffplay, ffprobe，来编辑你的音视频文件。

安装

源码安装

➜  GitHub git clone https://git.ffmpeg.org/ffmpeg.git ffmpeg
Cloning into 'ffmpeg'...
remote: Counting objects: 588505, done.
remote: Compressing objects: 100% (120835/120835), done.
remote: Total 588505 (delta 471727), reused 581424 (delta 466456)
Receiving objects: 100% (588505/588505), 138.43 MiB | 2.74 MiB/s, done.
Resolving deltas: 100% (471727/471727), done.
Checking out files: 100% (7264/7264), done.
➜  GitHub cd ffmpeg 
➜  ffmpeg git:(master) ls
CONTRIBUTING.md  LICENSE.md       ffbuild          libpostproc
COPYING.GPLv2    MAINTAINERS      fftools          libswresample
COPYING.GPLv3    Makefile         libavcodec       libswscale
COPYING.LGPLv2.1 README.md        libavdevice      presets
COPYING.LGPLv3   RELEASE          libavfilter      tests
CREDITS          compat           libavformat      tools
Changelog        configure        libavresample
INSTALL.md       doc              libavutil
➜  ffmpeg git:(master) ./configure --help
➜  ffmpeg git:(master) ./configure --help | more 
Usage: configure [options]
Options: [defaults in brackets after descriptions]

➜  ffmpeg git:(master) ./configure --prefix=/usr/local/ffmpeg --enable-gpl  --enable-nonfree  --enable-libfdk-aac  --enable-libx264   --enable-libx265  --enable-filter=delogo  --enable-debug  --disable-optimizations --enable-libspeex  --enable-videotoolbox  --enable-shared  --enable-pthreads  --enable-version3  --enable-hardcoded-tables --cc=clang --host-cflags=  --host-ldflags=


报错、报错、报错、报错、
nasm/yasm not found or too old. Use --disable-x86asm for a crippled build.
ERROR: libfdk_aac not found
ERROR: speex not found using pkg-config
ERROR: libx264 not found

前面三种都可以通过brew install来解决，但是libx264怎么搞都拉不下。。。

通过brew安装

➜  ffmpeg git:(master) brew install ffmpeg
Updating Homebrew...
==> Installing dependencies for ffmpeg: aom,,,,

==> Caveats
gettext is keg-only, which means it was not symlinked into /usr/local,
because macOS provides the BSD gettext library & some software gets confused if both are in the library path.

If you need to have gettext first in your PATH run:
  echo 'export PATH="/usr/local/opt/gettext/bin:$PATH"' >> ~/.zshrc

For compilers to find gettext you may need to set:
  export LDFLAGS="-L/usr/local/opt/gettext/lib"
  export CPPFLAGS="-I/usr/local/opt/gettext/include"
==> Caveats
libffi is keg-only, which means it was not symlinked into /usr/local,
because some formulae require a newer version of libffi.

For compilers to find libffi you may need to set:
  export LDFLAGS="-L/usr/local/opt/libffi/lib"

For pkg-config to find libffi you may need to set:
  export PKG_CONFIG_PATH="/usr/local/opt/libffi/lib/pkgconfig"


==> Caveats
==> gettext
gettext is keg-only, which means it was not symlinked into /usr/local,
because macOS provides the BSD gettext library & some software gets confused if both are in the library path.

If you need to have gettext first in your PATH run:
  echo 'export PATH="/usr/local/opt/gettext/bin:$PATH"' >> ~/.zshrc

For compilers to find gettext you may need to set:
  export LDFLAGS="-L/usr/local/opt/gettext/lib"
  export CPPFLAGS="-I/usr/local/opt/gettext/include"

==> libffi
libffi is keg-only, which means it was not symlinked into /usr/local,
because some formulae require a newer version of libffi.

For compilers to find libffi you may need to set:
  export LDFLAGS="-L/usr/local/opt/libffi/lib"

For pkg-config to find libffi you may need to set:
  export PKG_CONFIG_PATH="/usr/local/opt/libffi/lib/pkgconfig"

==> unbound
To have launchd start unbound now and restart at startup:
  sudo brew services start unbound
==> glib
Bash completion has been installed to:
  /usr/local/etc/bash_completion.d
==> tesseract
This formula contains only the "eng", "osd", and "snum" language data files.
If you need any other supported languages, run `brew install tesseract-lang`.

brew info ffmpeg可以看到x264, x265这些包都是有安装的。升级则通过brew update && brew upgrade ffmpeg.

第二种方式安装连环境变量都不需要设置，完美极了。

目录及作用

libavcodec：提供了一系列编码器的实现。
libavformat：实现在流协议，容器格式及其本IO访问。
libavutil：包括了hash器，解码器和各利工具函数。
libavfilter：提供了各种音视频过滤器。
libavdevice：提供了访问捕获设备和回放设备的接口。
libswresample：实现了混音和重采样。
libswscale：实现了色彩转换和缩放工能。

基本概念

音／视频流 在音视频领域，我们把一路音／视频称为一路流。如我们小时候经常使用VCD看港片，在里边可以选择粤语或国语声音，其实就是CD视频文件中存放了两路音频流，用户可以选择其中一路进行播放。

容器 我们一般把 MP4､ FLV、MOV等文件格式称之为容器。也就是在这些常用格式文件中，可以存放多路音视频文件。以 MP4 为例，就可以存放一路视频流，多路音频流，多路字幕流。

channel 是音频中的概念，称之为声道。在一路音频流中，可以有单声道，双声道或立体声。

参考链接：

https://blog.csdn.net/weixin_33985507/article/details/94470495

https://blog.csdn.net/leixiaohua1020/article/details/15811977