为什么 ffmpeg 需要 DNS 解析器作为其依赖项？

Question

brew install ffmpeg libav当我unbound在依赖项列表中注意到时，我今天正在安装 FFmpeg 和 libav 。

这很奇怪，因为unbound是 DNS 解析器以及为什么 ffmpeg 需要它。

? brew install ffmpeg libav
==> Installing dependencies for ffmpeg: aom, frei0r, gmp, libtasn1, nettle, p11-kit, unbound, gnutls, lame, libass, libbluray, libsoxr, libvidstab, libvpx, opencore-amr, opus, libsndfile, libsamplerate, rubberband, sdl2, speex, giflib, leptonica, tesseract, theora, x264, x265 and xvid

我什至检查了 ffmpeg 的信息列表，但unbound那里没有

? brew info ffmpeg
ffmpeg: stable 4.2.1 (bottled), HEAD
Play, record, convert, and stream audio and video
https://ffmpeg.org/
/usr/local/Cellar/ffmpeg/4.2.1_2 (287 files, 56.6MB)*
- Poured from bottle on 2019-12-19 at 10:45:56
From: https://github.com/Homebrew/homebrew-core/blob/master/Formula/ffmpeg.rb
==> Dependencies
Build: nasm ?, pkg-config ?, texi2html ?
Required: aom ?, fontconfig ?, freetype ?, frei0r ?, gnutls ?, lame ?, libass ?, libbluray ?, libsoxr ?, libvidstab ?, libvorbis ?, libvpx ?, opencore-amr ?, openjpeg ?, opus ?, rtmpdump ?, rubberband ?, sdl2 ?, snappy ?, speex ?, tesseract ?, theora ?, x264 ?, x265 ?, xvid ?, xz ?
==> Options
--HEAD
    Install HEAD version
==> Analytics
install: 66,434 (30 days), 280,128 (90 days), 1,079,492 (365 days)
install-on-request: 48,053 (30 days), 203,583 (90 days), 759,254 (365 days)
build-error: 0 (30 days)

参考链接

• https://formulae.brew.sh/formula/ffmpeg
• https://formulae.brew.sh/formula/unbound

Answer 1

brew deps --tree可以帮助你解决这个问题。在 的情况下ffmpeg，unbound被拉入以gnutls支持 HTTPS。

% brew deps --tree ffmpeg        
ffmpeg
??? aom
??? fontconfig
?   ??? freetype
?       ??? libpng
??? freetype
?   ??? libpng
??? frei0r
??? gnutls
?   ??? gmp
?   ??? libidn2
?   ?   ??? gettext
?   ?   ??? libunistring
?   ??? libtasn1
?   ??? libunistring
?   ??? nettle
?   ?   ??? gmp
?   ??? p11-kit
?   ?   ??? libffi
?   ??? unbound
?       ??? libevent
?       ?   ??? openssl@1.1
?       ??? openssl@1.1
??? lame
??? libass
?   ??? freetype
?   ?   ??? libpng
?   ??? fribidi
?   ??? harfbuzz
?       ??? cairo
?       ?   ??? fontconfig
?       ?   ?   ??? freetype
?       ?   ?       ??? libpng
?       ?   ??? freetype
?       ?   ?   ??? libpng
?       ?   ??? glib
?       ?   ?   ??? gettext
?       ?   ?   ??? libffi
?       ?   ?   ??? pcre
?       ?   ?   ??? python
?       ?   ?       ??? gdbm
?       ?   ?       ??? openssl@1.1
?       ?   ?       ??? readline
?       ?   ?       ??? sqlite
?       ?   ?       ?   ??? readline
?       ?   ?       ??? xz
?       ?   ??? libpng
?       ?   ??? lzo
?       ?   ??? pixman
?       ??? freetype
?       ?   ??? libpng
?       ??? glib
?       ?   ??? gettext
?       ?   ??? libffi
?       ?   ??? pcre
?       ?   ??? python
?       ?       ??? gdbm
?       ?       ??? openssl@1.1
?       ?       ??? readline
?       ?       ??? sqlite
?       ?       ?   ??? readline
?       ?       ??? xz
?       ??? graphite2
?       ??? icu4c
??? libbluray
?   ??? fontconfig
?   ?   ??? freetype
?   ?       ??? libpng
?   ??? freetype
?       ??? libpng
??? libsoxr
??? libvidstab
??? libvorbis
?   ??? libogg
??? libvpx
??? opencore-amr
??? openjpeg
?   ??? libpng
?   ??? libtiff
?   ?   ??? jpeg
?   ??? little-cms2
?       ??? jpeg
?       ??? libtiff
?           ??? jpeg
??? opus
??? rtmpdump
?   ??? openssl@1.1
??? rubberband
?   ??? libsamplerate
?   ?   ??? libsndfile
?   ?       ??? flac
?   ?       ?   ??? libogg
?   ?       ??? libogg
?   ?       ??? libvorbis
?   ?           ??? libogg
?   ??? libsndfile
?       ??? flac
?       ?   ??? libogg
?       ??? libogg
?       ??? libvorbis
?           ??? libogg
??? sdl2
??? snappy
??? speex
?   ??? libogg
??? tesseract
?   ??? leptonica
?   ?   ??? giflib
?   ?   ??? jpeg
?   ?   ??? libpng
?   ?   ??? libtiff
?   ?   ?   ??? jpeg
?   ?   ??? openjpeg
?   ?   ?   ??? libpng
?   ?   ?   ??? libtiff
?   ?   ?   ?   ??? jpeg
?   ?   ?   ??? little-cms2
?   ?   ?       ??? jpeg
?   ?   ?       ??? libtiff
?   ?   ?           ??? jpeg
?   ?   ??? webp
?   ?       ??? jpeg
?   ?       ??? libpng
?   ?       ??? libtiff
?   ?           ??? jpeg
?   ??? libtiff
?       ??? jpeg
??? theora
?   ??? libogg
?   ??? libvorbis
?       ??? libogg
??? x264
??? x265
??? xvid
??? xz