我在三台电脑上使用 Ubuntu Studio 20.04 LTS：两台台式机和一台笔记本电脑。
但是，由于某些我不知道的原因，笔记本电脑中没有台式机中的某些 DVD 库。
该库与应用程序相关mkvtoolnix，主要调用：libdvdread4。
在笔记本电脑中我只有libdvdread7图书馆。
丢失的库不会出现在 Synaptic 包管理器中。
从命令行，当我尝试下载并安装错过的库时，我收到消息：
该软件包已过时或无法找到。但是，另一个软件包引用了它...
我不知道设备存储库之间的区别是什么。我检查了两次以上，并且...三个设备中的存储库列表完全相同！
我怎样才能将libdvdread4库放到 20.04 环境？？？
apt-cache policy在笔记本电脑中，该命令的输出是：
Archivos de paquetes:
100 /var/lib/dpkg/status
release a=now
500 https://repo.skype.com/deb stable/main amd64 Packages
release o=. stable,a=stable,n=stable,l=. stable,c=main,b=amd64
origin repo.skype.com
500 http://ppa.launchpad.net/mscore-ubuntu/mscore3-stable/ubuntu focal/main i386 Packages
release v=20.04,o=LP-PPA-mscore-ubuntu-mscore3-stable,a=focal,n=focal,l=Stable releases of MuseScore 3,c=main,b=i386
origin ppa.launchpad.net
500 http://ppa.launchpad.net/mscore-ubuntu/mscore3-stable/ubuntu focal/main amd64 Packages
release v=20.04,o=LP-PPA-mscore-ubuntu-mscore3-stable,a=focal,n=focal,l=Stable releases of MuseScore 3,c=main,b=amd64
origin ppa.launchpad.net
500 http://ppa.launchpad.net/mikhailnov/pulseeffects/ubuntu focal/main i386 Packages
release v=20.04,o=LP-PPA-mikhailnov-pulseeffects,a=focal,n=focal,l=PulseEffects PPA,c=main,b=i386
origin ppa.launchpad.net
500 http://ppa.launchpad.net/mikhailnov/pulseeffects/ubuntu focal/main amd64 Packages
release v=20.04,o=LP-PPA-mikhailnov-pulseeffects,a=focal,n=focal,l=PulseEffects PPA,c=main,b=amd64
origin ppa.launchpad.net
500 http://ppa.launchpad.net/libreoffice/ppa/ubuntu focal/main i386 Packages
release v=20.04,o=LP-PPA-libreoffice,a=focal,n=focal,l=LibreOffice Fresh,c=main,b=i386
origin ppa.launchpad.net
500 http://ppa.launchpad.net/libreoffice/ppa/ubuntu focal/main amd64 Packages
release v=20.04,o=LP-PPA-libreoffice,a=focal,n=focal,l=LibreOffice Fresh,c=main,b=amd64
origin ppa.launchpad.net
100 http://cl.archive.ubuntu.com/ubuntu focal-backports/universe i386 Packages
release v=20.04,o=Ubuntu,a=focal-backports,n=focal,l=Ubuntu,c=universe,b=i386
origin cl.archive.ubuntu.com
100 http://cl.archive.ubuntu.com/ubuntu focal-backports/universe amd64 Packages
release v=20.04,o=Ubuntu,a=focal-backports,n=focal,l=Ubuntu,c=universe,b=amd64
origin cl.archive.ubuntu.com
500 http://ppa.launchpad.net/otto-kesselgulasch/gimp/ubuntu focal/main i386 Packages
release v=20.04,o=LP-PPA-otto-kesselgulasch-gimp,a=focal,n=focal,l=gimp stable,c=main,b=i386
origin ppa.launchpad.net
500 http://ppa.launchpad.net/otto-kesselgulasch/gimp/ubuntu focal/main amd64 Packages
release v=20.04,o=LP-PPA-otto-kesselgulasch-gimp,a=focal,n=focal,l=gimp stable,c=main,b=amd64
origin ppa.launchpad.net
500 https://dl.winehq.org/wine-builds/ubuntu focal/main i386 Packages
release o=dl.winehq.org,a=focal,n=focal,l=winehq,c=main,b=i386
origin dl.winehq.org
500 https://dl.winehq.org/wine-builds/ubuntu focal/main amd64 Packages
release o=dl.winehq.org,a=focal,n=focal,l=winehq,c=main,b=amd64
origin dl.winehq.org
500 http://security.ubuntu.com/ubuntu focal-security/multiverse amd64 Packages
release v=20.04,o=Ubuntu,a=focal-security,n=focal,l=Ubuntu,c=multiverse,b=amd64
origin security.ubuntu.com
500 http://security.ubuntu.com/ubuntu focal-security/universe i386 Packages
release v=20.04,o=Ubuntu,a=focal-security,n=focal,l=Ubuntu,c=universe,b=i386
origin security.ubuntu.com
500 http://security.ubuntu.com/ubuntu focal-security/universe amd64 Packages
release v=20.04,o=Ubuntu,a=focal-security,n=focal,l=Ubuntu,c=universe,b=amd64
origin security.ubuntu.com
500 http://security.ubuntu.com/ubuntu focal-security/main i386 Packages
release v=20.04,o=Ubuntu,a=focal-security,n=focal,l=Ubuntu,c=main,b=i386
origin security.ubuntu.com
500 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages
release v=20.04,o=Ubuntu,a=focal-security,n=focal,l=Ubuntu,c=main,b=amd64
origin security.ubuntu.com
500 http://security.ubuntu.com/ubuntu focal-security/restricted i386 Packages
release v=20.04,o=Ubuntu,a=focal-security,n=focal,l=Ubuntu,c=restricted,b=i386
origin security.ubuntu.com
500 http://security.ubuntu.com/ubuntu focal-security/restricted amd64 Packages
release v=20.04,o=Ubuntu,a=focal-security,n=focal,l=Ubuntu,c=restricted,b=amd64
origin security.ubuntu.com
500 http://archive.canonical.com/ubuntu focal/partner i386 Packages
release v=20.04,o=Canonical,a=focal,n=focal,l=Partner archive,c=partner,b=i386
origin archive.canonical.com
500 http://archive.canonical.com/ubuntu focal/partner amd64 Packages
release v=20.04,o=Canonical,a=focal,n=focal,l=Partner archive,c=partner,b=amd64
origin archive.canonical.com
500 http://cl.archive.ubuntu.com/ubuntu focal-updates/multiverse amd64 Packages
release v=20.04,o=Ubuntu,a=focal-updates,n=focal,l=Ubuntu,c=multiverse,b=amd64
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal-updates/universe i386 Packages
release v=20.04,o=Ubuntu,a=focal-updates,n=focal,l=Ubuntu,c=universe,b=i386
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal-updates/universe amd64 Packages
release v=20.04,o=Ubuntu,a=focal-updates,n=focal,l=Ubuntu,c=universe,b=amd64
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal-updates/main i386 Packages
release v=20.04,o=Ubuntu,a=focal-updates,n=focal,l=Ubuntu,c=main,b=i386
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
release v=20.04,o=Ubuntu,a=focal-updates,n=focal,l=Ubuntu,c=main,b=amd64
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal-updates/restricted i386 Packages
release v=20.04,o=Ubuntu,a=focal-updates,n=focal,l=Ubuntu,c=restricted,b=i386
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal-updates/restricted amd64 Packages
release v=20.04,o=Ubuntu,a=focal-updates,n=focal,l=Ubuntu,c=restricted,b=amd64
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal/multiverse i386 Packages
release v=20.04,o=Ubuntu,a=focal,n=focal,l=Ubuntu,c=multiverse,b=i386
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal/multiverse amd64 Packages
release v=20.04,o=Ubuntu,a=focal,n=focal,l=Ubuntu,c=multiverse,b=amd64
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal/universe i386 Packages
release v=20.04,o=Ubuntu,a=focal,n=focal,l=Ubuntu,c=universe,b=i386
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal/universe amd64 Packages
release v=20.04,o=Ubuntu,a=focal,n=focal,l=Ubuntu,c=universe,b=amd64
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal/restricted i386 Packages
release v=20.04,o=Ubuntu,a=focal,n=focal,l=Ubuntu,c=restricted,b=i386
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal/restricted amd64 Packages
release v=20.04,o=Ubuntu,a=focal,n=focal,l=Ubuntu,c=restricted,b=amd64
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal/main i386 Packages
release v=20.04,o=Ubuntu,a=focal,n=focal,l=Ubuntu,c=main,b=i386
origin cl.archive.ubuntu.com
500 http://cl.archive.ubuntu.com/ubuntu focal/main amd64 Packages
release v=20.04,o=Ubuntu,a=focal,n=focal,l=Ubuntu,c=main,b=amd64
origin cl.archive.ubuntu.com
Paquetes con pin:
这就是笔记本电脑中的全部命令。