我认为在处理Multi-Architecture软件包管理时这是一个已知的问题。apt-get提出了首选的解决方案，以保持当前安装的相同软件包的体系结构，这在某些情况下不是您想要的。
在这种情况下，最好的解决方案是将它们:i386（libavcodec54或libavcodec-extra-54，libavformat54，..依赖关系树中的其他软件包）替换为相应的:amd64软件包。
AFAIK是最简单的解决方案，aptitude它可以提供所有其他可能的解决方案，并让您选择自己喜欢的解决方案。
在VirtualBox（Ubuntu 14.04）上进行了测试。我安装了：
sudo apt-get install gstreamer1.0-libav:i386 libavcodec54:i386 libavformat54:i386 \
libopus0:i386
尝试安装gstreamer1.0-libav会产生相同的错误消息：
# apt-get install gstreamer1.0-libav
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
gstreamer1.0-libav : Depends: libavcodec54 (>= 6:9.1-1) but it is not going to be installed or
libavcodec-extra-54 (>= 6:9.13) but it is not going to be installed
Depends: libavformat54 (>= 6:9.1-1) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
解决此类情况的说明：
安装能力：
sudo apt-get install aptitude
运行：
sudo aptitude
新闻/和搜索gstreamer1.0-libav，然后Enter
如果不是gstreamer1.0-libav:i368，则用于n搜索。
然后按+标记以进行安装
在这种情况下，有两种解决方案，请参阅底部的红色消息。使用.或,选择“ 建议删除4条建议”，这是我们正在寻找的建议。
要确认它是正确的解决方案，请按e以便对其进行检查并显示将要执行的操作。
如果可以，请按“ !应用该解决方案”，然后g开始安装过程。
(Reading database ... 58187 files and directories currently installed.)
Removing gstreamer1.0-libav:i386 (1.2.4-1~ubuntu1) ...
Removing libavformat54:i386 (6:9.16-0ubuntu0.14.04.1) ...
Removing libavcodec54:i386 (6:9.16-0ubuntu0.14.04.1) ...
Removing libavutil52:i386 (6:9.16-0ubuntu0.14.04.1) ...
Removing libgstreamer-plugins-base1.0-0:i386 (1.2.4-1~ubuntu1) ...
Removing libgstreamer1.0-0:i386 (1.2.4-0ubuntu1) ...
Removing libglib2.0-0:i386 (2.40.2-0ubuntu1) ...
Removing librtmp0:i386 (2.4+20121230.gitdf6c518-1) ...
Removing libgnutls26:i386 (2.12.23-12ubuntu2.1) ...
Removing libp11-kit0:i386 (0.20.2-2ubuntu2) ...
Removing libffi6:i386 (3.1~rc1+r3.0.13-12) ...
Removing libgcrypt11:i386 (1.5.3-2ubuntu4.1) ...
Removing libgpg-error0:i386 (1.12-0.2ubuntu1) ...
Removing libgsm1:i386 (1.0.13-4) ...
Removing libmp3lame0:i386 (3.99.5+repack1-3ubuntu1) ...
Removing libvorbisenc2:i386 (1.3.2-1.3ubuntu1) ...
Removing libvorbis0a:i386 (1.3.2-1.3ubuntu1) ...
Removing libtheora0:i386 (1.1.1+dfsg.1-3.2) ...
Removing libogg0:i386 (1.3.1-1ubuntu1) ...
Removing libopenjpeg2:i386 (1.3+dfsg-4.7ubuntu1) ...
Removing libopus0 (1.1-0ubuntu1) ...
Removing libschroedinger-1.0-0:i386 (1.0.11-2ubuntu1) ...
Removing liborc-0.4-0:i386 (1:0.4.18-1ubuntu1) ...
Removing libspeex1:i386 (1.2~rc1.1-1ubuntu1) ...
Removing libtasn1-6:i386 (3.4-3ubuntu0.1) ...
Removing libva1:i386 (1.3.0-2) ...
Removing libvpx1:i386 (1.3.0-2) ...
Removing libx264-142:i386 (2:0.142.2389+git956c8d8-2) ...
Removing libxvidcore4:i386 (2:1.3.2-9ubuntu1) ...
Processing triggers for libc-bin (2.19-0ubuntu6) ...
Selecting previously unselected package libopus0.
(Reading database ... 58038 files and directories currently installed.)
Preparing to unpack .../libopus0_1.1-0ubuntu1_amd64.deb ...
Unpacking libopus0 (1.1-0ubuntu1) ...
Selecting previously unselected package libavcodec54:amd64.
Preparing to unpack .../libavcodec54_6%3a9.16-0ubuntu0.14.04.1_amd64.deb ...
Unpacking libavcodec54:amd64 (6:9.16-0ubuntu0.14.04.1) ...
Selecting previously unselected package libavformat54:amd64.
Preparing to unpack .../libavformat54_6%3a9.16-0ubuntu0.14.04.1_amd64.deb ...
Unpacking libavformat54:amd64 (6:9.16-0ubuntu0.14.04.1) ...
Selecting previously unselected package gstreamer1.0-libav:amd64.
Preparing to unpack .../gstreamer1.0-libav_1.2.4-1~ubuntu1_amd64.deb ...
Unpacking gstreamer1.0-libav:amd64 (1.2.4-1~ubuntu1) ...
Setting up libopus0 (1.1-0ubuntu1) ...
Setting up libavcodec54:amd64 (6:9.16-0ubuntu0.14.04.1) ...
Setting up libavformat54:amd64 (6:9.16-0ubuntu0.14.04.1) ...
Setting up gstreamer1.0-libav:amd64 (1.2.4-1~ubuntu1) ...
Processing triggers for libc-bin (2.19-0ubuntu6) ...
Press Return to continue.