Difference between pages "Package:AMD Catalyst Video Drivers" and "FLOP:FFmpeg"

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(add technical details to the FLOP)
 
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{{Ebuild
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{{FLOP
|Summary=Accelerated ATI/AMD binary drivers for Radeon HD 5000 and newer chipsets.
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|Created on=2015/01/31
|CatPkg=x11-drivers/ati-drivers
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|Summary=Funtoo Linux prefers FFmpeg. Some enlightenment about our choice and why we prefer this  or could switch to alternative in future.
|Maintainer=Drobbins
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|Author=Oleg, Mgorny
|Homepage=
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|Maintainer=Oleg, Mgorny
|Repository=Funtoo Overlay
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|Reference Bug=FL-844
|Overlay=Funtoo
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}}
 
}}
{{Warning|These drivers are not being regularly maintained by AMD, resulting in a sub-optimal and unreliable experience for many users. Symptoms generally involve X not starting at all, things like gnome-shell crashing on startup, etc. If you have problems with these drivers, consider using the free {{Package|x11-drivers/xf86-video-ati}}, which are actually quite good and hassle-free.}}
 
 
 
== Introduction ==
 
== Introduction ==
 +
FFmpeg and Libav are library sets for multimedia decoding (and more). Both libraries expose similar API and features.
  
<tt>x11-drivers/ati-drivers</tt> (often referred to as "<tt>fglrx</tt>", the name of its kernel module) is the proprietary, accelerated driver for AMD (ATI) graphics cards.  
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Both project have common origins and diverged only recently. The developers share the same bad coding practices causing permanent lack of API and ABI stability, therefore requiring frequent rebuilds of reverse dependencies.
  
== Preparing to Install ==
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Worse than that, after the split projects use colliding SONAMEs for libraries with potentially different ABI. This means that after switching from one implementation to another, the reverse dependencies may become broken instantly (preserved-libs doesn't help) and need to be rebuilt ASAP.
 
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=== Xorg-server compatibility ===
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{{Note|The release of the 14.9-r1 driver ebuild eliminates the need to mask <code>xorg-server-1.16</code>.}}
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<code>ati-drivers-14.9-r1</code> has been added to the Funtoo Portage tree which contains a special Ubuntu-only release of the drivers that are compatible with {{Package|x11-base/xorg-server}} version 1.16. If you are using the "stock" drivers, then typically, you would need to mask <code>xorg-server</code> as follows. This is not necessary with 14.9-r1:
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Add the following to <code>/etc/portage/package.mask</code>:
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{{File|name=/etc/portage/package.mask|body=
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>=x11-base/xorg-server-1.16
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}}
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If X is already installed, force it to downgrade by typing:
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<console>
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# ##i##emerge -auDN world
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</console>
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A few packages will downgrade, and you'll be ready to go.
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=== Configuring the kernel ===
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Configure the kernel as follows. Note that the Direct Rendering Manager is '''not''' enabled. It's possible to have it selected as a kernel module, but should not be built-in to your kernel.
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{{kernelop|desc=
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[*] Enable loadable module support
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Processor type and features --->
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      [*] MTRR (Memory Type Range Register) support
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Bus options (PCI etc.) --->
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      [*] PCI Express Port Bus Support
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      [*] Message Signaled Interrupts (MSI and MSI-X)
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Device Drivers --->
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      Graphics support --->
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            < > Direct Rendering Manager (xFree86 4.1.0 and higher DRI support) --->
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}}
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{{note|If you need support for AGP cards, enable the following kernel options:}}
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{{kernelop|desc=
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Device Drivers --->
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      Graphics support --->
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            <*> /dev/agpgart (AGP Support) --->
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                  Select an appropriate AGP driver:
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                  <*> AMD Opteron/Athlon64 on-CPU GART support
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}}
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=== Editing make.conf ===
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Many packages for video decoding, are done via FFmpeg or Libav.  Differences between FFmpeg and Libav can have a major impact on its behavior: the number of files it can decode, whether it decodes correctly, what video and audio filters are provided, network behavior, and more.
  
Add the following to your <code>/etc/make.conf</code>:
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== Current status ==
<console>
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=== Gentoo ===
# ##i##nano /etc/make.conf
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Gentoo supports both ffmpeg and libav, with a weak preference towards libav. The preference is caused by package order in virtual/ffmpeg — when no other circumstance affects the package choice, Portage will prefer libav. However, if ffmpeg is already installed or a package incompatible with libav is requested, Portage will use ffmpeg instead.
VIDEO_CARDS="fglrx"
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</console>
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=== Enabling AMD Catalyst Control Center ===
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Then, add the following to <code>/etc/portage/package.use</code> if you would like to enable support for AMD Catalyst Control Center:
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There are two major technical issues with this design:
<console>
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# there is no technically correct way of forcing rebuilds on ABI changes — subslot dependencies do not work with virtuals or || () deps,
###i## nano /etc/portage/package.use
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# there is no way of forcing rebuilds when switching from libav to ffmpeg, and the other way around.
x11-drivers/ati-drivers qt4
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</console>
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{{Note|If you are using a desktop or workstation profile, this USE flag will be enabled by default.}}
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=== Funtoo ===
 +
Funtoo supports only FFmpeg. It is forced by Funtoo version of virtual/ffmpeg. While this provides the ability to avoid the Gentoo issues, virtual still breaks ABI rebuilds.
  
== Installing ==
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Decision made by Oleg, forced by #funtoo community and bugtracker reports.
  
=== Emerging the package ===
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== Future status ==
To emerge the drivers, run the following command:
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=== Gentoo ===
<console>
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There is a planned Gentoo change which will eventually replace virtual/ffmpeg and explicit || () deps with 'libav' USE flag. The flag will be added to all packages that support both FFmpeg and libav. When the flag is enabled, the package will use libav; otherwise it will use FFmpeg. The choice of flag name is forced by the fact that USE=ffmpeg is already used as generic ffmpeg-or-libav flag.
###i## emerge -av --changed-use --deep @world
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</console>
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== Configuring ==
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This change fixes both Gentoo issues:
 +
# USE-conditional dependencies allow subslot dependencies to force rebuilds on ABI changes,
 +
# provider change will force rebuild because of USE flag change.
  
Next, set ati-drivers to manage the system's OpenGL and OpenCL implementations:
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The change may also eventually make it possible to install FFmpeg and libav side-by-side. Until then, the flag state would involve 'strong' preference of one implementation over the other, and user will have to change USE=libav as a global flag. '''Installing a package that supports only one of the two implementations will result in blocker that needs to be handled manually'''.
<console>
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###i## eselect opengl set ati
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###i## eselect opencl set amd
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</console>
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Afterwards, run <code>aticonfig</code> to modify the X-server configuration file to work with the ati-drivers:  
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=== Funtoo ===
<console>
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If Funtoo decides to keep supporting FFmpeg only, it only needs to mask libav in the profiles. Then dependencies on updated packages will unconditionally use FFmpeg. Eventually Funtoo will want to remove virtual/ffmpeg and depend on media-video/ffmpeg:0= directly in forked packages.
###i## aticonfig --initial
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</console>
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{{tip|If you would like to have a full-resolution framebuffer with ati-drivers, check out [[uvesafb| uvesafb]]}}
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If Funtoo decides to start supporting libav as an option, it may need to add USE="-libav" to profiles if Gentoo decides for libav default. Funtoo will want to progressively update forked packages to match Gentoo dependency specifications.
  
== Troubleshooting ==
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== Detailed information on FFmpeg and libav ==
=== I am using a HDMI connection, and my monitor's display has a black border around it. ===
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=== FFmpeg and Libav history ===
Disable overscan using the following command, as root:
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In 2011, parts of the FFmpeg developers were unhappy about the FFmpeg leadership, and decided to take over. This didn't quite work out. Apparently Fabrice Bellard, original FFmpeg developer and owner of the ffmpeg.org domain name, decided not to hand over the domain name to the new maintainers. So they followed Plan B, and forked FFmpeg, resulting in Libav. Since then, Libav did its own development, and completely ignored whatever FFmpeg did. FFmpeg, on the other hand, started to merge literally everything Libav did.
  
<console>
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The reason for the fork is most likely that the developers hate each other. While this formulation seems somewhat sloppy, it is most likely the truth. To this date, the #libav-devel IRC channel still has Michael Niedermayer (the FFmpeg maintainer since 2004 according to Wikipedia) on their ban list (similar misbehavior is exhibited by some FFmpeg developers). There is little to no cooperation between the two projects.
# ##i##aticonfig --set-pcs-val=MCIL,DigitalHDTVDefaultUnderscan,0
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</console>
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You may need to restart your X session.
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More about FFmpeg's history and the fork incident can be found on Wikipedia
  
=== GNOME 3 windows only refresh when I drag them. ===
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=== Situation today ===
This is a known issue, reported in [http://bugs.funtoo.org/browse/FL-1130 Funtoo Bug 1130]. This issue has been fixed by addressing a bug in cogl -- upgrade to cogl-1.12.2-r2 to fix it.
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FFmpeg has more features and slightly more active development than Libav, going by mailing list and commit volume. In particular, FFmpeg's features are a superset of Libav's features. This is because FFmpeg merges Libav's git master on a daily basis. Libav on the other hand seems to prefer to ignore FFmpeg development (with occasional cherry-picking of bug fixes and features).
  
=== Compton with backend glx does not work well with ati-drivers ===
+
Some Linux distributions, especially those that had Libav developers as FFmpeg package maintainers, replaced FFmpeg with Libav, while other distributions stick with FFmpeg. Application developers typically have to make sure their code works with both libraries. This can be trivial to hard, depending on the details. One larger problem is that the difference between the libraries makes it hard to keep up a consistent level of the user experience, since either library might silently or blatantly be not up to the task. It also encourages library users to implement some features themselves, rather than dealing with the library differences, or the question to which project to contribute.
Try running compton with the following switches:
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<console>
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###i## compton --backend glx --vsync none --paint-on-overlay
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</console>
+
  
[[Category:Video Cards]]
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FFmpeg and Libav developers also seem to have the tendency to ignore the damage their rivalry is causing. Apparently fighting out these issues on the users' backs is better than reconciling. This means everyone using these libraries either has to suffer from the differences, or reimplement functionality that is not the same between FFmpeg and Libav.
[[Category:First Steps]]
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{{FLOPFooter}}
{{EbuildFooter}}
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Revision as of 23:22, January 31, 2015

Created on
2015/01/31
Original Author(s)
Oleg Vinichenko,Michał Górny
Current Maintainer(s)
Oleg Vinichenko,Michał Górny
Status
Reference Bug
FL-844

Funtoo Linux Optimization Proposal: FFmpeg

Funtoo Linux prefers FFmpeg. Some enlightenment about our choice and why we prefer this or could switch to alternative in future.

Introduction

FFmpeg and Libav are library sets for multimedia decoding (and more). Both libraries expose similar API and features.

Both project have common origins and diverged only recently. The developers share the same bad coding practices causing permanent lack of API and ABI stability, therefore requiring frequent rebuilds of reverse dependencies.

Worse than that, after the split projects use colliding SONAMEs for libraries with potentially different ABI. This means that after switching from one implementation to another, the reverse dependencies may become broken instantly (preserved-libs doesn't help) and need to be rebuilt ASAP.

Many packages for video decoding, are done via FFmpeg or Libav. Differences between FFmpeg and Libav can have a major impact on its behavior: the number of files it can decode, whether it decodes correctly, what video and audio filters are provided, network behavior, and more.

Current status

Gentoo

Gentoo supports both ffmpeg and libav, with a weak preference towards libav. The preference is caused by package order in virtual/ffmpeg — when no other circumstance affects the package choice, Portage will prefer libav. However, if ffmpeg is already installed or a package incompatible with libav is requested, Portage will use ffmpeg instead.

There are two major technical issues with this design:

  1. there is no technically correct way of forcing rebuilds on ABI changes — subslot dependencies do not work with virtuals or || () deps,
  2. there is no way of forcing rebuilds when switching from libav to ffmpeg, and the other way around.

Funtoo

Funtoo supports only FFmpeg. It is forced by Funtoo version of virtual/ffmpeg. While this provides the ability to avoid the Gentoo issues, virtual still breaks ABI rebuilds.

Decision made by Oleg, forced by #funtoo community and bugtracker reports.

Future status

Gentoo

There is a planned Gentoo change which will eventually replace virtual/ffmpeg and explicit || () deps with 'libav' USE flag. The flag will be added to all packages that support both FFmpeg and libav. When the flag is enabled, the package will use libav; otherwise it will use FFmpeg. The choice of flag name is forced by the fact that USE=ffmpeg is already used as generic ffmpeg-or-libav flag.

This change fixes both Gentoo issues:

  1. USE-conditional dependencies allow subslot dependencies to force rebuilds on ABI changes,
  2. provider change will force rebuild because of USE flag change.

The change may also eventually make it possible to install FFmpeg and libav side-by-side. Until then, the flag state would involve 'strong' preference of one implementation over the other, and user will have to change USE=libav as a global flag. Installing a package that supports only one of the two implementations will result in blocker that needs to be handled manually.

Funtoo

If Funtoo decides to keep supporting FFmpeg only, it only needs to mask libav in the profiles. Then dependencies on updated packages will unconditionally use FFmpeg. Eventually Funtoo will want to remove virtual/ffmpeg and depend on media-video/ffmpeg:0= directly in forked packages.

If Funtoo decides to start supporting libav as an option, it may need to add USE="-libav" to profiles if Gentoo decides for libav default. Funtoo will want to progressively update forked packages to match Gentoo dependency specifications.

Detailed information on FFmpeg and libav

FFmpeg and Libav history

In 2011, parts of the FFmpeg developers were unhappy about the FFmpeg leadership, and decided to take over. This didn't quite work out. Apparently Fabrice Bellard, original FFmpeg developer and owner of the ffmpeg.org domain name, decided not to hand over the domain name to the new maintainers. So they followed Plan B, and forked FFmpeg, resulting in Libav. Since then, Libav did its own development, and completely ignored whatever FFmpeg did. FFmpeg, on the other hand, started to merge literally everything Libav did.

The reason for the fork is most likely that the developers hate each other. While this formulation seems somewhat sloppy, it is most likely the truth. To this date, the #libav-devel IRC channel still has Michael Niedermayer (the FFmpeg maintainer since 2004 according to Wikipedia) on their ban list (similar misbehavior is exhibited by some FFmpeg developers). There is little to no cooperation between the two projects.

More about FFmpeg's history and the fork incident can be found on Wikipedia

Situation today

FFmpeg has more features and slightly more active development than Libav, going by mailing list and commit volume. In particular, FFmpeg's features are a superset of Libav's features. This is because FFmpeg merges Libav's git master on a daily basis. Libav on the other hand seems to prefer to ignore FFmpeg development (with occasional cherry-picking of bug fixes and features).

Some Linux distributions, especially those that had Libav developers as FFmpeg package maintainers, replaced FFmpeg with Libav, while other distributions stick with FFmpeg. Application developers typically have to make sure their code works with both libraries. This can be trivial to hard, depending on the details. One larger problem is that the difference between the libraries makes it hard to keep up a consistent level of the user experience, since either library might silently or blatantly be not up to the task. It also encourages library users to implement some features themselves, rather than dealing with the library differences, or the question to which project to contribute.

FFmpeg and Libav developers also seem to have the tendency to ignore the damage their rivalry is causing. Apparently fighting out these issues on the users' backs is better than reconciling. This means everyone using these libraries either has to suffer from the differences, or reimplement functionality that is not the same between FFmpeg and Libav.

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