GStreamer 1.20.x stable series

WHAT IT IS
----------

This is GStreamer, a framework for streaming media.

WHERE TO START
--------------

We have a website at

  https://gstreamer.freedesktop.org

Our documentation, including tutorials, API reference and FAQ can be found at

  https://gstreamer.freedesktop.org/documentation/

You can subscribe to our mailing lists:

  https://lists.freedesktop.org/mailman/listinfo/gstreamer-announce

  https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

We track bugs, feature requests and merge requests (patches) in GitLab at

  https://gitlab.freedesktop.org/gstreamer/

You can join us on IRC - #gstreamer on irc.oftc.net

GStreamer 1.0 series
--------------------

Starring

  GSTREAMER

The core around which all other modules revolve.  Base functionality and
libraries, some essential elements, documentation, and testing.

  BASE

A well-groomed and well-maintained collection of GStreamer plug-ins and
elements, spanning the range of possible types of elements one would want
to write for GStreamer.

And introducing, for the first time ever, on the development screen ...

  THE GOOD

 --- "Such ingratitude.  After all the times I've saved your life."

A collection of plug-ins you'd want to have right next to you on the
battlefield.  Shooting sharp and making no mistakes, these plug-ins have it
all: good looks, good code, and good licensing.  Documented and dressed up
in tests.  If you're looking for a role model to base your own plug-in on,
here it is.

If you find a plot hole or a badly lip-synced line of code in them,
let us know - it is a matter of honour for us to ensure Blondie doesn't look
like he's been walking 100 miles through the desert without water.

  THE UGLY

  --- "When you have to shoot, shoot.  Don't talk."

There are times when the world needs a color between black and white.
Quality code to match the good's, but two-timing, backstabbing and ready to
sell your freedom down the river.  These plug-ins might have a patent noose
around their neck, or a lock-up license, or any other problem that makes you
think twice about shipping them.

We don't call them ugly because we like them less.  Does a mother love her
son less because he's not as pretty as the other ones ? No  - she commends
him on his great personality.  These plug-ins are the life of the party.
And we'll still step in and set them straight if you report any unacceptable
behaviour - because there are two kinds of people in the world, my friend:
those with a rope around their neck and the people who do the cutting.

  THE BAD

  --- "That an accusation?"

No perfectly groomed moustache or any amount of fine clothing is going to
cover up the truth - these plug-ins are Bad with a capital B.
They look fine on the outside, and might even appear to get the job done, but
at the end of the day they're a black sheep. Without a golden-haired angel
to watch over them, they'll probably land in an unmarked grave at the final
showdown.

Don't bug us about their quality - exercise your Free Software rights,
patch up the offender and send us the patch on the fastest steed you can
steal from the Confederates. Because you see, in this world, there's two
kinds of people, my friend: those with loaded guns and those who dig.
You dig.

The Lowdown
-----------

  --- "I've never seen so many plug-ins wasted so badly."

GStreamer Plug-ins has grown so big that it's hard to separate the wheat from
the chaff.  Also, distributors have brought up issues about the legal status
of some of the plug-ins we ship.  To remedy this, we've divided the previous
set of available plug-ins into four modules:

- gst-plugins-base: a small and fixed set of plug-ins, covering a wide range
  of possible types of elements; these are continuously kept up-to-date
  with any core changes during the development series.

  - We believe distributors can safely ship these plug-ins.
  - People writing elements should base their code on these elements.
  - These elements come with examples, documentation, and regression tests.

- gst-plugins-good: a set of plug-ins that we consider to have good quality
  code, correct functionality, our preferred license (LGPL for the plug-in
  code, LGPL or LGPL-compatible for the supporting library).

  - We believe distributors can safely ship these plug-ins.
  - People writing elements should base their code on these elements.

- gst-plugins-ugly: a set of plug-ins that have good quality and correct
  functionality, but distributing them might pose problems.  The license
  on either the plug-ins or the supporting libraries might not be how we'd
  like. The code might be widely known to present patent problems.

  - Distributors should check if they want/can ship these plug-ins.
  - People writing elements should base their code on these elements.

- gst-plugins-bad: a set of plug-ins that aren't up to par compared to the
  rest.  They might be close to being good quality, but they're missing
  something - be it a good code review, some documentation, a set of tests,
  a real live maintainer, or some actual wide use.
  If the blanks are filled in they might be upgraded to become part of
  either gst-plugins-good or gst-plugins-ugly, depending on the other factors.

  - If the plug-ins break, you can't complain - instead, you can fix the
    problem and send us a patch, or bribe someone into fixing them for you.
  - New contributors can start here for things to work on.

PLATFORMS
---------

- Linux is of course fully supported
- FreeBSD is reported to work; other BSDs should work too; same for Solaris
- MacOS works, binary 1.x packages can be built using the cerbero build tool
- Windows works; binary 1.x packages can be built using the cerbero build tool
  - MSys/MinGW builds
  - Microsoft Visual Studio builds are also available and supported
- Android works, binary 1.x packages can be built using the cerbero build tool
- iOS works

INSTALLING FROM PACKAGES
------------------------

You should always prefer installing from packages first.  GStreamer is
well-maintained for a number of distributions, including Fedora, Debian,
Ubuntu, Mandrake, Arch Linux, Gentoo, ...

Only in cases where you:

 - want to hack on GStreamer
 - want to verify that a bug has been fixed
 - do not have a sane distribution

should you choose to build from source tarballs or git.

Find more information about the various packages at

  https://gstreamer.freedesktop.org/download/

For in-depth instructions about building GStreamer visit:
[getting-started](https://gitlab.freedesktop.org/gstreamer/gstreamer/-/blob/main/README.md#getting-started).

PLUG-IN DEPENDENCIES AND LICENSES
---------------------------------

GStreamer is developed under the terms of the LGPL (see COPYING file for
details). Some of our plug-ins however rely on libraries which are available
under other licenses. This means that if you are distributing an application
which has a non-GPL compatible license (for instance a closed-source
application) with GStreamer, you have to make sure not to distribute GPL-linked
plug-ins.

When using GPL-linked plug-ins, GStreamer is for all practical reasons
under the GPL itself.

HISTORY
-------

The fundamental design comes from the video pipeline at Oregon Graduate
Institute, as well as some ideas from DirectMedia.  It's based on plug-ins that
will provide the various codec and other functionality.  The interface
hopefully is generic enough for various companies (ahem, Apple) to release
binary codecs for Linux, until such time as they get a clue and release the
source.

=================================
 GStreamer Static Linking README
=================================

DRAFT, April 2013


   I. INTRODUCTION

It is possible to link GStreamer libraries, plugins and applications
statically, both in case of free/libre/open-source software applications
and proprietary applications. On some platforms static linking may even
be required.

However, distributing statically linked binaries using GStreamer usually
requires additional effort to stay compliant with the GNU LGPL v2.1 license.

The purpose of this document is to draw attention to this fact, and to
summarise in layman's terms what we believe is required from anyone
distributing statically linked GStreamer binaries. Most of this also
applies to dynamically linked GStreamer binaries.


   II. DISCLAIMER

This document is not legal advice, nor is it comprehensive. It may use
words in ways that do not match the definition or use in the license
text. It may even be outright wrong. Read the license text for all the
details, it is the only legally binding document in this respect.

This document is primarily concerned with the implications for the
distribution of binaries based on LGPL-licensed software as imposed by
the LGPL license, but there may be other restrictions to the distribution
of such binaries, such as terms and conditions of distribution channels
(e.g. "app stores").


   III. THE SPIRIT OF THE LGPL LICENSE

The GNU LGPL v2.1 license allows use of such-licensed software by
proprietary applications, but still aims to ensure that at least the
LGPL-licensed software parts remain free under all circumstances. This
means any changes to LGPL-licensed source code must be documented and
be made available on request to those who received binaries of the
software. It also means that it must be possible to make changes to the
LGPL-licensed software parts and make the application use those, as far
as that is possible. And that recipients of an application using
LGPL-licensed software are made aware of their rights according to the
LGPL license.

In an environment where GStreamer libraries and plugins are used as
dynamically-loaded shared objects (DLL/.so/.dyn files), this is usually
not a big problem, because it is fairly easy to compile a modified version
of the GStreamer libraries or LGPL plugins, and the application will/should
just pick up and use the modified version automatically. All that is needed
is for the original, LGPL-licensed source code and source code modifications
to be made available, and for a way to build the libraries or plugins for
the platform required (usually that will be using the build system scripts
that come with GStreamer, and using the typical build environment on the
system in question, but where that is not the case the needed build scripts
and/or tools would need to be provided as well).


   IV. THINGS YOU NEED TO DO

  * You must tell users of your application that you are using LGPL-licensed
    software, which LGPL-licensed software exactly, and you must provide them
    with a copy of the license so they know their rights under the LGPL.

  * You must provide (on request) all the source code and all the changes
    or additions you have made to the LGPL-licensed software you are using.

    For GStreamer code we would recommend that the changes be provided either
    in form of a branch in a git repository, or as a set of "git format-patch"-
    style patches against a GStreamer release or a snapshot of a GStreamer git
    repository. The patches should ideally say what was changed and why it
    was changed, and there should ideally be separate patches for independent
    changes.

  * You must provide a way for users of your application to make changes to
    the LGPL-licensed parts of the code, and re-create a full application
    binary with the changes (using the standard toolchain and tools of the
    target platform; if you are using a custom toolchain or custom tools
    you must provide these and document how to use them to create a new
    application binary).

    Note that this of course does not mean that the user is allowed to
    re-distribute the changed application. Nor does it mean that you have
    to provide your proprietary source code - it is sufficient to provide a
    ready-made compiled object file that can be relinked into an application
    binary with the re-compiled LGPL components.


   V. THINGS TO LOOK OUT FOR

While most GStreamer plugins and the libraries they depend on are licensed
under the LGPL or even more permissive licenses, that is not the case for
all plugins and libraries used, esp. those in the gst-plugins-ugly or
some of those in the gst-plugins-bad set of plugins.

When statically linking proprietary code, care must be taken not to
statically link plugins or libraries that are licensed under less permissive
terms than the LGPL, such as e.g. GPL-licensed libraries.


   VI. SPECIAL CONSIDERATIONS FOR SPECIFIC USE-CASES


   1. Proprietary GStreamer/GLib-based Application On iOS

Let's assume an individual or a company wants to distribute a proprietary
iOS application that is built on top of GStreamer and GLib through
Apple's App Store. At the time of writing the Apple iPhone developer
agreement didn’t allow the bundling of shared libraries, so distributing
a proprietary iOS application with shared libraries is only possible using
distribution mechanisms outside of the App Store and/or only to jailbroken
devices, a prospect that may not appeal to our individual or company. So the
only alternative then is to link everything statically, which means the
obligations mentioned above come into play.


   2. Example: Jabber on iOS

Tandberg (now Cisco) created a Jabber application for iOS, based on GStreamer.
On request they provided an LGPL compliance bundle in form of a zip file, with
roughly the following contents:

buildapp.sh
readme.txt
Jabber/Jabber-Info.plist
Jabber/libip.a [236MB binary with proprietary code]
Jabber/main.mm
Jabber/xcconfig/Application.xcconfig
Jabber/xcconfig/Debug.xcconfig
Jabber/xcconfig/Release.xcconfig
Jabber/xcconfig/Shared.xcconfig
Jabber/Resources/*.lproj/Localizable.strings
Jabber/Resources/{Images,Audio,Sounds,IB,Message Styles,Emoticons,Fonts}/*
Jabber/Resources/*
Jabber.xcodeproj/project.pbxproj
Jabber.xcodeproj/project.xcworkspace/contents.xcworkspacedata
opensource/build/config.site
opensource/build/m4/movi.m4
opensource/build/scripts/clean-deps.sh
opensource/build/scripts/fixup-makefile.sh
opensource/build/scripts/MoviMaker.py
opensource/build.sh
opensource/env.sh
opensource/Makefile
opensource/external/glib/*
opensource/external/gstreamer/{gstreamer,gst-plugins-*}/*
opensource/external/openssl/*
opensource/external/proxy-libintl/*
opensource/toolchain/darwin-x86/bin/{misc autotoools,m4,glib-mkenums,glib-genmarshal,libtool,pkg-config,etc.}
opensource/toolchain/darwin-x86/share/{aclocal,aclocal-1.11,autoconf,automake-1.11,libtool}/*
opensource/toolchain/darwin-x86/share/Config.pm
opensource/toolchain/darwin-x86/share/Config.pm.movi.in
patches/glib/glib.patch
patches/gst-plugins-bad/gst-plugins-bad.patch
patches/gst-plugins-base/gst-plugins-base.patch
patches/gst-plugins-good/gst-plugins-good.patch
patches/gstreamer/gstreamer.patch
patches/openssl/openssl.patch

readme.txt starts with "This Readme file describes how to build the Cisco
Jabber for iPad application. You need to install Xcode, but the final package
is built by running buildapp.sh." and describes how to build project,
prerequisites, the procedure in detail, and a "How to Include Provisioning
Profile Manually / Alternate Code Signing Instructions" section.


   3. Random Links Which May Be Of Interest

[0] http://multinc.com/2009/08/24/compatibility-between-the-iphone-app-store-and-the-lgpl/