1026 lines
54 KiB
HTML
1026 lines
54 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Created by GNU Texinfo 6.8, https://www.gnu.org/software/texinfo/ -->
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<head>
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<meta charset="utf-8">
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<title>
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Developer Documentation
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</title>
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<meta name="viewport" content="width=device-width,initial-scale=1.0">
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<link rel="stylesheet" type="text/css" href="bootstrap.min.css">
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<link rel="stylesheet" type="text/css" href="style.min.css">
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</head>
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<body>
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<div class="container">
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<h1>
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Developer Documentation
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</h1>
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<div align="center">
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</div>
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<a name="SEC_Top"></a>
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<div class="Contents_element" id="SEC_Contents">
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<h2 class="contents-heading">Table of Contents</h2>
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<div class="contents">
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<ul class="no-bullet">
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<li><a id="toc-Introduction" href="#Introduction">1 Introduction</a>
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<ul class="no-bullet">
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<li><a id="toc-Contributing-code" href="#Contributing-code">1.1 Contributing code</a></li>
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</ul></li>
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<li><a id="toc-Coding-Rules-1" href="#Coding-Rules-1">2 Coding Rules</a>
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<ul class="no-bullet">
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<li><a id="toc-Language" href="#Language">2.1 Language</a>
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<ul class="no-bullet">
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<li><a id="toc-SIMD_002fDSP-1" href="#SIMD_002fDSP-1">2.1.1 SIMD/DSP</a></li>
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<li><a id="toc-Other-languages" href="#Other-languages">2.1.2 Other languages</a></li>
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</ul></li>
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<li><a id="toc-Code-formatting-conventions" href="#Code-formatting-conventions">2.2 Code formatting conventions</a>
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<ul class="no-bullet">
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<li><a id="toc-Vim-configuration" href="#Vim-configuration">2.2.1 Vim configuration</a></li>
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<li><a id="toc-Emacs-configuration" href="#Emacs-configuration">2.2.2 Emacs configuration</a></li>
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||
</ul></li>
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<li><a id="toc-Comments" href="#Comments">2.3 Comments</a></li>
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<li><a id="toc-Naming-conventions-1" href="#Naming-conventions-1">2.4 Naming conventions</a></li>
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<li><a id="toc-Miscellaneous-conventions" href="#Miscellaneous-conventions">2.5 Miscellaneous conventions</a></li>
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</ul></li>
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<li><a id="toc-Development-Policy-1" href="#Development-Policy-1">3 Development Policy</a>
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<ul class="no-bullet">
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<li><a id="toc-Patches_002fCommitting" href="#Patches_002fCommitting">3.1 Patches/Committing</a></li>
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<li><a id="toc-Code" href="#Code">3.2 Code</a></li>
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<li><a id="toc-Library-public-interfaces" href="#Library-public-interfaces">3.3 Library public interfaces</a>
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<ul class="no-bullet">
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<li><a id="toc-Adding-new-interfaces" href="#Adding-new-interfaces">3.3.1 Adding new interfaces</a></li>
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<li><a id="toc-Removing-interfaces-1" href="#Removing-interfaces-1">3.3.2 Removing interfaces</a></li>
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<li><a id="toc-Major-version-bumps-1" href="#Major-version-bumps-1">3.3.3 Major version bumps</a></li>
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</ul></li>
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<li><a id="toc-Documentation_002fOther" href="#Documentation_002fOther">3.4 Documentation/Other</a></li>
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</ul></li>
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<li><a id="toc-Submitting-patches-1" href="#Submitting-patches-1">4 Submitting patches</a></li>
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<li><a id="toc-New-codecs-or-formats-checklist" href="#New-codecs-or-formats-checklist">5 New codecs or formats checklist</a></li>
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<li><a id="toc-Patch-submission-checklist" href="#Patch-submission-checklist">6 Patch submission checklist</a></li>
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<li><a id="toc-Patch-review-process" href="#Patch-review-process">7 Patch review process</a></li>
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<li><a id="toc-Regression-tests-1" href="#Regression-tests-1">8 Regression tests</a>
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<ul class="no-bullet">
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<li><a id="toc-Adding-files-to-the-fate_002dsuite-dataset" href="#Adding-files-to-the-fate_002dsuite-dataset">8.1 Adding files to the fate-suite dataset</a></li>
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<li><a id="toc-Visualizing-Test-Coverage" href="#Visualizing-Test-Coverage">8.2 Visualizing Test Coverage</a></li>
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<li><a id="toc-Using-Valgrind" href="#Using-Valgrind">8.3 Using Valgrind</a></li>
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</ul></li>
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<li><a id="toc-Release-process-1" href="#Release-process-1">9 Release process</a>
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<ul class="no-bullet">
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<li><a id="toc-Criteria-for-Point-Releases-1" href="#Criteria-for-Point-Releases-1">9.1 Criteria for Point Releases</a></li>
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<li><a id="toc-Release-Checklist" href="#Release-Checklist">9.2 Release Checklist</a></li>
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</ul></li>
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</ul>
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</div>
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</div>
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<a name="Introduction"></a>
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<h2 class="chapter">1 Introduction<span class="pull-right"><a class="anchor hidden-xs" href="#Introduction" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Introduction" aria-hidden="true">TOC</a></span></h2>
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<p>This text is concerned with the development <em>of</em> FFmpeg itself. Information
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on using the FFmpeg libraries in other programs can be found elsewhere, e.g. in:
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</p><ul>
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<li> the installed header files
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</li><li> <a href="http://ffmpeg.org/doxygen/trunk/index.html">the Doxygen documentation</a>
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generated from the headers
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</li><li> the examples under <samp>doc/examples</samp>
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</li></ul>
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<p>If you modify FFmpeg code for your own use case, you are highly encouraged to
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<em>submit your changes back to us</em>, using this document as a guide. There are
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both pragmatic and ideological reasons to do so:
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</p><ul>
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<li> Maintaining external changes to keep up with upstream development is
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time-consuming and error-prone. With your code in the main tree, it will be
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maintained by FFmpeg developers.
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</li><li> FFmpeg developers include leading experts in the field who can find bugs or
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design flaws in your code.
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</li><li> By supporting the project you find useful you ensure it continues to be
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maintained and developed.
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</li></ul>
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<p>For more detailed legal information about the use of FFmpeg in
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external programs read the <samp>LICENSE</samp> file in the source tree and
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consult <a href="https://ffmpeg.org/legal.html">https://ffmpeg.org/legal.html</a>.
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</p>
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<a name="Contributing-code"></a>
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<h3 class="section">1.1 Contributing code<span class="pull-right"><a class="anchor hidden-xs" href="#Contributing-code" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Contributing-code" aria-hidden="true">TOC</a></span></h3>
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<p>All proposed code changes should be submitted for review to
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<a href="mailto:ffmpeg-devel@ffmpeg.org">the development mailing list</a>, as
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described in more detail in the <a href="#Submitting-patches">Submitting patches</a> chapter. The code
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should comply with the <a href="#Development-Policy">Development Policy</a> and follow the <a href="#Coding-Rules">Coding Rules</a>.
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The developer making the commit and the author are responsible for their changes
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and should try to fix issues their commit causes.
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</p>
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<span id="Coding-Rules"></span><a name="Coding-Rules-1"></a>
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<h2 class="chapter">2 Coding Rules<span class="pull-right"><a class="anchor hidden-xs" href="#Coding-Rules-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Coding-Rules-1" aria-hidden="true">TOC</a></span></h2>
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<a name="Language"></a>
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<h3 class="section">2.1 Language<span class="pull-right"><a class="anchor hidden-xs" href="#Language" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Language" aria-hidden="true">TOC</a></span></h3>
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<p>FFmpeg is mainly programmed in the ISO C99 language, extended with:
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</p><ul>
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<li> Atomic operations from C11 <samp>stdatomic.h</samp>. They are emulated on
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architectures/compilers that do not support them, so all FFmpeg-internal code
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may use atomics without any extra checks. However, <samp>stdatomic.h</samp> must not
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be included in public headers, so they stay C99-compatible.
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</li></ul>
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<p>Compiler-specific extensions may be used with good reason, but must not be
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depended on, i.e. the code must still compile and work with compilers lacking
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the extension.
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||
</p>
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||
<p>The following C99 features must not be used anywhere in the codebase:
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||
</p><ul>
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<li> variable-length arrays;
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</li><li> complex numbers;
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</li><li> mixed statements and declarations.
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||
</li></ul>
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||
<a name="SIMD_002fDSP-1"></a>
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<h4 class="subsection">2.1.1 SIMD/DSP<span class="pull-right"><a class="anchor hidden-xs" href="#SIMD_002fDSP-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-SIMD_002fDSP-1" aria-hidden="true">TOC</a></span></h4>
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<span id="SIMD_002fDSP"></span>
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<p>As modern compilers are unable to generate efficient SIMD or other
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performance-critical DSP code from plain C, handwritten assembly is used.
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Usually such code is isolated in a separate function. Then the standard approach
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is writing multiple versions of this function – a plain C one that works
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everywhere and may also be useful for debugging, and potentially multiple
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architecture-specific optimized implementations. Initialization code then
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chooses the best available version at runtime and loads it into a function
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pointer; the function in question is then always called through this pointer.
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</p>
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<p>The specific syntax used for writing assembly is:
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</p><ul>
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<li> NASM on x86;
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</li><li> GAS on ARM.
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</li></ul>
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<p>A unit testing framework for assembly called <code>checkasm</code> lives under
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<samp>tests/checkasm</samp>. All new assembly should come with <code>checkasm</code> tests;
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||
adding tests for existing assembly that lacks them is also strongly encouraged.
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||
</p>
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||
<a name="Other-languages"></a>
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<h4 class="subsection">2.1.2 Other languages<span class="pull-right"><a class="anchor hidden-xs" href="#Other-languages" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Other-languages" aria-hidden="true">TOC</a></span></h4>
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<p>Other languages than C may be used in special cases:
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</p><ul>
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<li> Compiler intrinsics or inline assembly when the code in question cannot be
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written in the standard way described in the <a href="#SIMD_002fDSP">SIMD/DSP</a> section. This
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||
typically applies to code that needs to be inlined.
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</li><li> Objective-C where required for interacting with macOS-specific interfaces.
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</li></ul>
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<a name="Code-formatting-conventions"></a>
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<h3 class="section">2.2 Code formatting conventions<span class="pull-right"><a class="anchor hidden-xs" href="#Code-formatting-conventions" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Code-formatting-conventions" aria-hidden="true">TOC</a></span></h3>
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||
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<p>There are the following guidelines regarding the indentation in files:
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||
</p>
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<ul>
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<li> Indent size is 4.
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</li><li> The TAB character is forbidden outside of Makefiles as is any
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form of trailing whitespace. Commits containing either will be
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||
rejected by the git repository.
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</li><li> You should try to limit your code lines to 80 characters; however, do so if
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and only if this improves readability.
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</li><li> K&R coding style is used.
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||
</li></ul>
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||
<p>The presentation is one inspired by ’indent -i4 -kr -nut’.
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||
</p>
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||
<a name="Vim-configuration"></a>
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||
<h4 class="subsection">2.2.1 Vim configuration<span class="pull-right"><a class="anchor hidden-xs" href="#Vim-configuration" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Vim-configuration" aria-hidden="true">TOC</a></span></h4>
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||
<p>In order to configure Vim to follow FFmpeg formatting conventions, paste
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the following snippet into your <samp>.vimrc</samp>:
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||
</p><div class="example">
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||
<pre class="example">" indentation rules for FFmpeg: 4 spaces, no tabs
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set expandtab
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set shiftwidth=4
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set softtabstop=4
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set cindent
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set cinoptions=(0
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" Allow tabs in Makefiles.
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autocmd FileType make,automake set noexpandtab shiftwidth=8 softtabstop=8
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" Trailing whitespace and tabs are forbidden, so highlight them.
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highlight ForbiddenWhitespace ctermbg=red guibg=red
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match ForbiddenWhitespace /\s\+$\|\t/
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" Do not highlight spaces at the end of line while typing on that line.
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||
autocmd InsertEnter * match ForbiddenWhitespace /\t\|\s\+\%#\@<!$/
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||
</pre></div>
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||
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||
<a name="Emacs-configuration"></a>
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||
<h4 class="subsection">2.2.2 Emacs configuration<span class="pull-right"><a class="anchor hidden-xs" href="#Emacs-configuration" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Emacs-configuration" aria-hidden="true">TOC</a></span></h4>
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<p>For Emacs, add these roughly equivalent lines to your <samp>.emacs.d/init.el</samp>:
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</p><div class="example lisp">
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<pre class="lisp">(c-add-style "ffmpeg"
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'("k&r"
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(c-basic-offset . 4)
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(indent-tabs-mode . nil)
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(show-trailing-whitespace . t)
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(c-offsets-alist
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(statement-cont . (c-lineup-assignments +)))
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)
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)
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(setq c-default-style "ffmpeg")
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</pre></div>
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<a name="Comments"></a>
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<h3 class="section">2.3 Comments<span class="pull-right"><a class="anchor hidden-xs" href="#Comments" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Comments" aria-hidden="true">TOC</a></span></h3>
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||
<p>Use the JavaDoc/Doxygen format (see examples below) so that code documentation
|
||
can be generated automatically. All nontrivial functions should have a comment
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above them explaining what the function does, even if it is just one sentence.
|
||
All structures and their member variables should be documented, too.
|
||
</p>
|
||
<p>Avoid Qt-style and similar Doxygen syntax with <code>!</code> in it, i.e. replace
|
||
<code>//!</code> with <code>///</code> and similar. Also @ syntax should be employed
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||
for markup commands, i.e. use <code>@param</code> and not <code>\param</code>.
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||
</p>
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<div class="example">
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<pre class="example">/**
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* @file
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* MPEG codec.
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* @author ...
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||
*/
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||
|
||
/**
|
||
* Summary sentence.
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||
* more text ...
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||
* ...
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*/
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typedef struct Foobar {
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int var1; /**< var1 description */
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int var2; ///< var2 description
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/** var3 description */
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int var3;
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} Foobar;
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||
|
||
/**
|
||
* Summary sentence.
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||
* more text ...
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||
* ...
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* @param my_parameter description of my_parameter
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||
* @return return value description
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*/
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int myfunc(int my_parameter)
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||
...
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||
</pre></div>
|
||
|
||
<span id="Naming-conventions"></span><a name="Naming-conventions-1"></a>
|
||
<h3 class="section">2.4 Naming conventions<span class="pull-right"><a class="anchor hidden-xs" href="#Naming-conventions-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Naming-conventions-1" aria-hidden="true">TOC</a></span></h3>
|
||
|
||
<p>Names of functions, variables, and struct members must be lowercase, using
|
||
underscores (_) to separate words. For example, ‘<samp>avfilter_get_video_buffer</samp>’
|
||
is an acceptable function name and ‘<samp>AVFilterGetVideo</samp>’ is not.
|
||
</p>
|
||
<p>Struct, union, enum, and typedeffed type names must use CamelCase. All structs
|
||
and unions should be typedeffed to the same name as the struct/union tag, e.g.
|
||
<code>typedef struct AVFoo { ... } AVFoo;</code>. Enums are typically not
|
||
typedeffed.
|
||
</p>
|
||
<p>Enumeration constants and macros must be UPPERCASE, except for macros
|
||
masquerading as functions, which should use the function naming convention.
|
||
</p>
|
||
<p>All identifiers in the libraries should be namespaced as follows:
|
||
</p><ul>
|
||
<li> No namespacing for identifiers with file and lower scope (e.g. local variables,
|
||
static functions), and struct and union members,
|
||
|
||
</li><li> The <code>ff_</code> prefix must be used for variables and functions visible outside
|
||
of file scope, but only used internally within a single library, e.g.
|
||
‘<samp>ff_w64_demuxer</samp>’. This prevents name collisions when FFmpeg is statically
|
||
linked.
|
||
|
||
</li><li> For variables and functions visible outside of file scope, used internally
|
||
across multiple libraries, use <code>avpriv_</code> as prefix, for example,
|
||
‘<samp>avpriv_report_missing_feature</samp>’.
|
||
|
||
</li><li> All other internal identifiers, like private type or macro names, should be
|
||
namespaced only to avoid possible internal conflicts. E.g. <code>H264_NAL_SPS</code>
|
||
vs. <code>HEVC_NAL_SPS</code>.
|
||
|
||
</li><li> Each library has its own prefix for public symbols, in addition to the
|
||
commonly used <code>av_</code> (<code>avformat_</code> for libavformat,
|
||
<code>avcodec_</code> for libavcodec, <code>swr_</code> for libswresample, etc).
|
||
Check the existing code and choose names accordingly.
|
||
|
||
</li><li> Other public identifiers (struct, union, enum, macro, type names) must use their
|
||
library’s public prefix (<code>AV</code>, <code>Sws</code>, or <code>Swr</code>).
|
||
</li></ul>
|
||
|
||
<p>Furthermore, name space reserved for the system should not be invaded.
|
||
Identifiers ending in <code>_t</code> are reserved by
|
||
<a href="http://pubs.opengroup.org/onlinepubs/007904975/functions/xsh_chap02_02.html#tag_02_02_02">POSIX</a>.
|
||
Also avoid names starting with <code>__</code> or <code>_</code> followed by an uppercase
|
||
letter as they are reserved by the C standard. Names starting with <code>_</code>
|
||
are reserved at the file level and may not be used for externally visible
|
||
symbols. If in doubt, just avoid names starting with <code>_</code> altogether.
|
||
</p>
|
||
<a name="Miscellaneous-conventions"></a>
|
||
<h3 class="section">2.5 Miscellaneous conventions<span class="pull-right"><a class="anchor hidden-xs" href="#Miscellaneous-conventions" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Miscellaneous-conventions" aria-hidden="true">TOC</a></span></h3>
|
||
|
||
<ul>
|
||
<li> fprintf and printf are forbidden in libavformat and libavcodec,
|
||
please use av_log() instead.
|
||
|
||
</li><li> Casts should be used only when necessary. Unneeded parentheses
|
||
should also be avoided if they don’t make the code easier to understand.
|
||
</li></ul>
|
||
|
||
<span id="Development-Policy"></span><a name="Development-Policy-1"></a>
|
||
<h2 class="chapter">3 Development Policy<span class="pull-right"><a class="anchor hidden-xs" href="#Development-Policy-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Development-Policy-1" aria-hidden="true">TOC</a></span></h2>
|
||
|
||
<a name="Patches_002fCommitting"></a>
|
||
<h3 class="section">3.1 Patches/Committing<span class="pull-right"><a class="anchor hidden-xs" href="#Patches_002fCommitting" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Patches_002fCommitting" aria-hidden="true">TOC</a></span></h3>
|
||
<a name="Licenses-for-patches-must-be-compatible-with-FFmpeg_002e"></a>
|
||
<p>Contributions should be licensed under the
|
||
<a href="http://www.gnu.org/licenses/lgpl-2.1.html">LGPL 2.1</a>,
|
||
including an "or any later version" clause, or, if you prefer
|
||
a gift-style license, the
|
||
<a href="http://opensource.org/licenses/isc-license.txt">ISC</a> or
|
||
<a href="http://mit-license.org/">MIT</a> license.
|
||
<a href="http://www.gnu.org/licenses/gpl-2.0.html">GPL 2</a> including
|
||
an "or any later version" clause is also acceptable, but LGPL is
|
||
preferred.
|
||
If you add a new file, give it a proper license header. Do not copy and
|
||
paste it from a random place, use an existing file as template.
|
||
</p>
|
||
<a name="You-must-not-commit-code-which-breaks-FFmpeg_0021"></a>
|
||
<p>This means unfinished code which is enabled and breaks compilation,
|
||
or compiles but does not work/breaks the regression tests. Code which
|
||
is unfinished but disabled may be permitted under-circumstances, like
|
||
missing samples or an implementation with a small subset of features.
|
||
Always check the mailing list for any reviewers with issues and test
|
||
FATE before you push.
|
||
</p>
|
||
<a name="Keep-the-main-commit-message-short-with-an-extended-description-below_002e"></a>
|
||
<p>The commit message should have a short first line in the form of
|
||
a ‘<samp>topic: short description</samp>’ as a header, separated by a newline
|
||
from the body consisting of an explanation of why the change is necessary.
|
||
If the commit fixes a known bug on the bug tracker, the commit message
|
||
should include its bug ID. Referring to the issue on the bug tracker does
|
||
not exempt you from writing an excerpt of the bug in the commit message.
|
||
</p>
|
||
<a name="Testing-must-be-adequate-but-not-excessive_002e"></a>
|
||
<p>If it works for you, others, and passes FATE then it should be OK to commit
|
||
it, provided it fits the other committing criteria. You should not worry about
|
||
over-testing things. If your code has problems (portability, triggers
|
||
compiler bugs, unusual environment etc) they will be reported and eventually
|
||
fixed.
|
||
</p>
|
||
<a name="Do-not-commit-unrelated-changes-together_002e"></a>
|
||
<p>They should be split them into self-contained pieces. Also do not forget
|
||
that if part B depends on part A, but A does not depend on B, then A can
|
||
and should be committed first and separate from B. Keeping changes well
|
||
split into self-contained parts makes reviewing and understanding them on
|
||
the commit log mailing list easier. This also helps in case of debugging
|
||
later on.
|
||
Also if you have doubts about splitting or not splitting, do not hesitate to
|
||
ask/discuss it on the developer mailing list.
|
||
</p>
|
||
<a name="Ask-before-you-change-the-build-system-_0028configure_002c-etc_0029_002e"></a>
|
||
<p>Do not commit changes to the build system (Makefiles, configure script)
|
||
which change behavior, defaults etc, without asking first. The same
|
||
applies to compiler warning fixes, trivial looking fixes and to code
|
||
maintained by other developers. We usually have a reason for doing things
|
||
the way we do. Send your changes as patches to the ffmpeg-devel mailing
|
||
list, and if the code maintainers say OK, you may commit. This does not
|
||
apply to files you wrote and/or maintain.
|
||
</p>
|
||
<a name="Cosmetic-changes-should-be-kept-in-separate-patches_002e"></a>
|
||
<p>We refuse source indentation and other cosmetic changes if they are mixed
|
||
with functional changes, such commits will be rejected and removed. Every
|
||
developer has his own indentation style, you should not change it. Of course
|
||
if you (re)write something, you can use your own style, even though we would
|
||
prefer if the indentation throughout FFmpeg was consistent (Many projects
|
||
force a given indentation style - we do not.). If you really need to make
|
||
indentation changes (try to avoid this), separate them strictly from real
|
||
changes.
|
||
</p>
|
||
<p>NOTE: If you had to put if(){ .. } over a large (> 5 lines) chunk of code,
|
||
then either do NOT change the indentation of the inner part within (do not
|
||
move it to the right)! or do so in a separate commit
|
||
</p>
|
||
<a name="Commit-messages-should-always-be-filled-out-properly_002e"></a>
|
||
<p>Always fill out the commit log message. Describe in a few lines what you
|
||
changed and why. You can refer to mailing list postings if you fix a
|
||
particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
|
||
Recommended format:
|
||
</p>
|
||
<div class="example">
|
||
<pre class="example">area changed: Short 1 line description
|
||
|
||
details describing what and why and giving references.
|
||
</pre></div>
|
||
|
||
<a name="Credit-the-author-of-the-patch_002e"></a>
|
||
<p>Make sure the author of the commit is set correctly. (see git commit –author)
|
||
If you apply a patch, send an
|
||
answer to ffmpeg-devel (or wherever you got the patch from) saying that
|
||
you applied the patch.
|
||
</p>
|
||
<a name="Complex-patches-should-refer-to-discussion-surrounding-them_002e"></a>
|
||
<p>When applying patches that have been discussed (at length) on the mailing
|
||
list, reference the thread in the log message.
|
||
</p>
|
||
<a name="Always-wait-long-enough-before-pushing-changes"></a>
|
||
<p>Do NOT commit to code actively maintained by others without permission.
|
||
Send a patch to ffmpeg-devel. If no one answers within a reasonable
|
||
time-frame (12h for build failures and security fixes, 3 days small changes,
|
||
1 week for big patches) then commit your patch if you think it is OK.
|
||
Also note, the maintainer can simply ask for more time to review!
|
||
</p>
|
||
<a name="Code"></a>
|
||
<h3 class="section">3.2 Code<span class="pull-right"><a class="anchor hidden-xs" href="#Code" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Code" aria-hidden="true">TOC</a></span></h3>
|
||
<a name="Warnings-for-correct-code-may-be-disabled-if-there-is-no-other-option_002e"></a>
|
||
<p>Compiler warnings indicate potential bugs or code with bad style. If a type of
|
||
warning always points to correct and clean code, that warning should
|
||
be disabled, not the code changed.
|
||
Thus the remaining warnings can either be bugs or correct code.
|
||
If it is a bug, the bug has to be fixed. If it is not, the code should
|
||
be changed to not generate a warning unless that causes a slowdown
|
||
or obfuscates the code.
|
||
</p>
|
||
<a name="Check-untrusted-input-properly_002e"></a>
|
||
<p>Never write to unallocated memory, never write over the end of arrays,
|
||
always check values read from some untrusted source before using them
|
||
as array index or other risky things.
|
||
</p>
|
||
<a name="Library-public-interfaces"></a>
|
||
<h3 class="section">3.3 Library public interfaces<span class="pull-right"><a class="anchor hidden-xs" href="#Library-public-interfaces" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Library-public-interfaces" aria-hidden="true">TOC</a></span></h3>
|
||
<p>Every library in FFmpeg provides a set of public APIs in its installed headers,
|
||
which are those listed in the variable <code>HEADERS</code> in that library’s
|
||
<samp>Makefile</samp>. All identifiers defined in those headers (except for those
|
||
explicitly documented otherwise), and corresponding symbols exported from
|
||
compiled shared or static libraries are considered public interfaces and must
|
||
comply with the API and ABI compatibility rules described in this section.
|
||
</p>
|
||
<p>Public APIs must be backward compatible within a given major version. I.e. any
|
||
valid user code that compiles and works with a given library version must still
|
||
compile and work with any later version, as long as the major version number is
|
||
unchanged. "Valid user code" here means code that is calling our APIs in a
|
||
documented and/or intended manner and is not relying on any undefined behavior.
|
||
Incrementing the major version may break backward compatibility, but only to the
|
||
extent described in <a href="#Major-version-bumps">Major version bumps</a>.
|
||
</p>
|
||
<p>We also guarantee backward ABI compatibility for shared and static libraries.
|
||
I.e. it should be possible to replace a shared or static build of our library
|
||
with a build of any later version (re-linking the user binary in the static
|
||
case) without breaking any valid user binaries, as long as the major version
|
||
number remains unchanged.
|
||
</p>
|
||
<a name="Adding-new-interfaces"></a>
|
||
<h4 class="subsection">3.3.1 Adding new interfaces<span class="pull-right"><a class="anchor hidden-xs" href="#Adding-new-interfaces" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Adding-new-interfaces" aria-hidden="true">TOC</a></span></h4>
|
||
<p>Any new public identifiers in installed headers are considered new API - this
|
||
includes new functions, structs, macros, enum values, typedefs, new fields in
|
||
existing functions, new installed headers, etc. Consider the following
|
||
guidelines when adding new APIs.
|
||
</p>
|
||
<a name="Motivation"></a>
|
||
<p>While new APIs can be added relatively easily, changing or removing them is much
|
||
harder due to abovementioned compatibility requirements. You should then
|
||
consider carefully whether the functionality you are adding really needs to be
|
||
exposed to our callers as new public API.
|
||
</p>
|
||
<p>Your new API should have at least one well-established use case outside of the
|
||
library that cannot be easily achieved with existing APIs. Every library in
|
||
FFmpeg also has a defined scope - your new API must fit within it.
|
||
</p>
|
||
<a name="Replacing-existing-APIs"></a>
|
||
<p>If your new API is replacing an existing one, it should be strictly superior to
|
||
it, so that the advantages of using the new API outweight the cost to the
|
||
callers of changing their code. After adding the new API you should then
|
||
deprecate the old one and schedule it for removal, as described in
|
||
<a href="#Removing-interfaces">Removing interfaces</a>.
|
||
</p>
|
||
<p>If you deem an existing API deficient and want to fix it, the preferred approach
|
||
in most cases is to add a differently-named replacement and deprecate the
|
||
existing API rather than modify it. It is important to make the changes visible
|
||
to our callers (e.g. through compile- or run-time deprecation warnings) and make
|
||
it clear how to transition to the new API (e.g. in the Doxygen documentation or
|
||
on the wiki).
|
||
</p>
|
||
<a name="API-design"></a>
|
||
<p>The FFmpeg libraries are used by a variety of callers to perform a wide range of
|
||
multimedia-related processing tasks. You should therefore - within reason - try
|
||
to design your new API for the broadest feasible set of use cases and avoid
|
||
unnecessarily limiting it to a specific type of callers (e.g. just media
|
||
playback or just transcoding).
|
||
</p>
|
||
<a name="Consistency"></a>
|
||
<p>Check whether similar APIs already exist in FFmpeg. If they do, try to model
|
||
your new addition on them to achieve better overall consistency.
|
||
</p>
|
||
<p>The naming of your new identifiers should follow the <a href="#Naming-conventions">Naming conventions</a>
|
||
and be aligned with other similar APIs, if applicable.
|
||
</p>
|
||
<a name="Extensibility"></a>
|
||
<p>You should also consider how your API might be extended in the future in a
|
||
backward-compatible way. If you are adding a new struct <code>AVFoo</code>, the
|
||
standard approach is requiring the caller to always allocate it through a
|
||
constructor function, typically named <code>av_foo_alloc()</code>. This way new fields
|
||
may be added to the end of the struct without breaking ABI compatibility.
|
||
Typically you will also want a destructor - <code>av_foo_free(AVFoo**)</code> that
|
||
frees the indirectly supplied object (and its contents, if applicable) and
|
||
writes <code>NULL</code> to the supplied pointer, thus eliminating the potential
|
||
dangling pointer in the caller’s memory.
|
||
</p>
|
||
<p>If you are adding new functions, consider whether it might be desirable to tweak
|
||
their behavior in the future - you may want to add a flags argument, even though
|
||
it would be unused initially.
|
||
</p>
|
||
<a name="Documentation"></a>
|
||
<p>All new APIs must be documented as Doxygen-formatted comments above the
|
||
identifiers you add to the public headers. You should also briefly mention the
|
||
change in <samp>doc/APIchanges</samp>.
|
||
</p>
|
||
<a name="Bump-the-version"></a>
|
||
<p>Backward-incompatible API or ABI changes require incrementing (bumping) the
|
||
major version number, as described in <a href="#Major-version-bumps">Major version bumps</a>. Major
|
||
bumps are significant events that happen on a schedule - so if your change
|
||
strictly requires one you should add it under <code>#if</code> preprocesor guards that
|
||
disable it until the next major bump happens.
|
||
</p>
|
||
<p>New APIs that can be added without breaking API or ABI compatibility require
|
||
bumping the minor version number.
|
||
</p>
|
||
<p>Incrementing the third (micro) version component means a noteworthy binary
|
||
compatible change (e.g. encoder bug fix that matters for the decoder). The third
|
||
component always starts at 100 to distinguish FFmpeg from Libav.
|
||
</p>
|
||
<span id="Removing-interfaces"></span><a name="Removing-interfaces-1"></a>
|
||
<h4 class="subsection">3.3.2 Removing interfaces<span class="pull-right"><a class="anchor hidden-xs" href="#Removing-interfaces-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Removing-interfaces-1" aria-hidden="true">TOC</a></span></h4>
|
||
<p>Due to abovementioned compatibility guarantees, removing APIs is an involved
|
||
process that should only be undertaken with good reason. Typically a deficient,
|
||
restrictive, or otherwise inadequate API is replaced by a superior one, though
|
||
it does at times happen that we remove an API without any replacement (e.g. when
|
||
the feature it provides is deemed not worth the maintenance effort, out of scope
|
||
of the project, fundamentally flawed, etc.).
|
||
</p>
|
||
<p>The removal has two steps - first the API is deprecated and scheduled for
|
||
removal, but remains present and functional. The second step is actually
|
||
removing the API - this is described in <a href="#Major-version-bumps">Major version bumps</a>.
|
||
</p>
|
||
<p>To deprecate an API you should signal to our users that they should stop using
|
||
it. E.g. if you intend to remove struct members or functions, you should mark
|
||
them with <code>attribute_deprecated</code>. When this cannot be done, it may be
|
||
possible to detect the use of the deprecated API at runtime and print a warning
|
||
(though take care not to print it too often). You should also document the
|
||
deprecation (and the replacement, if applicable) in the relevant Doxygen
|
||
documentation block.
|
||
</p>
|
||
<p>Finally, you should define a deprecation guard along the lines of
|
||
<code>#define FF_API_<FOO> (LIBAVBAR_VERSION_MAJOR < XX)</code> (where XX is the major
|
||
version in which the API will be removed) in <samp>libavbar/version_major.h</samp>
|
||
(<samp>version.h</samp> in case of <code>libavutil</code>). Then wrap all uses of the
|
||
deprecated API in <code>#if FF_API_<FOO> .... #endif</code>, so that the code will
|
||
automatically get disabled once the major version reaches XX. You can also use
|
||
<code>FF_DISABLE_DEPRECATION_WARNINGS</code> and <code>FF_ENABLE_DEPRECATION_WARNINGS</code>
|
||
to suppress compiler deprecation warnings inside these guards. You should test
|
||
that the code compiles and works with the guard macro evaluating to both true
|
||
and false.
|
||
</p>
|
||
<span id="Major-version-bumps"></span><a name="Major-version-bumps-1"></a>
|
||
<h4 class="subsection">3.3.3 Major version bumps<span class="pull-right"><a class="anchor hidden-xs" href="#Major-version-bumps-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Major-version-bumps-1" aria-hidden="true">TOC</a></span></h4>
|
||
<p>A major version bump signifies an API and/or ABI compatibility break. To reduce
|
||
the negative effects on our callers, who are required to adapt their code,
|
||
backward-incompatible changes during a major bump should be limited to:
|
||
</p><ul>
|
||
<li> Removing previously deprecated APIs.
|
||
|
||
</li><li> Performing ABI- but not API-breaking changes, like reordering struct contents.
|
||
</li></ul>
|
||
|
||
<a name="Documentation_002fOther"></a>
|
||
<h3 class="section">3.4 Documentation/Other<span class="pull-right"><a class="anchor hidden-xs" href="#Documentation_002fOther" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Documentation_002fOther" aria-hidden="true">TOC</a></span></h3>
|
||
<a name="Subscribe-to-the-ffmpeg_002ddevel-mailing-list_002e"></a>
|
||
<p>It is important to be subscribed to the
|
||
<a href="https://lists.ffmpeg.org/mailman/listinfo/ffmpeg-devel">ffmpeg-devel</a>
|
||
mailing list. Almost any non-trivial patch is to be sent there for review.
|
||
Other developers may have comments about your contribution. We expect you see
|
||
those comments, and to improve it if requested. (N.B. Experienced committers
|
||
have other channels, and may sometimes skip review for trivial fixes.) Also,
|
||
discussion here about bug fixes and FFmpeg improvements by other developers may
|
||
be helpful information for you. Finally, by being a list subscriber, your
|
||
contribution will be posted immediately to the list, without the moderation
|
||
hold which messages from non-subscribers experience.
|
||
</p>
|
||
<p>However, it is more important to the project that we receive your patch than
|
||
that you be subscribed to the ffmpeg-devel list. If you have a patch, and don’t
|
||
want to subscribe and discuss the patch, then please do send it to the list
|
||
anyway.
|
||
</p>
|
||
<a name="Subscribe-to-the-ffmpeg_002dcvslog-mailing-list_002e"></a>
|
||
<p>Diffs of all commits are sent to the
|
||
<a href="https://lists.ffmpeg.org/mailman/listinfo/ffmpeg-cvslog">ffmpeg-cvslog</a>
|
||
mailing list. Some developers read this list to review all code base changes
|
||
from all sources. Subscribing to this list is not mandatory.
|
||
</p>
|
||
<a name="Keep-the-documentation-up-to-date_002e"></a>
|
||
<p>Update the documentation if you change behavior or add features. If you are
|
||
unsure how best to do this, send a patch to ffmpeg-devel, the documentation
|
||
maintainer(s) will review and commit your stuff.
|
||
</p>
|
||
<a name="Important-discussions-should-be-accessible-to-all_002e"></a>
|
||
<p>Try to keep important discussions and requests (also) on the public
|
||
developer mailing list, so that all developers can benefit from them.
|
||
</p>
|
||
<a name="Check-your-entries-in-MAINTAINERS_002e"></a>
|
||
<p>Make sure that no parts of the codebase that you maintain are missing from the
|
||
<samp>MAINTAINERS</samp> file. If something that you want to maintain is missing add it with
|
||
your name after it.
|
||
If at some point you no longer want to maintain some code, then please help in
|
||
finding a new maintainer and also don’t forget to update the <samp>MAINTAINERS</samp> file.
|
||
</p>
|
||
<p>We think our rules are not too hard. If you have comments, contact us.
|
||
</p>
|
||
<span id="Submitting-patches"></span><a name="Submitting-patches-1"></a>
|
||
<h2 class="chapter">4 Submitting patches<span class="pull-right"><a class="anchor hidden-xs" href="#Submitting-patches-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Submitting-patches-1" aria-hidden="true">TOC</a></span></h2>
|
||
|
||
<p>First, read the <a href="#Coding-Rules">Coding Rules</a> above if you did not yet, in particular
|
||
the rules regarding patch submission.
|
||
</p>
|
||
<p>When you submit your patch, please use <code>git format-patch</code> or
|
||
<code>git send-email</code>. We cannot read other diffs :-).
|
||
</p>
|
||
<p>Also please do not submit a patch which contains several unrelated changes.
|
||
Split it into separate, self-contained pieces. This does not mean splitting
|
||
file by file. Instead, make the patch as small as possible while still
|
||
keeping it as a logical unit that contains an individual change, even
|
||
if it spans multiple files. This makes reviewing your patches much easier
|
||
for us and greatly increases your chances of getting your patch applied.
|
||
</p>
|
||
<p>Use the patcheck tool of FFmpeg to check your patch.
|
||
The tool is located in the tools directory.
|
||
</p>
|
||
<p>Run the <a href="#Regression-tests">Regression tests</a> before submitting a patch in order to verify
|
||
it does not cause unexpected problems.
|
||
</p>
|
||
<p>It also helps quite a bit if you tell us what the patch does (for example
|
||
’replaces lrint by lrintf’), and why (for example ’*BSD isn’t C99 compliant
|
||
and has no lrint()’)
|
||
</p>
|
||
<p>Also please if you send several patches, send each patch as a separate mail,
|
||
do not attach several unrelated patches to the same mail.
|
||
</p>
|
||
<p>Patches should be posted to the
|
||
<a href="https://lists.ffmpeg.org/mailman/listinfo/ffmpeg-devel">ffmpeg-devel</a>
|
||
mailing list. Use <code>git send-email</code> when possible since it will properly
|
||
send patches without requiring extra care. If you cannot, then send patches
|
||
as base64-encoded attachments, so your patch is not trashed during
|
||
transmission. Also ensure the correct mime type is used
|
||
(text/x-diff or text/x-patch or at least text/plain) and that only one
|
||
patch is inline or attached per mail.
|
||
You can check <a href="https://patchwork.ffmpeg.org">https://patchwork.ffmpeg.org</a>, if your patch does not show up, its mime type
|
||
likely was wrong.
|
||
</p>
|
||
<a name="Sending-patches-from-email-clients"></a>
|
||
<p>Using <code>git send-email</code> might not be desirable for everyone. The
|
||
following trick allows to send patches via email clients in a safe
|
||
way. It has been tested with Outlook and Thunderbird (with X-Unsent
|
||
extension) and might work with other applications.
|
||
</p>
|
||
<p>Create your patch like this:
|
||
</p>
|
||
<pre class="verbatim">git format-patch -s -o "outputfolder" --add-header "X-Unsent: 1" --suffix .eml --to ffmpeg-devel@ffmpeg.org -1 1a2b3c4d
|
||
</pre>
|
||
<p>Now you’ll just need to open the eml file with the email application
|
||
and execute ’Send’.
|
||
</p>
|
||
<a name="Reviews"></a>
|
||
<p>Your patch will be reviewed on the mailing list. You will likely be asked
|
||
to make some changes and are expected to send in an improved version that
|
||
incorporates the requests from the review. This process may go through
|
||
several iterations. Once your patch is deemed good enough, some developer
|
||
will pick it up and commit it to the official FFmpeg tree.
|
||
</p>
|
||
<p>Give us a few days to react. But if some time passes without reaction,
|
||
send a reminder by email. Your patch should eventually be dealt with.
|
||
</p>
|
||
|
||
<a name="New-codecs-or-formats-checklist"></a>
|
||
<h2 class="chapter">5 New codecs or formats checklist<span class="pull-right"><a class="anchor hidden-xs" href="#New-codecs-or-formats-checklist" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-New-codecs-or-formats-checklist" aria-hidden="true">TOC</a></span></h2>
|
||
|
||
<ol>
|
||
<li> Did you use av_cold for codec initialization and close functions?
|
||
|
||
</li><li> Did you add a long_name under NULL_IF_CONFIG_SMALL to the AVCodec or
|
||
AVInputFormat/AVOutputFormat struct?
|
||
|
||
</li><li> Did you bump the minor version number (and reset the micro version
|
||
number) in <samp>libavcodec/version.h</samp> or <samp>libavformat/version.h</samp>?
|
||
|
||
</li><li> Did you register it in <samp>allcodecs.c</samp> or <samp>allformats.c</samp>?
|
||
|
||
</li><li> Did you add the AVCodecID to <samp>avcodec.h</samp>?
|
||
When adding new codec IDs, also add an entry to the codec descriptor
|
||
list in <samp>libavcodec/codec_desc.c</samp>.
|
||
|
||
</li><li> If it has a FourCC, did you add it to <samp>libavformat/riff.c</samp>,
|
||
even if it is only a decoder?
|
||
|
||
</li><li> Did you add a rule to compile the appropriate files in the Makefile?
|
||
Remember to do this even if you’re just adding a format to a file that is
|
||
already being compiled by some other rule, like a raw demuxer.
|
||
|
||
</li><li> Did you add an entry to the table of supported formats or codecs in
|
||
<samp>doc/general.texi</samp>?
|
||
|
||
</li><li> Did you add an entry in the Changelog?
|
||
|
||
</li><li> If it depends on a parser or a library, did you add that dependency in
|
||
configure?
|
||
|
||
</li><li> Did you <code>git add</code> the appropriate files before committing?
|
||
|
||
</li><li> Did you make sure it compiles standalone, i.e. with
|
||
<code>configure --disable-everything --enable-decoder=foo</code>
|
||
(or <code>--enable-demuxer</code> or whatever your component is)?
|
||
</li></ol>
|
||
|
||
|
||
<a name="Patch-submission-checklist"></a>
|
||
<h2 class="chapter">6 Patch submission checklist<span class="pull-right"><a class="anchor hidden-xs" href="#Patch-submission-checklist" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Patch-submission-checklist" aria-hidden="true">TOC</a></span></h2>
|
||
|
||
<ol>
|
||
<li> Does <code>make fate</code> pass with the patch applied?
|
||
|
||
</li><li> Was the patch generated with git format-patch or send-email?
|
||
|
||
</li><li> Did you sign-off your patch? (<code>git commit -s</code>)
|
||
See <a href="https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Documentation/process/submitting-patches.rst">Sign your work</a> for the meaning
|
||
of <em>sign-off</em>.
|
||
|
||
</li><li> Did you provide a clear git commit log message?
|
||
|
||
</li><li> Is the patch against latest FFmpeg git master branch?
|
||
|
||
</li><li> Are you subscribed to ffmpeg-devel?
|
||
(the list is subscribers only due to spam)
|
||
|
||
</li><li> Have you checked that the changes are minimal, so that the same cannot be
|
||
achieved with a smaller patch and/or simpler final code?
|
||
|
||
</li><li> If the change is to speed critical code, did you benchmark it?
|
||
|
||
</li><li> If you did any benchmarks, did you provide them in the mail?
|
||
|
||
</li><li> Have you checked that the patch does not introduce buffer overflows or
|
||
other security issues?
|
||
|
||
</li><li> Did you test your decoder or demuxer against damaged data? If no, see
|
||
tools/trasher, the noise bitstream filter, and
|
||
<a href="http://caca.zoy.org/wiki/zzuf">zzuf</a>. Your decoder or demuxer
|
||
should not crash, end in a (near) infinite loop, or allocate ridiculous
|
||
amounts of memory when fed damaged data.
|
||
|
||
</li><li> Did you test your decoder or demuxer against sample files?
|
||
Samples may be obtained at <a href="https://samples.ffmpeg.org">https://samples.ffmpeg.org</a>.
|
||
|
||
</li><li> Does the patch not mix functional and cosmetic changes?
|
||
|
||
</li><li> Did you add tabs or trailing whitespace to the code? Both are forbidden.
|
||
|
||
</li><li> Is the patch attached to the email you send?
|
||
|
||
</li><li> Is the mime type of the patch correct? It should be text/x-diff or
|
||
text/x-patch or at least text/plain and not application/octet-stream.
|
||
|
||
</li><li> If the patch fixes a bug, did you provide a verbose analysis of the bug?
|
||
|
||
</li><li> If the patch fixes a bug, did you provide enough information, including
|
||
a sample, so the bug can be reproduced and the fix can be verified?
|
||
Note please do not attach samples >100k to mails but rather provide a
|
||
URL, you can upload to <a href="https://streams.videolan.org/upload/">https://streams.videolan.org/upload/</a>.
|
||
|
||
</li><li> Did you provide a verbose summary about what the patch does change?
|
||
|
||
</li><li> Did you provide a verbose explanation why it changes things like it does?
|
||
|
||
</li><li> Did you provide a verbose summary of the user visible advantages and
|
||
disadvantages if the patch is applied?
|
||
|
||
</li><li> Did you provide an example so we can verify the new feature added by the
|
||
patch easily?
|
||
|
||
</li><li> If you added a new file, did you insert a license header? It should be
|
||
taken from FFmpeg, not randomly copied and pasted from somewhere else.
|
||
|
||
</li><li> You should maintain alphabetical order in alphabetically ordered lists as
|
||
long as doing so does not break API/ABI compatibility.
|
||
|
||
</li><li> Lines with similar content should be aligned vertically when doing so
|
||
improves readability.
|
||
|
||
</li><li> Consider adding a regression test for your code. All new modules
|
||
should be covered by tests. That includes demuxers, muxers, decoders, encoders
|
||
filters, bitstream filters, parsers. If its not possible to do that, add
|
||
an explanation why to your patchset, its ok to not test if theres a reason.
|
||
|
||
</li><li> If you added YASM code please check that things still work with –disable-yasm.
|
||
|
||
</li><li> Make sure you check the return values of function and return appropriate
|
||
error codes. Especially memory allocation functions like <code>av_malloc()</code>
|
||
are notoriously left unchecked, which is a serious problem.
|
||
|
||
</li><li> Test your code with valgrind and or Address Sanitizer to ensure it’s free
|
||
of leaks, out of array accesses, etc.
|
||
</li></ol>
|
||
|
||
<a name="Patch-review-process"></a>
|
||
<h2 class="chapter">7 Patch review process<span class="pull-right"><a class="anchor hidden-xs" href="#Patch-review-process" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Patch-review-process" aria-hidden="true">TOC</a></span></h2>
|
||
|
||
<p>All patches posted to ffmpeg-devel will be reviewed, unless they contain a
|
||
clear note that the patch is not for the git master branch.
|
||
Reviews and comments will be posted as replies to the patch on the
|
||
mailing list. The patch submitter then has to take care of every comment,
|
||
that can be by resubmitting a changed patch or by discussion. Resubmitted
|
||
patches will themselves be reviewed like any other patch. If at some point
|
||
a patch passes review with no comments then it is approved, that can for
|
||
simple and small patches happen immediately while large patches will generally
|
||
have to be changed and reviewed many times before they are approved.
|
||
After a patch is approved it will be committed to the repository.
|
||
</p>
|
||
<p>We will review all submitted patches, but sometimes we are quite busy so
|
||
especially for large patches this can take several weeks.
|
||
</p>
|
||
<p>If you feel that the review process is too slow and you are willing to try to
|
||
take over maintainership of the area of code you change then just clone
|
||
git master and maintain the area of code there. We will merge each area from
|
||
where its best maintained.
|
||
</p>
|
||
<p>When resubmitting patches, please do not make any significant changes
|
||
not related to the comments received during review. Such patches will
|
||
be rejected. Instead, submit significant changes or new features as
|
||
separate patches.
|
||
</p>
|
||
<p>Everyone is welcome to review patches. Also if you are waiting for your patch
|
||
to be reviewed, please consider helping to review other patches, that is a great
|
||
way to get everyone’s patches reviewed sooner.
|
||
</p>
|
||
<span id="Regression-tests"></span><a name="Regression-tests-1"></a>
|
||
<h2 class="chapter">8 Regression tests<span class="pull-right"><a class="anchor hidden-xs" href="#Regression-tests-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Regression-tests-1" aria-hidden="true">TOC</a></span></h2>
|
||
|
||
<p>Before submitting a patch (or committing to the repository), you should at least
|
||
test that you did not break anything.
|
||
</p>
|
||
<p>Running ’make fate’ accomplishes this, please see <a href="fate.html">fate.html</a> for details.
|
||
</p>
|
||
<p>[Of course, some patches may change the results of the regression tests. In
|
||
this case, the reference results of the regression tests shall be modified
|
||
accordingly].
|
||
</p>
|
||
<a name="Adding-files-to-the-fate_002dsuite-dataset"></a>
|
||
<h3 class="section">8.1 Adding files to the fate-suite dataset<span class="pull-right"><a class="anchor hidden-xs" href="#Adding-files-to-the-fate_002dsuite-dataset" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Adding-files-to-the-fate_002dsuite-dataset" aria-hidden="true">TOC</a></span></h3>
|
||
|
||
<p>If you need a sample uploaded send a mail to samples-request.
|
||
</p>
|
||
<p>When there is no muxer or encoder available to generate test media for a
|
||
specific test then the media has to be included in the fate-suite.
|
||
First please make sure that the sample file is as small as possible to test the
|
||
respective decoder or demuxer sufficiently. Large files increase network
|
||
bandwidth and disk space requirements.
|
||
Once you have a working fate test and fate sample, provide in the commit
|
||
message or introductory message for the patch series that you post to
|
||
the ffmpeg-devel mailing list, a direct link to download the sample media.
|
||
</p>
|
||
<a name="Visualizing-Test-Coverage"></a>
|
||
<h3 class="section">8.2 Visualizing Test Coverage<span class="pull-right"><a class="anchor hidden-xs" href="#Visualizing-Test-Coverage" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Visualizing-Test-Coverage" aria-hidden="true">TOC</a></span></h3>
|
||
|
||
<p>The FFmpeg build system allows visualizing the test coverage in an easy
|
||
manner with the coverage tools <code>gcov</code>/<code>lcov</code>. This involves
|
||
the following steps:
|
||
</p>
|
||
<ol>
|
||
<li> Configure to compile with instrumentation enabled:
|
||
<code>configure --toolchain=gcov</code>.
|
||
|
||
</li><li> Run your test case, either manually or via FATE. This can be either
|
||
the full FATE regression suite, or any arbitrary invocation of any
|
||
front-end tool provided by FFmpeg, in any combination.
|
||
|
||
</li><li> Run <code>make lcov</code> to generate coverage data in HTML format.
|
||
|
||
</li><li> View <code>lcov/index.html</code> in your preferred HTML viewer.
|
||
</li></ol>
|
||
|
||
<p>You can use the command <code>make lcov-reset</code> to reset the coverage
|
||
measurements. You will need to rerun <code>make lcov</code> after running a
|
||
new test.
|
||
</p>
|
||
<a name="Using-Valgrind"></a>
|
||
<h3 class="section">8.3 Using Valgrind<span class="pull-right"><a class="anchor hidden-xs" href="#Using-Valgrind" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Using-Valgrind" aria-hidden="true">TOC</a></span></h3>
|
||
|
||
<p>The configure script provides a shortcut for using valgrind to spot bugs
|
||
related to memory handling. Just add the option
|
||
<code>--toolchain=valgrind-memcheck</code> or <code>--toolchain=valgrind-massif</code>
|
||
to your configure line, and reasonable defaults will be set for running
|
||
FATE under the supervision of either the <strong>memcheck</strong> or the
|
||
<strong>massif</strong> tool of the valgrind suite.
|
||
</p>
|
||
<p>In case you need finer control over how valgrind is invoked, use the
|
||
<code>--target-exec='valgrind <your_custom_valgrind_options></code> option in
|
||
your configure line instead.
|
||
</p>
|
||
<span id="Release-process"></span><a name="Release-process-1"></a>
|
||
<h2 class="chapter">9 Release process<span class="pull-right"><a class="anchor hidden-xs" href="#Release-process-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Release-process-1" aria-hidden="true">TOC</a></span></h2>
|
||
|
||
<p>FFmpeg maintains a set of <strong>release branches</strong>, which are the
|
||
recommended deliverable for system integrators and distributors (such as
|
||
Linux distributions, etc.). At regular times, a <strong>release
|
||
manager</strong> prepares, tests and publishes tarballs on the
|
||
<a href="https://ffmpeg.org">https://ffmpeg.org</a> website.
|
||
</p>
|
||
<p>There are two kinds of releases:
|
||
</p>
|
||
<ol>
|
||
<li> <strong>Major releases</strong> always include the latest and greatest
|
||
features and functionality.
|
||
|
||
</li><li> <strong>Point releases</strong> are cut from <strong>release</strong> branches,
|
||
which are named <code>release/X</code>, with <code>X</code> being the release
|
||
version number.
|
||
</li></ol>
|
||
|
||
<p>Note that we promise to our users that shared libraries from any FFmpeg
|
||
release never break programs that have been <strong>compiled</strong> against
|
||
previous versions of <strong>the same release series</strong> in any case!
|
||
</p>
|
||
<p>However, from time to time, we do make API changes that require adaptations
|
||
in applications. Such changes are only allowed in (new) major releases and
|
||
require further steps such as bumping library version numbers and/or
|
||
adjustments to the symbol versioning file. Please discuss such changes
|
||
on the <strong>ffmpeg-devel</strong> mailing list in time to allow forward planning.
|
||
</p>
|
||
<span id="Criteria-for-Point-Releases"></span><a name="Criteria-for-Point-Releases-1"></a>
|
||
<h3 class="section">9.1 Criteria for Point Releases<span class="pull-right"><a class="anchor hidden-xs" href="#Criteria-for-Point-Releases-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Criteria-for-Point-Releases-1" aria-hidden="true">TOC</a></span></h3>
|
||
|
||
<p>Changes that match the following criteria are valid candidates for
|
||
inclusion into a point release:
|
||
</p>
|
||
<ol>
|
||
<li> Fixes a security issue, preferably identified by a <strong>CVE
|
||
number</strong> issued by <a href="http://cve.mitre.org/">http://cve.mitre.org/</a>.
|
||
|
||
</li><li> Fixes a documented bug in <a href="https://trac.ffmpeg.org">https://trac.ffmpeg.org</a>.
|
||
|
||
</li><li> Improves the included documentation.
|
||
|
||
</li><li> Retains both source code and binary compatibility with previous
|
||
point releases of the same release branch.
|
||
</li></ol>
|
||
|
||
<p>The order for checking the rules is (1 OR 2 OR 3) AND 4.
|
||
</p>
|
||
|
||
<a name="Release-Checklist"></a>
|
||
<h3 class="section">9.2 Release Checklist<span class="pull-right"><a class="anchor hidden-xs" href="#Release-Checklist" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Release-Checklist" aria-hidden="true">TOC</a></span></h3>
|
||
|
||
<p>The release process involves the following steps:
|
||
</p>
|
||
<ol>
|
||
<li> Ensure that the <samp>RELEASE</samp> file contains the version number for
|
||
the upcoming release.
|
||
|
||
</li><li> Add the release at <a href="https://trac.ffmpeg.org/admin/ticket/versions">https://trac.ffmpeg.org/admin/ticket/versions</a>.
|
||
|
||
</li><li> Announce the intent to do a release to the mailing list.
|
||
|
||
</li><li> Make sure all relevant security fixes have been backported. See
|
||
<a href="https://ffmpeg.org/security.html">https://ffmpeg.org/security.html</a>.
|
||
|
||
</li><li> Ensure that the FATE regression suite still passes in the release
|
||
branch on at least <strong>i386</strong> and <strong>amd64</strong>
|
||
(cf. <a href="#Regression-tests">Regression tests</a>).
|
||
|
||
</li><li> Prepare the release tarballs in <code>bz2</code> and <code>gz</code> formats, and
|
||
supplementing files that contain <code>gpg</code> signatures
|
||
|
||
</li><li> Publish the tarballs at <a href="https://ffmpeg.org/releases">https://ffmpeg.org/releases</a>. Create and
|
||
push an annotated tag in the form <code>nX</code>, with <code>X</code>
|
||
containing the version number.
|
||
|
||
</li><li> Propose and send a patch to the <strong>ffmpeg-devel</strong> mailing list
|
||
with a news entry for the website.
|
||
|
||
</li><li> Publish the news entry.
|
||
|
||
</li><li> Send an announcement to the mailing list.
|
||
</li></ol>
|
||
|
||
<p style="font-size: small;">
|
||
This document was generated using <a href="https://www.gnu.org/software/texinfo/"><em>makeinfo</em></a>.
|
||
</p>
|
||
</div>
|
||
</body>
|
||
</html>
|