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976 lines
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976 lines
42 KiB
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</head>
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<body>
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<div class="container">
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<h1 class="titlefont">Developer Documentation</h1>
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<hr>
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<a name="SEC_Top"></a>
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<a name="SEC_Contents"></a>
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<h1>Table of Contents</h1>
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<div class="contents">
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<ul class="no-bullet">
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<li><a name="toc-Notes-for-external-developers" href="#Notes-for-external-developers">1 Notes for external developers</a></li>
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<li><a name="toc-Contributing" href="#Contributing">2 Contributing</a></li>
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<li><a name="toc-Coding-Rules-1" href="#Coding-Rules-1">3 Coding Rules</a>
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<ul class="no-bullet">
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<li><a name="toc-Code-formatting-conventions" href="#Code-formatting-conventions">3.1 Code formatting conventions</a></li>
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<li><a name="toc-Comments" href="#Comments">3.2 Comments</a></li>
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<li><a name="toc-C-language-features" href="#C-language-features">3.3 C language features</a></li>
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<li><a name="toc-Naming-conventions" href="#Naming-conventions">3.4 Naming conventions</a></li>
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<li><a name="toc-Miscellaneous-conventions" href="#Miscellaneous-conventions">3.5 Miscellaneous conventions</a></li>
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<li><a name="toc-Editor-configuration" href="#Editor-configuration">3.6 Editor configuration</a></li>
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</ul></li>
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<li><a name="toc-Development-Policy" href="#Development-Policy">4 Development Policy</a>
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<ul class="no-bullet">
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<li><a name="toc-Patches_002fCommitting" href="#Patches_002fCommitting">4.1 Patches/Committing</a></li>
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<li><a name="toc-Code" href="#Code">4.2 Code</a></li>
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<li><a name="toc-Documentation_002fOther" href="#Documentation_002fOther">4.3 Documentation/Other</a></li>
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</ul></li>
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<li><a name="toc-Code-of-conduct" href="#Code-of-conduct">5 Code of conduct</a></li>
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<li><a name="toc-Submitting-patches-1" href="#Submitting-patches-1">6 Submitting patches</a></li>
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<li><a name="toc-New-codecs-or-formats-checklist" href="#New-codecs-or-formats-checklist">7 New codecs or formats checklist</a></li>
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<li><a name="toc-Patch-submission-checklist" href="#Patch-submission-checklist">8 Patch submission checklist</a></li>
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<li><a name="toc-Patch-review-process" href="#Patch-review-process">9 Patch review process</a></li>
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<li><a name="toc-Regression-tests-1" href="#Regression-tests-1">10 Regression tests</a>
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<ul class="no-bullet">
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<li><a name="toc-Adding-files-to-the-fate_002dsuite-dataset" href="#Adding-files-to-the-fate_002dsuite-dataset">10.1 Adding files to the fate-suite dataset</a></li>
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<li><a name="toc-Visualizing-Test-Coverage" href="#Visualizing-Test-Coverage">10.2 Visualizing Test Coverage</a></li>
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<li><a name="toc-Using-Valgrind" href="#Using-Valgrind">10.3 Using Valgrind</a></li>
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</ul></li>
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<li><a name="toc-Release-process-1" href="#Release-process-1">11 Release process</a>
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<ul class="no-bullet">
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<li><a name="toc-Criteria-for-Point-Releases-1" href="#Criteria-for-Point-Releases-1">11.1 Criteria for Point Releases</a></li>
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<li><a name="toc-Release-Checklist" href="#Release-Checklist">11.2 Release Checklist</a></li>
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</ul>
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</li>
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</ul>
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</div>
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<hr size="6">
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<a name="Notes-for-external-developers"></a>
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<h1 class="chapter"><a href="developer.html#toc-Notes-for-external-developers">1 Notes for external developers</a></h1>
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<p>This document is mostly useful for internal FFmpeg developers.
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External developers who need to use the API in their application should
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refer to the API doxygen documentation in the public headers, and
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check the examples in ‘<tt>doc/examples</tt>’ and in the source code to
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see how the public API is employed.
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</p>
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<p>You can use the FFmpeg libraries in your commercial program, but you
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are encouraged to <em>publish any patch you make</em>. In this case the
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best way to proceed is to send your patches to the ffmpeg-devel
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mailing list following the guidelines illustrated in the remainder of
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this document.
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</p>
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<p>For more detailed legal information about the use of FFmpeg in
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external programs read the ‘<tt>LICENSE</tt>’ 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"></a>
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<h1 class="chapter"><a href="developer.html#toc-Contributing">2 Contributing</a></h1>
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<p>There are 2 ways by which code gets into FFmpeg:
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</p><ul>
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<li> Submitting patches to the ffmpeg-devel mailing list.
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See <a href="#Submitting-patches">Submitting patches</a> for details.
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</li><li> Directly committing changes to the main tree.
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</li></ul>
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<p>Whichever way, changes should be reviewed by the maintainer of the code
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before they are committed. And they should 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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<p><a name="Coding-Rules"></a>
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</p><a name="Coding-Rules-1"></a>
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<h1 class="chapter"><a href="developer.html#toc-Coding-Rules-1">3 Coding Rules</a></h1>
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<a name="Code-formatting-conventions"></a>
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<h2 class="section"><a href="developer.html#toc-Code-formatting-conventions">3.1 Code formatting conventions</a></h2>
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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>
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Indent size is 4.
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</li><li>
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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>
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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>
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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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<p>The main priority in FFmpeg is simplicity and small code size in order to
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minimize the bug count.
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</p>
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<a name="Comments"></a>
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<h2 class="section"><a href="developer.html#toc-Comments">3.2 Comments</a></h2>
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<p>Use the JavaDoc/Doxygen format (see examples below) so that code documentation
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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.
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All structures and their member variables should be documented, too.
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</p>
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<p>Avoid Qt-style and similar Doxygen syntax with <code>!</code> in it, i.e. replace
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<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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/**
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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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|
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/**
|
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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>
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|
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<a name="C-language-features"></a>
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<h2 class="section"><a href="developer.html#toc-C-language-features">3.3 C language features</a></h2>
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<p>FFmpeg is programmed in the ISO C90 language with a few additional
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features from ISO C99, namely:
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</p>
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<ul>
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<li>
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the ‘<samp>inline</samp>’ keyword;
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</li><li>
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‘<samp>//</samp>’ comments;
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</li><li>
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designated struct initializers (‘<samp>struct s x = { .i = 17 };</samp>’);
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</li><li>
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compound literals (‘<samp>x = (struct s) { 17, 23 };</samp>’).
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</li><li>
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for loops with variable definition (‘<samp>for (int i = 0; i < 8; i++)</samp>’);
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</li><li>
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Implementation defined behavior for signed integers is assumed to match the
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expected behavior for two’s complement. Non representable values in integer
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casts are binary truncated. Shift right of signed values uses sign extension.
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</li></ul>
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<p>These features are supported by all compilers we care about, so we will not
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accept patches to remove their use unless they absolutely do not impair
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clarity and performance.
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</p>
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<p>All code must compile with recent versions of GCC and a number of other
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currently supported compilers. To ensure compatibility, please do not use
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additional C99 features or GCC extensions. Especially watch out for:
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</p>
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<ul>
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<li>
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mixing statements and declarations;
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</li><li>
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‘<samp>long long</samp>’ (use ‘<samp>int64_t</samp>’ instead);
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</li><li>
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‘<samp>__attribute__</samp>’ not protected by ‘<samp>#ifdef __GNUC__</samp>’ or similar;
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</li><li>
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GCC statement expressions (‘<samp>(x = ({ int y = 4; y; })</samp>’).
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</li></ul>
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|
|
<a name="Naming-conventions"></a>
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|
<h2 class="section"><a href="developer.html#toc-Naming-conventions">3.4 Naming conventions</a></h2>
|
|
<p>All names should be composed with underscores (_), not CamelCase. For example,
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|
‘<samp>avfilter_get_video_buffer</samp>’ is an acceptable function name and
|
|
‘<samp>AVFilterGetVideo</samp>’ is not. The exception from this are type names, like
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for example structs and enums; they should always be in CamelCase.
|
|
</p>
|
|
<p>There are the following conventions for naming variables and functions:
|
|
</p>
|
|
<ul>
|
|
<li>
|
|
For local variables no prefix is required.
|
|
|
|
</li><li>
|
|
For file-scope variables and functions declared as <code>static</code>, no prefix
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is required.
|
|
|
|
</li><li>
|
|
For variables and functions visible outside of file scope, but only used
|
|
internally by a library, an <code>ff_</code> prefix should be used,
|
|
e.g. ‘<samp>ff_w64_demuxer</samp>’.
|
|
|
|
</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>
|
|
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.
|
|
Note that some symbols without these prefixes are also exported for
|
|
retro-compatibility reasons. These exceptions are declared in the
|
|
<code>lib<name>/lib<name>.v</code> files.
|
|
</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>
|
|
<h2 class="section"><a href="developer.html#toc-Miscellaneous-conventions">3.5 Miscellaneous conventions</a></h2>
|
|
|
|
<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>
|
|
|
|
<a name="Editor-configuration"></a>
|
|
<h2 class="section"><a href="developer.html#toc-Editor-configuration">3.6 Editor configuration</a></h2>
|
|
<p>In order to configure Vim to follow FFmpeg formatting conventions, paste
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the following snippet into your ‘<tt>.vimrc</tt>’:
|
|
</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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<p>For Emacs, add these roughly equivalent lines to your ‘<tt>.emacs.d/init.el</tt>’:
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|
</p><div class="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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)
|
|
(setq c-default-style "ffmpeg")
|
|
</pre></div>
|
|
|
|
<a name="Development-Policy"></a>
|
|
<h1 class="chapter"><a href="developer.html#toc-Development-Policy">4 Development Policy</a></h1>
|
|
|
|
<a name="Patches_002fCommitting"></a>
|
|
<h2 class="section"><a href="developer.html#toc-Patches_002fCommitting">4.1 Patches/Committing</a></h2>
|
|
<a name="Licenses-for-patches-must-be-compatible-with-FFmpeg_002e"></a>
|
|
<h3 class="subheading">Licenses for patches must be compatible with FFmpeg.</h3>
|
|
<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>
|
|
<h3 class="subheading">You must not commit code which breaks FFmpeg!</h3>
|
|
<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>
|
|
<h3 class="subheading">Keep the main commit message short with an extended description below.</h3>
|
|
<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>
|
|
<h3 class="subheading">Testing must be adequate but not excessive.</h3>
|
|
<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>
|
|
<h3 class="subheading">Do not commit unrelated changes together.</h3>
|
|
<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>
|
|
<h3 class="subheading">Ask before you change the build system (configure, etc).</h3>
|
|
<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>
|
|
<h3 class="subheading">Cosmetic changes should be kept in separate patches.</h3>
|
|
<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>
|
|
<h3 class="subheading">Commit messages should always be filled out properly.</h3>
|
|
<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>
|
|
<h3 class="subheading">Credit the author of the patch.</h3>
|
|
<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>
|
|
<h3 class="subheading">Complex patches should refer to discussion surrounding them.</h3>
|
|
<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>
|
|
<h3 class="subheading">Always wait long enough before pushing changes</h3>
|
|
<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>
|
|
<h2 class="section"><a href="developer.html#toc-Code">4.2 Code</a></h2>
|
|
<a name="API_002fABI-changes-should-be-discussed-before-they-are-made_002e"></a>
|
|
<h3 class="subheading">API/ABI changes should be discussed before they are made.</h3>
|
|
<p>Do not change behavior of the programs (renaming options etc) or public
|
|
API or ABI without first discussing it on the ffmpeg-devel mailing list.
|
|
Do not remove widely used functionality or features (redundant code can be removed).
|
|
</p>
|
|
<a name="Remember-to-check-if-you-need-to-bump-versions-for-libav_002a_002e"></a>
|
|
<h3 class="subheading">Remember to check if you need to bump versions for libav*.</h3>
|
|
<p>Depending on the change, you may need to change the version integer.
|
|
Incrementing the first component means no backward compatibility to
|
|
previous versions (e.g. removal of a function from the public API).
|
|
Incrementing the second component means backward compatible change
|
|
(e.g. addition of a function to the public API or extension of an
|
|
existing data structure).
|
|
Incrementing the third 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>
|
|
<a name="Warnings-for-correct-code-may-be-disabled-if-there-is-no-other-option_002e"></a>
|
|
<h3 class="subheading">Warnings for correct code may be disabled if there is no other option.</h3>
|
|
<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>
|
|
<h3 class="subheading">Check untrusted input properly.</h3>
|
|
<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="Documentation_002fOther"></a>
|
|
<h2 class="section"><a href="developer.html#toc-Documentation_002fOther">4.3 Documentation/Other</a></h2>
|
|
<a name="Subscribe-to-the-ffmpeg_002ddevel-mailing-list_002e"></a>
|
|
<h3 class="subheading">Subscribe to the ffmpeg-devel mailing list.</h3>
|
|
<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>
|
|
<h3 class="subheading">Subscribe to the ffmpeg-cvslog mailing list.</h3>
|
|
<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>
|
|
<h3 class="subheading">Keep the documentation up to date.</h3>
|
|
<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>
|
|
<h3 class="subheading">Important discussions should be accessible to all.</h3>
|
|
<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>
|
|
<h3 class="subheading">Check your entries in MAINTAINERS.</h3>
|
|
<p>Make sure that no parts of the codebase that you maintain are missing from the
|
|
‘<tt>MAINTAINERS</tt>’ 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 ‘<tt>MAINTAINERS</tt>’ file.
|
|
</p>
|
|
<p>We think our rules are not too hard. If you have comments, contact us.
|
|
</p>
|
|
<a name="Code-of-conduct"></a>
|
|
<h1 class="chapter"><a href="developer.html#toc-Code-of-conduct">5 Code of conduct</a></h1>
|
|
|
|
<p>Be friendly and respectful towards others and third parties.
|
|
Treat others the way you yourself want to be treated.
|
|
</p>
|
|
<p>Be considerate. Not everyone shares the same viewpoint and priorities as you do.
|
|
Different opinions and interpretations help the project.
|
|
Looking at issues from a different perspective assists development.
|
|
</p>
|
|
<p>Do not assume malice for things that can be attributed to incompetence. Even if
|
|
it is malice, it’s rarely good to start with that as initial assumption.
|
|
</p>
|
|
<p>Stay friendly even if someone acts contrarily. Everyone has a bad day
|
|
once in a while.
|
|
If you yourself have a bad day or are angry then try to take a break and reply
|
|
once you are calm and without anger if you have to.
|
|
</p>
|
|
<p>Try to help other team members and cooperate if you can.
|
|
</p>
|
|
<p>The goal of software development is to create technical excellence, not for any
|
|
individual to be better and "win" against the others. Large software projects
|
|
are only possible and successful through teamwork.
|
|
</p>
|
|
<p>If someone struggles do not put them down. Give them a helping hand
|
|
instead and point them in the right direction.
|
|
</p>
|
|
<p>Finally, keep in mind the immortal words of Bill and Ted,
|
|
"Be excellent to each other."
|
|
</p>
|
|
<p><a name="Submitting-patches"></a>
|
|
</p><a name="Submitting-patches-1"></a>
|
|
<h1 class="chapter"><a href="developer.html#toc-Submitting-patches-1">6 Submitting patches</a></h1>
|
|
|
|
<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>
|
|
<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>
|
|
<h1 class="chapter"><a href="developer.html#toc-New-codecs-or-formats-checklist">7 New codecs or formats checklist</a></h1>
|
|
|
|
<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 ‘<tt>libavcodec/version.h</tt>’ or ‘<tt>libavformat/version.h</tt>’?
|
|
|
|
</li><li>
|
|
Did you register it in ‘<tt>allcodecs.c</tt>’ or ‘<tt>allformats.c</tt>’?
|
|
|
|
</li><li>
|
|
Did you add the AVCodecID to ‘<tt>avcodec.h</tt>’?
|
|
When adding new codec IDs, also add an entry to the codec descriptor
|
|
list in ‘<tt>libavcodec/codec_desc.c</tt>’.
|
|
|
|
</li><li>
|
|
If it has a FourCC, did you add it to ‘<tt>libavformat/riff.c</tt>’,
|
|
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
|
|
‘<tt>doc/general.texi</tt>’?
|
|
|
|
</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>
|
|
<h1 class="chapter"><a href="developer.html#toc-Patch-submission-checklist">8 Patch submission checklist</a></h1>
|
|
|
|
<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 ftp://upload.ffmpeg.org.
|
|
|
|
</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.
|
|
|
|
</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>
|
|
<h1 class="chapter"><a href="developer.html#toc-Patch-review-process">9 Patch review process</a></h1>
|
|
|
|
<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>
|
|
<p><a name="Regression-tests"></a>
|
|
</p><a name="Regression-tests-1"></a>
|
|
<h1 class="chapter"><a href="developer.html#toc-Regression-tests-1">10 Regression tests</a></h1>
|
|
|
|
<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>
|
|
<h2 class="section"><a href="developer.html#toc-Adding-files-to-the-fate_002dsuite-dataset">10.1 Adding files to the fate-suite dataset</a></h2>
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<p>When there is no muxer or encoder available to generate test media for a
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specific test then the media has to be included in the fate-suite.
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First please make sure that the sample file is as small as possible to test the
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respective decoder or demuxer sufficiently. Large files increase network
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bandwidth and disk space requirements.
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Once you have a working fate test and fate sample, provide in the commit
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message or introductory message for the patch series that you post to
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the ffmpeg-devel mailing list, a direct link to download the sample media.
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</p>
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<a name="Visualizing-Test-Coverage"></a>
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<h2 class="section"><a href="developer.html#toc-Visualizing-Test-Coverage">10.2 Visualizing Test Coverage</a></h2>
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<p>The FFmpeg build system allows visualizing the test coverage in an easy
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manner with the coverage tools <code>gcov</code>/<code>lcov</code>. This involves
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the following steps:
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</p>
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|
<ol>
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<li>
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Configure to compile with instrumentation enabled:
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<code>configure --toolchain=gcov</code>.
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|
|
|
</li><li>
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Run your test case, either manually or via FATE. This can be either
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|
the full FATE regression suite, or any arbitrary invocation of any
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|
front-end tool provided by FFmpeg, in any combination.
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|
|
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</li><li>
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Run <code>make lcov</code> to generate coverage data in HTML format.
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|
|
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</li><li>
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View <code>lcov/index.html</code> in your preferred HTML viewer.
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</li></ol>
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<p>You can use the command <code>make lcov-reset</code> to reset the coverage
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measurements. You will need to rerun <code>make lcov</code> after running a
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new test.
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</p>
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<a name="Using-Valgrind"></a>
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<h2 class="section"><a href="developer.html#toc-Using-Valgrind">10.3 Using Valgrind</a></h2>
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<p>The configure script provides a shortcut for using valgrind to spot bugs
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related to memory handling. Just add the option
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<code>--toolchain=valgrind-memcheck</code> or <code>--toolchain=valgrind-massif</code>
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to your configure line, and reasonable defaults will be set for running
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FATE under the supervision of either the <strong>memcheck</strong> or the
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<strong>massif</strong> tool of the valgrind suite.
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|
</p>
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<p>In case you need finer control over how valgrind is invoked, use the
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<code>--target-exec='valgrind <your_custom_valgrind_options></code> option in
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|
your configure line instead.
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</p>
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|
<p><a name="Release-process"></a>
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|
</p><a name="Release-process-1"></a>
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<h1 class="chapter"><a href="developer.html#toc-Release-process-1">11 Release process</a></h1>
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|
<p>FFmpeg maintains a set of <strong>release branches</strong>, which are the
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|
recommended deliverable for system integrators and distributors (such as
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|
Linux distributions, etc.). At regular times, a <strong>release
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|
manager</strong> prepares, tests and publishes tarballs on the
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|
<a href="https://ffmpeg.org">https://ffmpeg.org</a> website.
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|
</p>
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|
<p>There are two kinds of releases:
|
|
</p>
|
|
<ol>
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|
<li>
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|
<strong>Major releases</strong> always include the latest and greatest
|
|
features and functionality.
|
|
|
|
</li><li>
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|
<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
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|
release never break programs that have been <strong>compiled</strong> against
|
|
previous versions of <strong>the same release series</strong> in any case!
|
|
</p>
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|
<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
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|
require further steps such as bumping library version numbers and/or
|
|
adjustments to the symbol versioning file. Please discuss such changes
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|
on the <strong>ffmpeg-devel</strong> mailing list in time to allow forward planning.
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|
</p>
|
|
<p><a name="Criteria-for-Point-Releases"></a>
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|
</p><a name="Criteria-for-Point-Releases-1"></a>
|
|
<h2 class="section"><a href="developer.html#toc-Criteria-for-Point-Releases-1">11.1 Criteria for Point Releases</a></h2>
|
|
|
|
<p>Changes that match the following criteria are valid candidates for
|
|
inclusion into a point release:
|
|
</p>
|
|
<ol>
|
|
<li>
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|
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>.
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|
|
|
</li><li>
|
|
Fixes a documented bug in <a href="https://trac.ffmpeg.org">https://trac.ffmpeg.org</a>.
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|
|
|
</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>
|
|
<h2 class="section"><a href="developer.html#toc-Release-Checklist">11.2 Release Checklist</a></h2>
|
|
|
|
<p>The release process involves the following steps:
|
|
</p>
|
|
<ol>
|
|
<li>
|
|
Ensure that the ‘<tt>RELEASE</tt>’ 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>
|
|
|
|
</div>
|
|
</body>
|
|
</html>
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