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| author | Indrajith K L | 2022-12-03 17:00:20 +0530 |
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| committer | Indrajith K L | 2022-12-03 17:00:20 +0530 |
| commit | f5c4671bfbad96bf346bd7e9a21fc4317b4959df (patch) | |
| tree | 2764fc62da58f2ba8da7ed341643fc359873142f /ffmpeg/doc/developer.html | |
| download | cli-tools-windows-master.tar.gz cli-tools-windows-master.tar.bz2 cli-tools-windows-master.zip | |
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| -rw-r--r-- | ffmpeg/doc/developer.html | 883 |
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diff --git a/ffmpeg/doc/developer.html b/ffmpeg/doc/developer.html new file mode 100644 index 0000000..2d58e42 --- /dev/null +++ b/ffmpeg/doc/developer.html @@ -0,0 +1,883 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Created by GNU Texinfo 6.8, https://www.gnu.org/software/texinfo/ --> + <head> + <meta charset="utf-8"> + <title> + Developer Documentation + </title> + <meta name="viewport" content="width=device-width,initial-scale=1.0"> + <link rel="stylesheet" type="text/css" href="bootstrap.min.css"> + <link rel="stylesheet" type="text/css" href="style.min.css"> + </head> + <body> + <div class="container"> + <h1> + Developer Documentation + </h1> +<div align="center"> +</div> + + +<a name="SEC_Top"></a> + +<div class="Contents_element" id="SEC_Contents"> +<h2 class="contents-heading">Table of Contents</h2> + +<div class="contents"> + +<ul class="no-bullet"> + <li><a id="toc-Introduction" href="#Introduction">1 Introduction</a> + <ul class="no-bullet"> + <li><a id="toc-Contributing-code" href="#Contributing-code">1.1 Contributing code</a></li> + </ul></li> + <li><a id="toc-Coding-Rules-1" href="#Coding-Rules-1">2 Coding Rules</a> + <ul class="no-bullet"> + <li><a id="toc-Code-formatting-conventions" href="#Code-formatting-conventions">2.1 Code formatting conventions</a></li> + <li><a id="toc-Comments" href="#Comments">2.2 Comments</a></li> + <li><a id="toc-C-language-features" href="#C-language-features">2.3 C language features</a></li> + <li><a id="toc-Naming-conventions" href="#Naming-conventions">2.4 Naming conventions</a></li> + <li><a id="toc-Miscellaneous-conventions" href="#Miscellaneous-conventions">2.5 Miscellaneous conventions</a></li> + <li><a id="toc-Editor-configuration" href="#Editor-configuration">2.6 Editor configuration</a></li> + </ul></li> + <li><a id="toc-Development-Policy-1" href="#Development-Policy-1">3 Development Policy</a> + <ul class="no-bullet"> + <li><a id="toc-Patches_002fCommitting" href="#Patches_002fCommitting">3.1 Patches/Committing</a></li> + <li><a id="toc-Code" href="#Code">3.2 Code</a></li> + <li><a id="toc-Documentation_002fOther" href="#Documentation_002fOther">3.3 Documentation/Other</a></li> + </ul></li> + <li><a id="toc-Code-of-conduct" href="#Code-of-conduct">4 Code of conduct</a></li> + <li><a id="toc-Submitting-patches-1" href="#Submitting-patches-1">5 Submitting patches</a></li> + <li><a id="toc-New-codecs-or-formats-checklist" href="#New-codecs-or-formats-checklist">6 New codecs or formats checklist</a></li> + <li><a id="toc-Patch-submission-checklist" href="#Patch-submission-checklist">7 Patch submission checklist</a></li> + <li><a id="toc-Patch-review-process" href="#Patch-review-process">8 Patch review process</a></li> + <li><a id="toc-Regression-tests-1" href="#Regression-tests-1">9 Regression tests</a> + <ul class="no-bullet"> + <li><a id="toc-Adding-files-to-the-fate_002dsuite-dataset" href="#Adding-files-to-the-fate_002dsuite-dataset">9.1 Adding files to the fate-suite dataset</a></li> + <li><a id="toc-Visualizing-Test-Coverage" href="#Visualizing-Test-Coverage">9.2 Visualizing Test Coverage</a></li> + <li><a id="toc-Using-Valgrind" href="#Using-Valgrind">9.3 Using Valgrind</a></li> + </ul></li> + <li><a id="toc-Release-process-1" href="#Release-process-1">10 Release process</a> + <ul class="no-bullet"> + <li><a id="toc-Criteria-for-Point-Releases-1" href="#Criteria-for-Point-Releases-1">10.1 Criteria for Point Releases</a></li> + <li><a id="toc-Release-Checklist" href="#Release-Checklist">10.2 Release Checklist</a></li> + </ul></li> +</ul> +</div> +</div> + +<a name="Introduction"></a> +<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> + +<p>This text is concerned with the development <em>of</em> FFmpeg itself. Information +on using the FFmpeg libraries in other programs can be found elsewhere, e.g. in: +</p><ul> +<li> the installed header files +</li><li> <a href="http://ffmpeg.org/doxygen/trunk/index.html">the Doxygen documentation</a> +generated from the headers +</li><li> the examples under <samp>doc/examples</samp> +</li></ul> + +<p>If you modify FFmpeg code for your own use case, you are highly encouraged to +<em>submit your changes back to us</em>, using this document as a guide. There are +both pragmatic and ideological reasons to do so: +</p><ul> +<li> Maintaining external changes to keep up with upstream development is +time-consuming and error-prone. With your code in the main tree, it will be +maintained by FFmpeg developers. +</li><li> FFmpeg developers include leading experts in the field who can find bugs or +design flaws in your code. +</li><li> By supporting the project you find useful you ensure it continues to be +maintained and developed. +</li></ul> + +<p>For more detailed legal information about the use of FFmpeg in +external programs read the <samp>LICENSE</samp> file in the source tree and +consult <a href="https://ffmpeg.org/legal.html">https://ffmpeg.org/legal.html</a>. +</p> +<a name="Contributing-code"></a> +<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> + +<p>All proposed code changes should be submitted for review to +<a href="mailto:ffmpeg-devel@ffmpeg.org">the development mailing list</a>, as +described in more detail in the <a href="#Submitting-patches">Submitting patches</a> chapter. The code +should comply with the <a href="#Development-Policy">Development Policy</a> and follow the <a href="#Coding-Rules">Coding Rules</a>. +The developer making the commit and the author are responsible for their changes +and should try to fix issues their commit causes. +</p> +<span id="Coding-Rules"></span><a name="Coding-Rules-1"></a> +<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> + +<a name="Code-formatting-conventions"></a> +<h3 class="section">2.1 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> + +<p>There are the following guidelines regarding the indentation in files: +</p> +<ul> +<li> Indent size is 4. + +</li><li> The TAB character is forbidden outside of Makefiles as is any +form of trailing whitespace. Commits containing either will be +rejected by the git repository. + +</li><li> You should try to limit your code lines to 80 characters; however, do so if +and only if this improves readability. + +</li><li> K&R coding style is used. +</li></ul> +<p>The presentation is one inspired by ’indent -i4 -kr -nut’. +</p> +<p>The main priority in FFmpeg is simplicity and small code size in order to +minimize the bug count. +</p> +<a name="Comments"></a> +<h3 class="section">2.2 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> +<p>Use the JavaDoc/Doxygen format (see examples below) so that code documentation +can be generated automatically. All nontrivial functions should have a comment +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 +for markup commands, i.e. use <code>@param</code> and not <code>\param</code>. +</p> +<div class="example"> +<pre class="example">/** + * @file + * MPEG codec. + * @author ... + */ + +/** + * Summary sentence. + * more text ... + * ... + */ +typedef struct Foobar { + int var1; /**< var1 description */ + int var2; ///< var2 description + /** var3 description */ + int var3; +} Foobar; + +/** + * Summary sentence. + * more text ... + * ... + * @param my_parameter description of my_parameter + * @return return value description + */ +int myfunc(int my_parameter) +... +</pre></div> + +<a name="C-language-features"></a> +<h3 class="section">2.3 C language features<span class="pull-right"><a class="anchor hidden-xs" href="#C-language-features" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-C-language-features" aria-hidden="true">TOC</a></span></h3> + +<p>FFmpeg is programmed in the ISO C90 language with a few additional +features from ISO C99, namely: +</p> +<ul> +<li> the ‘<samp>inline</samp>’ keyword; + +</li><li> ‘<samp>//</samp>’ comments; + +</li><li> designated struct initializers (‘<samp>struct s x = { .i = 17 };</samp>’); + +</li><li> compound literals (‘<samp>x = (struct s) { 17, 23 };</samp>’). + +</li><li> for loops with variable definition (‘<samp>for (int i = 0; i < 8; i++)</samp>’); + +</li><li> Variadic macros (‘<samp>#define ARRAY(nb, ...) (int[nb + 1]){ nb, __VA_ARGS__ }</samp>’); + +</li><li> Implementation defined behavior for signed integers is assumed to match the +expected behavior for two’s complement. Non representable values in integer +casts are binary truncated. Shift right of signed values uses sign extension. +</li></ul> + +<p>These features are supported by all compilers we care about, so we will not +accept patches to remove their use unless they absolutely do not impair +clarity and performance. +</p> +<p>All code must compile with recent versions of GCC and a number of other +currently supported compilers. To ensure compatibility, please do not use +additional C99 features or GCC extensions. Especially watch out for: +</p> +<ul> +<li> mixing statements and declarations; + +</li><li> ‘<samp>long long</samp>’ (use ‘<samp>int64_t</samp>’ instead); + +</li><li> ‘<samp>__attribute__</samp>’ not protected by ‘<samp>#ifdef __GNUC__</samp>’ or similar; + +</li><li> GCC statement expressions (‘<samp>(x = ({ int y = 4; y; })</samp>’). +</li></ul> + +<a name="Naming-conventions"></a> +<h3 class="section">2.4 Naming conventions<span class="pull-right"><a class="anchor hidden-xs" href="#Naming-conventions" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Naming-conventions" aria-hidden="true">TOC</a></span></h3> +<p>All names should be composed with underscores (_), not CamelCase. For example, +‘<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 +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 +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> +<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> + +<a name="Editor-configuration"></a> +<h3 class="section">2.6 Editor configuration<span class="pull-right"><a class="anchor hidden-xs" href="#Editor-configuration" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Editor-configuration" aria-hidden="true">TOC</a></span></h3> +<p>In order to configure Vim to follow FFmpeg formatting conventions, paste +the following snippet into your <samp>.vimrc</samp>: +</p><div class="example"> +<pre class="example">" indentation rules for FFmpeg: 4 spaces, no tabs +set expandtab +set shiftwidth=4 +set softtabstop=4 +set cindent +set cinoptions=(0 +" Allow tabs in Makefiles. +autocmd FileType make,automake set noexpandtab shiftwidth=8 softtabstop=8 +" Trailing whitespace and tabs are forbidden, so highlight them. +highlight ForbiddenWhitespace ctermbg=red guibg=red +match ForbiddenWhitespace /\s\+$\|\t/ +" Do not highlight spaces at the end of line while typing on that line. +autocmd InsertEnter * match ForbiddenWhitespace /\t\|\s\+\%#\@<!$/ +</pre></div> + +<p>For Emacs, add these roughly equivalent lines to your <samp>.emacs.d/init.el</samp>: +</p><div class="example lisp"> +<pre class="lisp">(c-add-style "ffmpeg" + '("k&r" + (c-basic-offset . 4) + (indent-tabs-mode . nil) + (show-trailing-whitespace . t) + (c-offsets-alist + (statement-cont . (c-lineup-assignments +))) + ) + ) +(setq c-default-style "ffmpeg") +</pre></div> + +<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="API_002fABI-changes-should-be-discussed-before-they-are-made_002e"></a> +<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> +<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> +<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="Documentation_002fOther"></a> +<h3 class="section">3.3 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> +<a name="Code-of-conduct"></a> +<h2 class="chapter">4 Code of conduct<span class="pull-right"><a class="anchor hidden-xs" href="#Code-of-conduct" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Code-of-conduct" aria-hidden="true">TOC</a></span></h2> + +<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> +<span id="Submitting-patches"></span><a name="Submitting-patches-1"></a> +<h2 class="chapter">5 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">6 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">7 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. + +</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">8 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">9 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">9.1 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>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">9.2 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">9.3 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">10 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">10.1 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">10.2 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> |