1\input texinfo @c -*- texinfo -*- 2 3@settitle Developer Documentation 4@titlepage 5@center @titlefont{Developer Documentation} 6@end titlepage 7 8@top 9 10@contents 11 12@chapter Developers Guide 13 14@section Notes for external developers 15 16This document is mostly useful for internal FFmpeg developers. 17External developers who need to use the API in their application should 18refer to the API doxygen documentation in the public headers, and 19check the examples in @file{doc/examples} and in the source code to 20see how the public API is employed. 21 22You can use the FFmpeg libraries in your commercial program, but you 23are encouraged to @emph{publish any patch you make}. In this case the 24best way to proceed is to send your patches to the ffmpeg-devel 25mailing list following the guidelines illustrated in the remainder of 26this document. 27 28For more detailed legal information about the use of FFmpeg in 29external programs read the @file{LICENSE} file in the source tree and 30consult @url{http://ffmpeg.org/legal.html}. 31 32@section Contributing 33 34There are 3 ways by which code gets into ffmpeg. 35@itemize @bullet 36@item Submitting Patches to the main developer mailing list 37 see @ref{Submitting patches} for details. 38@item Directly committing changes to the main tree. 39@item Committing changes to a git clone, for example on github.com or 40 gitorious.org. And asking us to merge these changes. 41@end itemize 42 43Whichever way, changes should be reviewed by the maintainer of the code 44before they are committed. And they should follow the @ref{Coding Rules}. 45The developer making the commit and the author are responsible for their changes 46and should try to fix issues their commit causes. 47 48@anchor{Coding Rules} 49@section Coding Rules 50 51@subsection Code formatting conventions 52 53There are the following guidelines regarding the indentation in files: 54 55@itemize @bullet 56@item 57Indent size is 4. 58 59@item 60The TAB character is forbidden outside of Makefiles as is any 61form of trailing whitespace. Commits containing either will be 62rejected by the git repository. 63 64@item 65You should try to limit your code lines to 80 characters; however, do so if 66and only if this improves readability. 67@end itemize 68The presentation is one inspired by 'indent -i4 -kr -nut'. 69 70The main priority in FFmpeg is simplicity and small code size in order to 71minimize the bug count. 72 73@subsection Comments 74Use the JavaDoc/Doxygen format (see examples below) so that code documentation 75can be generated automatically. All nontrivial functions should have a comment 76above them explaining what the function does, even if it is just one sentence. 77All structures and their member variables should be documented, too. 78 79Avoid Qt-style and similar Doxygen syntax with @code{!} in it, i.e. replace 80@code{//!} with @code{///} and similar. Also @@ syntax should be employed 81for markup commands, i.e. use @code{@@param} and not @code{\param}. 82 83@example 84/** 85 * @@file 86 * MPEG codec. 87 * @@author ... 88 */ 89 90/** 91 * Summary sentence. 92 * more text ... 93 * ... 94 */ 95typedef struct Foobar @{ 96 int var1; /**< var1 description */ 97 int var2; ///< var2 description 98 /** var3 description */ 99 int var3; 100@} Foobar; 101 102/** 103 * Summary sentence. 104 * more text ... 105 * ... 106 * @@param my_parameter description of my_parameter 107 * @@return return value description 108 */ 109int myfunc(int my_parameter) 110... 111@end example 112 113@subsection C language features 114 115FFmpeg is programmed in the ISO C90 language with a few additional 116features from ISO C99, namely: 117 118@itemize @bullet 119@item 120the @samp{inline} keyword; 121 122@item 123@samp{//} comments; 124 125@item 126designated struct initializers (@samp{struct s x = @{ .i = 17 @};}) 127 128@item 129compound literals (@samp{x = (struct s) @{ 17, 23 @};}) 130@end itemize 131 132These features are supported by all compilers we care about, so we will not 133accept patches to remove their use unless they absolutely do not impair 134clarity and performance. 135 136All code must compile with recent versions of GCC and a number of other 137currently supported compilers. To ensure compatibility, please do not use 138additional C99 features or GCC extensions. Especially watch out for: 139 140@itemize @bullet 141@item 142mixing statements and declarations; 143 144@item 145@samp{long long} (use @samp{int64_t} instead); 146 147@item 148@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar; 149 150@item 151GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}). 152@end itemize 153 154@subsection Naming conventions 155All names should be composed with underscores (_), not CamelCase. For example, 156@samp{avfilter_get_video_buffer} is an acceptable function name and 157@samp{AVFilterGetVideo} is not. The exception from this are type names, like 158for example structs and enums; they should always be in the CamelCase 159 160There are the following conventions for naming variables and functions: 161 162@itemize @bullet 163@item 164For local variables no prefix is required. 165 166@item 167For file-scope variables and functions declared as @code{static}, no prefix 168is required. 169 170@item 171For variables and functions visible outside of file scope, but only used 172internally by a library, an @code{ff_} prefix should be used, 173e.g. @samp{ff_w64_demuxer}. 174 175@item 176For variables and functions visible outside of file scope, used internally 177across multiple libraries, use @code{avpriv_} as prefix, for example, 178@samp{avpriv_aac_parse_header}. 179 180@item 181Each library has its own prefix for public symbols, in addition to the 182commonly used @code{av_} (@code{avformat_} for libavformat, 183@code{avcodec_} for libavcodec, @code{swr_} for libswresample, etc). 184Check the existing code and choose names accordingly. 185Note that some symbols without these prefixes are also exported for 186retro-compatibility reasons. These exceptions are declared in the 187@code{lib<name>/lib<name>.v} files. 188@end itemize 189 190Furthermore, name space reserved for the system should not be invaded. 191Identifiers ending in @code{_t} are reserved by 192@url{http://pubs.opengroup.org/onlinepubs/007904975/functions/xsh_chap02_02.html#tag_02_02_02, POSIX}. 193Also avoid names starting with @code{__} or @code{_} followed by an uppercase 194letter as they are reserved by the C standard. Names starting with @code{_} 195are reserved at the file level and may not be used for externally visible 196symbols. If in doubt, just avoid names starting with @code{_} altogether. 197 198@subsection Miscellaneous conventions 199 200@itemize @bullet 201@item 202fprintf and printf are forbidden in libavformat and libavcodec, 203please use av_log() instead. 204 205@item 206Casts should be used only when necessary. Unneeded parentheses 207should also be avoided if they don't make the code easier to understand. 208@end itemize 209 210@subsection Editor configuration 211In order to configure Vim to follow FFmpeg formatting conventions, paste 212the following snippet into your @file{.vimrc}: 213@example 214" indentation rules for FFmpeg: 4 spaces, no tabs 215set expandtab 216set shiftwidth=4 217set softtabstop=4 218set cindent 219set cinoptions=(0 220" Allow tabs in Makefiles. 221autocmd FileType make,automake set noexpandtab shiftwidth=8 softtabstop=8 222" Trailing whitespace and tabs are forbidden, so highlight them. 223highlight ForbiddenWhitespace ctermbg=red guibg=red 224match ForbiddenWhitespace /\s\+$\|\t/ 225" Do not highlight spaces at the end of line while typing on that line. 226autocmd InsertEnter * match ForbiddenWhitespace /\t\|\s\+\%#\@@<!$/ 227@end example 228 229For Emacs, add these roughly equivalent lines to your @file{.emacs.d/init.el}: 230@example 231(c-add-style "ffmpeg" 232 '("k&r" 233 (c-basic-offset . 4) 234 (indent-tabs-mode . nil) 235 (show-trailing-whitespace . t) 236 (c-offsets-alist 237 (statement-cont . (c-lineup-assignments +))) 238 ) 239 ) 240(setq c-default-style "ffmpeg") 241@end example 242 243@section Development Policy 244 245@enumerate 246@item 247Contributions should be licensed under the 248@uref{http://www.gnu.org/licenses/lgpl-2.1.html, LGPL 2.1}, 249including an "or any later version" clause, or, if you prefer 250a gift-style license, the 251@uref{http://opensource.org/licenses/isc-license.txt, ISC} or 252@uref{http://mit-license.org/, MIT} license. 253@uref{http://www.gnu.org/licenses/gpl-2.0.html, GPL 2} including 254an "or any later version" clause is also acceptable, but LGPL is 255preferred. 256If you add a new file, give it a proper license header. Do not copy and 257paste it from a random place, use an existing file as template. 258 259@item 260You must not commit code which breaks FFmpeg! (Meaning unfinished but 261enabled code which breaks compilation or compiles but does not work or 262breaks the regression tests) 263You can commit unfinished stuff (for testing etc), but it must be disabled 264(#ifdef etc) by default so it does not interfere with other developers' 265work. 266 267@item 268The commit message should have a short first line in the form of 269a @samp{topic: short description} as a header, separated by a newline 270from the body consisting of an explanation of why the change is necessary. 271If the commit fixes a known bug on the bug tracker, the commit message 272should include its bug ID. Referring to the issue on the bug tracker does 273not exempt you from writing an excerpt of the bug in the commit message. 274 275@item 276You do not have to over-test things. If it works for you, and you think it 277should work for others, then commit. If your code has problems 278(portability, triggers compiler bugs, unusual environment etc) they will be 279reported and eventually fixed. 280 281@item 282Do not commit unrelated changes together, split them into self-contained 283pieces. Also do not forget that if part B depends on part A, but A does not 284depend on B, then A can and should be committed first and separate from B. 285Keeping changes well split into self-contained parts makes reviewing and 286understanding them on the commit log mailing list easier. This also helps 287in case of debugging later on. 288Also if you have doubts about splitting or not splitting, do not hesitate to 289ask/discuss it on the developer mailing list. 290 291@item 292Do not change behavior of the programs (renaming options etc) or public 293API or ABI without first discussing it on the ffmpeg-devel mailing list. 294Do not remove functionality from the code. Just improve! 295 296Note: Redundant code can be removed. 297 298@item 299Do not commit changes to the build system (Makefiles, configure script) 300which change behavior, defaults etc, without asking first. The same 301applies to compiler warning fixes, trivial looking fixes and to code 302maintained by other developers. We usually have a reason for doing things 303the way we do. Send your changes as patches to the ffmpeg-devel mailing 304list, and if the code maintainers say OK, you may commit. This does not 305apply to files you wrote and/or maintain. 306 307@item 308We refuse source indentation and other cosmetic changes if they are mixed 309with functional changes, such commits will be rejected and removed. Every 310developer has his own indentation style, you should not change it. Of course 311if you (re)write something, you can use your own style, even though we would 312prefer if the indentation throughout FFmpeg was consistent (Many projects 313force a given indentation style - we do not.). If you really need to make 314indentation changes (try to avoid this), separate them strictly from real 315changes. 316 317NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code, 318then either do NOT change the indentation of the inner part within (do not 319move it to the right)! or do so in a separate commit 320 321@item 322Always fill out the commit log message. Describe in a few lines what you 323changed and why. You can refer to mailing list postings if you fix a 324particular bug. Comments such as "fixed!" or "Changed it." are unacceptable. 325Recommended format: 326area changed: Short 1 line description 327 328details describing what and why and giving references. 329 330@item 331Make sure the author of the commit is set correctly. (see git commit --author) 332If you apply a patch, send an 333answer to ffmpeg-devel (or wherever you got the patch from) saying that 334you applied the patch. 335 336@item 337When applying patches that have been discussed (at length) on the mailing 338list, reference the thread in the log message. 339 340@item 341Do NOT commit to code actively maintained by others without permission. 342Send a patch to ffmpeg-devel instead. If no one answers within a reasonable 343timeframe (12h for build failures and security fixes, 3 days small changes, 3441 week for big patches) then commit your patch if you think it is OK. 345Also note, the maintainer can simply ask for more time to review! 346 347@item 348Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits 349are sent there and reviewed by all the other developers. Bugs and possible 350improvements or general questions regarding commits are discussed there. We 351expect you to react if problems with your code are uncovered. 352 353@item 354Update the documentation if you change behavior or add features. If you are 355unsure how best to do this, send a patch to ffmpeg-devel, the documentation 356maintainer(s) will review and commit your stuff. 357 358@item 359Try to keep important discussions and requests (also) on the public 360developer mailing list, so that all developers can benefit from them. 361 362@item 363Never write to unallocated memory, never write over the end of arrays, 364always check values read from some untrusted source before using them 365as array index or other risky things. 366 367@item 368Remember to check if you need to bump versions for the specific libav* 369parts (libavutil, libavcodec, libavformat) you are changing. You need 370to change the version integer. 371Incrementing the first component means no backward compatibility to 372previous versions (e.g. removal of a function from the public API). 373Incrementing the second component means backward compatible change 374(e.g. addition of a function to the public API or extension of an 375existing data structure). 376Incrementing the third component means a noteworthy binary compatible 377change (e.g. encoder bug fix that matters for the decoder). The third 378component always starts at 100 to distinguish FFmpeg from Libav. 379 380@item 381Compiler warnings indicate potential bugs or code with bad style. If a type of 382warning always points to correct and clean code, that warning should 383be disabled, not the code changed. 384Thus the remaining warnings can either be bugs or correct code. 385If it is a bug, the bug has to be fixed. If it is not, the code should 386be changed to not generate a warning unless that causes a slowdown 387or obfuscates the code. 388 389@item 390Make sure that no parts of the codebase that you maintain are missing from the 391@file{MAINTAINERS} file. If something that you want to maintain is missing add it with 392your name after it. 393If at some point you no longer want to maintain some code, then please help 394finding a new maintainer and also don't forget updating the @file{MAINTAINERS} file. 395@end enumerate 396 397We think our rules are not too hard. If you have comments, contact us. 398 399@anchor{Submitting patches} 400@section Submitting patches 401 402First, read the @ref{Coding Rules} above if you did not yet, in particular 403the rules regarding patch submission. 404 405When you submit your patch, please use @code{git format-patch} or 406@code{git send-email}. We cannot read other diffs :-) 407 408Also please do not submit a patch which contains several unrelated changes. 409Split it into separate, self-contained pieces. This does not mean splitting 410file by file. Instead, make the patch as small as possible while still 411keeping it as a logical unit that contains an individual change, even 412if it spans multiple files. This makes reviewing your patches much easier 413for us and greatly increases your chances of getting your patch applied. 414 415Use the patcheck tool of FFmpeg to check your patch. 416The tool is located in the tools directory. 417 418Run the @ref{Regression tests} before submitting a patch in order to verify 419it does not cause unexpected problems. 420 421It also helps quite a bit if you tell us what the patch does (for example 422'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant 423and has no lrint()') 424 425Also please if you send several patches, send each patch as a separate mail, 426do not attach several unrelated patches to the same mail. 427 428Patches should be posted to the 429@uref{http://lists.ffmpeg.org/mailman/listinfo/ffmpeg-devel, ffmpeg-devel} 430mailing list. Use @code{git send-email} when possible since it will properly 431send patches without requiring extra care. If you cannot, then send patches 432as base64-encoded attachments, so your patch is not trashed during 433transmission. 434 435Your patch will be reviewed on the mailing list. You will likely be asked 436to make some changes and are expected to send in an improved version that 437incorporates the requests from the review. This process may go through 438several iterations. Once your patch is deemed good enough, some developer 439will pick it up and commit it to the official FFmpeg tree. 440 441Give us a few days to react. But if some time passes without reaction, 442send a reminder by email. Your patch should eventually be dealt with. 443 444 445@section New codecs or formats checklist 446 447@enumerate 448@item 449Did you use av_cold for codec initialization and close functions? 450 451@item 452Did you add a long_name under NULL_IF_CONFIG_SMALL to the AVCodec or 453AVInputFormat/AVOutputFormat struct? 454 455@item 456Did you bump the minor version number (and reset the micro version 457number) in @file{libavcodec/version.h} or @file{libavformat/version.h}? 458 459@item 460Did you register it in @file{allcodecs.c} or @file{allformats.c}? 461 462@item 463Did you add the AVCodecID to @file{avcodec.h}? 464When adding new codec IDs, also add an entry to the codec descriptor 465list in @file{libavcodec/codec_desc.c}. 466 467@item 468If it has a FourCC, did you add it to @file{libavformat/riff.c}, 469even if it is only a decoder? 470 471@item 472Did you add a rule to compile the appropriate files in the Makefile? 473Remember to do this even if you're just adding a format to a file that is 474already being compiled by some other rule, like a raw demuxer. 475 476@item 477Did you add an entry to the table of supported formats or codecs in 478@file{doc/general.texi}? 479 480@item 481Did you add an entry in the Changelog? 482 483@item 484If it depends on a parser or a library, did you add that dependency in 485configure? 486 487@item 488Did you @code{git add} the appropriate files before committing? 489 490@item 491Did you make sure it compiles standalone, i.e. with 492@code{configure --disable-everything --enable-decoder=foo} 493(or @code{--enable-demuxer} or whatever your component is)? 494@end enumerate 495 496 497@section patch submission checklist 498 499@enumerate 500@item 501Does @code{make fate} pass with the patch applied? 502 503@item 504Was the patch generated with git format-patch or send-email? 505 506@item 507Did you sign off your patch? (git commit -s) 508See @url{http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob_plain;f=Documentation/SubmittingPatches} for the meaning 509of sign off. 510 511@item 512Did you provide a clear git commit log message? 513 514@item 515Is the patch against latest FFmpeg git master branch? 516 517@item 518Are you subscribed to ffmpeg-devel? 519(the list is subscribers only due to spam) 520 521@item 522Have you checked that the changes are minimal, so that the same cannot be 523achieved with a smaller patch and/or simpler final code? 524 525@item 526If the change is to speed critical code, did you benchmark it? 527 528@item 529If you did any benchmarks, did you provide them in the mail? 530 531@item 532Have you checked that the patch does not introduce buffer overflows or 533other security issues? 534 535@item 536Did you test your decoder or demuxer against damaged data? If no, see 537tools/trasher, the noise bitstream filter, and 538@uref{http://caca.zoy.org/wiki/zzuf, zzuf}. Your decoder or demuxer 539should not crash, end in a (near) infinite loop, or allocate ridiculous 540amounts of memory when fed damaged data. 541 542@item 543Does the patch not mix functional and cosmetic changes? 544 545@item 546Did you add tabs or trailing whitespace to the code? Both are forbidden. 547 548@item 549Is the patch attached to the email you send? 550 551@item 552Is the mime type of the patch correct? It should be text/x-diff or 553text/x-patch or at least text/plain and not application/octet-stream. 554 555@item 556If the patch fixes a bug, did you provide a verbose analysis of the bug? 557 558@item 559If the patch fixes a bug, did you provide enough information, including 560a sample, so the bug can be reproduced and the fix can be verified? 561Note please do not attach samples >100k to mails but rather provide a 562URL, you can upload to ftp://upload.ffmpeg.org 563 564@item 565Did you provide a verbose summary about what the patch does change? 566 567@item 568Did you provide a verbose explanation why it changes things like it does? 569 570@item 571Did you provide a verbose summary of the user visible advantages and 572disadvantages if the patch is applied? 573 574@item 575Did you provide an example so we can verify the new feature added by the 576patch easily? 577 578@item 579If you added a new file, did you insert a license header? It should be 580taken from FFmpeg, not randomly copied and pasted from somewhere else. 581 582@item 583You should maintain alphabetical order in alphabetically ordered lists as 584long as doing so does not break API/ABI compatibility. 585 586@item 587Lines with similar content should be aligned vertically when doing so 588improves readability. 589 590@item 591Consider to add a regression test for your code. 592 593@item 594If you added YASM code please check that things still work with --disable-yasm 595 596@item 597Make sure you check the return values of function and return appropriate 598error codes. Especially memory allocation functions like @code{av_malloc()} 599are notoriously left unchecked, which is a serious problem. 600 601@item 602Test your code with valgrind and or Address Sanitizer to ensure it's free 603of leaks, out of array accesses, etc. 604@end enumerate 605 606@section Patch review process 607 608All patches posted to ffmpeg-devel will be reviewed, unless they contain a 609clear note that the patch is not for the git master branch. 610Reviews and comments will be posted as replies to the patch on the 611mailing list. The patch submitter then has to take care of every comment, 612that can be by resubmitting a changed patch or by discussion. Resubmitted 613patches will themselves be reviewed like any other patch. If at some point 614a patch passes review with no comments then it is approved, that can for 615simple and small patches happen immediately while large patches will generally 616have to be changed and reviewed many times before they are approved. 617After a patch is approved it will be committed to the repository. 618 619We will review all submitted patches, but sometimes we are quite busy so 620especially for large patches this can take several weeks. 621 622If you feel that the review process is too slow and you are willing to try to 623take over maintainership of the area of code you change then just clone 624git master and maintain the area of code there. We will merge each area from 625where its best maintained. 626 627When resubmitting patches, please do not make any significant changes 628not related to the comments received during review. Such patches will 629be rejected. Instead, submit significant changes or new features as 630separate patches. 631 632@anchor{Regression tests} 633@section Regression tests 634 635Before submitting a patch (or committing to the repository), you should at least 636test that you did not break anything. 637 638Running 'make fate' accomplishes this, please see @url{fate.html} for details. 639 640[Of course, some patches may change the results of the regression tests. In 641this case, the reference results of the regression tests shall be modified 642accordingly]. 643 644@subsection Adding files to the fate-suite dataset 645 646When there is no muxer or encoder available to generate test media for a 647specific test then the media has to be inlcuded in the fate-suite. 648First please make sure that the sample file is as small as possible to test the 649respective decoder or demuxer sufficiently. Large files increase network 650bandwidth and disk space requirements. 651Once you have a working fate test and fate sample, provide in the commit 652message or introductionary message for the patch series that you post to 653the ffmpeg-devel mailing list, a direct link to download the sample media. 654 655 656@subsection Visualizing Test Coverage 657 658The FFmpeg build system allows visualizing the test coverage in an easy 659manner with the coverage tools @code{gcov}/@code{lcov}. This involves 660the following steps: 661 662@enumerate 663@item 664 Configure to compile with instrumentation enabled: 665 @code{configure --toolchain=gcov}. 666 667@item 668 Run your test case, either manually or via FATE. This can be either 669 the full FATE regression suite, or any arbitrary invocation of any 670 front-end tool provided by FFmpeg, in any combination. 671 672@item 673 Run @code{make lcov} to generate coverage data in HTML format. 674 675@item 676 View @code{lcov/index.html} in your preferred HTML viewer. 677@end enumerate 678 679You can use the command @code{make lcov-reset} to reset the coverage 680measurements. You will need to rerun @code{make lcov} after running a 681new test. 682 683@subsection Using Valgrind 684 685The configure script provides a shortcut for using valgrind to spot bugs 686related to memory handling. Just add the option 687@code{--toolchain=valgrind-memcheck} or @code{--toolchain=valgrind-massif} 688to your configure line, and reasonable defaults will be set for running 689FATE under the supervision of either the @strong{memcheck} or the 690@strong{massif} tool of the valgrind suite. 691 692In case you need finer control over how valgrind is invoked, use the 693@code{--target-exec='valgrind <your_custom_valgrind_options>} option in 694your configure line instead. 695 696@anchor{Release process} 697@section Release process 698 699FFmpeg maintains a set of @strong{release branches}, which are the 700recommended deliverable for system integrators and distributors (such as 701Linux distributions, etc.). At regular times, a @strong{release 702manager} prepares, tests and publishes tarballs on the 703@url{http://ffmpeg.org} website. 704 705There are two kinds of releases: 706 707@enumerate 708@item 709@strong{Major releases} always include the latest and greatest 710features and functionality. 711 712@item 713@strong{Point releases} are cut from @strong{release} branches, 714which are named @code{release/X}, with @code{X} being the release 715version number. 716@end enumerate 717 718Note that we promise to our users that shared libraries from any FFmpeg 719release never break programs that have been @strong{compiled} against 720previous versions of @strong{the same release series} in any case! 721 722However, from time to time, we do make API changes that require adaptations 723in applications. Such changes are only allowed in (new) major releases and 724require further steps such as bumping library version numbers and/or 725adjustments to the symbol versioning file. Please discuss such changes 726on the @strong{ffmpeg-devel} mailing list in time to allow forward planning. 727 728@anchor{Criteria for Point Releases} 729@subsection Criteria for Point Releases 730 731Changes that match the following criteria are valid candidates for 732inclusion into a point release: 733 734@enumerate 735@item 736Fixes a security issue, preferably identified by a @strong{CVE 737number} issued by @url{http://cve.mitre.org/}. 738 739@item 740Fixes a documented bug in @url{https://trac.ffmpeg.org}. 741 742@item 743Improves the included documentation. 744 745@item 746Retains both source code and binary compatibility with previous 747point releases of the same release branch. 748@end enumerate 749 750The order for checking the rules is (1 OR 2 OR 3) AND 4. 751 752 753@subsection Release Checklist 754 755The release process involves the following steps: 756 757@enumerate 758@item 759Ensure that the @file{RELEASE} file contains the version number for 760the upcoming release. 761 762@item 763Add the release at @url{https://trac.ffmpeg.org/admin/ticket/versions}. 764 765@item 766Announce the intent to do a release to the mailing list. 767 768@item 769Make sure all relevant security fixes have been backported. See 770@url{https://ffmpeg.org/security.html}. 771 772@item 773Ensure that the FATE regression suite still passes in the release 774branch on at least @strong{i386} and @strong{amd64} 775(cf. @ref{Regression tests}). 776 777@item 778Prepare the release tarballs in @code{bz2} and @code{gz} formats, and 779supplementing files that contain @code{gpg} signatures 780 781@item 782Publish the tarballs at @url{http://ffmpeg.org/releases}. Create and 783push an annotated tag in the form @code{nX}, with @code{X} 784containing the version number. 785 786@item 787Propose and send a patch to the @strong{ffmpeg-devel} mailing list 788with a news entry for the website. 789 790@item 791Publish the news entry. 792 793@item 794Send announcement to the mailing list. 795@end enumerate 796 797@bye 798