1 \input texinfo @c -*- texinfo -*-
2 @documentencoding UTF-8
4 @settitle Developer Documentation
6 @center @titlefont{Developer Documentation}
13 @chapter Notes for external developers
15 This document is mostly useful for internal FFmpeg developers.
16 External developers who need to use the API in their application should
17 refer to the API doxygen documentation in the public headers, and
18 check the examples in @file{doc/examples} and in the source code to
19 see how the public API is employed.
21 You can use the FFmpeg libraries in your commercial program, but you
22 are encouraged to @emph{publish any patch you make}. In this case the
23 best way to proceed is to send your patches to the ffmpeg-devel
24 mailing list following the guidelines illustrated in the remainder of
27 For more detailed legal information about the use of FFmpeg in
28 external programs read the @file{LICENSE} file in the source tree and
29 consult @url{https://ffmpeg.org/legal.html}.
33 There are 2 ways by which code gets into FFmpeg:
35 @item Submitting patches to the ffmpeg-devel mailing list.
36 See @ref{Submitting patches} for details.
37 @item Directly committing changes to the main tree.
40 Whichever way, changes should be reviewed by the maintainer of the code
41 before they are committed. And they should follow the @ref{Coding Rules}.
42 The developer making the commit and the author are responsible for their changes
43 and should try to fix issues their commit causes.
48 @section Code formatting conventions
50 There are the following guidelines regarding the indentation in files:
57 The TAB character is forbidden outside of Makefiles as is any
58 form of trailing whitespace. Commits containing either will be
59 rejected by the git repository.
62 You should try to limit your code lines to 80 characters; however, do so if
63 and only if this improves readability.
66 K&R coding style is used.
68 The presentation is one inspired by 'indent -i4 -kr -nut'.
70 The main priority in FFmpeg is simplicity and small code size in order to
71 minimize the bug count.
74 Use the JavaDoc/Doxygen format (see examples below) so that code documentation
75 can be generated automatically. All nontrivial functions should have a comment
76 above them explaining what the function does, even if it is just one sentence.
77 All structures and their member variables should be documented, too.
79 Avoid Qt-style and similar Doxygen syntax with @code{!} in it, i.e. replace
80 @code{//!} with @code{///} and similar. Also @@ syntax should be employed
81 for markup commands, i.e. use @code{@@param} and not @code{\param}.
95 typedef struct Foobar @{
96 int var1; /**< var1 description */
97 int var2; ///< var2 description
98 /** var3 description */
106 * @@param my_parameter description of my_parameter
107 * @@return return value description
109 int myfunc(int my_parameter)
113 @section C language features
115 FFmpeg is programmed in the ISO C90 language with a few additional
116 features from ISO C99, namely:
120 the @samp{inline} keyword;
126 designated struct initializers (@samp{struct s x = @{ .i = 17 @};});
129 compound literals (@samp{x = (struct s) @{ 17, 23 @};}).
132 Implementation defined behavior for signed integers is assumed to match the
133 expected behavior for two's complement. Non representable values in integer
134 casts are binary truncated. Shift right of signed values uses sign extension.
137 These features are supported by all compilers we care about, so we will not
138 accept patches to remove their use unless they absolutely do not impair
139 clarity and performance.
141 All code must compile with recent versions of GCC and a number of other
142 currently supported compilers. To ensure compatibility, please do not use
143 additional C99 features or GCC extensions. Especially watch out for:
147 mixing statements and declarations;
150 @samp{long long} (use @samp{int64_t} instead);
153 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
156 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
159 @section Naming conventions
160 All names should be composed with underscores (_), not CamelCase. For example,
161 @samp{avfilter_get_video_buffer} is an acceptable function name and
162 @samp{AVFilterGetVideo} is not. The exception from this are type names, like
163 for example structs and enums; they should always be in CamelCase.
165 There are the following conventions for naming variables and functions:
169 For local variables no prefix is required.
172 For file-scope variables and functions declared as @code{static}, no prefix
176 For variables and functions visible outside of file scope, but only used
177 internally by a library, an @code{ff_} prefix should be used,
178 e.g. @samp{ff_w64_demuxer}.
181 For variables and functions visible outside of file scope, used internally
182 across multiple libraries, use @code{avpriv_} as prefix, for example,
183 @samp{avpriv_report_missing_feature}.
186 Each library has its own prefix for public symbols, in addition to the
187 commonly used @code{av_} (@code{avformat_} for libavformat,
188 @code{avcodec_} for libavcodec, @code{swr_} for libswresample, etc).
189 Check the existing code and choose names accordingly.
190 Note that some symbols without these prefixes are also exported for
191 retro-compatibility reasons. These exceptions are declared in the
192 @code{lib<name>/lib<name>.v} files.
195 Furthermore, name space reserved for the system should not be invaded.
196 Identifiers ending in @code{_t} are reserved by
197 @url{http://pubs.opengroup.org/onlinepubs/007904975/functions/xsh_chap02_02.html#tag_02_02_02, POSIX}.
198 Also avoid names starting with @code{__} or @code{_} followed by an uppercase
199 letter as they are reserved by the C standard. Names starting with @code{_}
200 are reserved at the file level and may not be used for externally visible
201 symbols. If in doubt, just avoid names starting with @code{_} altogether.
203 @section Miscellaneous conventions
207 fprintf and printf are forbidden in libavformat and libavcodec,
208 please use av_log() instead.
211 Casts should be used only when necessary. Unneeded parentheses
212 should also be avoided if they don't make the code easier to understand.
215 @section Editor configuration
216 In order to configure Vim to follow FFmpeg formatting conventions, paste
217 the following snippet into your @file{.vimrc}:
219 " indentation rules for FFmpeg: 4 spaces, no tabs
225 " Allow tabs in Makefiles.
226 autocmd FileType make,automake set noexpandtab shiftwidth=8 softtabstop=8
227 " Trailing whitespace and tabs are forbidden, so highlight them.
228 highlight ForbiddenWhitespace ctermbg=red guibg=red
229 match ForbiddenWhitespace /\s\+$\|\t/
230 " Do not highlight spaces at the end of line while typing on that line.
231 autocmd InsertEnter * match ForbiddenWhitespace /\t\|\s\+\%#\@@<!$/
234 For Emacs, add these roughly equivalent lines to your @file{.emacs.d/init.el}:
236 (c-add-style "ffmpeg"
239 (indent-tabs-mode . nil)
240 (show-trailing-whitespace . t)
242 (statement-cont . (c-lineup-assignments +)))
245 (setq c-default-style "ffmpeg")
248 @chapter Development Policy
250 @section Patches/Committing
251 @subheading Licenses for patches must be compatible with FFmpeg.
252 Contributions should be licensed under the
253 @uref{http://www.gnu.org/licenses/lgpl-2.1.html, LGPL 2.1},
254 including an "or any later version" clause, or, if you prefer
255 a gift-style license, the
256 @uref{http://opensource.org/licenses/isc-license.txt, ISC} or
257 @uref{http://mit-license.org/, MIT} license.
258 @uref{http://www.gnu.org/licenses/gpl-2.0.html, GPL 2} including
259 an "or any later version" clause is also acceptable, but LGPL is
261 If you add a new file, give it a proper license header. Do not copy and
262 paste it from a random place, use an existing file as template.
264 @subheading You must not commit code which breaks FFmpeg!
265 This means unfinished code which is enabled and breaks compilation,
266 or compiles but does not work/breaks the regression tests. Code which
267 is unfinished but disabled may be permitted under-circumstances, like
268 missing samples or an implementation with a small subset of features.
269 Always check the mailing list for any reviewers with issues and test
270 FATE before you push.
272 @subheading Keep the main commit message short with an extended description below.
273 The commit message should have a short first line in the form of
274 a @samp{topic: short description} as a header, separated by a newline
275 from the body consisting of an explanation of why the change is necessary.
276 If the commit fixes a known bug on the bug tracker, the commit message
277 should include its bug ID. Referring to the issue on the bug tracker does
278 not exempt you from writing an excerpt of the bug in the commit message.
280 @subheading Testing must be adequate but not excessive.
281 If it works for you, others, and passes FATE then it should be OK to commit
282 it, provided it fits the other committing criteria. You should not worry about
283 over-testing things. If your code has problems (portability, triggers
284 compiler bugs, unusual environment etc) they will be reported and eventually
287 @subheading Do not commit unrelated changes together.
288 They should be split them into self-contained pieces. Also do not forget
289 that if part B depends on part A, but A does not depend on B, then A can
290 and should be committed first and separate from B. Keeping changes well
291 split into self-contained parts makes reviewing and understanding them on
292 the commit log mailing list easier. This also helps in case of debugging
294 Also if you have doubts about splitting or not splitting, do not hesitate to
295 ask/discuss it on the developer mailing list.
297 @subheading Ask before you change the build system (configure, etc).
298 Do not commit changes to the build system (Makefiles, configure script)
299 which change behavior, defaults etc, without asking first. The same
300 applies to compiler warning fixes, trivial looking fixes and to code
301 maintained by other developers. We usually have a reason for doing things
302 the way we do. Send your changes as patches to the ffmpeg-devel mailing
303 list, and if the code maintainers say OK, you may commit. This does not
304 apply to files you wrote and/or maintain.
306 @subheading Cosmetic changes should be kept in separate patches.
307 We refuse source indentation and other cosmetic changes if they are mixed
308 with functional changes, such commits will be rejected and removed. Every
309 developer has his own indentation style, you should not change it. Of course
310 if you (re)write something, you can use your own style, even though we would
311 prefer if the indentation throughout FFmpeg was consistent (Many projects
312 force a given indentation style - we do not.). If you really need to make
313 indentation changes (try to avoid this), separate them strictly from real
316 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
317 then either do NOT change the indentation of the inner part within (do not
318 move it to the right)! or do so in a separate commit
320 @subheading Commit messages should always be filled out properly.
321 Always fill out the commit log message. Describe in a few lines what you
322 changed and why. You can refer to mailing list postings if you fix a
323 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
327 area changed: Short 1 line description
329 details describing what and why and giving references.
332 @subheading Credit the author of the patch.
333 Make sure the author of the commit is set correctly. (see git commit --author)
334 If you apply a patch, send an
335 answer to ffmpeg-devel (or wherever you got the patch from) saying that
336 you applied the patch.
338 @subheading Complex patches should refer to discussion surrounding them.
339 When applying patches that have been discussed (at length) on the mailing
340 list, reference the thread in the log message.
342 @subheading Always wait long enough before pushing changes
343 Do NOT commit to code actively maintained by others without permission.
344 Send a patch to ffmpeg-devel. If no one answers within a reasonable
345 time-frame (12h for build failures and security fixes, 3 days small changes,
346 1 week for big patches) then commit your patch if you think it is OK.
347 Also note, the maintainer can simply ask for more time to review!
350 @subheading API/ABI changes should be discussed before they are made.
351 Do not change behavior of the programs (renaming options etc) or public
352 API or ABI without first discussing it on the ffmpeg-devel mailing list.
353 Do not remove widely used functionality or features (redundant code can be removed).
355 @subheading Remember to check if you need to bump versions for libav*.
356 Depending on the change, you may need to change the version integer.
357 Incrementing the first component means no backward compatibility to
358 previous versions (e.g. removal of a function from the public API).
359 Incrementing the second component means backward compatible change
360 (e.g. addition of a function to the public API or extension of an
361 existing data structure).
362 Incrementing the third component means a noteworthy binary compatible
363 change (e.g. encoder bug fix that matters for the decoder). The third
364 component always starts at 100 to distinguish FFmpeg from Libav.
366 @subheading Warnings for correct code may be disabled if there is no other option.
367 Compiler warnings indicate potential bugs or code with bad style. If a type of
368 warning always points to correct and clean code, that warning should
369 be disabled, not the code changed.
370 Thus the remaining warnings can either be bugs or correct code.
371 If it is a bug, the bug has to be fixed. If it is not, the code should
372 be changed to not generate a warning unless that causes a slowdown
373 or obfuscates the code.
375 @subheading Check untrusted input properly.
376 Never write to unallocated memory, never write over the end of arrays,
377 always check values read from some untrusted source before using them
378 as array index or other risky things.
380 @section Documentation/Other
381 @subheading Subscribe to the ffmpeg-devel mailing list.
382 It is important to be subscribed to the
383 @uref{https://lists.ffmpeg.org/mailman/listinfo/ffmpeg-devel, ffmpeg-devel}
384 mailing list. Almost any non-trivial patch is to be sent there for review.
385 Other developers may have comments about your contribution. We expect you see
386 those comments, and to improve it if requested. (N.B. Experienced committers
387 have other channels, and may sometimes skip review for trivial fixes.) Also,
388 discussion here about bug fixes and FFmpeg improvements by other developers may
389 be helpful information for you. Finally, by being a list subscriber, your
390 contribution will be posted immediately to the list, without the moderation
391 hold which messages from non-subscribers experience.
393 However, it is more important to the project that we receive your patch than
394 that you be subscribed to the ffmpeg-devel list. If you have a patch, and don't
395 want to subscribe and discuss the patch, then please do send it to the list
398 @subheading Subscribe to the ffmpeg-cvslog mailing list.
399 Diffs of all commits are sent to the
400 @uref{https://lists.ffmpeg.org/mailman/listinfo/ffmpeg-cvslog, ffmpeg-cvslog}
401 mailing list. Some developers read this list to review all code base changes
402 from all sources. Subscribing to this list is not mandatory.
404 @subheading Keep the documentation up to date.
405 Update the documentation if you change behavior or add features. If you are
406 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
407 maintainer(s) will review and commit your stuff.
409 @subheading Important discussions should be accessible to all.
410 Try to keep important discussions and requests (also) on the public
411 developer mailing list, so that all developers can benefit from them.
413 @subheading Check your entries in MAINTAINERS.
414 Make sure that no parts of the codebase that you maintain are missing from the
415 @file{MAINTAINERS} file. If something that you want to maintain is missing add it with
417 If at some point you no longer want to maintain some code, then please help in
418 finding a new maintainer and also don't forget to update the @file{MAINTAINERS} file.
420 We think our rules are not too hard. If you have comments, contact us.
422 @chapter Code of conduct
424 Be friendly and respectful towards others and third parties.
425 Treat others the way you yourself want to be treated.
427 Be considerate. Not everyone shares the same viewpoint and priorities as you do.
428 Different opinions and interpretations help the project.
429 Looking at issues from a different perspective assists development.
431 Do not assume malice for things that can be attributed to incompetence. Even if
432 it is malice, it's rarely good to start with that as initial assumption.
434 Stay friendly even if someone acts contrarily. Everyone has a bad day
436 If you yourself have a bad day or are angry then try to take a break and reply
437 once you are calm and without anger if you have to.
439 Try to help other team members and cooperate if you can.
441 The goal of software development is to create technical excellence, not for any
442 individual to be better and "win" against the others. Large software projects
443 are only possible and successful through teamwork.
445 If someone struggles do not put them down. Give them a helping hand
446 instead and point them in the right direction.
448 Finally, keep in mind the immortal words of Bill and Ted,
449 "Be excellent to each other."
451 @anchor{Submitting patches}
452 @chapter Submitting patches
454 First, read the @ref{Coding Rules} above if you did not yet, in particular
455 the rules regarding patch submission.
457 When you submit your patch, please use @code{git format-patch} or
458 @code{git send-email}. We cannot read other diffs :-).
460 Also please do not submit a patch which contains several unrelated changes.
461 Split it into separate, self-contained pieces. This does not mean splitting
462 file by file. Instead, make the patch as small as possible while still
463 keeping it as a logical unit that contains an individual change, even
464 if it spans multiple files. This makes reviewing your patches much easier
465 for us and greatly increases your chances of getting your patch applied.
467 Use the patcheck tool of FFmpeg to check your patch.
468 The tool is located in the tools directory.
470 Run the @ref{Regression tests} before submitting a patch in order to verify
471 it does not cause unexpected problems.
473 It also helps quite a bit if you tell us what the patch does (for example
474 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
477 Also please if you send several patches, send each patch as a separate mail,
478 do not attach several unrelated patches to the same mail.
480 Patches should be posted to the
481 @uref{https://lists.ffmpeg.org/mailman/listinfo/ffmpeg-devel, ffmpeg-devel}
482 mailing list. Use @code{git send-email} when possible since it will properly
483 send patches without requiring extra care. If you cannot, then send patches
484 as base64-encoded attachments, so your patch is not trashed during
485 transmission. Also ensure the correct mime type is used
486 (text/x-diff or text/x-patch or at least text/plain) and that only one
487 patch is inline or attached per mail.
488 You can check @url{https://patchwork.ffmpeg.org}, if your patch does not show up, its mime type
491 Your patch will be reviewed on the mailing list. You will likely be asked
492 to make some changes and are expected to send in an improved version that
493 incorporates the requests from the review. This process may go through
494 several iterations. Once your patch is deemed good enough, some developer
495 will pick it up and commit it to the official FFmpeg tree.
497 Give us a few days to react. But if some time passes without reaction,
498 send a reminder by email. Your patch should eventually be dealt with.
501 @chapter New codecs or formats checklist
505 Did you use av_cold for codec initialization and close functions?
508 Did you add a long_name under NULL_IF_CONFIG_SMALL to the AVCodec or
509 AVInputFormat/AVOutputFormat struct?
512 Did you bump the minor version number (and reset the micro version
513 number) in @file{libavcodec/version.h} or @file{libavformat/version.h}?
516 Did you register it in @file{allcodecs.c} or @file{allformats.c}?
519 Did you add the AVCodecID to @file{avcodec.h}?
520 When adding new codec IDs, also add an entry to the codec descriptor
521 list in @file{libavcodec/codec_desc.c}.
524 If it has a FourCC, did you add it to @file{libavformat/riff.c},
525 even if it is only a decoder?
528 Did you add a rule to compile the appropriate files in the Makefile?
529 Remember to do this even if you're just adding a format to a file that is
530 already being compiled by some other rule, like a raw demuxer.
533 Did you add an entry to the table of supported formats or codecs in
534 @file{doc/general.texi}?
537 Did you add an entry in the Changelog?
540 If it depends on a parser or a library, did you add that dependency in
544 Did you @code{git add} the appropriate files before committing?
547 Did you make sure it compiles standalone, i.e. with
548 @code{configure --disable-everything --enable-decoder=foo}
549 (or @code{--enable-demuxer} or whatever your component is)?
553 @chapter Patch submission checklist
557 Does @code{make fate} pass with the patch applied?
560 Was the patch generated with git format-patch or send-email?
563 Did you sign-off your patch? (@code{git commit -s})
564 See @uref{https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Documentation/process/submitting-patches.rst, Sign your work} for the meaning
568 Did you provide a clear git commit log message?
571 Is the patch against latest FFmpeg git master branch?
574 Are you subscribed to ffmpeg-devel?
575 (the list is subscribers only due to spam)
578 Have you checked that the changes are minimal, so that the same cannot be
579 achieved with a smaller patch and/or simpler final code?
582 If the change is to speed critical code, did you benchmark it?
585 If you did any benchmarks, did you provide them in the mail?
588 Have you checked that the patch does not introduce buffer overflows or
589 other security issues?
592 Did you test your decoder or demuxer against damaged data? If no, see
593 tools/trasher, the noise bitstream filter, and
594 @uref{http://caca.zoy.org/wiki/zzuf, zzuf}. Your decoder or demuxer
595 should not crash, end in a (near) infinite loop, or allocate ridiculous
596 amounts of memory when fed damaged data.
599 Did you test your decoder or demuxer against sample files?
600 Samples may be obtained at @url{https://samples.ffmpeg.org}.
603 Does the patch not mix functional and cosmetic changes?
606 Did you add tabs or trailing whitespace to the code? Both are forbidden.
609 Is the patch attached to the email you send?
612 Is the mime type of the patch correct? It should be text/x-diff or
613 text/x-patch or at least text/plain and not application/octet-stream.
616 If the patch fixes a bug, did you provide a verbose analysis of the bug?
619 If the patch fixes a bug, did you provide enough information, including
620 a sample, so the bug can be reproduced and the fix can be verified?
621 Note please do not attach samples >100k to mails but rather provide a
622 URL, you can upload to ftp://upload.ffmpeg.org.
625 Did you provide a verbose summary about what the patch does change?
628 Did you provide a verbose explanation why it changes things like it does?
631 Did you provide a verbose summary of the user visible advantages and
632 disadvantages if the patch is applied?
635 Did you provide an example so we can verify the new feature added by the
639 If you added a new file, did you insert a license header? It should be
640 taken from FFmpeg, not randomly copied and pasted from somewhere else.
643 You should maintain alphabetical order in alphabetically ordered lists as
644 long as doing so does not break API/ABI compatibility.
647 Lines with similar content should be aligned vertically when doing so
648 improves readability.
651 Consider adding a regression test for your code.
654 If you added YASM code please check that things still work with --disable-yasm.
657 Make sure you check the return values of function and return appropriate
658 error codes. Especially memory allocation functions like @code{av_malloc()}
659 are notoriously left unchecked, which is a serious problem.
662 Test your code with valgrind and or Address Sanitizer to ensure it's free
663 of leaks, out of array accesses, etc.
666 @chapter Patch review process
668 All patches posted to ffmpeg-devel will be reviewed, unless they contain a
669 clear note that the patch is not for the git master branch.
670 Reviews and comments will be posted as replies to the patch on the
671 mailing list. The patch submitter then has to take care of every comment,
672 that can be by resubmitting a changed patch or by discussion. Resubmitted
673 patches will themselves be reviewed like any other patch. If at some point
674 a patch passes review with no comments then it is approved, that can for
675 simple and small patches happen immediately while large patches will generally
676 have to be changed and reviewed many times before they are approved.
677 After a patch is approved it will be committed to the repository.
679 We will review all submitted patches, but sometimes we are quite busy so
680 especially for large patches this can take several weeks.
682 If you feel that the review process is too slow and you are willing to try to
683 take over maintainership of the area of code you change then just clone
684 git master and maintain the area of code there. We will merge each area from
685 where its best maintained.
687 When resubmitting patches, please do not make any significant changes
688 not related to the comments received during review. Such patches will
689 be rejected. Instead, submit significant changes or new features as
692 Everyone is welcome to review patches. Also if you are waiting for your patch
693 to be reviewed, please consider helping to review other patches, that is a great
694 way to get everyone's patches reviewed sooner.
696 @anchor{Regression tests}
697 @chapter Regression tests
699 Before submitting a patch (or committing to the repository), you should at least
700 test that you did not break anything.
702 Running 'make fate' accomplishes this, please see @url{fate.html} for details.
704 [Of course, some patches may change the results of the regression tests. In
705 this case, the reference results of the regression tests shall be modified
708 @section Adding files to the fate-suite dataset
710 When there is no muxer or encoder available to generate test media for a
711 specific test then the media has to be included in the fate-suite.
712 First please make sure that the sample file is as small as possible to test the
713 respective decoder or demuxer sufficiently. Large files increase network
714 bandwidth and disk space requirements.
715 Once you have a working fate test and fate sample, provide in the commit
716 message or introductory message for the patch series that you post to
717 the ffmpeg-devel mailing list, a direct link to download the sample media.
719 @section Visualizing Test Coverage
721 The FFmpeg build system allows visualizing the test coverage in an easy
722 manner with the coverage tools @code{gcov}/@code{lcov}. This involves
727 Configure to compile with instrumentation enabled:
728 @code{configure --toolchain=gcov}.
731 Run your test case, either manually or via FATE. This can be either
732 the full FATE regression suite, or any arbitrary invocation of any
733 front-end tool provided by FFmpeg, in any combination.
736 Run @code{make lcov} to generate coverage data in HTML format.
739 View @code{lcov/index.html} in your preferred HTML viewer.
742 You can use the command @code{make lcov-reset} to reset the coverage
743 measurements. You will need to rerun @code{make lcov} after running a
746 @section Using Valgrind
748 The configure script provides a shortcut for using valgrind to spot bugs
749 related to memory handling. Just add the option
750 @code{--toolchain=valgrind-memcheck} or @code{--toolchain=valgrind-massif}
751 to your configure line, and reasonable defaults will be set for running
752 FATE under the supervision of either the @strong{memcheck} or the
753 @strong{massif} tool of the valgrind suite.
755 In case you need finer control over how valgrind is invoked, use the
756 @code{--target-exec='valgrind <your_custom_valgrind_options>} option in
757 your configure line instead.
759 @anchor{Release process}
760 @chapter Release process
762 FFmpeg maintains a set of @strong{release branches}, which are the
763 recommended deliverable for system integrators and distributors (such as
764 Linux distributions, etc.). At regular times, a @strong{release
765 manager} prepares, tests and publishes tarballs on the
766 @url{https://ffmpeg.org} website.
768 There are two kinds of releases:
772 @strong{Major releases} always include the latest and greatest
773 features and functionality.
776 @strong{Point releases} are cut from @strong{release} branches,
777 which are named @code{release/X}, with @code{X} being the release
781 Note that we promise to our users that shared libraries from any FFmpeg
782 release never break programs that have been @strong{compiled} against
783 previous versions of @strong{the same release series} in any case!
785 However, from time to time, we do make API changes that require adaptations
786 in applications. Such changes are only allowed in (new) major releases and
787 require further steps such as bumping library version numbers and/or
788 adjustments to the symbol versioning file. Please discuss such changes
789 on the @strong{ffmpeg-devel} mailing list in time to allow forward planning.
791 @anchor{Criteria for Point Releases}
792 @section Criteria for Point Releases
794 Changes that match the following criteria are valid candidates for
795 inclusion into a point release:
799 Fixes a security issue, preferably identified by a @strong{CVE
800 number} issued by @url{http://cve.mitre.org/}.
803 Fixes a documented bug in @url{https://trac.ffmpeg.org}.
806 Improves the included documentation.
809 Retains both source code and binary compatibility with previous
810 point releases of the same release branch.
813 The order for checking the rules is (1 OR 2 OR 3) AND 4.
816 @section Release Checklist
818 The release process involves the following steps:
822 Ensure that the @file{RELEASE} file contains the version number for
823 the upcoming release.
826 Add the release at @url{https://trac.ffmpeg.org/admin/ticket/versions}.
829 Announce the intent to do a release to the mailing list.
832 Make sure all relevant security fixes have been backported. See
833 @url{https://ffmpeg.org/security.html}.
836 Ensure that the FATE regression suite still passes in the release
837 branch on at least @strong{i386} and @strong{amd64}
838 (cf. @ref{Regression tests}).
841 Prepare the release tarballs in @code{bz2} and @code{gz} formats, and
842 supplementing files that contain @code{gpg} signatures
845 Publish the tarballs at @url{https://ffmpeg.org/releases}. Create and
846 push an annotated tag in the form @code{nX}, with @code{X}
847 containing the version number.
850 Propose and send a patch to the @strong{ffmpeg-devel} mailing list
851 with a news entry for the website.
854 Publish the news entry.
857 Send an announcement to the mailing list.