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867 lines
32 KiB
Plaintext
Executable File
867 lines
32 KiB
Plaintext
Executable File
\input texinfo @c -*- texinfo -*-
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@documentencoding UTF-8
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@settitle Developer Documentation
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@titlepage
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@center @titlefont{Developer Documentation}
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@end titlepage
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@top
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@contents
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@chapter Notes for external developers
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This document is mostly useful for internal FFmpeg developers.
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External developers who need to use the API in their application should
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refer to the API doxygen documentation in the public headers, and
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check the examples in @file{doc/examples} and in the source code to
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see how the public API is employed.
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You can use the FFmpeg libraries in your commercial program, but you
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are encouraged to @emph{publish any patch you make}. In this case the
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best way to proceed is to send your patches to the ffmpeg-devel
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mailing list following the guidelines illustrated in the remainder of
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this document.
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For more detailed legal information about the use of FFmpeg in
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external programs read the @file{LICENSE} file in the source tree and
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consult @url{https://ffmpeg.org/legal.html}.
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@chapter Contributing
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There are 2 ways by which code gets into FFmpeg:
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@itemize @bullet
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@item Submitting patches to the ffmpeg-devel mailing list.
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See @ref{Submitting patches} for details.
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@item Directly committing changes to the main tree.
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@end itemize
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Whichever way, changes should be reviewed by the maintainer of the code
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before they are committed. And they should follow the @ref{Coding Rules}.
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The developer making the commit and the author are responsible for their changes
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and should try to fix issues their commit causes.
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@anchor{Coding Rules}
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@chapter Coding Rules
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@section Code formatting conventions
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There are the following guidelines regarding the indentation in files:
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@itemize @bullet
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@item
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Indent size is 4.
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@item
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The TAB character is forbidden outside of Makefiles as is any
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form of trailing whitespace. Commits containing either will be
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rejected by the git repository.
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@item
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You should try to limit your code lines to 80 characters; however, do so if
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and only if this improves readability.
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@item
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K&R coding style is used.
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@end itemize
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The presentation is one inspired by 'indent -i4 -kr -nut'.
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The main priority in FFmpeg is simplicity and small code size in order to
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minimize the bug count.
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@section Comments
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Use the JavaDoc/Doxygen format (see examples below) so that code documentation
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can be generated automatically. All nontrivial functions should have a comment
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above them explaining what the function does, even if it is just one sentence.
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All structures and their member variables should be documented, too.
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Avoid Qt-style and similar Doxygen syntax with @code{!} in it, i.e. replace
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@code{//!} with @code{///} and similar. Also @@ syntax should be employed
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for markup commands, i.e. use @code{@@param} and not @code{\param}.
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@example
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/**
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* @@file
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* MPEG codec.
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* @@author ...
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*/
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/**
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* Summary sentence.
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* more text ...
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* ...
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*/
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typedef struct Foobar @{
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int var1; /**< var1 description */
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int var2; ///< var2 description
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/** var3 description */
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int var3;
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@} Foobar;
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/**
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* Summary sentence.
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* more text ...
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* ...
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* @@param my_parameter description of my_parameter
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* @@return return value description
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*/
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int myfunc(int my_parameter)
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...
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@end example
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@section C language features
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FFmpeg is programmed in the ISO C90 language with a few additional
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features from ISO C99, namely:
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@itemize @bullet
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@item
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the @samp{inline} keyword;
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@item
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@samp{//} comments;
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@item
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designated struct initializers (@samp{struct s x = @{ .i = 17 @};});
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@item
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compound literals (@samp{x = (struct s) @{ 17, 23 @};}).
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@item
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for loops with variable definition (@samp{for (int i = 0; i < 8; i++)});
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@item
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Variadic macros (@samp{#define ARRAY(nb, ...) (int[nb + 1])@{ nb, __VA_ARGS__ @}});
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@item
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Implementation defined behavior for signed integers is assumed to match the
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expected behavior for two's complement. Non representable values in integer
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casts are binary truncated. Shift right of signed values uses sign extension.
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@end itemize
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These features are supported by all compilers we care about, so we will not
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accept patches to remove their use unless they absolutely do not impair
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clarity and performance.
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All code must compile with recent versions of GCC and a number of other
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currently supported compilers. To ensure compatibility, please do not use
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additional C99 features or GCC extensions. Especially watch out for:
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@itemize @bullet
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@item
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mixing statements and declarations;
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@item
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@samp{long long} (use @samp{int64_t} instead);
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@item
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@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
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@item
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GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
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@end itemize
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@section Naming conventions
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All names should be composed with underscores (_), not CamelCase. For example,
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@samp{avfilter_get_video_buffer} is an acceptable function name and
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@samp{AVFilterGetVideo} is not. The exception from this are type names, like
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for example structs and enums; they should always be in CamelCase.
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There are the following conventions for naming variables and functions:
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@itemize @bullet
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@item
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For local variables no prefix is required.
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@item
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For file-scope variables and functions declared as @code{static}, no prefix
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is required.
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@item
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For variables and functions visible outside of file scope, but only used
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internally by a library, an @code{ff_} prefix should be used,
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e.g. @samp{ff_w64_demuxer}.
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@item
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For variables and functions visible outside of file scope, used internally
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across multiple libraries, use @code{avpriv_} as prefix, for example,
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@samp{avpriv_report_missing_feature}.
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@item
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Each library has its own prefix for public symbols, in addition to the
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commonly used @code{av_} (@code{avformat_} for libavformat,
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@code{avcodec_} for libavcodec, @code{swr_} for libswresample, etc).
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Check the existing code and choose names accordingly.
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Note that some symbols without these prefixes are also exported for
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retro-compatibility reasons. These exceptions are declared in the
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@code{lib<name>/lib<name>.v} files.
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@end itemize
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Furthermore, name space reserved for the system should not be invaded.
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Identifiers ending in @code{_t} are reserved by
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@url{http://pubs.opengroup.org/onlinepubs/007904975/functions/xsh_chap02_02.html#tag_02_02_02, POSIX}.
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Also avoid names starting with @code{__} or @code{_} followed by an uppercase
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letter as they are reserved by the C standard. Names starting with @code{_}
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are reserved at the file level and may not be used for externally visible
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symbols. If in doubt, just avoid names starting with @code{_} altogether.
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@section Miscellaneous conventions
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@itemize @bullet
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@item
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fprintf and printf are forbidden in libavformat and libavcodec,
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please use av_log() instead.
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@item
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Casts should be used only when necessary. Unneeded parentheses
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should also be avoided if they don't make the code easier to understand.
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@end itemize
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@section Editor configuration
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In order to configure Vim to follow FFmpeg formatting conventions, paste
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the following snippet into your @file{.vimrc}:
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@example
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" indentation rules for FFmpeg: 4 spaces, no tabs
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set expandtab
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set shiftwidth=4
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set softtabstop=4
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set cindent
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set cinoptions=(0
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" Allow tabs in Makefiles.
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autocmd FileType make,automake set noexpandtab shiftwidth=8 softtabstop=8
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" Trailing whitespace and tabs are forbidden, so highlight them.
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highlight ForbiddenWhitespace ctermbg=red guibg=red
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match ForbiddenWhitespace /\s\+$\|\t/
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" Do not highlight spaces at the end of line while typing on that line.
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autocmd InsertEnter * match ForbiddenWhitespace /\t\|\s\+\%#\@@<!$/
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@end example
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For Emacs, add these roughly equivalent lines to your @file{.emacs.d/init.el}:
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@lisp
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(c-add-style "ffmpeg"
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'("k&r"
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(c-basic-offset . 4)
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(indent-tabs-mode . nil)
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(show-trailing-whitespace . t)
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(c-offsets-alist
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(statement-cont . (c-lineup-assignments +)))
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)
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)
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(setq c-default-style "ffmpeg")
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@end lisp
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@chapter Development Policy
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@section Patches/Committing
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@subheading Licenses for patches must be compatible with FFmpeg.
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Contributions should be licensed under the
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@uref{http://www.gnu.org/licenses/lgpl-2.1.html, LGPL 2.1},
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including an "or any later version" clause, or, if you prefer
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a gift-style license, the
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@uref{http://opensource.org/licenses/isc-license.txt, ISC} or
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@uref{http://mit-license.org/, MIT} license.
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@uref{http://www.gnu.org/licenses/gpl-2.0.html, GPL 2} including
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an "or any later version" clause is also acceptable, but LGPL is
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preferred.
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If you add a new file, give it a proper license header. Do not copy and
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paste it from a random place, use an existing file as template.
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@subheading You must not commit code which breaks FFmpeg!
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This means unfinished code which is enabled and breaks compilation,
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or compiles but does not work/breaks the regression tests. Code which
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is unfinished but disabled may be permitted under-circumstances, like
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missing samples or an implementation with a small subset of features.
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Always check the mailing list for any reviewers with issues and test
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FATE before you push.
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@subheading Keep the main commit message short with an extended description below.
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The commit message should have a short first line in the form of
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a @samp{topic: short description} as a header, separated by a newline
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from the body consisting of an explanation of why the change is necessary.
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If the commit fixes a known bug on the bug tracker, the commit message
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should include its bug ID. Referring to the issue on the bug tracker does
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not exempt you from writing an excerpt of the bug in the commit message.
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@subheading Testing must be adequate but not excessive.
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If it works for you, others, and passes FATE then it should be OK to commit
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it, provided it fits the other committing criteria. You should not worry about
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over-testing things. If your code has problems (portability, triggers
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compiler bugs, unusual environment etc) they will be reported and eventually
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fixed.
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@subheading Do not commit unrelated changes together.
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They should be split them into self-contained pieces. Also do not forget
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that if part B depends on part A, but A does not depend on B, then A can
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and should be committed first and separate from B. Keeping changes well
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split into self-contained parts makes reviewing and understanding them on
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the commit log mailing list easier. This also helps in case of debugging
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later on.
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Also if you have doubts about splitting or not splitting, do not hesitate to
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ask/discuss it on the developer mailing list.
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@subheading Ask before you change the build system (configure, etc).
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Do not commit changes to the build system (Makefiles, configure script)
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which change behavior, defaults etc, without asking first. The same
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applies to compiler warning fixes, trivial looking fixes and to code
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maintained by other developers. We usually have a reason for doing things
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the way we do. Send your changes as patches to the ffmpeg-devel mailing
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list, and if the code maintainers say OK, you may commit. This does not
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apply to files you wrote and/or maintain.
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@subheading Cosmetic changes should be kept in separate patches.
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We refuse source indentation and other cosmetic changes if they are mixed
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with functional changes, such commits will be rejected and removed. Every
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developer has his own indentation style, you should not change it. Of course
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if you (re)write something, you can use your own style, even though we would
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prefer if the indentation throughout FFmpeg was consistent (Many projects
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force a given indentation style - we do not.). If you really need to make
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indentation changes (try to avoid this), separate them strictly from real
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changes.
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NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
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then either do NOT change the indentation of the inner part within (do not
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move it to the right)! or do so in a separate commit
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@subheading Commit messages should always be filled out properly.
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Always fill out the commit log message. Describe in a few lines what you
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changed and why. You can refer to mailing list postings if you fix a
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particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
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Recommended format:
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@example
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area changed: Short 1 line description
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details describing what and why and giving references.
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@end example
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@subheading Credit the author of the patch.
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Make sure the author of the commit is set correctly. (see git commit --author)
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If you apply a patch, send an
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answer to ffmpeg-devel (or wherever you got the patch from) saying that
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you applied the patch.
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@subheading Complex patches should refer to discussion surrounding them.
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When applying patches that have been discussed (at length) on the mailing
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list, reference the thread in the log message.
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@subheading Always wait long enough before pushing changes
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Do NOT commit to code actively maintained by others without permission.
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Send a patch to ffmpeg-devel. If no one answers within a reasonable
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time-frame (12h for build failures and security fixes, 3 days small changes,
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1 week for big patches) then commit your patch if you think it is OK.
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Also note, the maintainer can simply ask for more time to review!
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@section Code
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@subheading API/ABI changes should be discussed before they are made.
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Do not change behavior of the programs (renaming options etc) or public
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API or ABI without first discussing it on the ffmpeg-devel mailing list.
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Do not remove widely used functionality or features (redundant code can be removed).
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@subheading Remember to check if you need to bump versions for libav*.
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Depending on the change, you may need to change the version integer.
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Incrementing the first component means no backward compatibility to
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previous versions (e.g. removal of a function from the public API).
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Incrementing the second component means backward compatible change
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(e.g. addition of a function to the public API or extension of an
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existing data structure).
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Incrementing the third component means a noteworthy binary compatible
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change (e.g. encoder bug fix that matters for the decoder). The third
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component always starts at 100 to distinguish FFmpeg from Libav.
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@subheading Warnings for correct code may be disabled if there is no other option.
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Compiler warnings indicate potential bugs or code with bad style. If a type of
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warning always points to correct and clean code, that warning should
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be disabled, not the code changed.
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Thus the remaining warnings can either be bugs or correct code.
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If it is a bug, the bug has to be fixed. If it is not, the code should
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be changed to not generate a warning unless that causes a slowdown
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or obfuscates the code.
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@subheading Check untrusted input properly.
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Never write to unallocated memory, never write over the end of arrays,
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always check values read from some untrusted source before using them
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as array index or other risky things.
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@section Documentation/Other
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@subheading Subscribe to the ffmpeg-devel mailing list.
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It is important to be subscribed to the
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@uref{https://lists.ffmpeg.org/mailman/listinfo/ffmpeg-devel, ffmpeg-devel}
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mailing list. Almost any non-trivial patch is to be sent there for review.
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Other developers may have comments about your contribution. We expect you see
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those comments, and to improve it if requested. (N.B. Experienced committers
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have other channels, and may sometimes skip review for trivial fixes.) Also,
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discussion here about bug fixes and FFmpeg improvements by other developers may
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be helpful information for you. Finally, by being a list subscriber, your
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contribution will be posted immediately to the list, without the moderation
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hold which messages from non-subscribers experience.
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However, it is more important to the project that we receive your patch than
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that you be subscribed to the ffmpeg-devel list. If you have a patch, and don't
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want to subscribe and discuss the patch, then please do send it to the list
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anyway.
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@subheading Subscribe to the ffmpeg-cvslog mailing list.
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Diffs of all commits are sent to the
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@uref{https://lists.ffmpeg.org/mailman/listinfo/ffmpeg-cvslog, ffmpeg-cvslog}
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mailing list. Some developers read this list to review all code base changes
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from all sources. Subscribing to this list is not mandatory.
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@subheading Keep the documentation up to date.
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Update the documentation if you change behavior or add features. If you are
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unsure how best to do this, send a patch to ffmpeg-devel, the documentation
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maintainer(s) will review and commit your stuff.
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@subheading Important discussions should be accessible to all.
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Try to keep important discussions and requests (also) on the public
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developer mailing list, so that all developers can benefit from them.
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@subheading Check your entries in MAINTAINERS.
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Make sure that no parts of the codebase that you maintain are missing from the
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@file{MAINTAINERS} file. If something that you want to maintain is missing add it with
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your name after it.
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If at some point you no longer want to maintain some code, then please help in
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finding a new maintainer and also don't forget to update the @file{MAINTAINERS} file.
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We think our rules are not too hard. If you have comments, contact us.
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@chapter Code of conduct
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|
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Be friendly and respectful towards others and third parties.
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Treat others the way you yourself want to be treated.
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Be considerate. Not everyone shares the same viewpoint and priorities as you do.
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|
Different opinions and interpretations help the project.
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|
Looking at issues from a different perspective assists development.
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|
Do not assume malice for things that can be attributed to incompetence. Even if
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it is malice, it's rarely good to start with that as initial assumption.
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|
Stay friendly even if someone acts contrarily. Everyone has a bad day
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once in a while.
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|
If you yourself have a bad day or are angry then try to take a break and reply
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|
once you are calm and without anger if you have to.
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|
Try to help other team members and cooperate if you can.
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|
The goal of software development is to create technical excellence, not for any
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|
individual to be better and "win" against the others. Large software projects
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|
are only possible and successful through teamwork.
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|
If someone struggles do not put them down. Give them a helping hand
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|
instead and point them in the right direction.
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|
Finally, keep in mind the immortal words of Bill and Ted,
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"Be excellent to each other."
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|
@anchor{Submitting patches}
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|
@chapter Submitting patches
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|
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|
First, read the @ref{Coding Rules} above if you did not yet, in particular
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|
the rules regarding patch submission.
|
|
|
|
When you submit your patch, please use @code{git format-patch} or
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@code{git send-email}. We cannot read other diffs :-).
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|
|
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
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|
if it spans multiple files. This makes reviewing your patches much easier
|
|
for us and greatly increases your chances of getting your patch applied.
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|
Use the patcheck tool of FFmpeg to check your patch.
|
|
The tool is located in the tools directory.
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|
Run the @ref{Regression tests} before submitting a patch in order to verify
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|
it does not cause unexpected problems.
|
|
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|
It also helps quite a bit if you tell us what the patch does (for example
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|
'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
|
|
and has no lrint()')
|
|
|
|
Also please if you send several patches, send each patch as a separate mail,
|
|
do not attach several unrelated patches to the same mail.
|
|
|
|
Patches should be posted to the
|
|
@uref{https://lists.ffmpeg.org/mailman/listinfo/ffmpeg-devel, ffmpeg-devel}
|
|
mailing list. Use @code{git send-email} 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 @url{https://patchwork.ffmpeg.org}, if your patch does not show up, its mime type
|
|
likely was wrong.
|
|
|
|
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.
|
|
|
|
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.
|
|
|
|
|
|
@chapter New codecs or formats checklist
|
|
|
|
@enumerate
|
|
@item
|
|
Did you use av_cold for codec initialization and close functions?
|
|
|
|
@item
|
|
Did you add a long_name under NULL_IF_CONFIG_SMALL to the AVCodec or
|
|
AVInputFormat/AVOutputFormat struct?
|
|
|
|
@item
|
|
Did you bump the minor version number (and reset the micro version
|
|
number) in @file{libavcodec/version.h} or @file{libavformat/version.h}?
|
|
|
|
@item
|
|
Did you register it in @file{allcodecs.c} or @file{allformats.c}?
|
|
|
|
@item
|
|
Did you add the AVCodecID to @file{avcodec.h}?
|
|
When adding new codec IDs, also add an entry to the codec descriptor
|
|
list in @file{libavcodec/codec_desc.c}.
|
|
|
|
@item
|
|
If it has a FourCC, did you add it to @file{libavformat/riff.c},
|
|
even if it is only a decoder?
|
|
|
|
@item
|
|
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.
|
|
|
|
@item
|
|
Did you add an entry to the table of supported formats or codecs in
|
|
@file{doc/general.texi}?
|
|
|
|
@item
|
|
Did you add an entry in the Changelog?
|
|
|
|
@item
|
|
If it depends on a parser or a library, did you add that dependency in
|
|
configure?
|
|
|
|
@item
|
|
Did you @code{git add} the appropriate files before committing?
|
|
|
|
@item
|
|
Did you make sure it compiles standalone, i.e. with
|
|
@code{configure --disable-everything --enable-decoder=foo}
|
|
(or @code{--enable-demuxer} or whatever your component is)?
|
|
@end enumerate
|
|
|
|
|
|
@chapter Patch submission checklist
|
|
|
|
@enumerate
|
|
@item
|
|
Does @code{make fate} pass with the patch applied?
|
|
|
|
@item
|
|
Was the patch generated with git format-patch or send-email?
|
|
|
|
@item
|
|
Did you sign-off your patch? (@code{git commit -s})
|
|
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
|
|
of @dfn{sign-off}.
|
|
|
|
@item
|
|
Did you provide a clear git commit log message?
|
|
|
|
@item
|
|
Is the patch against latest FFmpeg git master branch?
|
|
|
|
@item
|
|
Are you subscribed to ffmpeg-devel?
|
|
(the list is subscribers only due to spam)
|
|
|
|
@item
|
|
Have you checked that the changes are minimal, so that the same cannot be
|
|
achieved with a smaller patch and/or simpler final code?
|
|
|
|
@item
|
|
If the change is to speed critical code, did you benchmark it?
|
|
|
|
@item
|
|
If you did any benchmarks, did you provide them in the mail?
|
|
|
|
@item
|
|
Have you checked that the patch does not introduce buffer overflows or
|
|
other security issues?
|
|
|
|
@item
|
|
Did you test your decoder or demuxer against damaged data? If no, see
|
|
tools/trasher, the noise bitstream filter, and
|
|
@uref{http://caca.zoy.org/wiki/zzuf, zzuf}. Your decoder or demuxer
|
|
should not crash, end in a (near) infinite loop, or allocate ridiculous
|
|
amounts of memory when fed damaged data.
|
|
|
|
@item
|
|
Did you test your decoder or demuxer against sample files?
|
|
Samples may be obtained at @url{https://samples.ffmpeg.org}.
|
|
|
|
@item
|
|
Does the patch not mix functional and cosmetic changes?
|
|
|
|
@item
|
|
Did you add tabs or trailing whitespace to the code? Both are forbidden.
|
|
|
|
@item
|
|
Is the patch attached to the email you send?
|
|
|
|
@item
|
|
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.
|
|
|
|
@item
|
|
If the patch fixes a bug, did you provide a verbose analysis of the bug?
|
|
|
|
@item
|
|
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 @url{https://streams.videolan.org/upload/}.
|
|
|
|
@item
|
|
Did you provide a verbose summary about what the patch does change?
|
|
|
|
@item
|
|
Did you provide a verbose explanation why it changes things like it does?
|
|
|
|
@item
|
|
Did you provide a verbose summary of the user visible advantages and
|
|
disadvantages if the patch is applied?
|
|
|
|
@item
|
|
Did you provide an example so we can verify the new feature added by the
|
|
patch easily?
|
|
|
|
@item
|
|
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.
|
|
|
|
@item
|
|
You should maintain alphabetical order in alphabetically ordered lists as
|
|
long as doing so does not break API/ABI compatibility.
|
|
|
|
@item
|
|
Lines with similar content should be aligned vertically when doing so
|
|
improves readability.
|
|
|
|
@item
|
|
Consider adding a regression test for your code.
|
|
|
|
@item
|
|
If you added YASM code please check that things still work with --disable-yasm.
|
|
|
|
@item
|
|
Make sure you check the return values of function and return appropriate
|
|
error codes. Especially memory allocation functions like @code{av_malloc()}
|
|
are notoriously left unchecked, which is a serious problem.
|
|
|
|
@item
|
|
Test your code with valgrind and or Address Sanitizer to ensure it's free
|
|
of leaks, out of array accesses, etc.
|
|
@end enumerate
|
|
|
|
@chapter Patch review process
|
|
|
|
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.
|
|
|
|
We will review all submitted patches, but sometimes we are quite busy so
|
|
especially for large patches this can take several weeks.
|
|
|
|
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.
|
|
|
|
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.
|
|
|
|
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.
|
|
|
|
@anchor{Regression tests}
|
|
@chapter Regression tests
|
|
|
|
Before submitting a patch (or committing to the repository), you should at least
|
|
test that you did not break anything.
|
|
|
|
Running 'make fate' accomplishes this, please see @url{fate.html} for details.
|
|
|
|
[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].
|
|
|
|
@section Adding files to the fate-suite dataset
|
|
|
|
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.
|
|
|
|
@section Visualizing Test Coverage
|
|
|
|
The FFmpeg build system allows visualizing the test coverage in an easy
|
|
manner with the coverage tools @code{gcov}/@code{lcov}. This involves
|
|
the following steps:
|
|
|
|
@enumerate
|
|
@item
|
|
Configure to compile with instrumentation enabled:
|
|
@code{configure --toolchain=gcov}.
|
|
|
|
@item
|
|
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.
|
|
|
|
@item
|
|
Run @code{make lcov} to generate coverage data in HTML format.
|
|
|
|
@item
|
|
View @code{lcov/index.html} in your preferred HTML viewer.
|
|
@end enumerate
|
|
|
|
You can use the command @code{make lcov-reset} to reset the coverage
|
|
measurements. You will need to rerun @code{make lcov} after running a
|
|
new test.
|
|
|
|
@section Using Valgrind
|
|
|
|
The configure script provides a shortcut for using valgrind to spot bugs
|
|
related to memory handling. Just add the option
|
|
@code{--toolchain=valgrind-memcheck} or @code{--toolchain=valgrind-massif}
|
|
to your configure line, and reasonable defaults will be set for running
|
|
FATE under the supervision of either the @strong{memcheck} or the
|
|
@strong{massif} tool of the valgrind suite.
|
|
|
|
In case you need finer control over how valgrind is invoked, use the
|
|
@code{--target-exec='valgrind <your_custom_valgrind_options>} option in
|
|
your configure line instead.
|
|
|
|
@anchor{Release process}
|
|
@chapter Release process
|
|
|
|
FFmpeg maintains a set of @strong{release branches}, which are the
|
|
recommended deliverable for system integrators and distributors (such as
|
|
Linux distributions, etc.). At regular times, a @strong{release
|
|
manager} prepares, tests and publishes tarballs on the
|
|
@url{https://ffmpeg.org} website.
|
|
|
|
There are two kinds of releases:
|
|
|
|
@enumerate
|
|
@item
|
|
@strong{Major releases} always include the latest and greatest
|
|
features and functionality.
|
|
|
|
@item
|
|
@strong{Point releases} are cut from @strong{release} branches,
|
|
which are named @code{release/X}, with @code{X} being the release
|
|
version number.
|
|
@end enumerate
|
|
|
|
Note that we promise to our users that shared libraries from any FFmpeg
|
|
release never break programs that have been @strong{compiled} against
|
|
previous versions of @strong{the same release series} in any case!
|
|
|
|
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} mailing list in time to allow forward planning.
|
|
|
|
@anchor{Criteria for Point Releases}
|
|
@section Criteria for Point Releases
|
|
|
|
Changes that match the following criteria are valid candidates for
|
|
inclusion into a point release:
|
|
|
|
@enumerate
|
|
@item
|
|
Fixes a security issue, preferably identified by a @strong{CVE
|
|
number} issued by @url{http://cve.mitre.org/}.
|
|
|
|
@item
|
|
Fixes a documented bug in @url{https://trac.ffmpeg.org}.
|
|
|
|
@item
|
|
Improves the included documentation.
|
|
|
|
@item
|
|
Retains both source code and binary compatibility with previous
|
|
point releases of the same release branch.
|
|
@end enumerate
|
|
|
|
The order for checking the rules is (1 OR 2 OR 3) AND 4.
|
|
|
|
|
|
@section Release Checklist
|
|
|
|
The release process involves the following steps:
|
|
|
|
@enumerate
|
|
@item
|
|
Ensure that the @file{RELEASE} file contains the version number for
|
|
the upcoming release.
|
|
|
|
@item
|
|
Add the release at @url{https://trac.ffmpeg.org/admin/ticket/versions}.
|
|
|
|
@item
|
|
Announce the intent to do a release to the mailing list.
|
|
|
|
@item
|
|
Make sure all relevant security fixes have been backported. See
|
|
@url{https://ffmpeg.org/security.html}.
|
|
|
|
@item
|
|
Ensure that the FATE regression suite still passes in the release
|
|
branch on at least @strong{i386} and @strong{amd64}
|
|
(cf. @ref{Regression tests}).
|
|
|
|
@item
|
|
Prepare the release tarballs in @code{bz2} and @code{gz} formats, and
|
|
supplementing files that contain @code{gpg} signatures
|
|
|
|
@item
|
|
Publish the tarballs at @url{https://ffmpeg.org/releases}. Create and
|
|
push an annotated tag in the form @code{nX}, with @code{X}
|
|
containing the version number.
|
|
|
|
@item
|
|
Propose and send a patch to the @strong{ffmpeg-devel} mailing list
|
|
with a news entry for the website.
|
|
|
|
@item
|
|
Publish the news entry.
|
|
|
|
@item
|
|
Send an announcement to the mailing list.
|
|
@end enumerate
|
|
|
|
@bye
|