\input texinfo @c -*- texinfo -*-
 

 @settitle Using git to develop FFmpeg

 
 @titlepage

 @center @titlefont{Using git to develop FFmpeg}

 @end titlepage
 
 @top
 
 @contents
 
 @chapter Introduction
 
 This document aims in giving some quick references on a set of useful git
 commands. You should always use the extensive and detailed documentation
 provided directly by git:
 
 @example
 git --help
 man git
 @end example
 
 shows you the available subcommands,
 
 @example
 git <command> --help
 man git-<command>
 @end example
 
 shows information about the subcommand <command>.
 
 Additional information could be found on the
 @url{http://gitref.org, Git Reference} website
 
 For more information about the Git project, visit the
 
 @url{http://git-scm.com/, Git website}
 
 Consult these resources whenever you have problems, they are quite exhaustive.
 

 What follows now is a basic introduction to Git and some FFmpeg-specific

 guidelines to ease the contribution to the project
 
 @chapter Basics Usage
 
 @section Get GIT
 
 You can get git from @url{http://git-scm.com/}
 Most distribution and operating system provide a package for it.
 
 
 @section Cloning the source tree
 
 @example

 git clone git://source.ffmpeg.org/ffmpeg <target>

 @end example
 

 This will put the FFmpeg sources into the directory @var{<target>}.

 
 @example

 git clone git@@source.ffmpeg.org:ffmpeg <target>

 @end example
 

 This will put the FFmpeg sources into the directory @var{<target>} and let

 you push back your changes to the remote repository.
 

 Make sure that you do not have Windows line endings in your checkouts,
 otherwise you may experience spurious compilation failures. One way to
 achieve this is to run
 
 @example
 git config --global core.autocrlf false
 @end example
 

 
 @section Updating the source tree to the latest revision
 
 @example
 git pull (--rebase)
 @end example
 
 pulls in the latest changes from the tracked branch. The tracked branch
 can be remote. By default the master branch tracks the branch master in
 the remote origin.
 
 @float IMPORTANT

 @command{--rebase} (see below) is recommended.

 @end float
 
 @section Rebasing your local branches
 
 @example
 git pull --rebase
 @end example
 
 fetches the changes from the main repository and replays your local commits
 over it. This is required to keep all your local changes at the top of

 FFmpeg's master tree. The master tree will reject pushes with merge commits.

 
 
 @section Adding/removing files/directories
 
 @example
 git add [-A] <filename/dirname>
 git rm [-r] <filename/dirname>
 @end example
 
 GIT needs to get notified of all changes you make to your working
 directory that makes files appear or disappear.
 Line moves across files are automatically tracked.
 
 
 @section Showing modifications
 
 @example
 git diff <filename(s)>
 @end example
 
 will show all local modifications in your working directory as unified diff.
 
 
 @section Inspecting the changelog
 
 @example
 git log <filename(s)>
 @end example
 
 You may also use the graphical tools like gitview or gitk or the web

 interface available at http://source.ffmpeg.org/

 
 @section Checking source tree status
 
 @example
 git status
 @end example
 
 detects all the changes you made and lists what actions will be taken in case
 of a commit (additions, modifications, deletions, etc.).
 
 
 @section Committing
 
 @example
 git diff --check
 @end example
 
 to double check your changes before committing them to avoid trouble later
 on. All experienced developers do this on each and every commit, no matter
 how small.
 Every one of them has been saved from looking like a fool by this many times.
 It's very easy for stray debug output or cosmetic modifications to slip in,
 please avoid problems through this extra level of scrutiny.
 
 For cosmetics-only commits you should get (almost) empty output from
 
 @example
 git diff -w -b <filename(s)>
 @end example
 
 Also check the output of
 
 @example
 git status
 @end example
 
 to make sure you don't have untracked files or deletions.
 
 @example
 git add [-i|-p|-A] <filenames/dirnames>
 @end example
 
 Make sure you have told git your name and email address
 
 @example
 git config --global user.name "My Name"
 git config --global user.email my@@email.invalid
 @end example
 
 Use @var{--global} to set the global configuration for all your git checkouts.
 
 Git will select the changes to the files for commit. Optionally you can use
 the interactive or the patch mode to select hunk by hunk what should be
 added to the commit.
 
 
 @example
 git commit
 @end example
 
 Git will commit the selected changes to your current local branch.
 
 You will be prompted for a log message in an editor, which is either
 set in your personal configuration file through
 
 @example
 git config --global core.editor
 @end example
 
 or set by one of the following environment variables:
 @var{GIT_EDITOR}, @var{VISUAL} or @var{EDITOR}.
 
 Log messages should be concise but descriptive. Explain why you made a change,
 what you did will be obvious from the changes themselves most of the time.
 Saying just "bug fix" or "10l" is bad. Remember that people of varying skill
 levels look at and educate themselves while reading through your code. Don't
 include filenames in log messages, Git provides that information.
 
 Possibly make the commit message have a terse, descriptive first line, an
 empty line and then a full description. The first line will be used to name
 the patch by git format-patch.
 
 @section Preparing a patchset
 
 @example
 git format-patch <commit> [-o directory]
 @end example
 
 will generate a set of patches for each commit between @var{<commit>} and
 current @var{HEAD}. E.g.
 
 @example
 git format-patch origin/master
 @end example
 
 will generate patches for all commits on current branch which are not
 present in upstream.
 A useful shortcut is also
 
 @example
 git format-patch -n
 @end example
 
 which will generate patches from last @var{n} commits.
 By default the patches are created in the current directory.
 
 @section Sending patches for review
 
 @example
 git send-email <commit list|directory>
 @end example
 
 will send the patches created by @command{git format-patch} or directly
 generates them. All the email fields can be configured in the global/local
 configuration or overridden by command line.
 Note that this tool must often be installed separately (e.g. @var{git-email}
 package on Debian-based distros).
 
 
 @section Renaming/moving/copying files or contents of files
 
 Git automatically tracks such changes, making those normal commits.
 
 @example
 mv/cp path/file otherpath/otherfile
 git add [-A] .
 git commit
 @end example
 
 

 @chapter Git configuration
 
 In order to simplify a few workflows, it is advisable to configure both

 your personal Git installation and your local FFmpeg repository.

 
 @section Personal Git installation
 
 Add the following to your @file{~/.gitconfig} to help @command{git send-email}
 and @command{git format-patch} detect renames:
 
 @example
 [diff]
         renames = copy
 @end example
 
 @section Repository configuration
 
 In order to have @command{git send-email} automatically send patches

 to the ffmpeg-devel mailing list, add the following stanza
 to @file{/path/to/ffmpeg/repository/.git/config}:

 
 @example
 [sendemail]

         to = ffmpeg-devel@@ffmpeg.org

 @end example
 

 @chapter FFmpeg specific

 
 @section Reverting broken commits
 
 @example
 git reset <commit>
 @end example
 
 @command{git reset} will uncommit the changes till @var{<commit>} rewriting
 the current branch history.
 
 @example
 git commit --amend
 @end example
 
 allows to amend the last commit details quickly.
 
 @example
 git rebase -i origin/master
 @end example
 
 will replay local commits over the main repository allowing to edit, merge
 or remove some of them in the process.
 
 @float NOTE
 @command{git reset}, @command{git commit --amend} and @command{git rebase}
 rewrite history, so you should use them ONLY on your local or topic branches.
 The main repository will reject those changes.
 @end float
 
 @example
 git revert <commit>
 @end example
 
 @command{git revert} will generate a revert commit. This will not make the
 faulty commit disappear from the history.
 
 @section Pushing changes to remote trees
 
 @example
 git push
 @end example
 
 Will push the changes to the default remote (@var{origin}).
 Git will prevent you from pushing changes if the local and remote trees are
 out of sync. Refer to and to sync the local tree.
 
 @example
 git remote add <name> <url>
 @end example
 
 Will add additional remote with a name reference, it is useful if you want
 to push your local branch for review on a remote host.
 
 @example
 git push <remote> <refspec>
 @end example
 
 Will push the changes to the @var{<remote>} repository.
 Omitting @var{<refspec>} makes @command{git push} update all the remote
 branches matching the local ones.
 
 @section Finding a specific svn revision
 
 Since version 1.7.1 git supports @var{:/foo} syntax for specifying commits
 based on a regular expression. see man gitrevisions
 
 @example
 git show :/'as revision 23456'
 @end example
 
 will show the svn changeset @var{r23456}. With older git versions searching in
 the @command{git log} output is the easiest option (especially if a pager with
 search capabilities is used).
 This commit can be checked out with
 
 @example
 git checkout -b svn_23456 :/'as revision 23456'
 @end example
 
 or for git < 1.7.1 with
 
 @example
 git checkout -b svn_23456 $SHA1
 @end example
 
 where @var{$SHA1} is the commit hash from the @command{git log} output.
 

 
 @chapter pre-push checklist
 
 Once you have a set of commits that you feel are ready for pushing,
 work through the following checklist to doublecheck everything is in
 proper order. This list tries to be exhaustive. In case you are just
 pushing a typo in a comment, some of the steps may be unnecessary.
 Apply your common sense, but if in doubt, err on the side of caution.
 

 First, make sure that the commits and branches you are going to push
 match what you want pushed and that nothing is missing, extraneous or
 wrong. You can see what will be pushed by running the git push command
 with --dry-run first. And then inspecting the commits listed with

 @command{git log -p 1234567..987654}. The @command{git status} command

 may help in finding local changes that have been forgotten to be added.

 Next let the code pass through a full run of our testsuite.

 
 @itemize
 @item @command{make distclean}

 @item @command{/path/to/ffmpeg/configure}

 @item @command{make check}

 @item if fate fails due to missing samples run @command{make fate-rsync} and retry

 @end itemize
 

 Make sure all your changes have been checked before pushing them, the
 testsuite only checks against regressions and that only to some extend. It does
 obviously not check newly added features/code to be working unless you have

 added a test for that (which is recommended).

 
 Also note that every single commit should pass the test suite, not just

 the result of a series of patches.

 Once everything passed, push the changes to your public ffmpeg clone and post a
 merge request to ffmpeg-devel. You can also push them directly but this is not
 recommended.

 @chapter Server Issues
 

 Contact the project admins @email{root@@ffmpeg.org} if you have technical

 problems with the GIT server.