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4 @settitle Using Git to develop FFmpeg
7 @center @titlefont{Using Git to develop FFmpeg}
16 This document aims in giving some quick references on a set of useful Git
17 commands. You should always use the extensive and detailed documentation
18 provided directly by Git:
25 shows you the available subcommands,
32 shows information about the subcommand <command>.
34 Additional information could be found on the
35 @url{http://gitref.org, Git Reference} website.
37 For more information about the Git project, visit the
38 @url{http://git-scm.com/, Git website}.
40 Consult these resources whenever you have problems, they are quite exhaustive.
42 What follows now is a basic introduction to Git and some FFmpeg-specific
43 guidelines to ease the contribution to the project.
49 You can get Git from @url{http://git-scm.com/}
50 Most distribution and operating system provide a package for it.
53 @section Cloning the source tree
56 git clone git://source.ffmpeg.org/ffmpeg <target>
59 This will put the FFmpeg sources into the directory @var{<target>}.
62 git clone git@@source.ffmpeg.org:ffmpeg <target>
65 This will put the FFmpeg sources into the directory @var{<target>} and let
66 you push back your changes to the remote repository.
68 Make sure that you do not have Windows line endings in your checkouts,
69 otherwise you may experience spurious compilation failures. One way to
70 achieve this is to run
73 git config --global core.autocrlf false
77 @anchor{Updating the source tree to the latest revision}
78 @section Updating the source tree to the latest revision
84 pulls in the latest changes from the tracked branch. The tracked branch
85 can be remote. By default the master branch tracks the branch master in
89 @command{--rebase} (see below) is recommended.
92 @section Rebasing your local branches
98 fetches the changes from the main repository and replays your local commits
99 over it. This is required to keep all your local changes at the top of
100 FFmpeg's master tree. The master tree will reject pushes with merge commits.
103 @section Adding/removing files/directories
106 git add [-A] <filename/dirname>
107 git rm [-r] <filename/dirname>
110 Git needs to get notified of all changes you make to your working
111 directory that makes files appear or disappear.
112 Line moves across files are automatically tracked.
115 @section Showing modifications
118 git diff <filename(s)>
121 will show all local modifications in your working directory as unified diff.
124 @section Inspecting the changelog
127 git log <filename(s)>
130 You may also use the graphical tools like @command{gitview} or @command{gitk}
131 or the web interface available at @url{http://source.ffmpeg.org/}.
133 @section Checking source tree status
139 detects all the changes you made and lists what actions will be taken in case
140 of a commit (additions, modifications, deletions, etc.).
149 to double check your changes before committing them to avoid trouble later
150 on. All experienced developers do this on each and every commit, no matter
153 Every one of them has been saved from looking like a fool by this many times.
154 It's very easy for stray debug output or cosmetic modifications to slip in,
155 please avoid problems through this extra level of scrutiny.
157 For cosmetics-only commits you should get (almost) empty output from
160 git diff -w -b <filename(s)>
163 Also check the output of
169 to make sure you don't have untracked files or deletions.
172 git add [-i|-p|-A] <filenames/dirnames>
175 Make sure you have told Git your name and email address
178 git config --global user.name "My Name"
179 git config --global user.email my@@email.invalid
182 Use @option{--global} to set the global configuration for all your Git checkouts.
184 Git will select the changes to the files for commit. Optionally you can use
185 the interactive or the patch mode to select hunk by hunk what should be
193 Git will commit the selected changes to your current local branch.
195 You will be prompted for a log message in an editor, which is either
196 set in your personal configuration file through
199 git config --global core.editor
202 or set by one of the following environment variables:
203 @var{GIT_EDITOR}, @var{VISUAL} or @var{EDITOR}.
205 Log messages should be concise but descriptive. Explain why you made a change,
206 what you did will be obvious from the changes themselves most of the time.
207 Saying just "bug fix" or "10l" is bad. Remember that people of varying skill
208 levels look at and educate themselves while reading through your code. Don't
209 include filenames in log messages, Git provides that information.
211 Possibly make the commit message have a terse, descriptive first line, an
212 empty line and then a full description. The first line will be used to name
213 the patch by @command{git format-patch}.
215 @section Preparing a patchset
218 git format-patch <commit> [-o directory]
221 will generate a set of patches for each commit between @var{<commit>} and
222 current @var{HEAD}. E.g.
225 git format-patch origin/master
228 will generate patches for all commits on current branch which are not
230 A useful shortcut is also
236 which will generate patches from last @var{n} commits.
237 By default the patches are created in the current directory.
239 @section Sending patches for review
242 git send-email <commit list|directory>
245 will send the patches created by @command{git format-patch} or directly
246 generates them. All the email fields can be configured in the global/local
247 configuration or overridden by command line.
248 Note that this tool must often be installed separately (e.g. @var{git-email}
249 package on Debian-based distros).
252 @section Renaming/moving/copying files or contents of files
254 Git automatically tracks such changes, making those normal commits.
257 mv/cp path/file otherpath/otherfile
263 @chapter Git configuration
265 In order to simplify a few workflows, it is advisable to configure both
266 your personal Git installation and your local FFmpeg repository.
268 @section Personal Git installation
270 Add the following to your @file{~/.gitconfig} to help @command{git send-email}
271 and @command{git format-patch} detect renames:
278 @section Repository configuration
280 In order to have @command{git send-email} automatically send patches
281 to the ffmpeg-devel mailing list, add the following stanza
282 to @file{/path/to/ffmpeg/repository/.git/config}:
286 to = ffmpeg-devel@@ffmpeg.org
289 @chapter FFmpeg specific
291 @section Reverting broken commits
297 @command{git reset} will uncommit the changes till @var{<commit>} rewriting
298 the current branch history.
304 allows one to amend the last commit details quickly.
307 git rebase -i origin/master
310 will replay local commits over the main repository allowing to edit, merge
311 or remove some of them in the process.
314 @command{git reset}, @command{git commit --amend} and @command{git rebase}
315 rewrite history, so you should use them ONLY on your local or topic branches.
316 The main repository will reject those changes.
323 @command{git revert} will generate a revert commit. This will not make the
324 faulty commit disappear from the history.
326 @section Pushing changes to remote trees
329 git push origin master --dry-run
332 Will simulate a push of the local master branch to the default remote
333 (@var{origin}). And list which branches and ranges or commits would have been
335 Git will prevent you from pushing changes if the local and remote trees are
336 out of sync. Refer to @ref{Updating the source tree to the latest revision}.
339 git remote add <name> <url>
342 Will add additional remote with a name reference, it is useful if you want
343 to push your local branch for review on a remote host.
346 git push <remote> <refspec>
349 Will push the changes to the @var{<remote>} repository.
350 Omitting @var{<refspec>} makes @command{git push} update all the remote
351 branches matching the local ones.
353 @section Finding a specific svn revision
355 Since version 1.7.1 Git supports @samp{:/foo} syntax for specifying commits
356 based on a regular expression. see man gitrevisions
359 git show :/'as revision 23456'
362 will show the svn changeset @samp{r23456}. With older Git versions searching in
363 the @command{git log} output is the easiest option (especially if a pager with
364 search capabilities is used).
366 This commit can be checked out with
369 git checkout -b svn_23456 :/'as revision 23456'
372 or for Git < 1.7.1 with
375 git checkout -b svn_23456 $SHA1
378 where @var{$SHA1} is the commit hash from the @command{git log} output.
381 @chapter Pre-push checklist
383 Once you have a set of commits that you feel are ready for pushing,
384 work through the following checklist to doublecheck everything is in
385 proper order. This list tries to be exhaustive. In case you are just
386 pushing a typo in a comment, some of the steps may be unnecessary.
387 Apply your common sense, but if in doubt, err on the side of caution.
389 First, make sure that the commits and branches you are going to push
390 match what you want pushed and that nothing is missing, extraneous or
391 wrong. You can see what will be pushed by running the git push command
392 with @option{--dry-run} first. And then inspecting the commits listed with
393 @command{git log -p 1234567..987654}. The @command{git status} command
394 may help in finding local changes that have been forgotten to be added.
396 Next let the code pass through a full run of our testsuite.
399 @item @command{make distclean}
400 @item @command{/path/to/ffmpeg/configure}
401 @item @command{make fate}
402 @item if fate fails due to missing samples run @command{make fate-rsync} and retry
405 Make sure all your changes have been checked before pushing them, the
406 testsuite only checks against regressions and that only to some extend. It does
407 obviously not check newly added features/code to be working unless you have
408 added a test for that (which is recommended).
410 Also note that every single commit should pass the test suite, not just
411 the result of a series of patches.
413 Once everything passed, push the changes to your public ffmpeg clone and post a
414 merge request to ffmpeg-devel. You can also push them directly but this is not
417 @chapter Server Issues
419 Contact the project admins at @email{root@@ffmpeg.org} if you have technical
420 problems with the Git server.