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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
39 @url{http://git-scm.com/, Git website}
41 Consult these resources whenever you have problems, they are quite exhaustive.
43 What follows now is a basic introduction to Git and some FFmpeg-specific
44 guidelines to ease the contribution to the project
50 You can get git from @url{http://git-scm.com/}
51 Most distribution and operating system provide a package for it.
54 @section Cloning the source tree
57 git clone git://source.ffmpeg.org/ffmpeg <target>
60 This will put the FFmpeg sources into the directory @var{<target>}.
63 git clone git@@source.ffmpeg.org:ffmpeg <target>
66 This will put the FFmpeg sources into the directory @var{<target>} and let
67 you push back your changes to the remote repository.
69 Make sure that you do not have Windows line endings in your checkouts,
70 otherwise you may experience spurious compilation failures. One way to
71 achieve this is to run
74 git config --global core.autocrlf false
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 gitview or gitk or the web
131 interface available at 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
152 Every one of them has been saved from looking like a fool by this many times.
153 It's very easy for stray debug output or cosmetic modifications to slip in,
154 please avoid problems through this extra level of scrutiny.
156 For cosmetics-only commits you should get (almost) empty output from
159 git diff -w -b <filename(s)>
162 Also check the output of
168 to make sure you don't have untracked files or deletions.
171 git add [-i|-p|-A] <filenames/dirnames>
174 Make sure you have told git your name and email address
177 git config --global user.name "My Name"
178 git config --global user.email my@@email.invalid
181 Use @var{--global} to set the global configuration for all your git checkouts.
183 Git will select the changes to the files for commit. Optionally you can use
184 the interactive or the patch mode to select hunk by hunk what should be
192 Git will commit the selected changes to your current local branch.
194 You will be prompted for a log message in an editor, which is either
195 set in your personal configuration file through
198 git config --global core.editor
201 or set by one of the following environment variables:
202 @var{GIT_EDITOR}, @var{VISUAL} or @var{EDITOR}.
204 Log messages should be concise but descriptive. Explain why you made a change,
205 what you did will be obvious from the changes themselves most of the time.
206 Saying just "bug fix" or "10l" is bad. Remember that people of varying skill
207 levels look at and educate themselves while reading through your code. Don't
208 include filenames in log messages, Git provides that information.
210 Possibly make the commit message have a terse, descriptive first line, an
211 empty line and then a full description. The first line will be used to name
212 the patch by git format-patch.
214 @section Preparing a patchset
217 git format-patch <commit> [-o directory]
220 will generate a set of patches for each commit between @var{<commit>} and
221 current @var{HEAD}. E.g.
224 git format-patch origin/master
227 will generate patches for all commits on current branch which are not
229 A useful shortcut is also
235 which will generate patches from last @var{n} commits.
236 By default the patches are created in the current directory.
238 @section Sending patches for review
241 git send-email <commit list|directory>
244 will send the patches created by @command{git format-patch} or directly
245 generates them. All the email fields can be configured in the global/local
246 configuration or overridden by command line.
247 Note that this tool must often be installed separately (e.g. @var{git-email}
248 package on Debian-based distros).
251 @section Renaming/moving/copying files or contents of files
253 Git automatically tracks such changes, making those normal commits.
256 mv/cp path/file otherpath/otherfile
262 @chapter Git configuration
264 In order to simplify a few workflows, it is advisable to configure both
265 your personal Git installation and your local FFmpeg repository.
267 @section Personal Git installation
269 Add the following to your @file{~/.gitconfig} to help @command{git send-email}
270 and @command{git format-patch} detect renames:
277 @section Repository configuration
279 In order to have @command{git send-email} automatically send patches
280 to the ffmpeg-devel mailing list, add the following stanza
281 to @file{/path/to/ffmpeg/repository/.git/config}:
285 to = ffmpeg-devel@@ffmpeg.org
288 @chapter FFmpeg specific
290 @section Reverting broken commits
296 @command{git reset} will uncommit the changes till @var{<commit>} rewriting
297 the current branch history.
303 allows one to amend the last commit details quickly.
306 git rebase -i origin/master
309 will replay local commits over the main repository allowing to edit, merge
310 or remove some of them in the process.
313 @command{git reset}, @command{git commit --amend} and @command{git rebase}
314 rewrite history, so you should use them ONLY on your local or topic branches.
315 The main repository will reject those changes.
322 @command{git revert} will generate a revert commit. This will not make the
323 faulty commit disappear from the history.
325 @section Pushing changes to remote trees
331 Will push the changes to the default remote (@var{origin}).
332 Git will prevent you from pushing changes if the local and remote trees are
333 out of sync. Refer to and to sync the local tree.
336 git remote add <name> <url>
339 Will add additional remote with a name reference, it is useful if you want
340 to push your local branch for review on a remote host.
343 git push <remote> <refspec>
346 Will push the changes to the @var{<remote>} repository.
347 Omitting @var{<refspec>} makes @command{git push} update all the remote
348 branches matching the local ones.
350 @section Finding a specific svn revision
352 Since version 1.7.1 git supports @var{:/foo} syntax for specifying commits
353 based on a regular expression. see man gitrevisions
356 git show :/'as revision 23456'
359 will show the svn changeset @var{r23456}. With older git versions searching in
360 the @command{git log} output is the easiest option (especially if a pager with
361 search capabilities is used).
362 This commit can be checked out with
365 git checkout -b svn_23456 :/'as revision 23456'
368 or for git < 1.7.1 with
371 git checkout -b svn_23456 $SHA1
374 where @var{$SHA1} is the commit hash from the @command{git log} output.
377 @chapter pre-push checklist
379 Once you have a set of commits that you feel are ready for pushing,
380 work through the following checklist to doublecheck everything is in
381 proper order. This list tries to be exhaustive. In case you are just
382 pushing a typo in a comment, some of the steps may be unnecessary.
383 Apply your common sense, but if in doubt, err on the side of caution.
385 First, make sure that the commits and branches you are going to push
386 match what you want pushed and that nothing is missing, extraneous or
387 wrong. You can see what will be pushed by running the git push command
388 with --dry-run first. And then inspecting the commits listed with
389 @command{git log -p 1234567..987654}. The @command{git status} command
390 may help in finding local changes that have been forgotten to be added.
392 Next let the code pass through a full run of our testsuite.
395 @item @command{make distclean}
396 @item @command{/path/to/ffmpeg/configure}
397 @item @command{make check}
398 @item if fate fails due to missing samples run @command{make fate-rsync} and retry
401 Make sure all your changes have been checked before pushing them, the
402 testsuite only checks against regressions and that only to some extend. It does
403 obviously not check newly added features/code to be working unless you have
404 added a test for that (which is recommended).
406 Also note that every single commit should pass the test suite, not just
407 the result of a series of patches.
409 Once everything passed, push the changes to your public ffmpeg clone and post a
410 merge request to ffmpeg-devel. You can also push them directly but this is not
413 @chapter Server Issues
415 Contact the project admins @email{root@@ffmpeg.org} if you have technical
416 problems with the GIT server.