chaza@Mars ~ $ sudo emerge -av --depclean

*** WARNING ***  Depclean may break link level dependencies.  Thus, it is
*** WARNING ***  recommended to use a tool such as `revdep-rebuild` (from
*** WARNING ***  app-portage/gentoolkit) in order to detect such breakage.
*** WARNING ***
*** WARNING ***  Also study the list of packages to be cleaned for any obvious
*** WARNING ***  mistakes. Packages that are part of the world set will always
*** WARNING ***  be kept.  They can be manually added to this set with
*** WARNING ***  `emerge --noreplace <atom>`.
*** WARNING ***
*** WARNING ***  As a safety measure, depclean will not remove any packages
*** WARNING ***  unless *all* required dependencies have been resolved.  As a
*** WARNING ***  consequence, it is often necessary to run
*** WARNING ***  `emerge --update --deep world` prior to depclean.

Calculating dependencies       ... done!

Dependencies could not be completely resolved due to
the following required packages not being installed:

>=media-libs/x264-svn-20061014 required by media-libs/libquicktime-0.9.9-r1

Have you forgotten to run `emerge --update --deep world` prior to depclean?


chaza@Mars ~ $ sudo emerge -tavuD world

These are the packages that would be merged, in reverse order:

Calculating world dependencies  I
!!! Ebuilds for the following packages are either all
!!! masked or don't exist:
www-apps/phpBB app-cdr/simplecdrx
                                                                                                                                                           ... done!

Total size of downloads: 0 kB

Nothing to merge; would you like to auto-clean packages? [Yes/No]

Exiting on signal 2