On Friday 15 May 2015 18:30:29 Alexander Kapshuk wrote:
> On Fri, May 15, 2015 at 9:04 AM, Gevisz <gevisz@gmail.com> wrote:
> > On Fri, 15 May 2015 01:45:35 -0400 Gregory Woodbury <redwolfe@gmail.com>
> > 
> > wrote:
> > > I had a similar problem with some packages wanting virtual/ffmpeg  and
> > > it wouldn't take the -libav USE flag without adding a keyword for
> > > ~amd64 on the virtual.
> > > (yes, I am going the opposite way from you, but the cause seem the
> > > same -- various USE flags are not yet adjusted in the stable
> > > branches.)
> > > 
> > > Perhaps we need to request "stabilization" for some of the newer
> > > packages to solve this.
> > 
> > Thank you for confirming that libav USE flag do not work not only for me.
> > 
> > However, it would be interesting to hear what the Gentoo devs think about
> > this issue.
> 
> Portage news item No 19 has the answer you're looking for.
> 
> > eselect news read 19
> > 2015-04-16-ffmpeg-default
> > 
> >   Title                     FFmpeg default
> >   Author                    Ben de Groot <yngwin@gentoo.org>
> >   Posted                    2015-04-16
> >   Revision                  1
> > 
> > Since the choice between ffmpeg and libav has been made more
> > explicit, there has been a lot of discussion about what the
> > default implementation should be. It can be concluded that
> > media-video/ffmpeg has wider support, and would be somewhat
> > more convenient for most end-users.
> > 
> > For this reason the default implementation has been switched
> > back from media-video/libav to media-video/ffmpeg by removing
> > the libav useflag from the base profile.
> > 
> > If the libav useflag is already globally enabled or disabled
> > in /etc/portage/make.conf, then no further action is required.
> > 
> > Users who implicitly relied on libav being enabled in their
> > profile, and who wish to continue using libav, should enable
> > USE=libav in their /etc/portage/make.conf file.

No, this is not yet 100% true, or at least not true for some packages, which 
are also pulling in abi_x86_32 versions.

I came across this problem something like a week ago on a PC with no ffmpeg or 
libav USE flags.  I tried setting USE="-libav" and also +ffmpeg, but couldn't 
fix the blockers.  Eventually, I uninstalled the hard blockers like 'media-
libs/libpostproc' and then rebuilt any packages already installed which were 
causing portage to complain/want libav.  Can't recall fully which packages 
these were, k3b springs to mind.

There may be a more scientific way of resolving the conflict, but that's how I 
got around this problem.

HTH.
-- 
Regards,
Mick