On Wed, 2007-10-10 at 07:55 -0600, Steve Dibb wrote:
> Mart Raudsepp wrote:
> > On T, 2007-10-09 at 21:03 -0600, Steve Dibb wrote:
> >> The little lame use flag has started showing up more in local use flags, 
> >> and all for the same purpose, MP3 support using LAME libraries.  I vote 
> >> we move it into a global use flag.  Any objections, let me know.
> >>
> >> $ quse -D lame
> >>   local:lame:media-libs/libquicktime: Support LAME mp3 encoding
> >>   local:lame:media-libs/mlt: Support LAME mp3 encoding
> >>   local:lame:media-sound/abcde: Support LAME mp3 encoding
> >>   local:lame:media-sound/gnusound: Enable lame support
> >>   local:lame:media-video/mpeg4ip: Support LAME mp3 encoding in the 
> >> server/mp4live
> > 
> > Any reason to not use something like mp3enc flag instead at that point?
> > mp3 USE flag is already global, and appears to mean mp3 decoding, so how
> > about a general mp3 encoding USE flag? I guess merging decoding and
> > encoding behind the same USE flag might be an option too.
> > 
> 
> Ah, I knew this question was gonna come up, should have addresed it 
> first time around.
> 
> The reason we have mp3 and lame use flag is because there is more than 
> one mp3 encoder.  In almost every case of the use flag being applied 
> above, there is already support for another mp3 codec (ffmpeg).  So, 
> lame adds support for lame, not for mp3, which is also provided.
> 
> When there is just one mp3 codec used in an ebuild, then it makes sense 
> to use just the mp3 use flag.

Actually, the encode USE flag makes more sense, if encoding support is
optional.

Basically, it should be like so:

A is a mp3 program/library, which can do both encoding and decoding.  It
doesn't use USE=mp3, at all, since it is solely an mp3 program.
Encoding support is enabled via USE=encode.

B is a media program/library, which can do both encoding and decoding
for multiple formats.  It would use USE=mp3 to enable mp3 support.  It
would use USE=encode (with mp3 support enabled) to enable mp3 encoding
support.

C is an encoder for multiple formats.  It uses USE=mp3 for enabling mp3
encoding.

D is an encoder for mp3.  It uses no USE flags, since it is always a mp3
encoder.

I'm sure I missed other cases, but you get the point.

-- 
Chris Gianelloni
Release Engineering Strategic Lead
Alpha/AMD64/x86 Architecture Teams
Games Developer/Foundation Trustee
Gentoo Foundation