[MacPorts] #74179: mkvtoolnix: Questions RE install

[MacPorts]

#74179: mkvtoolnix: Questions RE install
---------------------------+--------------------
  Reporter:  seamusdemora  |      Owner:  (none)
      Type:  defect        |     Status:  new
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:  2.12.5
Resolution:                |   Keywords:  tahoe
      Port:  mkvtoolnix    |
---------------------------+--------------------

Comment (by seamusdemora):

 Replying to [comment:3 ryandesign]:
 > Questions about MacPorts are best asked on the
 [https://lists.macports.org/mailman/listinfo/macports-users macports-users
 mailing list]. The issue tracker is for bug reports and feature requests.
 >
 >
 > Replying to [ticket:74179 seamusdemora]:
 > > 1. {{{mkvtoolnix}}} has the {{{+qtgui}}} variant. I was overwhelmed by
 the number of dependencies I'd have to install using the {{{sudo port
 install mkvtoolnix +qtgui}}} command, and so I decided to drop that
 variant from the install. Accordingly, I ran the command: {{{sudo port
 install mkvtoolnix}}}. **Surprisingly, the dependencies were the same
 (AFAICT) with or without the {{{+qtgui}}} option!!**
 > >
 > >      ''**Q1 - Can someone explain why this is??**''
 >
 > As shown in the output of `port variants mkvtoolnix` (the `[+]` before
 `qtqui`), the qtgui variant is enabled by default. If you want to install
 without that variant, you have to disable it explicitly:
 >
 > {{{
 > sudo port install mkvtoolnix -qtgui
 > }}}

 OK, thanks - my bad... I've learned what this line in the documentation
 (https://guide.macports.org/#using.variants) actually means:
 {{{
 Variant lines that have a + are enabled and those with - are disabled.
 }}}
 I've been confused about that - I understood that all variants had to be
 specified at install time... silly me.


 > > 2.  I've been using {{{ffmpeg ver 7}}} for some time as I like to be
 ''"fairly current"'', but not ''"bleeding edge"''. I am also using
 {{{ffmpeg ver 7}}} in a few shell scripts I've created for processing
 video & audio files. However, installation of {{{mkvtoolnix}}} included
 {{{ffmpeg ver 8}}} as a dependency. I've tested my scripts, and run
 {{{ffmpeg ver 7}}} from the CLI --- it seems that {{{ffmpeg7}}} is "alive
 and well" on my system - so far.
 > >
 > >      **However:** In the "post install" instructions for
 {{{mkvtoolnix}}}, there is this statement that frankly baffles me
 completely:
 > >
 > > {{{
 > >      To compile and link with ffmpeg8, add
 -I/opt/local/libexec/ffmpeg8/include and -L/opt/local/libexec/ffmpeg8/lib
 to your compile command.
 > >      For builds using pkg-config, add
 /opt/local/libexec/ffmpeg8/lib/pkgconfig to $PKG_CONFIG_PATH.
 > > }}}
 > >
 > >      ''**Q2.1 - WRT {{{To compile and link with ffmpeg8 ...}}}:**''
 AFAICS, {{{mkvtoolnix}}} ''**has already been compiled**'', and that being
 the case, **how am I to compile it again**?!?!
 > >
 > >      ''**Q2.2 - WRT {{{For builds using pkg-config ...}}}:**'' How do
 I tell if I am using {{{pkg-config}}} or not?? The documentation says this
 re {{{pkg-config}}}:
 > >
 > > {{{
 > >      Default: ???
 > > }}}
 >
 > You can ignore these notes. They are printed by the ffmpeg8 port and are
 intended to help those people who are trying to compile their own
 software, outside of MacPorts, using ffmpeg8. Any ports that use ffmpeg8
 are already using the correct method internally.
 >
 >
 > >      ''**Q2.3 - Will {{{mkvtoolnix}}} "fall back" to {{{ffmpeg ver
 7}}} if {{{ffmpeg8}}} is NOT compiled and linked with
 {{{mkvtoolnix}}}??**''
 >
 > As far as I can tell, the mkvtoolnix port does not use any version of
 ffmpeg. I can find no occurrences of "ffmpeg" in the [source:macports-
 ports/multimedia/mkvtoolnix/Portfile mkvtoolnix Portfile].

 Hmm... well, according to this command:

 {{{
 % sudo port install mkvtoolnix +qtgui
 --->  Upgrading already installed dependencies of mkvtoolnix
 --->  Computing dependencies for mkvtoolnix
 The following dependencies will be installed:
 ...
 ffmpeg8 +gpl2+vmaf
 ...
 %
 }}}

 Does that line mean something different than what it says - or am I
 reading it incorrectly??


 > Ports that use ffmpeg8, or in general ports that depend on any port,
 always use that port, unless the port author has offered variants to let
 you change that. For an example of a port that lets you choose the ffmpeg
 version using variants, take a look at the output of `port variants
 opencv`. Most ports won't offer you that choice, and in general it's not
 our intention to offer such choice just because such a choice would be
 possible to offer. Offering such choice gives more opportunities for
 things to go wrong, which results in more tech support burden for us.

 Right...

-- 
Ticket URL: <https://trac.macports.org/ticket/74179#comment:4>
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