[Swfdec] [PATCH] Fix logic in ffmpeg detection

[Pavel Roskin]

Hello!

On Thu, 2007-10-25 at 23:07 +0200, Benjamin Otte wrote:
> Hi,
> 
> On 10/25/07, Pavel Roskin <proski at gnu.org> wrote:
> > If neither --enable-ffmpeg nor --disable-ffmpeg was given, try to find
> > ffmpeg.  If it wasn't found, print the warning, but don't fail.
> >
> I've had had some discussions about automagic dependencies back in the
> days with Mikel, and came to the conclusion that automagic is not a
> good thing to do. A part of that (I think the non-relevant part) is in
> bug 10333, I'll try to remember the important part:
> The problem is that when you forget to install a dependency that you
> would want to have, you will not notice (configure output is way too
> noisy) unless configure aborts.

Once possible solution would be to show the warning at the configure
output and make it very visible.

> This is why I decided to provide
> default settings and enforce them unless they were overwritten via
> configure. To be more exact, configure uses the suggested settings for
> distributors while autogen.sh uses the suggested settings for
> developers or people running through git.

Distributors may be reluctant to use non-default options other than
--prefix and similar stuff.  And that may be the reason why gnash is
more popular with the distributions.  This is a shame, since swfdec
seems to be more stable at the moment, at least for the casual end-user
stuff (youtube, newgrounds.com etc).

> So that's why I don't think that we should use automagic when
> detecting audio backends. I'll also disable it for audio, when I
> switch over to something more portable than alsa, like pulse. It's set
> to automagic currently only to not annoy non-linux users.
> 
> > If --enable-ffmpeg was given, fail if ffmpeg is not found.  If
> > --disable-ffmpeg was given, don't print the warning, as the user already
> > knows that ffmpeg won't be enabled.
> >
> That probably makes sense.

Too bad it's the least important part of the patch :)

> > It's important that ffmpeg is not viewed as a hard requirement, as it's
> > absent in most distros due to patent problems.
> >
> Yeah, we should disable mad and ffmpeg by default. They provide
> advantages to developers when debugging (like not spawning multiple
> threads), but users shouldn't have to care. Currently I would not want
> to do that, because mad and ffmpeg work better than GStreamer. This
> might change in the near future though. Still, GStreamer would
> definitely not be better technically, as it'd pretty much just be a
> layer between mad and ffmpeg.
> 
> A thing I'm wondering about is who views ffmpeg as a hard requirement
> by looking at our configure.ac. And we've been very careful to mark
> them as optional. The only hard dependencies of swfdec are cairo and
> glib after all. Could you elaborate on that point?

When I tried to compile swfdec, I saw the message, so I assumed that
ffmpeg was required.  The standard behavior of the configure script is
to abort only if the software cannot be compiled at all.

I only discovered --without-ffmpeg today, much to my surprise.  After I
sent the patch for ffmpeg, I removed all "-devel" packages that came
from livna, and found that mad was another pseudo-requirement.

My suggestion is that either the error message should suggest using the
"--disable" option, or it should be a warning, perhaps at the end of the
output.

-- 
Regards,
Pavel Roskin