[MPlayer-users] Mplayer-vaapi fails to compile.

[Tom Evans]

On Tue, Oct 2, 2012 at 1:17 PM, dE . <de.techno at gmail.com> wrote:
> As you might have know, Gentoo is a source based distro, and each of it's
> install (on various PCs) is not designed to be generic; so in Gentoo when we
> compile source tarballs (portage does this automatically, and that's how I
> get ffmpeg and mplayer from git), we use non generic flags (-march=native)
> since the binaries are not intended to be used on a different CPU; for this
> reason, no use adding AMD specific instructions (3dnow*) with an Intel CPU,
> or adding newer ssse* instructions for an older CPU.
>
> Also, things becomes more complicated when you cross compile (e.g. for ARM
> boards on an fast x64 processor), which's commonly done by Gentoo users. So
> it's a good idea to force instructions, cause mplayer auto detects it by
> default (right?).

It is almost always wrong to use --enable-foo in mplayer's configure
script, since this will unconditionally turn on options that normally
would be tested to see if the feature is supported by your currently
installed libraries and so on. Simply having a library is not enough,
you must have the right version, and that is what configure tests.

More specifically on processor flags, if you omitted all of the
--disable-3dnow --enable-sse flags, mplayer would test itself to see
what your processor supports and turn on the right flags for your
processor.

This problem comes from Gentoo's build system; each one of those
options will correspond to a USE flag in Gentoo, and the only thing
Gentoo can do with a USE flag is to turn on or turn off a configure
option. Most of them are unnecessary unless you are trying to produce
a packaged binary for many machines, which is the opposite of what
Gentoo is trying to do.

Gentoo isn't doing it "right" as far as mplayer is concerned - and you
will always get a little grief on here debugging with so many non
standard configure options -  but it is right from Gentoo's point of
view!

Cheers

Tom