Autotools automatically appends user CPPFLAGS after target
CPPFLAGS. Also, it puts all CPPFLAGS before CFLAGS in final
generated gcc compile command. The internal ffmpeg include
paths need to come before any other external include paths
to ensure we don't accidentally pickup external ffmpeg
headers first (i.e. from user CPPFLAGS include paths). Thus,
move the internal LIBAV include paths to LIBAV_CPPFLAGS so
that they come before any user defined CPPFLAGS.
This allows ffmpeg and gst-ffmpeg to coexist on users system.
https://bugzilla.gnome.org/show_bug.cgi?id=789379
While all this information is in the .la files, libtool seems to get
confused with ordering in presence of static system libraries. This could
cause missing symbol error at link time. Adding these depenencies explicitly
workaround the issue.
This should help libtool in getting the internal linking right.
Effectively, libtool can sometime get the link order wrong when
presented with a mix of .la and -l arguments. These .la file are
also required by the android build system and were previously
created by cerbero.
The install line was using -t parameter which is not supported on OSX.
Instead, use automake DATA installation mechanism, this way we rely on
automake to generate portable scripts.
In the last iteration, we kept the original method to link the shared
plugin and edited the .a and .la files so satisfy what cerbero needed.
Unfortunately, that required adding .a file into the archive which is
not allowed with iOS ar command for universal builds.
This patch uses standard method to link a static library. One of the
benefit is that it removes some libtool warning about portability.
For the static case, we implement an install hook that installs
FFMPEG internal .a files in the plugin directory (so it does not get
confused with a possible system FFMPEG. This makes the static plugin
usable without depending on cerbero recipe.
Libtool will produce libgstlibav.la and libgstlibav.lai (the installed
version). We need to edit at least the installed version for the final
linking of static application to work.
Some libtool will endup removing the shared build when running a static
build. That had unwanted side effect. Rather then fighting libtool to
get to build each static and shared seperatly, let libtool build with
the LIBAV_DEPS added to LIBADD (list of libav*.a) and finally remove the
extra .a from the archive and fix the .la to what cerbero will expect.
When building plugins with internal FFMPEG, we use different link
flags depending if it is static or shared. As we want to build both
static and dynamic plugins at once, rewrite the rules so we can
pass the right flags.
https://bugzilla.gnome.org/show_bug.cgi?id=779344
ffmpeg seems to be the one of the two forks, which is most widely used by
Linux distributions and in general. Also Google is using it for e.g. Chrome
and has engineers working on finding and fixing security issues in it.
https://bugzilla.gnome.org/show_bug.cgi?id=751607
