./configure include directories

[Ganado]

I'm wondering if anyone has an idea how to let ./configure be able to find the headers of another library that I installed.

In msys2 (so it is Windows, but this should be fully compatible with the Linux solution), I built LAME 3.100
https://sourceforge.net/projects/lame/?source=typ_redirect
through

./configure
make
make install

Had to deal with the this bug ( https://sourceforge.net/p/lame/bugs/487/ ) but the installation went smoothly otherwise.

Then I try to install libav 12.2 by typing
./configure --enable-libmp3lame --enable-libvpx

This eventually leads to the error,

gcc -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -U__STRICT_ANSI__ -D__USE_MINGW_ANSI_STDIO=1 -D__printf__=__gnu_printf__ -DPIC -std=c99 -fomit-frame-pointer -E -o /tmp/ffconf.DPVNZ61z.o /tmp/ffconf.8S39YF2b.c
C:/msys64/tmp/ffconf.8S39YF2b.c:1:10: fatal error: lame/lame.h: No such file or directory
 #include <lame/lame.h>
          ^~~~~~~~~~~~~
compilation terminated.

If this were just me compiling a project, I could pretty easily add the appropriate include dir to the compiler (gcc/g++) command line with -I<blah>.

But how do I get tell ./configure to know where to find lame/lame.h?
Or any particular include (or library) for the next time this happens?

I am trying to google the answer, but it's hard because the word "configure" gets overshadowed by so many other, unrelated search results.

Thank you for reading!

[keskiverto]

I think that the configure script should be able to show what options it does accept:
./configure --help

[Ganado]

Thank you. I ended up having to go inside the lame-3.100/include directory, add another folder called "lame", and then copy lame.h into that one, get the #include <lame/lame.h> to work properly.

Unlike, for example, fftw3, it seems that LAME didn't actually install any of the files into /usr/include or /usr/lib.

Adding --extra-ldflags="-L/c/dev/libs/lame-3.100/libmp3lame/.libs" --extra-cflags="-I/c/dev/libs/lame-3.100/include" seems to have made the LAME-related errors go away.

So that solves my initial OP question. Now the problem is libvpx, haha...

./configure --enable-libmp3lame --enable-libvpx --extra-ldflags="-L/c/dev/libs/lame-3.100/libmp3lame/.libs" --extra-cflags="-I/c/dev/libs/lame-3.100/include" --extra-ldflags="-L/c/dev/libs/libvpx-master" --extra-cflags="-I/c/dev/libs/libvpx-master"
produces the following error in config.log

gcc -D_ISOC99_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -U__STRICT_ANSI__ -D__USE_MINGW_ANSI_STDIO=1 -D__printf__=__gnu_printf__ -DPIC -I/c/dev/libs/lame-3.100/include -I/c/dev/libs/libvpx-master -std=c99 -fomit-frame-pointer -c -o /tmp/ffconf.cEigZyZ7.o /tmp/ffconf.wlP2ch1x.c
gcc -L/c/dev/libs/lame-3.100/libmp3lame/.libs -L/c/dev/libs/libvpx-master -Wl,--nxcompat -Wl,--dynamicbase -Wl,--as-needed -o /tmp/ffconf.y15eYjHC.exe /tmp/ffconf.cEigZyZ7.o -lmp3lame -lm -lpsapi -ladvapi32 -lshell32
check_pkg_config vpx >= 1.3.0 vpx/vpx_codec.h vpx_codec_version
false --exists --print-errors vpx >= 1.3.0
ERROR: vpx >= 1.3.0 not found

I know that my vpx version is above 1.3.0. So this is frustrating.

What a mess, lol. Going to keep searching google...

[Ganado]

Okay, so, just to update to bring this to some close.

To solve this error of it not finding vpx >= 1.3.0, despite my version of vpx being 1.6.1, I first made sure that pkg-config was working correctly. This required downloading and copying the correct DLLs on the Windows side, which can be gotten, for example, from
http://www.codeblocks.org/downloads/26 codeblocks-17.12mingw-nosetup.zip in mingw/bin

Once pkg-config can be run without complaining about needing a DLL to run, I ran
pkg-config --exists --print-errors vpx >= 1.3.0
This gives a hint,

Package vpx was not found in the pkg-config search path.
Perhaps you should add the directory containing `vpx.pc'
to the PKG_CONFIG_PATH environment variable 

vpx.pc is in my libvpx-master directory, so I added that path to PKG_CONFIG_PATH.

I ran the following commands:

PATH=$PATH:/c/mingw/bin
cd /c/dev/libs/libav-12.2
PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/c/dev/libs/libvpx-master
./configure --enable-libmp3lame --enable-libvpx --extra-ldflags="-L/c/dev/libs/lame-3.100/libmp3lame/.libs" --extra-cflags="-I/c/dev/libs/lame-3.100/include" --extra-ldflags="-L/c/dev/libs/libvpx-master" --extra-cflags="-I/c/dev/libs/libvpx-master"

And configuration seems to have completed successfully! Hopefully the rest of the installation will work as well.
Maybe this will help someone that might google this in the future, haha.

_______________________________________
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Update:
make and make install worked as well.

I was able to compile the sample project located at https://libav.org/documentation/doxygen/master/encode__video_8c_source.html with the following command line.

g++.exe -LC:\dev\libs\libav-12.2\libavcodec -LC:\dev\libs\libav-12.2\libavformat -LC:\dev\libs\libav-12.2\libavutil -LC:\dev\libs\lame-3.100\libmp3lame\.libs -LC:\dev\libs\libvpx-master -LC:\dev\libs\libav-12.2\libavresample -o bin\Debug\libav_test.exe obj\Debug\main.o -lavcodec -lavformat -lavutil -lmp3lame -lvpx -lavresample

The file it makes is 50 MB, although this is also without optimizations... I guess that's what static linking a bunch of things inevitably does.