Error building MLT framework on Windows

Question

I've been following the official building guide provided here. I need MLT to create a video player and I opted to only install the first 4 libraries, as stated on the guide (FFmpeg, SDL, dlfcn-win32, and libXML). I'm also using QT as my main framework for my application.

I'm a bit confused as far as this guide goes because I find the instructions for where the libraries should go a bit confusing. This is my current folder structure:

$HOME = C:\MinGW\msys\1.0\home\TKB (TKB is my user)
$HOME/build/lib -> libraries
$HOME/build/bin -> binaries
$HOME/build/include -> includes
$HOME/build/share/ffmpeg -> for the "presets" folder

At the same time, because I was confused, I have the same folders (bin, lib, include, share) inside $HOME/.

Then I have $HOME/src/mlt with the mlt files.

When I run the configure command I get this (I disabled the libraries I didn't install to reduce the output on the console):

Command: ./configure --prefix=$HOME/build --target-os=MinGW --enable-gpl --disable-decklink --disable-frei0r --disable-gtk2 --disable-sox --disable-jackrack --disable-swfdec --disable-resample

Configuring framework:
Configuring modules:
Configuring modules/avformat:
- libavformat not found: disabling
Configuring modules/core:
Configuring modules/feeds:
Configuring modules/kdenlive:
Configuring modules/linsys:
- does not build on OS X or Windows:disabling
Configuring modules/lumas:
Configuring modules/motion_est:
Configuring modules/normalize:
Configuring modules/oldfilm:
Configuring modules/opengl:
- movit not found: disabling
Configuring modules/plus:
Configuring modules/plusgpl:
Configuring modules/qt:
- Libexif not found, disabling exif features (auto rotate)
- Qt not found: disabling
Configuring modules/rtaudio:
Configuring modules/sdl:
Configuring modules/vid.stab:
- vid.stab not found: disabling
Configuring modules/videostab:
Configuring modules/vmfx:
Configuring modules/xine:
Configuring modules/xml:
- xml2 not found: disabling xml module
Configuring mlt++:
Configuring swig:
GPLv2 license used; GPLv3 components disabled

I have ffmpeg and the xml2 libraries on the folders but it looks like the script is not able to find them. I also have QT installed on the default folder and it also doesn't seem to find it.

I tried installing anyway (make all install) and I get the following error:

c:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: cannot find -ldl
c:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: cannot find -lpthread
collect2.exe: error: ld returned 1 exit status
make[1]: *** [libmlt-6.dll] Error 1
make[1]: Leaving directory '/home/TKB/src/mlt-0.9.6/src/framework'
make: *** [all] Error 1

Can anyone help me with these errors?

Thank you for your time.

EDIT: I found out that I made a naming mistake when creating the pkgconfig folder, changing that solved the xml2 not being detected problem. Also, I've added the paths for ffmpeg and qt manually and that also seemed to solve the problem. So now what I get with the configure is the following:

./configure --prefix=/home/TKB/build --enable-gpl --disable-decklink --disable-frei0r --disable-gtk2 --disable-sox --disable-jackrack --disable-swfdec --disable-resample --qt-libdir=C:/Qt/5.3/mingw482_32/lib --qt-includedir=C:/Qt/5.3/mingw482_32/include --avformat-shared=/home/TKB/share/ffmpeg --avformat-static=/home/TKB/bin

Configuring framework:
Configuring modules:
Configuring modules/avformat:
Configuring modules/core:
Configuring modules/feeds:
Configuring modules/kdenlive:
Configuring modules/linsys:
- does not build on OS X or Windows:disabling
Configuring modules/lumas:
Configuring modules/motion_est:
Configuring modules/normalize:
Configuring modules/oldfilm:
Configuring modules/opengl:
- movit not found: disabling
Configuring modules/plus:
Configuring modules/plusgpl:
Configuring modules/qt:
- Libexif not found, disabling exif features (auto rotate)
- Qt version 5.x detected
- Include directory: C:/Qt/5.3/mingw482_32/include
Configuring modules/rtaudio:
Configuring modules/sdl:
Configuring modules/vid.stab:
- vid.stab not found: disabling
Configuring modules/videostab:
Configuring modules/vmfx:
Configuring modules/xine:
Configuring modules/xml:
Configuring mlt++:
Configuring swig:
GPLv2 license used; GPLv3 components disabled

When I run make all install I still get an error, which is the following:

c:/Qt/Tools/mingw482_32/bin/../lib/gcc/i68-w64-mingw32/4.8.2/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -ldl
collect2.exe: error: ld returned 1 exit status
make[1]: *** [libmlt-6.dll] Error 1
make[1]: Leaving directory '/home/TKB/src/mlt/src/framework'
make: *** [all] Error 1

EDIT2: I have added dlfcn-win32's bin, lib and include to the respective bin, lib and include folders in c:/Qt/Tools/mingw482_32, which solved my problem. Now I am getting a new error, which seems of similar solution but I don't see what -lbz2 is. The error follows below:

c:/Qt/Tools/mingw482_32/bin/../lib/gcc/i68-w64-mingw32/4.8.2/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lbz2
collect2.exe: error: ld returned 1 exit status
make[2]: *** [../libmltavformat.dll] Error 1
make[2]: Leaving directory '/home/TKB/src/mlt/src/modules/avformat'
make[1]: *** [all] Error 1
make[1]: Leaving directory '/home/TKB/src/mlt/src/modules'
make: *** [all] Error 1

EDIT3: Right now I'm getting the following error: After the compile code runs (it generates the .o) I get "undefined reference to 'ffmpeg_function'" in every file of the avformat module. I've noticed that it locates the includes correctly, so the problem must be in finding the libs.

I've noticed that on the config.mak file the LDFLAGS are like this:

LDFLAGS+=-L/home/TKB/bin/libavformat -L/home/TKB/bin/libavcodec -L/home/TKB/bin/libavutil
LDFLAGS+=-L/home/TKB/bin/libswscale
LDFLAGS+=-L/home/TKB/bin/libavdevice

Shouldn't it be -l (lower case) to identify a file instead of a folder? Or is it expecting one folder per lib? Besides the ffmpeg libs are named differently (e.g. avformat-56.dll)

EDIT4: To test things out I have added the following to the config.mak of the avformat module:

LDFLAGS+=-l/home/TKB/bin/avformat-56 -l/home/TKB/bin/avcodec-56 -l/home/TKB/bin/avutil-54
LDFLAGS+=-l/home/TKB/bin/swscale-3
LDFLAGS+=-l/home/TKB/bin/avdevice-56

The previous error disappeared but now I am getting the following one:

c:/Qt/Tools/mingw482_32/bin/../lib/gcc/i68-w64-mingw32/4.8.2/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lC:/MinGW/mysys/1.0/home/TKB/bin/avformat-56
c:/Qt/Tools/mingw482_32/bin/../lib/gcc/i68-w64-mingw32/4.8.2/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lC:/MinGW/mysys/1.0/home/TKB/bin/avcodec-56
c:/Qt/Tools/mingw482_32/bin/../lib/gcc/i68-w64-mingw32/4.8.2/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lC:/MinGW/mysys/1.0/home/TKB/bin/avutil-54
c:/Qt/Tools/mingw482_32/bin/../lib/gcc/i68-w64-mingw32/4.8.2/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lC:/MinGW/mysys/1.0/home/TKB/bin/swscale-3
c:/Qt/Tools/mingw482_32/bin/../lib/gcc/i68-w64-mingw32/4.8.2/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lC:/MinGW/mysys/1.0/home/TKB/bin/avdevice-56
collect2.exe: error: ld returned 1 exit status
make[2]: *** [../libmltavformat.dll] Error 1
make[2]: Leaving directory '/home/TKB/src/mlt/src/modules/avformat'
make[1]: *** [all] Error 1
make[1]: Leaving directory '/home/TKB/src/mlt/src/modules'
make: *** [all] Error 1

The dlls are on that folder.

EDIT5: It seems I finally managed to compile! I changed the LDFLAGS to the following:

LDFLAGS+=-L/home/TKB/bin
LDFLAGS+=-lavformat-56 -lavcodec-56 -lavutil-54
LDFLAGS+=-lswscale-3
LDFLAGS+=-lavdevice-56

And it finished without errors.

Thank you Brian for all the time and help you gave me!

Answer 1

Make sure you have pkg-config installed:

http://www.mltframework.org/pub/Shotcut/SetupWindowsDev/pkg-config.exe

You should be able to run pkg-config from the command line and get a good response. e.g:

# pkg-config --modversion libxml-2.0
2.9.1
# pkg-config --modversion QtGui
4.8.6

If you don't get a good response from pkg-config, you may need to set PKG_CONFIG_PATH to point at the .pc files for each of the dependencies.

Also, have a good look at the pkg-config documentation. There are some special considerations you may need to make for Windows:

http://linux.die.net/man/1/pkg-config

You also need to install dlfcn-win32. From the MLT Windows instructions:

• Download dlfcn-win32
• cd ~/src/dlfcn-win32-r19
• ./configure --enable-shared make all install
• To make this redistributable, copy /mingw/bin/libdl.dll to your build directory.

If you did follow those instructions, perhaps you need to find a place to put libdl.dll so that the linker finds it.

For the "-lbz2" error, it looks like you need to download, compile and install the bzip2 library to match the one that ffmpeg was compiled against: bzip2 1.0.6

Have a look at the README.txt file that came with the ffmpeg-shared package you downloaded. There is a long list of external libraries that ffmpeg was compiled against. bzip2 is the first one. You might need to download/compile/install more of those.

EDIT 3:

You should not specify both --avformat-shared and --avformat-static - they are mutually exclusive. You could try specifying neither of them. Or, try setting --avformat-shared=$HOME/build/

EDIT 4:

I think the reason that you are having trouble linking is because the Zeranoe builds no longer include pkg-config files (.pc).

http://ffmpeg.zeranoe.com/forum/viewtopic.php?f=7&t=532&hilit=pkg+config

The MLT configure script relies on pkg-config to set the correct linker flags. The MLT configure script could be extended to allow the user to specify the correct linker flags. Until that happens, I think that hacking config.mak (like you did) will be the only way to make it work on Windows.

I'm glad you got it to work. Cheers!