\input texinfo @c -*- texinfo -*-

@settitle Platform Specific information
@titlepage
@center @titlefont{Platform Specific information}
@end titlepage

@top

@contents

@chapter Unix-like

Some parts of Libav cannot be built with version 2.15 of the GNU
assembler which is still provided by a few AMD64 distributions. To
make sure your compiler really uses the required version of gas
after a binutils upgrade, run:

@example
$(gcc -print-prog-name=as) --version
@end example

If not, then you should install a different compiler that has no
hard-coded path to gas. In the worst case pass @code{--disable-asm}
to configure.

@section BSD

BSD make will not build Libav, you need to install and use GNU Make
(@command{gmake}).

@section (Open)Solaris

GNU Make is required to build Libav, so you have to invoke (@command{gmake}),
standard Solaris Make will not work. When building with a non-c99 front-end
(gcc, generic suncc) add either @code{--extra-libs=/usr/lib/values-xpg6.o}
or @code{--extra-libs=/usr/lib/64/values-xpg6.o} to the configure options
since the libc is not c99-compliant by default. The probes performed by
configure may raise an exception leading to the death of configure itself
due to a bug in the system shell. Simply invoke a different shell such as
bash directly to work around this:

@example
bash ./configure
@end example

@anchor{Darwin}
@section Darwin (OS X, iPhone)

The toolchain provided with Xcode is sufficient to build the basic
unacelerated code.

OS X on PowerPC or ARM (iPhone) requires a preprocessor from
@url{http://github.com/yuvi/gas-preprocessor} to build the optimized
assembler functions. Just download the Perl script and put it somewhere
in your PATH, Libav's configure will pick it up automatically.

OS X on AMD64 and x86 requires @command{yasm} to build most of the
optimized assembler functions @url{http://mxcl.github.com/homebrew/, Homebrew},
@url{http://www.gentoo.org/proj/en/gentoo-alt/prefix/bootstrap-macos.xml, Gentoo Prefix}
or @url{http://www.macports.org, MacPorts} can easily provide it.


@chapter DOS

Using a cross-compiler is preferred for various reasons.
@url{http://www.delorie.com/howto/djgpp/linux-x-djgpp.html}


@chapter OS/2

For information about compiling Libav on OS/2 see
@url{http://www.edm2.com/index.php/FFmpeg}.


@chapter Windows

@section Native Windows compilation

Libav can be built to run natively on Windows using the MinGW tools. Install
the latest versions of MSYS and MinGW from @url{http://www.mingw.org/}.
You can find detailed installation
instructions in the download section and the FAQ.

Libav does not build out-of-the-box with the packages the automated MinGW
installer provides. It also requires coreutils to be installed and many other
packages updated to the latest version. The minimum versions for some packages
are listed below:

@itemize
@item bash 3.1
@item msys-make 3.81-2 (note: not mingw32-make)
@item w32api 3.13
@item mingw-runtime 3.15
@end itemize

Libav automatically passes @code{-fno-common} to the compiler to work around
a GCC bug (see @url{http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37216}).

Notes:

@itemize

@item Building natively using MSYS can be sped up by disabling implicit rules
in the Makefile by calling @code{make -r} instead of plain @code{make}. This
speed up is close to non-existent for normal one-off builds and is only
noticeable when running make for a second time (for example during
@code{make install}).

@item In order to compile AVplay, you must have the MinGW development library
of @uref{http://www.libsdl.org/, SDL} and @code{pkg-config} installed.

@item By using @code{./configure --enable-shared} when configuring Libav,
you can build all libraries as DLLs.

@end itemize

@section Microsoft Visual C++ compatibility

As stated in the FAQ, Libav will not compile under MSVC++. However, if you
want to use the libav* libraries in your own applications, you can still
compile those applications using MSVC++. But the libav* libraries you link
to @emph{must} be built with MinGW. However, you will not be able to debug
inside the libav* libraries, since MSVC++ does not recognize the debug
symbols generated by GCC.
We strongly recommend you to move over from MSVC++ to MinGW tools.

This description of how to use the Libav libraries with MSVC++ is based on
Microsoft Visual C++ 2005 Express Edition. If you have a different version,
you might have to modify the procedures slightly.

@subsection Using static libraries

Assuming you have just built and installed Libav in @file{/usr/local}:

@enumerate

@item Create a new console application ("File / New / Project") and then
select "Win32 Console Application". On the appropriate page of the
Application Wizard, uncheck the "Precompiled headers" option.

@item Write the source code for your application, or, for testing, just
copy the code from an existing sample application into the source file
that MSVC++ has already created for you. For example, you can copy
@file{libavformat/output-example.c} from the Libav distribution.

@item Open the "Project / Properties" dialog box. In the "Configuration"
combo box, select "All Configurations" so that the changes you make will
affect both debug and release builds. In the tree view on the left hand
side, select "C/C++ / General", then edit the "Additional Include
Directories" setting to contain the path where the Libav includes were
installed (i.e. @file{c:\msys\1.0\local\include}).
Do not add MinGW's include directory here, or the include files will
conflict with MSVC's.

@item Still in the "Project / Properties" dialog box, select
"Linker / General" from the tree view and edit the
"Additional Library Directories" setting to contain the @file{lib}
directory where Libav was installed (i.e. @file{c:\msys\1.0\local\lib}),
the directory where MinGW libs are installed (i.e. @file{c:\mingw\lib}),
and the directory where MinGW's GCC libs are installed
(i.e. @file{C:\mingw\lib\gcc\mingw32\4.2.1-sjlj}). Then select
"Linker / Input" from the tree view, and add the files @file{libavformat.a},
@file{libavcodec.a}, @file{libavutil.a}, @file{libmingwex.a},
@file{libgcc.a}, and any other libraries you used (i.e. @file{libz.a})
to the end of "Additional Dependencies".

@item Now, select "C/C++ / Code Generation" from the tree view. Select
"Debug" in the "Configuration" combo box. Make sure that "Runtime
Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
the "Configuration" combo box and make sure that "Runtime Library" is
set to "Multi-threaded DLL".

@item Click "OK" to close the "Project / Properties" dialog box.

@item MSVC++ lacks some C99 header files that are fundamental for Libav.
Get msinttypes from @url{http://code.google.com/p/msinttypes/downloads/list}
and install it in MSVC++'s include directory
(i.e. @file{C:\Program Files\Microsoft Visual Studio 8\VC\include}).

@item MSVC++ also does not understand the @code{inline} keyword used by
Libav, so you must add this line before @code{#include}ing libav*:
@example
#define inline _inline
@end example

@item Build your application, everything should work.

@end enumerate

@subsection Using shared libraries

This is how to create DLL and LIB files that are compatible with MSVC++:

Within the MSYS shell, build Libav with

@example
./configure --enable-shared
make
make install
@end example

Your install path (@file{/usr/local/} by default) should now have the
necessary DLL and LIB files under the @file{bin} directory.

Alternatively, build the libraries with a cross compiler, according to
the instructions below in @ref{Cross compilation for Windows with Linux}.

To use those files with MSVC++, do the same as you would do with
the static libraries, as described above. But in Step 4,
you should only need to add the directory where the LIB files are installed
(i.e. @file{c:\msys\usr\local\bin}). This is not a typo, the LIB files are
installed in the @file{bin} directory. And instead of adding the static
libraries (@file{libxxx.a} files) you should add the MSVC import libraries
(@file{avcodec.lib}, @file{avformat.lib}, and
@file{avutil.lib}). Note that you should not use the GCC import
libraries (@file{libxxx.dll.a} files), as these will give you undefined
reference errors. There should be no need for @file{libmingwex.a},
@file{libgcc.a}, and @file{wsock32.lib}, nor any other external library
statically linked into the DLLs.

Libav headers do not declare global data for Windows DLLs through the usual
dllexport/dllimport interface. Such data will be exported properly while
building, but to use them in your MSVC++ code you will have to edit the
appropriate headers and mark the data as dllimport. For example, in
libavutil/pixdesc.h you should have:
@example
extern __declspec(dllimport) const AVPixFmtDescriptor av_pix_fmt_descriptors[];
@end example

Note that using import libraries created by dlltool requires
the linker optimization option to be set to
"References: Keep Unreferenced Data (@code{/OPT:NOREF})", otherwise
the resulting binaries will fail during runtime. This isn't
required when using import libraries generated by lib.exe.
This issue is reported upstream at
@url{http://sourceware.org/bugzilla/show_bug.cgi?id=12633}.

To create import libraries that work with the @code{/OPT:REF} option
(which is enabled by default in Release mode), follow these steps:

@enumerate

@item Open @emph{Visual Studio 2005 Command Prompt}.

Alternatively, in a normal command line prompt, call @file{vcvars32.bat}
which sets up the environment variables for the Visual C++ tools
(the standard location for this file is
@file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat}).

@item Enter the @file{bin} directory where the created LIB and DLL files
are stored.

@item Generate new import libraries with @command{lib.exe}:

@example
lib /machine:i386 /def:..\lib\foo-version.def  /out:foo.lib
@end example

Replace @code{foo-version} and @code{foo} with the respective library names.

@end enumerate

@anchor{Cross compilation for Windows with Linux}
@section Cross compilation for Windows with Linux

You must use the MinGW cross compilation tools available at
@url{http://www.mingw.org/}.

Then configure Libav with the following options:
@example
./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
@end example
(you can change the cross-prefix according to the prefix chosen for the
MinGW tools).

Then you can easily test Libav with @uref{http://www.winehq.com/, Wine}.

@section Compilation under Cygwin

Please use Cygwin 1.7.x as the obsolete 1.5.x Cygwin versions lack
llrint() in its C library.

Install your Cygwin with all the "Base" packages, plus the
following "Devel" ones:
@example
binutils, gcc4-core, make, git, mingw-runtime, texi2html
@end example

And the following "Utils" one:
@example
diffutils
@end example

Then run

@example
./configure
@end example

to make a static build.

To build shared libraries add a special compiler flag to work around current
@code{gcc4-core} package bugs in addition to the normal configure flags:

@example
./configure --enable-shared --disable-static --extra-cflags=-fno-reorder-functions
@end example

If you want to build Libav with additional libraries, download Cygwin
"Devel" packages for Ogg and Vorbis from any Cygwin packages repository:
@example
libogg-devel, libvorbis-devel
@end example

These library packages are only available from
@uref{http://sourceware.org/cygwinports/, Cygwin Ports}:

@example
yasm, libSDL-devel, libfaac-devel, libgsm-devel, libmp3lame-devel,
libschroedinger1.0-devel, speex-devel, libtheora-devel, libxvidcore-devel
@end example

The recommendation for x264 is to build it from source, as it evolves too
quickly for Cygwin Ports to be up to date.

@section Crosscompilation for Windows under Cygwin

With Cygwin you can create Windows binaries that do not need the cygwin1.dll.

Just install your Cygwin as explained before, plus these additional
"Devel" packages:
@example
gcc-mingw-core, mingw-runtime, mingw-zlib
@end example

and add some special flags to your configure invocation.

For a static build run
@example
./configure --target-os=mingw32 --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
@end example

and for a build with shared libraries
@example
./configure --target-os=mingw32 --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
@end example

@bye
