path: root/doc/platform.texi

\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 or MinGW-w64
toolchains. Install the latest versions of MSYS and MinGW or MinGW-w64 from
@url{http://www.mingw.org/} or @url{http://mingw-w64.sourceforge.net/}.
You can find detailed installation instructions in the download section and
the FAQ.

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 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

In order to run FATE you will also need the following "Utils" packages:
@example
bc, diffutils
@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