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 Advanced linking configuration

If you compiled Libav libraries statically and you want to use them to
build your own shared library, you may need to force PIC support (with
@code{--enable-pic} during Libav configure) and add the following option
to your project LDFLAGS:

@example
-Wl,-Bsymbolic
@end example

If your target platform requires position independent binaries, you should
pass the correct linking flag (e.g. @code{-pie}) to @code{--extra-ldexeflags}.

@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{git://git.libav.org/gas-preprocessor.git} to build the optimized
assembly functions. Put the Perl script 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 assembly 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 using MinGW or MinGW-w64

Libav can be built to run natively on Windows using the MinGW-w64
toolchain. Install the latest versions of MSYS2 and MinGW-w64 from
@url{http://msys2.github.io/} and/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 MSYS2 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++ or Intel C++ Compiler for Windows

Libav can be built with MSVC 2012 or earlier using a C99-to-C89 conversion utility
and wrapper, or with MSVC 2013 and ICL natively.

You will need the following prerequisites:

@itemize
@item @uref{https://github.com/libav/c99-to-c89/, C99-to-C89 Converter & Wrapper}
(if using MSVC 2012 or earlier)
@item @uref{http://code.google.com/p/msinttypes/, msinttypes}
(if using MSVC 2012 or earlier)
@item @uref{http://msys2.github.io/, MSYS2}
@item @uref{http://yasm.tortall.net/, YASM}
(Also available via MSYS2's package manager.)
@end itemize

To set up a proper environment in MSYS2, you need to run @code{msys_shell.bat} from
the Visual Studio or Intel Compiler command prompt.

Place @code{yasm.exe} somewhere in your @code{PATH}. If using MSVC 2012 or
earlier, place @code{c99wrap.exe} and @code{c99conv.exe} somewhere in your
@code{PATH} as well.

Next, make sure any other headers and libs you want to use, such as zlib, are
located in a spot that the compiler can see. Do so by modifying the @code{LIB}
and @code{INCLUDE} environment variables to include the @strong{Windows-style}
paths to these directories. Alternatively, you can try and use the
@code{--extra-cflags}/@code{--extra-ldflags} configure options. If using MSVC
2012 or earlier, place @code{inttypes.h} somewhere the compiler can see too.

Finally, run:

@example
For MSVC:
./configure --toolchain=msvc

For ICL:
./configure --toolchain=icl

make
make install
@end example

If you wish to compile shared libraries, add @code{--enable-shared} to your
configure options. Note that due to the way MSVC and ICL handle DLL imports and
exports, you cannot compile static and shared libraries at the same time, and
enabling shared libraries will automatically disable the static ones.

Notes:

@itemize

@item It is possible that coreutils' @code{link.exe} conflicts with MSVC's linker.
You can find out by running @code{which link} to see which @code{link.exe} you
are using. If it is located at @code{/bin/link.exe}, then you have the wrong one
in your @code{PATH}. Either move or remove that copy, or make sure MSVC's
@code{link.exe} takes precedence in your @code{PATH} over coreutils'.

@item If you wish to build with zlib support, you will have to grab a compatible
zlib binary from somewhere, with an MSVC import lib, or if you wish to link
statically, you can follow the instructions below to build a compatible
@code{zlib.lib} with MSVC. Regardless of which method you use, you must still
follow step 3, or compilation will fail.
@enumerate
@item Grab the @uref{http://zlib.net/, zlib sources}.
@item Edit @code{win32/Makefile.msc} so that it uses -MT instead of -MD, since
this is how Libav is built as well.
@item Edit @code{zconf.h} and remove its inclusion of @code{unistd.h}. This gets
erroneously included when building Libav.
@item Run @code{nmake -f win32/Makefile.msc}.
@item Move @code{zlib.lib}, @code{zconf.h}, and @code{zlib.h} to somewhere MSVC
can see.
@end enumerate

@item Libav has been tested with the following on i686 and x86_64:
@itemize
@item Visual Studio 2010 Pro and Express
@item Visual Studio 2012 Pro and Express
@item Visual Studio 2013 Pro and Express
@item Intel Composer XE 2013
@item Intel Composer XE 2013 SP1
@end itemize
Anything else is not officially supported.

@end itemize

@subsection Linking to Libav with Microsoft Visual C++

If you plan to link with MSVC-built static libraries, you will need
to make sure you have @code{Runtime Library} set to
@code{Multi-threaded (/MT)} in your project's settings.

You will need to define @code{inline} to something MSVC understands:
@example
#define inline __inline
@end example

Also note, that as stated in @strong{Microsoft Visual C++}, you will need
an MSVC-compatible @uref{http://code.google.com/p/msinttypes/, inttypes.h}.

If you plan on using import libraries created by dlltool, you must
set @code{References} to @code{No (/OPT:NOREF)} under the linker optimization
settings, otherwise the resulting binaries will fail during runtime.
This is not required when using import libraries generated by @code{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 the @emph{Visual Studio 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 something like
@file{C:\Program Files (x86_\Microsoft Visual Studio 10.0\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
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

@chapter Plan 9

The native @uref{http://plan9.bell-labs.com/plan9/, Plan 9} compiler
does not implement all the C99 features needed by Libav so the gcc
port must be used.  Furthermore, a few items missing from the C
library and shell environment need to be fixed.

@itemize

@item GNU awk, grep, make, and sed

Working packages of these tools can be found at
@uref{http://code.google.com/p/ports2plan9/downloads/list, ports2plan9}.
They can be installed with @uref{http://9front.org/, 9front's} @code{pkg}
utility by setting @code{pkgpath} to
@code{http://ports2plan9.googlecode.com/files/}.

@item Missing/broken @code{head} and @code{printf} commands

Replacements adequate for building Libav can be found in the
@code{compat/plan9} directory.  Place these somewhere they will be
found by the shell.  These are not full implementations of the
commands and are @emph{not} suitable for general use.

@item Missing C99 @code{stdint.h} and @code{inttypes.h}

Replacement headers are available from
@url{http://code.google.com/p/plan9front/issues/detail?id=152}.

@item Missing or non-standard library functions

Some functions in the C library are missing or incomplete.  The
@code{@uref{http://ports2plan9.googlecode.com/files/gcc-apelibs-1207.tbz,
gcc-apelibs-1207}} package from
@uref{http://code.google.com/p/ports2plan9/downloads/list, ports2plan9}
includes an updated C library, but installing the full package gives
unusable executables.  Instead, keep the files from @code{gccbin.tgz}
under @code{/386/lib/gnu}.  From the @code{libc.a} archive in the
@code{gcc-apelibs-1207} package, extract the following object files and
turn them into a library:

@itemize
@item @code{strerror.o}
@item @code{strtoll.o}
@item @code{snprintf.o}
@item @code{vsnprintf.o}
@item @code{vfprintf.o}
@item @code{_IO_getc.o}
@item @code{_IO_putc.o}
@end itemize

Use the @code{--extra-libs} option of @code{configure} to inform the
build system of this library.

@item FPU exceptions enabled by default

Unlike most other systems, Plan 9 enables FPU exceptions by default.
These must be disabled before calling any Libav functions.  While the
included tools will do this automatically, other users of the
libraries must do it themselves.

@end itemize

@bye