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:

     $(gcc -print-prog-name=as) --version

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

BSD
===

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

(Open)Solaris
=============

GNU Make is required to build Libav, so you have to invoke (gmake), standard Solaris Make will not work. When building with a non-c99 front-end (gcc, generic suncc) add either --extra-libs=/usr/lib/values-xpg6.o or --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:

     bash ./configure

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 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 yasm to build most of the optimized assembler functions Homebrew (http://mxcl.github.com/homebrew/), Gentoo Prefix (http://www.gentoo.org/proj/en/gentoo-alt/prefix/bootstrap-macos.xml) or MacPorts (http://www.macports.org) can easily provide it.

DOS
***

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

OS/2
****

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

Windows
*******

Native Windows compilation using MinGW or MinGW-w64
===================================================

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 http://www.mingw.org/ or http://mingw-w64.sourceforge.net/. You can find detailed installation instructions in the download section and the FAQ.

Notes:

  * Building natively using MSYS can be sped up by disabling implicit rules in the Makefile by calling make -r instead of plain 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 make install).

  * In order to compile AVplay, you must have the MinGW development library of SDL (http://www.libsdl.org/) and pkg-config installed.

  * By using ./configure --enable-shared when configuring Libav, you can build all libraries as DLLs.

Microsoft Visual C++
====================

Libav can be built with MSVC using a C99-to-C89 conversion utility and wrapper.

You will need the following prerequisites:

  * C99-to-C89 Converter & Wrapper (https://github.com/libav/c99-to-c89/)

  * msinttypes (http://code.google.com/p/msinttypes/)

  * MSYS (http://www.mingw.org/)

  * YASM (http://yasm.tortall.net/)

  * bc for Windows (http://gnuwin32.sourceforge.net/packages/bc.htm) if you want to run FATE (fate.html).

To set up a proper MSVC environment in MSYS, you simply need to run msys.bat from the Visual Studio command prompt.

Place makedef, c99wrap.exe, c99conv.exe, and yasm.exe somewhere in your PATH.

Next, make sure inttypes.h and any other headers and libs you want to use are located in a spot that MSVC can see. Do so by modifying the LIB and INCLUDE environment variables to include the Windows paths to these directories. Alternatively, you can try and use the --extra-cflags/--extra-ldflags configure options.

Finally, run:

     ./configure --toolchain=msvc
     make
     make install

If you wish to compile shared libraries, add --enable-shared to your configure options. Note that due to the way MSVC handles 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:

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

  * 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 zlib.lib with MSVC. Regardless of which method you use, you must still follow step 3, or compilation will fail.

      1. Grab the zlib sources (http://zlib.net/).

      2. Edit win32/Makefile.msc so that it uses -MT instead of -MD, since this is how Libav is built as well.

      3. Edit zconf.h and remove its inclusion of unistd.h. This gets erroneously included when building Libav.

      4. Run nmake -f win32/Makefile.msc.

      5. Move zlib.lib, zconf.h, and zlib.h to somewhere MSVC can see.

  * Libav has been tested with Visual Studio 2010 and 2012, Pro and Express. Anything else is not officially supported.

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 Runtime Library set to Multi-threaded (/MT) in your project's settings.

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:

     extern __declspec(dllimport) const AVPixFmtDescriptor av_pix_fmt_descriptors[];

You will also need to define inline to something MSVC understands:

     #define inline __inline

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

If you plan on using import libraries created by dlltool, you must set References to 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 lib.exe. This issue is reported upstream at http://sourceware.org/bugzilla/show_bug.cgi?id=12633.

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

 1. Open the Visual Studio Command Prompt.

     Alternatively, in a normal command line prompt, call vcvars32.bat which sets up the environment variables for the Visual C++ tools (the standard location for this file is something like C:\Program Files (x86_\Microsoft Visual Studio 10.0\VC\bin\vcvars32.bat).

 2. Enter the bin directory where the created LIB and DLL files are stored.

 3. Generate new import libraries with lib.exe:

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

     Replace foo-version and foo with the respective library names.

Cross compilation for Windows with Linux
========================================

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

Then configure Libav with the following options:

     ./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-

(you can change the cross-prefix according to the prefix chosen for the MinGW tools).

Then you can easily test Libav with Wine (http://www.winehq.com/).

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:

     binutils, gcc4-core, make, git, mingw-runtime, texi2html

In order to run FATE you will also need the following "Utils" packages:

     bc, diffutils

If you want to build Libav with additional libraries, download Cygwin "Devel" packages for Ogg and Vorbis from any Cygwin packages repository:

     libogg-devel, libvorbis-devel

These library packages are only available from Cygwin Ports (http://sourceware.org/cygwinports/):

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

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

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:

     gcc-mingw-core, mingw-runtime, mingw-zlib

and add some special flags to your configure invocation.

For a static build run

     ./configure --target-os=mingw32 --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin

and for a build with shared libraries

     ./configure --target-os=mingw32 --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin

Plan 9
******

The native Plan 9 (http://plan9.bell-labs.com/plan9/) 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.

  * GNU awk, grep, make, and sed

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

  * Missing/broken head and printf commands

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

  * Missing C99 stdint.h and inttypes.h

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

  * Missing or non-standard library functions

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

       * strerror.o

       * strtoll.o

       * snprintf.o

       * vsnprintf.o

       * vfprintf.o

       * _IO_getc.o

       * _IO_putc.o

     Use the --extra-libs option of configure to inform the build system of this library.

  * 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.