# Platform Specific Information

# Table of Contents

- 1 Unix-like
  - 1.1 BSD
  - 1.2 (Open)Solaris
  - 1.3 Darwin (Mac OS X, iPhone)
- 2 DOS
- 3 OS/2
- 4 Windows
  - 4.1 Native Windows compilation using MinGW or MinGW-w64
  - 4.2 Microsoft Visual C++
    - 4.2.1 Linking to FFmpeg with Microsoft Visual C++
  - 4.3 Cross compilation for Windows with Linux
  - 4.4 Compilation under Cygwin
  - 4.5 Crosscompilation for Windows under Cygwin
- 5 Plan 9

# 1 Unix-like

Some parts of FFmpeg 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.

## 1.1 BSD

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

## 1.2 (Open)Solaris

GNU Make is required to build FFmpeg, 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

## 1.3 Darwin (Mac OS X, iPhone)

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

Mac 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, FFmpeg’s configure will pick it up automatically.

Mac OS X on amd64 and x86 requires `yasm` to build most of the optimized assembler functions. Fink, Gentoo Prefix, Homebrew or MacPorts can easily provide it.

# 2 DOS

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

# 3 OS/2

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

# 4 Windows

To get help and instructions for building FFmpeg under Windows, check out the FFmpeg Windows Help Forum at http://ffmpeg.zeranoe.com/forum/.

## 4.1 Native Windows compilation using MinGW or MinGW-w64

FFmpeg 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 FFplay, you must have the MinGW development library of SDL and `pkg-config` installed.
- By using `./configure --enable-shared` when configuring FFmpeg, you can build the FFmpeg libraries (e.g. libavutil, libavcodec, libavformat) as DLLs.

## 4.2 Microsoft Visual C++

FFmpeg 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
- msinttypes
- MSYS
- YASM
- bc for Windows if you want to run FATE.

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.
  2. Edit `win32/Makefile.msc` so that it uses -MT instead of -MD, since this is how FFmpeg is built as well.
  3. Edit `zconf.h` and remove its inclusion of `unistd.h`. This gets erroneously included when building FFmpeg.
  4. Run `nmake -f win32/Makefile.msc`.
  5. Move `zlib.lib`, `zconf.h`, and `zlib.h` to somewhere MSVC can see.
- FFmpeg has been tested with Visual Studio 2010 and 2012, Pro and Express. Anything else is not officially supported.

### 4.2.1 Linking to FFmpeg 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.

FFmpeg 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.

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.

## 4.3 Cross compilation for Windows with Linux

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

Then configure FFmpeg 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 FFmpeg with Wine.

## 4.4 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 FFmpeg 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:

    yasm, libSDL-devel, libfaac-devel, libaacplus-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.

## 4.5 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

# 5 Plan 9

The native Plan 9 compiler does not implement all the C99 features needed by FFmpeg 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. They can be installed with 9front’s `pkg` utility by setting `pkgpath` to `http://ports2plan9.googlecode.com/files/`.

- Missing/broken `head` and `printf` commands

  Replacements adequate for building FFmpeg 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` package from ports2plan9 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 FFmpeg functions. While the included tools will do this automatically, other users of the libraries must do it themselves.