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Building FFMpeg

16 June 2012
In the past building FFMpeg for Windows had to be done by cross-compiling from Linux, which is OK if you are a cross-platform developer, but an utter pain if you only develop for Windows (my own company went Windows-only a few months ago). Nowhere near as challenging as recompiling GTK, but also not without its gotchas.

Dependencies

For a proper build, you need the following two utilities:
Yasm
Download the Win32 .exe, and rename it to yasm.exe
Microsoft Library Manager
Download and install Visual C++ 2010 Express, and you will need to copy the following files:
  • Common7\IDE\mspdb100.dll
  • VC\bin\lib.exe
  • VC\bin\link.exe
I will assume all four required files have been put into C:\deps

Build environment

I am using the same build environment that I used for building GTK for Win32. See the section on Installing MinGW/MSYS.

Doing the build

Download the latest snap-shot from . The one I used had the name ffmpeg-HEAD-0f73ac3.tar.gz. I will assume this file has been copied into D:\src.

Start-up the MSYS shell and get a few things prepared:

export PATH=$PATH:/c/deps cd /d/src tar -xzvf ffmpeg-HEAD-0f73ac3.tar.gz cd ffmpeg-HEAD-0f73ac3

If you want a debug build, complete with GDB symbols, run the following. Bear in mind that this will take a but under 2 minutes, and it will not show any output until around halfway through:

./configure --arch=x86 --target-os=mingw32 \    --prefix=/d/FFmpeg \    --enable-memalign-hack --disable-static --enable-shared \    --extra-cflags=\"-mms-bitfields\" \    --extra-cflags=\"-ggdb\" \    --extra-ldflags=\"-Wl,-add-stdcall-alias\" \    --disable-stripping

If instead you want a release build, run the following.

./configure --arch=x86 --target-os=mingw32 \    --prefix=/d/FFmpeg \    --enable-memalign-hack --disable-static --enable-shared \    --extra-cflags=\"-mms-bitfields\" \    --extra-ldflags=\"-Wl,-add-stdcall-alias\" \

Once configuration is finished, start the build & install. On a 2010 Quad-Core i7 860 with 4GB RAM it took about 10 minutes.

make && make install

All done. Your newly build FFmpeg should be under D:\FFmpeg. Enjoy.. :)

Only building H.264 decoder

If you are only interested in building H.264 decoding libraries, you can add the following switches to the configure command. Bear in mind that intra-dependencies within FFmpeg sometimes change, so in a future build this list might become shorter: Actually these parameters only exclude unwanted modules (i.e. utilities & DLLs) rather than unwanted codecs, but I suspect removing unwanted codecs (e.g. audio decoders) is diminishing returns.

Pit-falls

Import libraries missing

If you are getting this when running make install:

INSTALL libavfilter/avfilter.dll install: cannot stat `libavfilter/avfilter.lib': No such file or directory make: *** [install-libavfilter-shared] Error 1

The problem is that lib.exe (which creates the .lib files) is called during the building stage, and if not present it fails silently. It is not enough to run make again - you have to do a make clean and do rebuild from scratch.

YASM not found

This is caused by yasm.exe:

yasm not found, use --disable-yasm for a crippled build

Did you copy (as opposed to copying then renaming) YASM?

Missing function references

FFmpeg is a collection of programs and libraries, and the inter-dependencies change with time. Don't be too surprised if you get errors like the following when you use the same configure script parameters with an upgraded FFmpeg source tree:

libavfilter/vf_scale.o: In function `query_formats': D:\ffmpeg-HEAD-0f73ac3/libavfilter/vf_scale.c:135: undefined reference to `sws_isSupportedInput' D:\ffmpeg-HEAD-0f73ac3/libavfilter/vf_scale.c:145: undefined reference to `sws_isSupportedOutput' libavfilter/vf_scale.o: In function `scale_slice': D:\ffmpeg-HEAD-0f73ac3/libavfilter/vf_scale.c:346: undefined reference to `sws_scale' libavfilter/vf_scale.o: In function `uninit': D:\ffmpeg-HEAD-0f73ac3/libavfilter/vf_scale.c:120: undefined reference to `sws_freeContext' D:\ffmpeg-HEAD-0f73ac3/libavfilter/vf_scale.c:121: undefined reference to `sws_freeContext' D:\ffmpeg-HEAD-0f73ac3/libavfilter/vf_scale.c:122: undefined reference to `sws_freeContext' libavfilter/vf_scale.o: In function `init': D:\ffmpeg-HEAD-0f73ac3/libavfilter/vf_scale.c:100: undefined reference to `sws_get_class' collect2: ld returned 1 exit status make: *** [libavfilter/avfilter-2.dll] Error 1

In this case, the culprit was using --disable-swscale, which is the software scaling module. I suspect someone realised that scaling & filtering had common code.

My videos are all Green

Chances are you are using headers from a previous version of FFmpeg, which is something that has a tendency to break the decoder. Clearing out the old headers and instead rebuilding using the new ones solved the problem.