From http://lumux.co.uk/2012/07/03/cross-compiling-ffmpeg-for-the-raspberry-pi/ and run on Black ASUS

ffmpeg

CROSS COMPILING FFMPEG FOR THE RASPBERRY PI

This is how to cross compile ffmpeg with x264 support for the Raspberry Pi on a Debian 6 64bit host.

Build environment

First set up your build environment by installing the build-essential and git packages from the Debian repo and cloning the debian cross compiling toolchain from GitHub:

$ sudo apt-get install build-essential git-core
$ sudo git clone https://github.com/raspberrypi/tools.git /opt/tools
Next, setup the CFLAGS environment variable with the correct options for the Broadcom BCM2835 SoC and create a variable to point to the toolchain binaries we downloaded in the previous step.

$ export CFLAGS="-O2 -pipe -mcpu=arm1176jzf-s -mfpu=vfp -mfloat-abi=hard -w"
$ export CCPREFIX="/opt/tools/arm-bcm2708/arm-bcm2708hardfp-linux-gnueabi/bin/arm-bcm2708hardfp-linux-gnueabi-"
Build ffmpeg

Now we have everything we need we can download the source code and start building.

Start with the ffmpeg source code

$ git clone git://source.ffmpeg.org/ffmpeg.git ffmpeg
Now the x264 libraries which will download in to the main ffmpeg source tree to keep things nice and tidy

$ cd ffmpeg
$ git clone git://git.videolan.org/x264
Now to actually compile the source code:

x264

$ cd x264
$ ./configure --host=arm-linux --cross-prefix=${CCPREFIX} --enable-static
$ make
$ cd ..
ffmpeg

$ ./configure --enable-cross-compile --cross-prefix=${CCPREFIX} \
--arch=armel --target-os=linux --enable-gpl --enable-libx264 \
--extra-cflags="-Ix264/" --extra-ldflags="-Lx264/"
$ make
If all has gone well you should be left with a ffmpeg binary which you can transfer to your Raspberry Pi.