Resampling with input channels greater than 2 unsupported.

http://hibari.2ch.net/test/read.cgi/software/1270542020/-100

mkdir ~/src/
cd ~/src/
svn co svn://svn.ffmpeg.org/soc/libavfilter
cd libavfilter/
sh checkout.sh
cd ffmpeg/libavcodec/
wget http://svn.xiph.org/trunk/ffmpeg2theora/patches/6to2channel-resample.patch
patch resample.c < 6to2channel-resample.patch
cd ../
mkdir ~/ffmpeg
./configure --prefix=$(realpath ~/ffmpeg) && make && make install