Convert ogv to mkv for WDTV

In order to view videos on the WDTV, it's sometimes necessary to convert the format first.

Get an ffmpeg version that supports x264: HowTo.

Then run something like this:
for i in *.ogv; do ffmpeg -i $i -y -vcodec libx264 -profile baseline -preset slow -crf 20 -threads 0 -acodec libfaac `basename $i .ogv`.mkv; done