(dd if=$1 bs=1024 count=`du -B 2048 $1 | cut -f 1` | pv -i 0.1 -s `du -B 2048 $1 | cut -f 1`k -c | bzip2 | dd \of=$1aa.bz2 bs=1024) &
(dd if=$1 bs=1024 skip=`du -B 2048 $1 | cut -f 1` count=`du -B 2048 $1 | cut -f 1` | pv -i 0.1 -s `du -B 2048 $1 | \cut -f 1`k -c | bzip2 | dd of=$1ab.bz2 bs=1024) &

wait

cat $1ab.bz2 >> $1aa.bz2
rm $1ab.bz2
mv $1aa.bz2 $1.bz2