#!/bin/bash
for i in *.mkv
do
mkvmerge -i "${i}" > /tmp/tracks.list
 
VIDEO_ID=`grep ": video" < /tmp/tracks.list | cut -f 3 -d " " | sed 's/://'`
AUDIO_ID=`grep ": audio" < /tmp/tracks.list | cut -f 3 -d " " | sed 's/://'`
 
mkvextract tracks "${i}" ${VIDEO_ID}:video.avi ${AUDIO_ID}:audio.mp3
 
y=`echo "${i}" | sed 's/mkv/avi/'`
 
avimerge -o "${y}" -i video.avi -p audio.mp3
 
rm -f video.avi audio.mp3 /tmp/tracks.list
done