bash script fro removing audio tracks from mkv

hysiria · 10-18-2011, 03:26 AM

hello,

i have a little problem writing a script to remove audio tracks from a mkv file.
what i want to do is:
in a folder are several mkv files with 2 audio tracks.
default track ID is 2 and the other audio track ID is 3.
i want to have a script that automatically removes all audio tracks with ID3 from any mkv file in the folder.
i found a .bat script for windows that is working very well but i dont know how to write that script for linux.

the windows script is as follows:

Code:

FOR /F "delims=*" %%A IN ('dir /b *.MKV') DO "<path_to_mkvmerge>mkvmerge.exe" -o "fixed_%%A" -a !3 --compression -1:none "%%A"

could someone help me please?

colucix · 10-18-2011, 03:47 AM

Hi and welcome to LinuxQuestions!

First you need the mkvtoolnix package which provides the mkvmerge command. Then you just need to translate the DOS for loop in a shell version, e.g using bash

Code:

#!/bin/bash
for file in *.mkv
do
  mkvmerge -o "fixed_$file" -a !3 --compression -1:none "$file"
done

This assumes that the extensions of all the mkv files to convert is lowercase and that there are no spaces in the file names. If this is not the case you need some little modification to this script.

hysiria · 10-18-2011, 03:57 AM

hey thank you very much for your fast answer.
alot of the mkv's have spaces in their file names but all extensions are lowercase.
how would the script look like to handly spaces in the file names?

David the H. · 10-18-2011, 08:46 AM

Actually, the above loop should have no problem processing filenames with spaces.

The *.mkv globbing pattern expands to a list of all .mkv filenames in the directory, however they're named, and the loop will read each one in turn. Since the shell does the glob expansion step after word-splitting has been completed, each expanded name is treated as a separate argument. Therefore it's safe to use glob input in a for loop.

http://mywiki.wooledge.org/glob

Note that other kinds of input string aren't safe, such as with the output of a command or variable substitution, because parameter expansions happen before word-splitting. The substituted strings will be broken up into individual words before the loop sees them. In these cases, you should use a while+read loop.

http://mywiki.wooledge.org/DontReadLinesWithFor
http://mywiki.wooledge.org/BashFAQ/001

The only other place where spaces would be a problem is when the variable is expanded later on in the mkvmerge command, and for the same reason. But since double-quoting variables protects the expanded string from word-splitting, we're safe here too.

For more on how the shell handles arguments and whitespace, see here:
http://mywiki.wooledge.org/Arguments
http://mywiki.wooledge.org/WordSplitting
http://mywiki.wooledge.org/Quotes

Edit: Incidentally, case matching can be handled simply by adding shopt -s nocaseglob to the script, or by using *.[mM][kK][vV] as your glob pattern.

hysiria · 10-18-2011, 10:44 AM

thank you all very much its working like a charm

hysiria · 10-21-2011, 03:06 AM

another question has come to my mind:

is it possible to extend the script in a way that mkvmerge can delete all non german audio tracks from the mkv?
for example i have a mkv with 2 audio tracks (english, german) but the german track (the one i want to keep) is ID3.
i now want mkvmerge to detect that there are an english and german track and then delete the english track regardless of its ID number.

is that even possible?

after that is finished i want to move the folder/file to another directory

my script i have so far:

Code:

cd /media/storage/mkvmerge
for file in *.mkv */*.mkv */*/*.mkv
do
	fdir=$( dirname "$file")
	mkvmerge -o "$fdir/fixed_$file" -a !3 --compression -1:none "$file" 
	mkdir "/media/storage/movies/$fdir"
	mv "$fdir/fixed_$file" "/media/storage/movies/$fdir/"	
	rm -r "$fdir"
done

it basically works but not very well ;(