BASH: Automatically Use File Name for file Out Put

[Xplorer4x4]

The thread title may not be the best wording, but I couldn't figure out a better way to word it so my apologies if you find this to be a poor thread title..moving on...

Occasionally I need to convert the audio of problematic MKVs and remux them back in to MKV. I use ffmpeg like so:

ffmpeg -i *.mkv -vcodec copy -acodec ac3 -ab 256000 output.mkv

This gets the job done but I either need to insert the target file name manually in the cli or I rename "output.mkv." Instead, is it possible to take the filename of the source mkv and simply append a 1 to the filename? So if *.mkv finds somevideo.mkv can I make it so the remux files would automaticly be named somevideo1.mkv?

[james147]

Simple solution is to create a script with the following:

#!/bin/bash
ffmpeg -i "${1}" -vcodec copy -acodec ac3 -ab 256000 "${2}"

you can then launch it with ./scriptname input_file_name.mkv output_file_name.mkv

or for a more advanced approach:

#!/bin/bash
input="${1}"

if [ -z "${2}" ] ; then
    extension="${input##*.}"
    filename="${input%.*}"
    output="${filename}-1.${extension}"
else
    output="${2}"
fi

ffmpeg -i "${input}" -vcodec copy -acodec ac3 -ab 256000 "${output}"

and invoke it with./scriptname input_file.mkv and it will create the output as input_file-1.mkv or execute it with ./scriptname input.mkv output.mkv to create output.mkv (though I have not tested this script)

You could use this with the find command to use this script on multiple files:

find -iname "*.mkv" -exec ./scriptname "{}" ";"

which will execute the script for each file it finds with the .mkv extension (recursively).

[claydoh]

you might want to investigate regexp (regular expressions), I know it is 100 percent possible to do what you want, but have no idea how. But it will involve regex

[Xplorer4x4]

James, thanks! that works great. I was hopping to keep it simple to add to a service menu but in my own research I pretty much conclude it is not possible to do it strictly in a service menu, which often seems to be the case with my service menu needs so I need to figure a way to keep the servicemenu folder organized.

Claydoh, thanks but I hate regex for the most part. php,bash,html even c++, sure no problem but I just never have been able to wrap my hear around regex.


I am a bit confused though, when I use ffmpeg through the service menu, the bitrate of the video drops by 2, so say the bitrate is 5000, the output video is 4998. However If I run ffmpeg using the code from the op, the bitrate does not change at all. I am bit confused why the bitrate would change since both use vcodec copy

[oshunluvr]

Two thoughts:

1. What if, rather than renaming the target, you rename the source prior to the ffmpeg command then use the input name as the output name? Then you need only delete the old file once you've verified the new one - rather than going through a round of renaming the files you're saving.

2. ffmpeg is being phased out in favor of avconv.

The service menu causing the bitrate drop is really wierd. I'm going to have to test this on my system to see if I get the same results.

[Xplorer4x4]

1. Not a bad idea but this is essentially the process I am used to and it would probably slow down my productivity, not that it matters that much since it is not like this is work related, as it would probably result in me transferring the wrong file to my "NAS" a lot of times. When transferring a 5+GB file at ~9MB/s I would rather not have to re-transfer often. I am sure other who find the thread might like this method more though if you want to share.

2. Thanks I will look in to that.

[oshunluvr]

Re. #1 I should have said "Have the script rename the original file". I was just thinking, since you're going to use a script, you might as well automate as much as possible.

[Xplorer4x4]

I understood, guess I read it wrong. I just don't see the point in doing any renaming. Typically I just remux and move the new file to my NAS. The original file is just deleted and the copy on my NAS is typically deleted after watching. On a rare occasion I may decide to archive it back on one of my internal HDDs but only then do I bother with any renaming.

Now I may not be thinking outside the box, so if I am missing how this would be beneficial in my case, I am all open for suggestions, but for my needs, it is adding a step I do not normally do anyways even if it is automated.

[james147]

This one is even better (and there is no need for renaming anything since it automatically outputs filename.extension to filename-1.extension thus keeping the original intact).

#!/bin/bash
convert() {
    input="${1}"
    extension="${input##*.}"
    filename="${input%.*}"
    output="${filename}-1.${extension}"


    if ffmpeg -i "${input}" -vcodec copy -acodec ac3 -ab 256000 "${output}"; then
        kdialog --passivepopup "Completed ${output}" 60
    else
        kdialog --passivepopup "Failed ${output}" 60
        return 1 # Change to exit 1 to stop the script on first failure
    fi
}

if [ -z "${1}" ] ; then
    echo "Not enough arguments, exiting"
    exit 1
fi

for file in ${@} ; do
    convert ${file}
done

You should be able to combine this with a service menu that contains the exec line:
exec=/path/to/script/scriptname %F

This should allow you to convert multiple files at once and tell you when it has finished each file

Again this is untested.

You can also add a

rm -f ${input}

after the success message to delete the input file if you never need it, but I would keep it just incase the convert fails.

[Xplorer4x4]

#Exec=konsole --hold --workdir %f -e find  -maxdepth 1 -iname "*.mkv" -exec ~/.kde/share/kde4/services/ServiceMenus/ffmpeg.sh "{}" ";"

This is what I was using but your method does look much nicer, but I can't get it to work. When I click the command in the service menu, nothing happens. Not even the new file is silently produced in the working dir.

[james147]

Does anything happen if you add "konsole --hold -e" before the command?

[Xplorer4x4]

Warning: Could not find '/home/xplorer4x4/.kde/share/kde4/services/ServiceMenus/ffmpeg2.sh', starting '/bin/bash' instead. Please check your profile settings.

The thing Is I am looking in the ServiceMenus folders and the script is there. :s

Update:
If I add konsole --hold -e sh /path/to.script.sh I get this:

/home/xplorer4x4/.kde/share/kde4/services/ServiceMenus/ffmpeg2.sh: 23: /home/xplorer4x4/.kde/share/kde4/services/ServiceMenus/ffmpeg2.sh: Syntax error: Unterminated quoted string

Going to look at line 23 and see what I find.

Update2:
Lines 23 is the last line that says done, so I tried done; but no luck.

Update 3:
Solved, on line 17 you had:

if [ -z "${1} ] ; then

You missed a closing quote:

if [ -z "${1}" ] ; then

So it works fine in konsole, and I tested the updated version in a service menu using Exec=/path/to/ffmpeg.sh %U and it is back to doing nothing at all. I am wondering if the script would need to be place in /usr/bin/ or atleast symlinked then called through the service menu as ffmpeg2.sh(Not I am actually using avconv now but for the sake of keeping it simple seems easier to follow the trend of using ffmpeg,

[james147]

I updated the script in comment #9 to fixs some errors (not just the missing ").

Is the script executable? It shouldn't matter where it is if you use the full path. Here is the service menu I used to test it

[Desktop Entry]
Actions=Convert;
Type=Service
ServiceTypes=KonqPopupMenu/Plugin
MimeType=all/all;


[Desktop Action Convert]
Name=Convert file
Type=Service
Exec=/home/james/test.sh %F

Note I change %U (list of URLs) to %F (list of files) but both should work for files, %F just stops it sending folders to the script.

[Xplorer4x4]

Thanks James, I updated the script and everything worked fine then. this is going to be so much more convenient and preferable to launching konsole.