Problems with ffmpeg input filenames when using bash script

user_14341334 0
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I'm trying to use ffmpeg to convert some .m4a audio files to .mp3, and have come across something that has me stumped. I'd like to create the .mp3 in the same location and with the same filename as the .m4a, and so I'm using a combination of find/exec and a bash script to do this, as follows:

find /Volumes/Untitled/ -name '[!.]*' -name '*.m4a' -exec ./m4atomp3.sh {} \;

where m4atomp3.sh looks like:

#!/usr/bin/env bash
[[ -f "$1" ]] || { echo "$1 not found" ; exit 1 ; }
P="$1"
echo "$P is the full filename"
filename=${P%.*}
echo "$filename is the stripped filename"
m4afilename=\"$filename.m4a\"
echo "$m4afilename is the input filename"
mp3filename=\"$filename.mp3\"
echo "$mp3filename is the output filename"
mycmd="/Users/nickstyles/Downloads/ffmpeg -i "$m4afilename" -codec:a libmp3lame -qscale:a 2  -nostdin "$mp3filename
echo $mycmd
$mycmd

Whenever I try this, it fails because ffmpeg doesn't find the file, seemingly because of the whitespace in the filename, e.g if the file was called /Volumes/Untitled/My M4As/My M4A.m4a I would see:

ffmpeg version N-99346-g003b5c800f-tessus  https://evermeet.cx/ffmpeg/  Copyright (c) 2000-2020 the FFmpeg developers
  built with Apple clang version 11.0.0 (clang-1100.0.33.17)

[configuration details]

"/Volumes/Untitled/My: No such file or directory

However, if I just paste what is returned by echo $mycmd into the command line, e.g:

/Users/nickstyles/Downloads/ffmpeg -i "/Volumes/Untitled/My M4As/My M4A.m4a" -codec:a libmp3lame -qscale:a 2 -nostdin "/Volumes/Untitled/My M4As/My M4A.mp3"

then it works absolutely fine. I'm sure I'm missing something very obvious, which hopefully someone can spot!

ffmpeg macos bash
2 Answers

As Benjamin W. pointed out the problem was that the variable was still getting split by bash, due to WordSplitting, and the quotes I was adding to the content of the variable were not helping against this. The key was to ensure that the quotes were placed around the variable itself like:

m4afilename=$filename.m4a
echo "$m4afilename is the input filename"
mp3filename=$filename.mp3
echo "$mp3filename is the output filename"
/Users/nickstyles/Downloads/ffmpeg -i "$m4afilename" -codec:a libmp3lame -qscale:a 2  -nostdin "$mp3filename"

and now this works!

user_143413340

Try this : mycmd="/Users/nickstyles/Downloads/ffmpeg -i $m4afilename -codec:a libmp3lame -qscale:a 2 -nostdin $mp3filename"

In bash, you can put variable straight into double quotes.

user_23511240
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