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I have composed the following bash script to automatically concatenate mp3 files using ffmpeg:

i=0
for f in "${@:2}"
do
        filter+="[$i:a:0]"
        i=`expr $i + 1`
        files+="-i $f "
done
filter+="concat=n=$i:v=0:a=1[outa]"
ffmpeg $files -filter_complex $filter -map '[outa]' "$1.mp3"

However, I often have to deal with files that have spaces in their filenames, but when dragged to the terminal, all spaces get escaped, generating the following command call:

./mergemp3.sh outfilename /path/to/my\ file\ with\ spaces.mp3 /path/to/another\ file\ with\ spaces.mp3

which seems correct to me. However, ffmpeg fails with

/path/to/my: No such file or directory

So obviously, ffmpeg does not understand the space in the filename, although it is properly escaped by a backslash. I guess there's just a nifty detail going on regarding that filename list. Any ideas?

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2 Answers 2

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3

For clarity and safety when building command lines, arrays are your friend:

files=()
i=0
for f in "${@:2}"
do
        filter+="[$((i++)):a:0]"
        files+=(-i "$f")
done
filter+="concat=n=$i:v=0:a=1[outa]"
ffmpeg "${files[@]}" -filter_complex "$filter" -map '[outa]' "$1.mp3"
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1

Try this, which should work with any shell, not just bash (based on a trick I've first seen in an answer by @Kusalananda):

output=$1; shift
i=0
for f in "$@"; do
        shift
        set -- "$@" -i "$f"
        filter="$filter[$i:a:0]"
        i=$((i+1))
done
filter="${filter}concat=n=$i:v=0:a=1[outa]"
ffmpeg "$@" -filter_complex $filter -map '[outa]' "$output.mp3"

This is only about the shell part; I'm not sure that complex filter stuff is really needed.

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