ffmpeg

Convert format

ffmpeg is most often used to convert file formats for media from the command-line

Convert mp3 to m4a

ffmpeg -i media.{mp3,m4a}

Display metadata

ffmpeg -hide_banner -i $INPUT

Specify metadata

Metadata is defined as key/value pairs, although not all formats support all metadata. This example adds metadata but does not reencode the input file.

ffmpeg -i $INPUTFILE -metadata title=$TITLE -metadata year=$YEAR -codec copy $OUTPUTFILE

Tag all audio in a directory

for INPUT in $(ls *.mp3);
do
    ffmpeg -i "$INPUT" -c copy -metadata genre=Amapiano "${INPUT/.mp3/_tagged.mp3}"
done

Concatenating multiple files

It is possible to combine many files into one. The canonical way of doing this is by first assembling a list of filenames. These must appear in a specific format:

file 'file1.mp3'
file 'file2.mp3'
# etc...

This can be done quickly by piping the output of ls to a file, then editing it manually.

echo $(ls -1 *.mp3) > files

Then this file can be used by ffmpeg, specifying the concat demuxer as the argument to -f

ffmpeg -f concat -i files -c copy compilation.mp3

Chapters will be accepted with the right container (apparently not mp3). Note that mp3 files cannot be placed into a m4a container without re-encoding. Also note that the -map_metadata option must be specified after the second infile, because its argument refers to the second infile as if it were zero-indexed.

ffmpeg -f concat -i files -i chapters -map_metadata 1 -c copy compilation.m4a