flacconv

flacconv is a 99.9% POSIX¹ shell script that recursively converts directories of flac files to opus/mp3.

when invoked with no arguments, it recursively converts the current directory's flac files to opus with a bitrate of 128k, retaining all metadata and not deleting the original flac files

it also has options for you to change the bitrate, use a variable quality for mp3, keep/remove metadata, and parallel processing

dependencies

• flac
• lame (required for mp3, not required otherwise)
• opus-tools (required for opus, not required otherwise)
• id3v2 (optional, for removing invalid ID3 tags in a flac file before converting)

usage

flacconv [-hdp3] [-b BITRATE] [-v LEVEL] [-k KEYS] [-r KEYS] [-j THREADS] [--] [DIRECTORY...]
DIRECTORY can be specified multiple times. if omitted, the current directory is used
if encoding to mp3, the only metadata that will be kept is the following:
  TITLE, ARTIST, ALBUM, ALBUMARTIST, DATE, GENRE, TRACKNUMBER, COMMENT, and the cover picture
  
 -h           show script help
 -i           ignore script-stopping warnings
 -d           delete original flac files after transcoding
 -3           switch output filetype to mp3
 -b <BITRATE> output bitrate in kbits (default 128)
              this value is variable for opus & CBR for mp3
 -v <LEVEL>   mp3 only: use specified mp3 variable quality (0-9). integer only
              OVERRIDES -b
 -k <KEYS>    keep specified flac metadata KEYS in output file
              keys can be checked with metaflac --export-tags-to=- FILE
              option argument is a PIPE-separated list of UPPERCASE keys to keep
              (i.e. -m 'ARTIST|TITLE|ALBUMARTIST|ALBUM|DATE')
              if both -k and -r are not present, all keys are kept.
 -r <KEYS>    remove specified flac metadata KEYS in output file
              cannot be used with -k
              option argument is of the same format as -k
              if set to 'ALL', all keys are removed
 -p           remove embedded picture in output files
 -j <THREADS> use the specified amount of threads for parallel processing
              if omitted, CPU core count will be used"

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1. /dev/stdin is not POSIX yet is used in this script, but it's supported basically everywhere ↩︎