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+date = 2022-07-30
+title = "Recursive Command-Line FLAC to Opus Conversion"
+description = "A retrospective on how I recursively converting my FLAC file music library to OPUS with opusenc."
++++
+
+## Converting FLAC to OPUS
+
+I am currently rebuilding my music library from scratch so that I can 
+effectively archive all the music I own in the [FLAC file 
+format](https://en.wikipedia.org/wiki/FLAC), a lossless audio codec.
+
+However, streaming FLAC files outside the home can be difficult due to the 
+size of the files, especially if you're using a weak connection.
+
+So, in order to archive the music in a lossless format and still be able to 
+stream it easily, I opted to create a copy of my FLAC files in the [Opus audio 
+codec](https://en.wikipedia.org/wiki/Opus_(audio_format)). This allows me to 
+archive a quality, lossless version of the music and then point my streaming 
+service to the smaller, stream-ready version.
+
+### Dependencies
+
+The process I follow utilizes the `opus-tools` package in Ubuntu. Before 
+proceeding, install the package:
+
+```sh
+sudo apt install opus-tools
+```
+
+If you want to use a different conversion method, such as `ffmpeg` or `avconv`, 
+simply install that package instead.
+
+### Conversion Process
+
+The script I'm using is stored in my home directory, but feel free to create it 
+wherever you want. It does not need to be in the same directory as your music 
+files.
+
+```sh
+cd ~ && nano transform.sh
+```
+
+Once you have your new bash script opened in an editor, go ahead and paste the 
+following logic into the script.
+
+You **MUST** edit the following variables in order for it to work:
+
+- `source`: The source directory where your FLAC files are stored.
+- `dest`: The destination directory where you want the resulting Opus files to 
+be stored.
+
+You **MAY** want to edit the following variables to suit your needs:
+
+- `filename`: If you are converting to a file format other than Opus, you'll 
+need to edit this so that your resulting files have the correct filename 
+extension.
+- `reldir`: This variable can be edited to strip out more leading directories in 
+the file path. As you'll see later, I ignore this for now and simply clean it up 
+afterward.
+- `opusenc`: This is the actual conversion process. You may want to edit the 
+bitrate to suit your needs. I set mine at 128 but some prefer 160 or higher.
+
+```sh
+#!/bin/bash
+## - The IFS takes care of spaces in file and dirnames
+## - your folders may vary
+## - what you mount to the folders does not matter
+## - in RELDIR, the f5 most likely MUST be edited,
+##    since its responsible, how many leading directories
+##    will be removed from the directory structure in order
+##    to append that exact path to the outfile
+## - the commented echos are still in place in order to give
+##    you the variables for testing, before running.
+
+IFS=$'\n'
+
+## the paths given here contain the directory structure that I want to keep
+## source=/mnt/music/archives/ARTIST/ALBUM/FLACFILE.flac
+## local=/mnt/music/library/ARTIST/ALBUM/OPUSFILE.opus
+
+source=/mnt/music/archives
+dest=/mnt/music/library
+
+for i in $(find $source -type f -iname '*.flac' );
+do
+## SET VARIABLES for PATHS and FILENAMES
+        fullfile=$i
+        filename="${i##*/}"
+        filename="${filename%.*}.opus"
+        fulldir=$(dirname "${i}")
+        reldir="$(echo $fulldir | cut -d'/' -f5-)"
+        reldir=${reldir//flac}
+        outdir="$dest/$reldir"
+        outfile="$outdir/$filename"
+
+# is that working?
+# outfile='$local/""$(echo $(dirname "${i}") | cut -d'/' -f5-)"//flac"/"${i##*/}"'
+#       echo 'output file: ' "$outfile"
+
+## SHOW ME THE CONTENTS of the VARIABLES
+#       echo 'File found:' "$i"
+#       echo 'Relative dir: ' "$reldir"
+#       echo 'directory will be created: ' "$outdir"
+#       echo 'Filename: ' "$filename"
+#       echo 'FileExt: ' "$extension"
+#       echo 'output file: ' "$outfile"
+
+echo "\n\n"
+
+## CREATE Output Folders
+        mkdir -p "$outdir"
+
+## RUN
+# ffmpeg and avconv are alternative options if opusenc isn't adequate
+opusenc --vbr --bitrate 128 --date "$DATE" \
+--title "$TITLE" --artist "$ARTIST" --album "$ALBUM" --genre "$GENRE" \
+--comment "ALBUMARTIST=$ALBUMARTIST" --comment "DISCNUMBER=$DISCNUMBER" \
+--comment "TRACKNUMBER=$TRACKNUMBER" --comment "TRACKTOTAL=$TRACKTOTAL" \
+--comment "LYRICS=$LYRICS" "$fullfile" "$outfile"
+
+
+## just for testing
+#        sleep 1
+done
+```
+
+Once you're done, simply save the file and exit your editor. Don't forget to 
+enable execution of the script:
+
+```sh
+chmod +x transform.sh
+```
+
+Finally, you may now run the script:
+
+```sh
+./transform.sh
+```
+
+If you used `opusenc`, you'll see the conversions happen within the terminal as 
+it progresses.
+You will also see variables printed if you uncommented any of the bash 
+script's comments.
+
+### Cleanup
+
+As I noted above, I didn't customize my `reldir` variable in the script, which 
+caused my output directory to be `/mnt/music/library/archives` instead of 
+`/mnt/music/library`. So, I moved the output up one level and deleted the 
+accidental directory.
+
+```sh
+cd /mnt/music/library
+mv archives/* .
+rm -rf archives
+```
+
+### Check the Resulting Size
+
+If you want to see what kind of file size savings you've gained, you can always 
+use the `du` command to check:
+
+```sh
+cd /mnt/music
+du -h --max-depth=1 .
+```
+
+In my case, my small library went from 78GB to 6.3GB!
+
+```txt
+78G    ./archives
+6.3G   ./library
+```