hdcd-fixup: a quick hack to help scan and decode (ie, remove) HDCD
encoding from your music collection.

You will need libsndfile (widely packaged) and libhdcd (not in Debian at least,
see https://github.com/bp0/libhdcd) to build this.

Usage:
    hdcp-fixup [options] file [fileN ...]

    -v: be verbose.  Use twice to be very chatty indeed.
    -b: do *NOT* create the .hdcd backup when replacing files.
    -s: scan only, returns true if the file has effectual HDCD encoding.

Some examples of use:

Check if a file has HDCD encoding:
    if [ hdcd-fixup -s somefile.flac ]; then
        echo sadface, this has HDCD
    fi

Spider your collection, scanning for HDCD and reporting back:
    find /music -type f -name "*.flac" -print0 | xargs -P$(nproc) -n1 -0 hdcd-fixup -vs

Spider your collection, scanning for HDCD and converting tracks where it is
used to some effect to a 24 bit version, keeping the old as filename.hdcd:

    find /music -type f -name "*.flac" -print0 | xargs -P$(nproc) -n8 -0 hdcd-fixup

Note, that this tool will attempt to copy tag information across to the newly
created file, but libsndfile's API does not support arbitrary keys, so only
common tags are transferred.  (Artist, track name, album, etc).

It supports FLAC, WAV, AIFF, AU, etc as input formats and will try to match
the output format to the input.  When using FLAC it always recompresses using
libFLAC's maximum compression.

There is no warranty for this.  If it destroys your record collection, I'm sorry
but you should have backups and not trust strangers on the internet.