Usage :

  sndfile-metadata-set [options] <file>
  sndfile-metadata-set [options] <input file> <output file>

Where an option is made up of a pair of a field to set (one of
the 'bext' or metadata fields below) and a string. Fields are
as follows :

    --bext-description       Set the 'bext' description.
    --bext-originator        Set the 'bext' originator.
    --bext-orig-ref          Set the 'bext' originator reference.
    --bext-umid              Set the 'bext' UMID.
    --bext-orig-date         Set the 'bext' origination date.
    --bext-orig-time         Set the 'bext' origination time.
    --bext-loudness-value    Set the 'bext' loudness value.
    --bext-loudness-range    Set the 'bext' loudness range.
    --bext-max-truepeak      Set the 'bext' max. true peak level
    --bext-max-momentary     Set the 'bext' max. momentary loudness
    --bext-max-shortterm     Set the 'bext' max. short term loudness
    --bext-coding-hist       Set the 'bext' coding history.
    --bext-time-ref          Set the 'bext' Time ref.

    --str-comment            Set the metadata comment.
    --str-title              Set the metadata title.
    --str-copyright          Set the metadata copyright.
    --str-artist             Set the metadata artist.
    --str-date               Set the metadata date.
    --str-album              Set the metadata album.
    --str-license            Set the metadata license.

There are also the following arguments which do not take a
parameter :

    --bext-auto-time-date    Set the 'bext' time and date to current time/date.
    --bext-auto-time         Set the 'bext' time to current time.
    --bext-auto-date         Set the 'bext' date to current date.
    --str-auto-date          Set the metadata date to current date.

Most of the above operations can be done in-place on an existing
file. If any operation cannot be performed, the application will
exit with an appropriate error message.

Using libsndfile-1.2.2.