.TL
Bulk-Edit Vorbis Metadata
.AU
tropf
.AB
A simple hack to bulk edit metadata of vorbis files using scripts.
.AE
.DA
.
.NH 1
Usecase
.PP
I regularly scrape or download music from a variety of sources.
These sources usually provide metadata which follows a certain schema – but not my schema.
.PP
So it is not uncommon that i wan't to transform some schema of metadata to another.
.PP
This article will use the convention of providing the license as URL in den
.CW "copyright"
data field:
.
.CB
[...]
copyright=http://creativecommons.org/licenses/by-nc-nd/3.0/
[...]
.CE
.
.PP
I personally prefer a human readable string, so I would use:
.
.CB
[...]
LICENSE=CC-BY-ND 3.0
[...]
.CE
.
.NOTE
I also use a different key.
.
.NH 1
Metadata of Vorbis Files
.NH 2
Data Structure
.PP
Metadata of vorbis files is a list of strings of the form
.CW "key=value" "."
.PP
Even though the keys are case sensitive,
most programs handling vorbis files
.B "don't care"
and can handle lower and upper case spelling.
.
.NH 2
Editing Metadata
.PP
A simple way to edit metadata of vorbis files is using the program
.CW "vorbistagedit" "."
When invoked by
.CW "vorbistagedit FILE"
it will open an editor with a temporary file looking like this:
.
.CB
# vorbistagedit ($Id$)
#
# Edit the lines in this file to your desire, but
# DO NOT touch lines starting with a colon (:)!
# You may use lines starting with a plus (+) to rename files.
#
# We are in directory:
#  /tmp
#
# Tags that should be applied to all files can be specified
# before the first per-file tag definiton starts.

: Carter_Vail_-_Veltvet.ogg
+ Carter_Vail_-_Veltvet.ogg
TITLE=Veltvet
ARTIST=Carter Vail
TRACKNUMBER=6
DATE=2019
COMPOSER=Carter Vail
LABEL=http://www.jamendo.com
ENCODEDBY=Jamendo:http://www.jamendo.com| LAME
LICENSE=CC-BY-NC-ND 3.0

: EOF
.CE
.PP
You can then edit, save and close the file and your changes will be applied.
.
.NH 1
Editing by Script
.NH 2
Concept
.PP
The basic idea is instead of invoking an interactive editor a script is executed on the file.
.PP
.CW "vorbistagedit"
executes
.CW "$EDITOR TMPFILENAME".
We just have to change
.CW "$EDITOR"
to a script accepting a filename as one argument and changes that file.
.NOTE
Obviously I will use
.CW "sed"
with the
.CW "-i"
flag.
.
.NH 2
Example
.CB
EDITOR='sed -i -E -e "/^license|LICENSE/d" -e "s,^copyright=http://creativecommons.org/licenses/([^/]+)/([^/]+)/,&\enLICENSE=CC-\eU\e1\eE \e2,gi"' vorbistagedit Carter_Vail_-_Veltvet.ogg
.CE
.
.NH 1
See also
.PP
.ULS
.LI
.B vorbistagedit (1):
program used to edit the tags
.LI
.B sed (1):
program i used to manipulate the file
.ULE