Mapping your Media file tags to the Twonky Database

From Twonky

Mapping your Media file tags to the Twonky Database

As you will already know, the way that Twonky Server displays your media content to your uPnP player depends crucially on how your media files are tagged.

Media files consist of a 'container' within which is meta data and the actual media data (music, picture, video). An example is a music file from the Apple iTunes store: this comes in a MP4 container (Apple call an audio file in this format an 'm4a' file) within which is the tag data and AAC, ALE or ALAC encoded music.

Twonky Server scans every new media file and from its meta data (ie the tags - I'll use this term from now on since it's shorter) derives values for its database. These values are then interpreted depending the Navigation Tree you select (using the Server configuration screen).

An explanation of how the Navigation Tree works is given in the Twonky download: http://www.twonkyforum.com/download/file.php?id=404 The main database values that Twonky depends on for navigation are:

- upnp:album
- upnp:albumArtist
- upnp:artist
- upnp:author
- upnp:genre
- upnp:actor
- upnp:originalTrackNumber
- dc:title
- dc:date
- pv:rating

What is not spelt out in the document is which tags in which container formats are mapped to these database values. Each container format includes are large number of tag options (most of which are not used by Twonky server). To complicate matters, no open specification is available for the proprietary formats such as Microsoft's WMA and WMV and Apple's m4a.

So this document - which is work in progress and needs your input- aims to tabulate the mapping between Twonky and the container formats. As a starting point, here is a list of four of the main audio file formats:

You will see that not all m4a tags are mapped: in particular, the '©wrt' tag is ignored. This tag typically contains the 'composer' name for a classical music track; without this information, Navigation is problematic - classical music users are well advised to avoid m4a music files until Twonky sort out this issue.

So far as I can find out, WAV files don't formally support metadata. I understand that some tag editors add ID3V1 tags to WAV files but I don't believe that Twonky maps these. So the only way you can find an album of WAV files is to navigate using 'Folder view'.

MP2 files do support metatdata; but I can't get Twonky server to read either ID3V1 or ID3V2 tags (MP2, although an old format, is used for streamed audio - for example, the BBC use it for both DAB and Freeview radio). So as for WAV files, the only way to navigate to an album of MP2 tracks is by using 'Folder view'. My solution for recorded radio data is to clean it up, split it into tracks and add metadata using an audio editor (I use Audacity) and then save as an MP3.

John Glasson Jan 2011