Difference between revisions of "MetaData Handling"

Revision as of 19:46, 4 October 2010

LinuxMCE has the ability to tag multiple types of files, even those with no native tagging ability. This allows the persistence of metadata from linuxmce installation to another as the data is written to file. This page is a wide overview of the process used depending on the types of files and their capabilities.

Basic Handling Overview

ANY attribute stored in the media database for a file be it audio, video or otherwise gets stored on a file level as well. How it gets stored, depends on the file:

mp3 files: Embed ALL the data into the ID3 section of the mp3 file. For any attributes that match analogously we use those attribute types for anything THAT DOESN'T we store it in a format that's read by SerializeClass, in a GEOB tag inside the ID3 section of the file.

Ogg and Flac files, we do similar, using Taglib to map attributes analogously into those media metadata types. TagLib does not support storing blobs, so it can't store everything into the ogg and flac files. Pictures, are stored, as APIC sections in MP3 files or as picture resources in ogg files. Flac files do not have this facility.

FOR ANYTHING ELSE We create what is essentially a file that just contains an ID3 section so it looks like an empty mp3 file alongside the existing file which stores the attributes and data in exactly the same way as mp3 files using APIC resources to store pictures, mapping common attributes to id3 attributes and anything else as a SerializeClass blob inside a GEOB section.

In Practice When a new file is detected by UpdateMedia, its data is interrogated, depending on whether there is an ID3 file, or an embedded id3 section, or something that taglib can handle and the data is brought back into the database. If there is a GEOB section then the other attributes not directly analogous will be brought back in.

When the pictures are brought in, a new picture row is made in the picture table, and the appropriate attribute and join tables. and the picture is stored in '/home/mediapics/xxxxx.jpg' where 'xxxxx' is the PK_Picture row. If tags change on the linuxmce side, they're supposed to be reincorporated back into the serialized tag form. The URL to an image resource if one was specified, is stored as well.

As per Tschak from IRC 7 sept 2010 --Langstonius 05:48, 8 September 2010 (CEST)

Manual file tagging

Manually adding or removing attributes can be accomplished by navigating in the webadmin to 'Media Files Sync'. You can then select the file or files in question and edit attributes or lookup extended metadata via Imdb, Amazon, or TheTVDB.

Automatic File tagging

Currently, audio files have the ability to have tags extracted from them and integrated into the LinuxMCE database. This is not the case for video media. A third party source is necessary to get the metadata. This means that updateMedia needs to be extended to do these lookups automatically to enhance and simplify the media experience. The current very basic outline is as follows:

• Identify video files via updateMedia
• kick the identified files to a subroutine that will extract identifying information
• identify as television show, film, or other video media
• select appropriate data provider and retrieve metadata
• insert data into Linuxmce database, ensure .id3 file is created.

Currently reading and understanding the relevant parts of updateMedia which include but are not limited to:

• filehandlerfactory.cpp(h)

This space to be updated with development progress. --Langstonius 20:46, 4 October 2010 (CEST)