>Date: Mon, 6 Jul 2009 06:51:01 -0400 (EDT)
>From: Mate Szarvas <community-noreply@qnx.com>
>Reply-To: post33148@community.qnx.com
>To: general-multimedia <post33148@community.qnx.com>
>Subject: Typical and maximal storage use by metadata per song
>
> While designing the storage needs for our application
> we came across the question of how much storage
> is needed for metadata per synchronized songs?
>
> Is there an upper limit for this value?

The docs cover setting a limit for this:

mme_en/mme_config/mme_conf_metadata.html#2sync_metadatamax

Limiting the length of metadata strings

The <MetadataStringMaximums> element contains <metadatastring> elements 
that you can use to limit the length of the metadata strings that the MME 
writes in its database.

The default configuration is to not limit the length of metadata strings. 
To change this configuration, remove the comments from around the 
<MetadataStringMaximums> element, and update the attributes for the 
<metadatastring> elements as required.

These attributes are:

     * field  identify the metadata; corresponds to a field in the library_* 
tables
     * maximum  sets the maximum number of characters the MME will write to 
the database for the field

Below is a sample <MetadataStringMaximums> element:

<MetadataStringMaximums>
 	<metadatastring field="artist" maximum="1024"/>
 	<metadatastring field="album" maximum="1024"/>
 	<metadatastring field="genre" maximum="1024"/>
 	<metadatastring field="composer" maximum="1024"/>
 	<metadatastring field="category" maximum="1024"/>
 	<metadatastring field="title" maximum="1024"/>
 	<metadatastring field="conductor" maximum="1024"/>
 	<metadatastring field="soloist" maximum="1024"/>
 	<metadatastring field="ensemble" maximum="1024"/>
 	<metadatastring field="opus" maximum="1024"/>
 	<metadatastring field="description" maximum="1024"/>
</MetadataStringMaximums>

This allows you to set a fixed upper limit on a per song basis.

There are also limits covered on the number of items that can be sync'd
(mme_en/mme_config/mme_conf_synch.html#limit)


> Is there a known typical or average value?

I haven't measured this value to try and gues-timate an average, but on my 
machine with 800+ files, the database is only about 400k after syncing.

Peter