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Subject: two questions on the rockbox tagcache DB format

two questions on the rockbox tagcache DB format

From: Aren Olson <>
Date: Tue, 26 Aug 2008 13:54:28 -0500

For the past couple weeks I've been attempting to implement a Tagcache
DB updater in python, for the purpose of allowing the DB to be updated
while connected to the computer, rather than under the device's own
power. You can find my current results at [1], but there are a couple
small questions I have left before I can fully implement this.

First, I noticed that in the individual tag files
(database_[0-8].tcd), values are padded out with Xes, to a length of
4+8*n bytes. However, rockbox appears to be capable of recognizing
that the tag ends in an X despite there not being anything special
done for this in the DB that I can see. Is there some hidden thing
that needs to be done to have this work, or can I safely ignore this
and let rockbox handle it internally?

Secondly, how exactly is the mtime in the database represented? The
code at [2] can read the values out of the DB perfectly, but as you
can see there are two bits in the middle that don't appear to have any
relation to the mtime at all. Thus I cannot determine what they should
be when I need to convert back to the DB's mtime format. Does anyone
know what these bits are supposed to be for?

Aren Olson

[1] -
[2] -

"Whoever said sunshine brings happiness has never danced in the rain."
- K. Jackson
Ubuntu Linux -
Received on 2008-08-26

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