Mcd.db

PhatDB

Introduction

Phatdb is the name I have given to the mcd.db file format created by PhatNoise Media Manager software to be playable by Kenwood Car Stereo head units supporting ACDrive Technology.

The PhatDB is a database of song metadata. It contains information on all tracks, artists, albums, genres and playlists in a compact format. The concept is similar to the itunesdb database found on ipods, though phatdb is less complex.

This document describes the format of the PhatDB file.

A Free Software program and library to build mcd.db files is available here:

http://phatdb.sourceforge.net/

File Format

All multibyte types are stored in big endian (network) byte order. They must be byte-swapped to be read on little-endian PC platforms.

The overall structure looks like this:

Header

Tracks List

Artist List

Album List

Genre List

Playlists List

Header

The file begins with a header containing the following elements:

Offset	Name	Type	Value	Description
0x00000000	magic	uint32	0x3af7d87c	File Signature
0x00000004	unknown	uint32	0x00000002	Version?
0x00000008	codepage	uint32	0x000001b6	Codepage 437
0x0000000c	unknown	uint32	0x00000002	Constant?
0x00000010	n_tracks	uint32		Total Number of Tracks
0x00000014	n_artists	uint32		Total Number of Artists
0x00000018	n_albums	uint32		Total Number of Albums
0x0000001c	n_genres	uint32		Total Number of Genres
0x00000020	n_playlists	uint32		Total Number of Playlists
0x00000024	artists_len	uint32		Len of Artists Array
0x00000028	albums_len	uint32		Len of Albumns Array
0x0000002c	genres_len	uint32		Len of Genres Array
0x00000030	playlists_len	uint32		Len of Playlist Array
0x00000034	unknown	uint32	0x00000000	Constant?

Track List

The File Header is immediately followed by an array of n_tracks track structures (offsets are relative to start of track structure). Tracks are stored in alphabetical order.:

Offset	Name	Type	Value	Description
0x00000000	artists_id	uint32		Artist ID
0x00000004	album_id	uint32		Album ID
0x00000008	genre_id	uint32		Genre ID
0x0000000c	unknown	uint32	0x00000000	Constant?
0x00000010	title	phat_str		Track Title
0x0000xxxx	path	phat_str		Track Path

Where the phat_str structure looks like this:

Offset	Name	Type	Value	Description
0x00000000	string_length	uint16		Length of String (bytes)
0x00000002	string_width	uint16		Width of String?
0x00000004	data	string		Character Array

When string_width is 2 (Track Title) data is UCS-2 encoded. When string_width is 1 (Track Path), data is CP437 encoded. data is null-terminated and padded to a multiple of 4 bytes. string_length is the length of data (including padding).

List Sections

Immediately following the track listing, there are sections for artists, albums and genres. All lists are in alphabetical order. Each section has the following format:

Offset	Name	Type	Value	Description
0x00000000	item_list	phat_list[]		PhatDB Item List
0x00000xxx	track_item_arr	uint32[]		Track/Item Assignment Array
0x00000xxx	item_index	uint32[28]		Item Index

The structure of the phat_list is as follows:

Offset	Name	Type	Value	Description
0x00000000	array_offset	uint32		Item Array Offset
0x00000004	name	phat_str		Item Name String

array_offset is an index into track_item_arr. This array contains a mapping of track id's relating to that item (artist, album, genre). The length of the each array is given by the fields in the header artists_len, albums_len and genre_len. item_index seems to be an index for skipping through large arrays, perhaps indexed alphabetically?

Playlists

The playlists section immediately follows the genre section. It is identical to the sections above except that it does not have the item_index.