Mcd.db
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[edit] PhatDB
[edit] 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/
[edit] 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 |
[edit] 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? |
[edit] 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).
[edit] 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?
[edit] 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.
