iTunes Music Library File Format
This file describes the iTunes Music Library file format for application versions 1.1.2 and 3.0.
iTunes Music Library
The iTunes Music Library file contains a series of variable length blocks. The first part of the file refers to iTunes in general and to the number of playlists the file contains. The middle part holds all of the MP3 data, which is only stored once per item. Each item has a unique identifier used later in the file. The last part of the file contains a list of playlists, and within each playlist is a list of the item identifiers from the middle of the file.
Each block of data begins with a four letter marker which denotes the type of block. Some blocks contain sub-blocks, which means you cannot simply read to the next marker.
The blocks show up roughly in this order:
Byte Length Comment ----------------------- 0 4 'hdfm' 4 4 L = header length 8 4 file length ? 12 4 ? 13 1 N = length of version string 14 N application version string 14+N L-N-17 ?
Byte Length Comment ----------------------- 0 4 'hdsm' 4 4 L = header length 8 4 ? 12 4 block type ? 16 L-16 ?
Byte Length Comment ----------------------- 0 4 'htlm' 4 4 L = header length 8 4 number of songs 12 L-12 ?
Byte Length Comment ----------------------- 0 4 'htim' 4 4 L = header length (usually 156, or 0x9C) 8 4 R = total record length, including sub-blocks 12 4 N = number of hohm sub-blocks 16 4 song identifier 20 4 block type => (1, ?) 24 4 ? 28 4 Mac OS file type (e.g. MPG3) 32 4 modification date 36 4 file size, in bytes 40 4 playtime, millisecs 44 4 track number 48 4 total number of tracks 52 2 ? 54 2 year 56 2 ? 58 2 bit rate 60 2 sample rate 62 2 ? 64 4 volume adjustment (signed) 68 4 start time, milliseconds 72 4 end time, milliseconds 76 4 playcount 80 2 ? 82 2 compilation (1 = yes, 0 = no) 84 12 ? 96 4 playcount again? 100 4 last play date 104 2 disk number 106 2 total disks 108 1 rating ( 0 to 100 ) 109 11 ? 120 4 add date 124 32 ? 156 R-L hohm sub blocks
The hohm block has a header, annotated immediately below, and a data-specific block.
Byte Length Comment ----------------------- 0 4 'hohm' 4 4 L = header length, usually 0x18 8 4 R = total record length 12 4 block type, (1, 2, 3, 4, 5, 6, 0x0b, 0x64) 16 12 ? 28 R-28 block specific data
The data-specific structure follows the header structure of the hohm block. Offsets start at 0', which is byte 28 in the record. Sometimes these data appear to have null bytes alternate with information bytes, as in the Perl string "\000H\000e\000l\000l\000o". In that case, the null bytes count in the length of the data.
Type Decimal Description -------------------------------------- 1 big bag of gook 2 song title 3 album title 4 artist name 5 genre string (not number) 6 file type (e.g. MPEG) 8 comments b 11 URL c 12 composer 3a 58 equalizer data? 3c 60 equalizer preset (text) 64 100 playlist name (used in hpim)
Byte Length Comment ----------------------- 0' 2 ? 2 2 n = length of next thingy ? 4 n ? 4+n 1 N = volume name length up to 27 (e.g. hard drive name) 5+n N volume name 27-N left over bytes from volume name (null bytes) 2 ?? (iTunes 3) 5+n+N 1 M = filename length 6+n+N M filename (let A = n+N+M ) 6+A 4 Mac OS file type 10+A 4 Mac OS creator 14+A 20 ? 24+A 4 B = directory name length 28+A B directory name 28+A+B C? ? gook up to the sequence 0x5a_00_02_00 ? (iTunes 1) ? gook up to the sequence 0x7f_00_02_00 ? (iTunes 3) (let A' = A+B+C ) 28+A' 2 D = length of fully qualified path 30+A' D path =item hohm type 11 (0x0b) Byte Length Comment ----------------------- 0' 12 ? 12 4 N = length of data 16 8 ? 24 N URL
Byte Length Comment ----------------------- 0' 12 ? 12 4 N = length of playlist name 16 8 ? 24 N playlist name
Byte Length Comment ----------------------- 0' 12 ? 12 4 N = length of data 16 8 ? 24 N data
Byte Length Comment ----------------------- 0 4 hpim 4 4 N = length of data 8 4 ? 12 4 ? 16 4 number of items (hptm) in playlist
Byte Length Comment ----------------------- 0 4 hpim 4 4 N = length of data 8 16 ? 24 4 song key (from htim) 28 N - 28 ?
* verify that this works on all available versions
* i've guessed on almost everything in this document, but it seems to work.
Copyright 2002, brian d foy <bdfoy@cpan.org>
You may redistribute this under the same terms as Perl.
To install Mac::iTunes, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Mac::iTunes
CPAN shell
perl -MCPAN -e shell install Mac::iTunes
For more information on module installation, please visit the detailed CPAN module installation guide.