ITunesDB/Equalizer Presets File

From iPodLinux

Equalizer Presets file

The EQPresets file consists of a Presets Container to specify the number of EQPresets in the file, and then a series of EQ Presets as its children.

Equalizer Presets Container

mqed format

field	size	value
header identifier	4	mqed
header size	4	the size of the mqed header
unk1	4	unknown
unk2	4	unknown
number of presets	4	the number of presets defined in this file
childsize	4	the size of an individual preset in bytes. Always 588, thus far.
rest of header is zero padded

Equalizer Preset

Each EQ Preset contains two actual presets. The first one is the representation you see in iTunes - a 10 band Equalizer. iTunes actually displays the given bands slightly wrong. The real values it uses are: 32Hz, 64Hz, 128Hz, 256Hz, 512Hz, 1024Hz, 2048Hz, 4096Hz, 8192Hz, 16384Hz

The EQ Preset also contains a 5 band version of the exact same preset. The algorithim it uses to determine this from the 10 band preset is not known, but you can assume it uses some form of curve fitting method. In any case, the 5 band version would be the EQ setting that the iPod actually would use, if it actually read and used this file as it obviously was supposed to do. The reason for this is that the iPod's audio DSP is capable of applying a 5 band EQ directly.

pqed format

field	size	value
header identifier	4	pqed
length of preset name	2	the length, in bytes, of the name of the preset
name	510	The name of the preset, padded with nulls at the end. This is always 510 bytes long.
preamp	4	The preamp value. Possible values are from -1200 to 1200, measured as dB * 100. This is a signed long.
number of bands	4	number of bands in the preset. This is always 10.
band values	40	10 bands of values, each a signed long from -1200 to 1200 (measured as dB * 100)
number of bands 2	4	number of bands in the second representation. This is always 5.
band values 2	20	5 bands of values, each a signed long from -1200 to 1200 (measured as dB * 100)
rest of pqed is NOT zero padded