分类：
2008-12-17 15:11:40
| offset | field | size | value |
|---|---|---|---|
| 0 | 头标识符 | 4 | mhsd |
| 4 | 块头长度 | 4 | 同上 |
| 8 | 块总长度 | 4 | 同上 |
| 12 | 块类型 | 4 | 一个类型标志数. 1 = 音轨列表 - 包含一个MHLT 2 = 播放列表 - 包含一个MHLP 3 = 广播列表 - 可能是一个可选项. 也包含一个MHLP. 这个MHLP基本上跟一个完全的播放列表一样, 除了他还包含一些采用略微不同的方式保存的podcast. 看看播放列表就知道了. 4 = 专辑列表, 从iTunes 7.1开始第一次出现. 5 = 新的播放列表(智能播放), iTunes 7.3开始出现 |
| 其他部分以零填充. | |||
根据数据集的结构表, 它要么包含一个音轨子节点列表, 要么包含一个播放子节点列表. 顺序则一般无关紧要. 在例子中类型3 MHSD 就要先于类型 2 MHSD. 但是为了使iPod顺序列出lpodcasts类型3数据集必须确保放在类型1和类型2 的数据集之间.
| offset | field | size | value |
|---|---|---|---|
| 0 | 块标识符 | 4 | mhlt |
| 4 | 块头长度 | 4 | 同上 |
| 8 | 歌曲总数 | 4 | 音轨列表中的歌曲总数量 |
| 其他位置填零 | |||
音轨列表的子节点是音轨.音轨的数量就是歌曲的数量
| offset | field | size | value |
|---|---|---|---|
| 0 | 块标识符 | 4 | mhit |
| 4 | 块头长度 | 4 | mhit头的长度. For dbversion <= 0x0b (iTunes 4.7 and earlier), the length is 0x9c. For dbversion >= 0x0c (iTunes 4.71 and later), the size is 0xf4. For dbversion = 0x12 (iTunes 6.0.5), 0x13 (iTunes 7.0) the size is 0x148. For dbversion >= 0x14 (iTunes 7.1) the size is 0x184. For dbversion >= 0x1b (iTunes 7.6), the size is 0x01b4. For dbversion >= 0x20 (iTunes 7.7.0), the size is 0x0208. For dbversion >= 0x23 (iTunes 8.0.0), the size is 0x0248. |
| 8 | 块总长度 | 4 | 块头和所有子节点的长度 |
| 12 | 字符串数量 | 4 | 该项含有的描述性字符串(mhods)的数量. |
| 16 | 唯一id | 4 | 音轨的唯一ID (在播放列表中被引用) |
| 20 | 可视控制 | 4 | 当该位置为1时, 在ipod中可视,当为其他任何值时, 在iPod中不可视. |
| 24 | 文件类型 | 4 | This appears to always be 0 on 1st through 4th generation hard drive-based iPods. For the iTunesDB that is written to the 5th generation iPod (iPod Video) and the iPod Shuffle, iTunes 4.7.1 (and greater) writes out the file's type as an ANSI string padded with spaces. For example, an MP3 file has a filetype of 0x4d503320 -> 0x4d = 'M', 0x50 = 'P', 0x33 = '3', 0x20 = |
| 28 | type1 | 1 | CBR MP3s are type 0x00, VBR MP3s are type 0x01, AAC are type 0x00 |
| 29 | type2 | 1 | CBR MP3s are type 0x01, VBR MP3s are type 0x01, AAC are type 0x00 (type1 and type2 used to be one 2 byte field, but by it doesn't get reversed in the reversed endian iTunesDB for mobile phones, so it must be two fields). |
| 30 | compilation flag | 1 | 1 if the flag is on, 0 if the flag is off |
| 31 | stars/rating | 1 | the rating of the track * 20. Note that the iPod does not update this value here when you change the rating. See the Play Counts file for more information. |
| 32 | last modified time | 4 | last modified time of the track |
| 36 | size | 4 | size of the track, in bytes |
| 40 | length | 4 | length of the track, in milliseconds |
| 44 | track number | 4 | the track number of the track (the 9 in 9/15) |
| 48 | total tracks | 4 | the total number of tracks on this album (the 15 in 9/15) |
| 52 | year | 4 | year of the track |
| 56 | bitrate | 4 | bitrate of the track (ie, 128, 320, etc) |
| 60 | sample rate | 4 | sample rate of the track (ie. 44100) multiplied by 0x10000. |
| 64 | volume | 4 | Volume adjustment field. This is a value from -255 to 255 that will be applied to the track on playback. If you adjust the volume slider in iTunes track info screen, this is what you are adjusting. |
| 68 | start time | 4 | time, in milliseconds, that the song will start playing at |
| 72 | stop time | 4 | time, in milliseconds, that the song will stop playing at |
| 76 | soundcheck | 4 | The SoundCheck value to apply to the song, when SoundCheck is switched on in the iPod settings. The value to put in this field can be determined by the equation: X = 1000 * 10 ^ (-.1 * Y) where Y is the adjustment value in dB and X is the value that goes into the SoundCheck field. The value 0 is special, the equation is not used and it is treated as "no Soundcheck" (basically the same as the value 1000). This equation works perfectly well with ReplayGain derived data instead of the iTunes SoundCheck derived information. |
| 80 | play count | 4 | play count of the song. Note that the iPod does not update this value here. See the Play Counts file for more information. |
| 84 | play count 2 | 4 | play count of the song since the last sync. Used to sync play count information back to iTunes. See the Play Counts file for more information. |
| 88 | last played time | 4 | time the song was last played. Note that the iPod does not update this value here. See the Play Counts file for more information. |
| 92 | disc number | 4 | disc number, for multi disc sets |
| 96 | total discs | 4 | total number of discs, for multi disc sets. |
| 100 | userid | 4 | Apple Store/Audible User ID (for DRM'ed files only, set to 0 otherwise). Previously known as unk5. |
| 104 | date added | 4 | date added to the iPod or iTunes (not certain which) |
| 108 | bookmark time | 4 | the point, in milliseconds, that the track will start playing back at. This is used for AudioBook filetypes (.AA and .M4B) based on the file extension. Note that there is also a bookmark value in the play counts file that will be set by the iPod and can be used instead of this value. See the Play Counts file for more information. |
| 112 | dbid | 8 | Unique 64 bit value that identifies this song across the databases on the iPod. For example, this id joins an iTunesDB mhit with a ArtworkDB mhii. iTunes appears to randomly create this value for a newly formatted iPod, then increments it by 1 for each additional song added. Previously known as unk7 and unk8. |
| 120 | checked | 1 | 0 if the track is checked, 1 if it is not (in iTunes) |
| 121 | application rating | 1 | This is the rating that the song had before it was last changed, sorta. If you sync iTunes and the iPod, and they have different (new) ratings, the rating from iTunes will go here and the iPod rating will take precedence and go into the normal rating field. I'm uncertain what exactly this is for, but it's always set to what the iTunes rating is before each sync. |
| 122 | BPM | 2 | the BPM of the track |
| 124 | artwork count | 2 | The number of album artwork items put into the tags of this song. Even if you don't put any artwork items into the tags of the song, this value must at least be 1 for the iPod to display any artwork stored in the ithmb files. |
| 126 | unk9 | 2 | unknown, but always seems to be 0xffff for MP3/AAC songs, 0x0 for uncompressed songs (like WAVE format), 0x1 for Audible |
| 128 | artwork size | 4 | The total size of artwork (in bytes) attached to this song (i.e. put into the song as tags). Observed in iPodDB version 0x0b and with an iPod Photo as well as with iPodDB version 0x0d and an iPod Nano. |
| 132 | unk11 | 4 | unknown |
| 136 | sample rate 2 | 4 | The sample rate of the song expressed as an IEEE 32 bit floating point number. It's uncertain why this is here. |
| 140 | date released | 4 | date/time added to music store? For podcasts this corresponds to the release date as displayed to the right of the podcast title. Formerly known as unk13. |
| 144 | unk14/1 | 2 | unknown, but MPEG-1 Layer-3 songs appear to be always 0x000c, MPEG-2 Layer 3 songs (extrem low bitrate) appear to be 0x0016, MPEG-2.5 Layer 3 songs are 0x0020, AAC songs are always 0x0033, Audible files are 0x0029, WAV files are 0x0000. |
| 146 | explicit flag | 2 | If this flag is set to 1, the track is shown as explicit content in iTunes. Otherwise set this flag to 0. Was previously known as unk14/2. |
| 148 | unk15 | 4 | unknown - used for Apple Store DRM songs (always 0x01010100?), zero otherwise |
| 152 | unk16 | 4 | unknown |
| 156 | Skip Count | 4 | Number of times the track has been skipped. Formerly unknown 17 (added in dbversion 0x0c) |
| 160 | Last Skipped | 4 | Date/time last skipped. Formerly unknown 18 (added in dbversion 0x0c) |
| 164 | has_artwork | 1 | added in dbversion 0xd. Seems to be set to 0x02 for tracks without associated artwork (even if artwork is present, it will not be shown on the iPod) and 0x01 for tracks with associated artwork. |
| 165 | skip_when_shuffling | 1 | sets "Skip When Shuffling" when set to 0x1 (added in dbversion 0xd, formerly known as flag2) |
| 166 | remember_playback_position | 1 | sets "Remember Playback Position" when set to 0x1 (added in dbversion 0xd). Note that Protected AAC files (.m4b extension) and Audible files (.aa extension) do not set this flag or the previous one (skip_when_shuffling), and yet are always bookmarkable and are never included in the song shuffle. To determine if a file is bookmarkable, therefore, check the file type first. If it's not an .m4b or .aa, then check this flag in iTunesDB. (Formerly known as flag3) |
| 167 | flag4 | 1 | some kind of "Podcast" flag (added in dbversion 0xd)? When this flag is set to 0x1 then the "Now playing" page will not show the artist name, but only title and album. When additionally has_artwork is 0x2 then there will be a new sub-page on the "Now playing" page with information about the podcast/song.
If the track item is a kind of podcast then this flag must be set to 0x1 or 0x2, otherwise this flag must be set to 0x0. If this flag do not follow this, it might be removed from iTunesDB when user change there iPod to sync podcasts/songs in iTunes. |
| 168 | dbid2 | 8 | Until dbversion 0x12, same data as dbid above (added in dbversion 0x0c). Since 0x12, this field value differs from the dbid one. |
| 176 | lyrics flag | 1 | set to 0x01 if lyrics are stored in the MP3 tags ("USLT"), 0 otherwise. |
| 177 | movie file flag | 1 | if 0x1, it is a movie file. Otherwise, it is an audio file. |
| 178 | played_mark | 1 | added in dbversion 0x0c, first values observed in 0x0d. Observed to be 0x01 for non-podcasts. With podcasts, a value of 0x02 marks this track with a bullet as 'not played' on the iPod, irrespective of the value of play count above. A value of 0x01 removes the bullet. Formerly known as unk20. |
| 179 | unk17 | 1 | unknown - added in dbversion 0x0c. So far always 0. |
| 180 | unk21 | 4 | unknown (added in dbversion 0x0c) |
| 184 | pregap | 4 | Number of samples of silence before the songs starts (for gapless playback). |
| 188 | sample count | 8 | Number of samples in the song (for gapless playback). |
| 196 | unk25 | 4 | unknown (added in dbversion 0x0c) |
| 200 | postgap | 4 | Number of samples of silence at the end of the song (for gapless playback). |
| 204 | unk27 | 4 | unknown - added in dbversion 0x0c, first values observed in 0x0d. Appears to be 0x1 for files encoded using the MP3 encoder, 0x0 otherwise. |
| 208 | Media Type | 4 | (formerly known as unk28; added in dbversion 0x0c). It seems that this field denotes the type of the file on (e.g.) the 5g video iPod. It must be set to 0x00000001 for audio files, and set to 0x00000002 for video files. If set to 0x00, the files show up in both, the audio menus ("Songs", "Artists", etc.) and the video menus ("Movies", "Music Videos", etc.). It appears to be set to 0x20 for music videos, and if set to 0x60 the file shows up in "TV Shows" rather than "Movies". The following list summarizes all observed types:
Caution: Even if a track is marked as "Audiobook" here (value 0x08), it will not show up in the "Audiobooks" menu on the iPod. Only *.aa and *.m4b are shown there by recent firmwares. One proven exception: On the nano they show if they have the correct media type set here and the MHIT also has a ! |
| 212 | season number | 4 | the season number of the track, for TV shows only. Previously known as unk29. (added in dbversion 0x0c) |
| 216 | episode number | 4 | the episode number of the track, for TV shows only - although not displayed on the iPod, the episodes are sorted by episode number. Previously known as unk30. (added in dbversion 0x0c) |
| 220 | unk31 | 4 | unknown (added in dbversion 0x0c). Has something to do with protected files - set to 0x0 for non-protected files. |
| 224 | unk32 | 4 | unknown (added in dbversion 0x0c) |
| 228 | unk33 | 4 | unknown (added in dbversion 0x0c) |
| 232 | unk34 | 4 | unknown (added in dbversion 0x0c) |
| 236 | unk35 | 4 | unknown (added in dbversion 0x0c) |
| 240 | unk36 | 4 | unknown (added in dbversion 0x0c) |
| 244 | unk37 | 4 | unknown (added in dbversion 0x13) |
| 248 | gaplessData | 4 | The size in bytes from first Synch Frame (which is usually the XING frame that includes the LAME tag) until the 8th before the last frame. The gapless playback does not work for MP3 files if this is set to zero. Maybe the iPod prepares the next track when rest 8 frames in the actual track. For AAC tracks, this may be zero. (added in dbversion 0x13) |
| 252 | unk38 | 4 | unknown (added in dbversion 0x0c) |
| 256 | gaplessTrackFlag | 2 | if 1, this track has gapless playback data (added in dbversion 0x13) |
| 258 | gaplessAlbumFlag | 2 | if 1, this track does not use crossfading in iTunes (added in dbversion 0x13) |
| 260 | unk39 | 20 | Appears to be a hash, not checked by the iPod |
| 280 | unk40 | 4 | unknown (seen set to 0xbf) |
| 284 | unk41 | 4 | unknown |
| 288 | unk42 | 4 | unknown (always 0x00 ?) |
| 292 | unk43 | 4 | unknown (previously length 8, seen as 0x818080808080) |
| 296 | unk44 | 2 | unknown (previously length 8, seen as 0x818080808080) |
| 298 | AlbumID | 2 | album id from the album list (previously unknown length 8, seen as 0x818080808080) |
| 352 | mhii-link | 4 | Setting this offset to != 0 triggers the 'Right-Pane-Artwork-Slideshow' on late 2007 iPods (3g Nano) and causes the iPod to use this value to do artwork lookups (dbid_1 will be ignored!). This value should be set to the id of the corresponding ArtworkDB mhii (Offset 16) |
| The rest of the mhit is zero padded. | |||
The MHIT is followed by several Data Objects which have string types. At minimum, it must have a Location type MHOD, in order to tell the iPod where the file is located on the iPod itself. It always has a FileType MHOD as well, although it's not totally necessary.
