From ba15707b292d827bdce732e7713b26fae3f75c74 Mon Sep 17 00:00:00 2001
From: Alex Bennee ID3v2 is a new tagging system that lets you put enriching and relevant information about your audio files within them. In more down to earth terms, ID3v2 is a chunk of data prepended to the binary audio data. Each ID3v2 tag holds one or more smaller chunks of information, called frames. These frames can contain any kind of information and data you could think of such as title, album, performer, website, lyrics, equalizer presets, pictures etc. The block scheme to the right is an example of how the layout of a typical ID3v2 tagged audio file may look like. One of the design goals were that the ID3v2 should be very flexible and expandable. It is very easy to add new functions to the ID3v2 tag, because, just like in HTML, all parsers will ignore any information they don't recognize. Since each frame can be 16MB and the entire tag can be 256MB you'll probably never again be in the same situation as when you tried to write a useful comment in the old ID3 being limited to 30 characters. Speaking of characters, the ID3v2 supports Unicode so even if you use the Bopomofo character set you'll be able to write in your native language. You can also include in which language you're writing so that one file might contain e.g. the same lyrics but in different languages. Even though the tag supports a lot of byte consuming capabilities like inline pictures and even the possibility to include any other file, ID3v2 still tries to use the bytes as efficient as possibly. If you convert an ID3v1 tag to an ID3v2 tag it is even likely that the new tag will be smaller. If you convert an ID3v1 tag where all fields are full (that is, all 30 characters are used in every field) to an ID3v2 tag it will be 56 bytes bigger. This is the worst case scenario for ID3v1 to ID3v2 conversion. Since it's so easy to implement new functionality into ID3v2, one can hope that we'll see a lot of creative uses for ID3v2 in the future. E.g. there is a built-in system for rating the music and counting how often you listen to a file, just to mention some brainstorm results that are included. This feature can be used to build playlists that play your favourite songs more often than others.
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+ ID3v2 made easy
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+
+
+What is ID3v2?
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+
Example of the internal layout
of an ID3v2 tagged file.
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+
+Some main features
+
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+
+
+
+Informal standard
Document: id3v2.3.0.html
+M. Nilsson
3rd February 1999
+This document is an informal standard and replaces the ID3v2.2.0 +standard. The informal standard is released so that +implementors could have a set standard before a formal standard is +set. The formal standard will use another version or revision number +if not identical to what is described in this document. The contents +in this document may change for clarifications but never for added or +altered functionallity. +
+Distribution of this document is unlimited. +
+ + ++This document describes the ID3v2.3.0, which is a more developed +version of the ID3v2 informal standard (version 2.2.0), +evolved from the ID3 tagging system. The ID3v2 offers a flexible way +of storing information about an audio file within itself to determine +its origin and contents. The information may be technical +information, such as equalisation curves, as well as related meta +information, such as title, performer, copyright etc. +
+ + ++In the examples, text within "" is a text string exactly as it +appears in a file. Numbers preceded with $ are hexadecimal and +numbers preceded with % are binary. $xx is used to indicate a byte +with unknown content. %x is used to indicate a bit with unknown +content. The most significant bit (MSB) of a byte is called 'bit 7' +and the least significant bit (LSB) is called 'bit 0'. +
+A tag is the whole tag described in this document. A frame is a block +of information in the tag. The tag consists of a header, frames and +optional padding. A field is a piece of information; one value, a +string etc. A numeric string is a string that consists of the +characters 0-9 only. +
+ + ++The two biggest design goals were to be able to implement ID3v2 +without disturbing old software too much and that ID3v2 should be +as flexible and expandable as possible. +
+The first criterion is met by the simple fact that the MPEG +decoding software uses a syncsignal, embedded in the audiostream, to +'lock on to' the audio. Since the ID3v2 tag doesn't contain a valid +syncsignal, no software will attempt to play the tag. If, for any +reason, coincidence make a syncsignal appear within the tag it will +be taken care of by the 'unsynchronisation scheme' described in +section 5. +
+The second criterion has made a more noticeable impact on the design +of the ID3v2 tag. It is constructed as a container for several +information blocks, called frames, whose format need not be known to +the software that encounters them. At the start of every frame there +is an identifier that explains the frames' format and content, and a +size descriptor that allows software to skip unknown frames. +
+If a total revision of the ID3v2 tag should be needed, there is a +version number and a size descriptor in the ID3v2 header. +
+The ID3 tag described in this document is mainly targeted at files +encoded with MPEG-1/2 layer I, MPEG-1/2 layer II, MPEG-1/2 layer III +and MPEG-2.5, but may work with other types of encoded audio. +
+The bitorder in ID3v2 is most significant bit first (MSB). The +byteorder in multibyte numbers is most significant byte first (e.g. +$12345678 would be encoded $12 34 56 78). +
+It is permitted to include padding after all the final frame (at the +end of the ID3 tag), making the size of all the frames together +smaller than the size given in the head of the tag. A possible +purpose of this padding is to allow for adding a few additional +frames or enlarge existing frames within the tag without having to +rewrite the entire file. The value of the padding bytes must be $00. +
+ + ++The ID3v2 tag header, which should be the first information in the +file, is 10 bytes as follows: +
+ID3v2/file identifier | "ID3" | |
ID3v2 version | $03 00 | |
ID3v2 flags | %abc00000 | |
ID3v2 size | 4 * %0xxxxxxx |
+The first three bytes of the tag are always "ID3" to indicate that +this is an ID3v2 tag, directly followed by the two version bytes. The +first byte of ID3v2 version is it's major version, while the second +byte is its revision number. In this case this is ID3v2.3.0. All +revisions are backwards compatible while major versions are not. If +software with ID3v2.2.0 and below support should encounter version +three or higher it should simply ignore the whole tag. Version and +revision will never be $FF. +
+The version is followed by one the ID3v2 flags field, of which +currently only three flags are used. +
++a - Unsynchronisation +
+Bit 7 in the 'ID3v2 flags' indicates whether or not unsynchronisation is used (see section 5 for details); a set bit indicates usage.
++b - Extended header +
+ The second bit (bit 6) indicates whether or not the header is + followed by an extended header. The extended header is described in + section 3.2. +
++c - Experimental indicator +
+ The third bit (bit 5) should be used as an 'experimental + indicator'. This flag should always be set when the tag is in an + experimental stage. +
+All the other flags should be cleared. If one of these undefined +flags are set that might mean that the tag is not readable for a +parser that does not know the flags function. +
+The ID3v2 tag size is encoded with four bytes where the most +significant bit (bit 7) is set to zero in every byte, making a total +of 28 bits. The zeroed bits are ignored, so a 257 bytes long tag is +represented as $00 00 02 01. +
+The ID3v2 tag size is the size of the complete tag after +unsychronisation, including padding, excluding the header but not +excluding the extended header (total tag size - 10). Only 28 bits +(representing up to 256MB) are used in the size description to avoid +the introducuction of 'false syncsignals'. +
+An ID3v2 tag can be detected with the following pattern:
+ $49 44 33 yy yy xx zz zz zz zz
+Where yy is less than $FF, xx is the 'flags' byte and zz is less than
+$80.
+
+The extended header contains information that is not vital to the +correct parsing of the tag information, hence the extended header is +optional. +
+Extended header size | $xx xx xx xx | |
Extended Flags | $xx xx | |
Size of padding | $xx xx xx xx |
+Where the 'Extended header size', currently 6 or 10 bytes, excludes +itself. The 'Size of padding' is simply the total tag size excluding +the frames and the headers, in other words the padding. The extended +header is considered separate from the header proper, and as such is +subject to unsynchronisation. +
+The extended flags are a secondary flag set which describes further +attributes of the tag. These attributes are currently defined as +follows +
+ %x0000000 00000000 +
++x - CRC data present +
+ If this flag is set four bytes of CRC-32 data is appended to the + extended header. The CRC should be calculated before + unsynchronisation on the data between the extended header and the + padding, i.e. the frames and only the frames. +
+Total frame CRC | $xx xx xx xx |
+As the tag consists of a tag header and a tag body with one or more +frames, all the frames consists of a frame header followed by one or +more fields containing the actual information. The layout of the +frame header: +
+Frame ID | $xx xx xx xx (four characters) | |
Size | $xx xx xx xx | |
Flags | $xx xx |
+The frame ID made out of the characters capital A-Z and 0-9. +Identifiers beginning with "X", "Y" and "Z" are for experimental use +and free for everyone to use, without the need to set the +experimental bit in the tag header. Have in mind that someone else +might have used the same identifier as you. All other identifiers are +either used or reserved for future use. +
+The frame ID is followed by a size descriptor, making a total header +size of ten bytes in every frame. The size is calculated as frame +size excluding frame header (frame size - 10). +
+In the frame header the size descriptor is followed by two flags +bytes. These flags are described in section 3.3.1. +
+There is no fixed order of the frames' appearance in the tag, +although it is desired that the frames are arranged in order of +significance concerning the recognition of the file. An example of +such order: UFID, TIT2, MCDI, TRCK ... +
+A tag must contain at least one frame. A frame must be at least 1 +byte big, excluding the header. +
+If nothing else is said a string is represented as +ISO-8859-1 characters in the range $20 - $FF. Such strings are +represented as <text string>, or <full text string> if newlines are +allowed, in the frame descriptions. All Unicode strings use +16-bit unicode 2.0 (ISO/IEC 10646-1:1993, UCS-2). Unicode strings +must begin with the Unicode BOM ($FF FE or $FE FF) to identify the +byte order. +
+All numeric strings and URLs are always encoded as ISO-8859-1. +Terminated strings are terminated with $00 if encoded with ISO-8859-1 +and $00 00 if encoded as unicode. If nothing else is said newline +character is forbidden. In ISO-8859-1 a new line is represented, when +allowed, with $0A only. Frames that allow different types of text +encoding have a text encoding description byte directly after the +frame size. If ISO-8859-1 is used this byte should be $00, if Unicode +is used it should be $01. Strings dependent on encoding is +represented as <text string according to encoding>, or <full text +string according to encoding> if newlines are allowed. Any empty +Unicode strings which are NULL-terminated may have the Unicode BOM +followed by a Unicode NULL ($FF FE 00 00 or $FE FF 00 00). +
+The three byte language field is used to describe the language of the +frame's content, according to ISO-639-2. +
+All URLs may be relative, e.g. "picture.png", "../doc.txt". +
+If a frame is longer than it should be, e.g. having more fields than +specified in this document, that indicates that additions to the +frame have been made in a later version of the ID3v2 standard. This +is reflected by the revision number in the header of the tag. +
+ + ++In the frame header the size descriptor is followed by two flags +bytes. All unused flags must be cleared. The first byte is for +'status messages' and the second byte is for encoding purposes. If an +unknown flag is set in the first byte the frame may not be changed +without the bit cleared. If an unknown flag is set in the second byte +it is likely to not be readable. The flags field is defined as +follows. +
+ %abc00000 %ijk00000 +
++a - Tag alter preservation +
+ This flag tells the software what to do with this frame if it is + unknown and the tag is altered in any way. This applies to all + kinds of alterations, including adding more padding and reordering + the frames.
+0 | Frame should be preserved. |
1 | Frame should be discarded. |
+b - File alter preservation +
+ This flag tells the software what to do with this frame if it is + unknown and the file, excluding the tag, is altered. This does not + apply when the audio is completely replaced with other audio data.
+0 | Frame should be preserved. |
1 | Frame should be discarded. |
+c - Read only +
+This flag, if set, tells the software that the contents of this +frame is intended to be read only. Changing the contents might +break something, e.g. a signature. If the contents are changed, +without knowledge in why the frame was flagged read only and +without taking the proper means to compensate, e.g. recalculating +the signature, the bit should be cleared. +
++i - Compression +
+This flag indicates whether or not the frame is compressed.
+0 | Frame is not compressed. |
1 | Frame is compressed using zlib with 4 bytes for 'decompressed size' appended to the frame header. |
+j - Encryption +
+This flag indicates wether or not the frame is enrypted. If set +one byte indicating with which method it was encrypted will be +appended to the frame header. See section 4.26. for more +information about encryption method registration. +
0 | Frame is not encrypted. |
1 | Frame is encrypted. |
+k - Grouping identity +
+This flag indicates whether or not this frame belongs in a group +with other frames. If set a group identifier byte is added to the +frame header. Every frame with the same group identifier belongs +to the same group. +
0 | Frame does not contain group information |
1 | Frame contains group information |
+Some flags indicates that the frame header is extended with +additional information. This information will be added to the frame +header in the same order as the flags indicating the additions. I.e. +the four bytes of decompressed size will preceed the encryption +method byte. These additions to the frame header, while not included +in the frame header size but are included in the 'frame size' field, +are not subject to encryption or compression. +
+ + ++The default settings for the frames described in this document can be +divided into the following classes. The flags may be set differently +if found more suitable by the software. +
+ 1. Discarded if tag is altered, discarded if file is altered. +
+ None. +
+ 2. Discarded if tag is altered, preserved if file is altered. +
+ None. +
+ 3. Preserved if tag is altered, discarded if file is altered. +
+ ETCO, EQUA, MLLT, POSS, SYLT, SYTC, RVAD, TENC, TLEN, TSIZ +
+ 4. Preserved if tag is altered, preserved if file is altered. +
+ The rest of the frames. +
+ + ++The following frames are declared in this draft. +
+This frame's purpose is to be able to identify the audio file in a +database that may contain more information relevant to the content. +Since standardisation of such a database is beyond this document, all +frames begin with a null-terminated string with a URL +containing an email address, or a link to a location where an email +address can be found, that belongs to the organisation responsible +for this specific database implementation. Questions regarding the +database should be sent to the indicated email address. The URL +should not be used for the actual database queries. The string +"http://www.id3.org/dummy/ufid.html" should be used for tests. +Software that isn't told otherwise may safely remove such frames. The +'Owner identifier' must be non-empty (more than just a termination). +The 'Owner identifier' is then followed by the actual identifier, +which may be up to 64 bytes. There may be more than one "UFID" frame +in a tag, but only one with the same 'Owner identifier'. +
+<Header for 'Unique file identifier', ID: "UFID"> | |
Owner identifier | <text string> $00 |
Identifier | <up to 64 bytes binary data> |
+The text information frames are the most important frames, containing +information like artist, album and more. There may only be one text +information frame of its kind in an tag. If the textstring is +followed by a termination ($00 (00)) all the following information +should be ignored and not be displayed. All text frame identifiers +begin with "T". Only text frame identifiers begin with "T", with the +exception of the "TXXX" frame. All the text information frames have +the following format: +
+<Header for 'Text information frame', ID: "T000" - "TZZZ", excluding "TXXX" described in 4.2.2.> | |
Text encoding | $xx |
Information | <text string according to encoding> |
RX | Remix |
CR | Cover |
MPG | MPEG Audio | |
/1 | MPEG 1/2 layer I | |
/2 | MPEG 1/2 layer II | |
/3 | MPEG 1/2 layer III | |
/2.5 | MPEG 2.5 | |
/AAC | Advanced audio compression | |
VQF | Transform-domain Weighted Interleave Vector Quantization | |
PCM | Pulse Code Modulated audio |
DIG | Other digital media | |
/A | Analog transfer from media | |
ANA | Other analog media | |
/WAC | Wax cylinder | |
/8CA | 8-track tape cassette | |
CD | CD | |
/A | Analog transfer from media | |
/DD | DDD | |
/AD | ADD | |
/AA | AAD | |
LD | Laserdisc | |
/A | Analog transfer from media | |
TT | Turntable records | |
/33 | 33.33 rpm | |
/45 | 45 rpm | |
/71 | 71.29 rpm | |
/76 | 76.59 rpm | |
/78 | 78.26 rpm | |
/80 | 80 rpm | |
MD | MiniDisc | |
/A | Analog transfer from media | |
DAT | DAT | |
/A | Analog transfer from media | |
/1 | standard, 48 kHz/16 bits, linear | |
/2 | mode 2, 32 kHz/16 bits, linear | |
/3 | mode 3, 32 kHz/12 bits, nonlinear, low speed | |
/4 | mode 4, 32 kHz/12 bits, 4 channels | |
/5 | mode 5, 44.1 kHz/16 bits, linear | |
/6 | mode 6, 44.1 kHz/16 bits, 'wide track' play | |
DCC | DCC | |
/A | Analog transfer from media | |
DVD | DVD | |
/A | Analog transfer from media | |
TV | Television | |
/PAL | PAL | |
/NTSC | NTSC | |
/SECAM | SECAM | |
VID | Video | |
/PAL | PAL | |
/NTSC | NTSC | |
/SECAM | SECAM | |
/VHS | VHS | |
/SVHS | S-VHS | |
/BETA | BETAMAX | |
RAD | Radio | |
/FM | FM | |
/AM | AM | |
/LW | LW | |
/MW | MW | |
TEL | Telephone | |
/I | ISDN | |
MC | MC (normal cassette) | |
/4 | 4.75 cm/s (normal speed for a two sided cassette) | |
/9 | 9.5 cm/s | |
/I | Type I cassette (ferric/normal) | |
/II | Type II cassette (chrome) | |
/III | Type III cassette (ferric chrome) | |
/IV | Type IV cassette (metal) | |
REE | Reel | |
/9 | 9.5 cm/s | |
/19 | 19 cm/s | |
/38 | 38 cm/s | |
/76 | 76 cm/s | |
/I | Type I cassette (ferric/normal) | |
/II | Type II cassette (chrome) | |
/III | Type III cassette (ferric chrome) | |
/IV | Type IV cassette (metal) |
+
<Header for 'User defined text information frame', ID: "TXXX"> + | |
Text encoding | $xx |
Description | <text string according to encoding> $00 (00) |
Value | <text string according to encoding> |
+With these frames dynamic data such as webpages with touring +information, price information or plain ordinary news can be added to +the tag. There may only be one URL link frame of its kind in an +tag, except when stated otherwise in the frame description. If the +textstring is followed by a termination ($00 (00)) all the following +information should be ignored and not be displayed. All URL link +frame identifiers begins with "W". Only URL link frame identifiers +begins with "W". All URL link frames have the following format: +
+<Header for 'URL link frame', ID: "W000" - "WZZZ", excluding "WXXX" described in 4.3.2.> | |
URL | <text string> |
+This frame is intended for URL links concerning the audiofile +in a similar way to the other "W"-frames. The frame body consists +of a description of the string, represented as a terminated string, +followed by the actual URL. The URL is always encoded with ISO-8859-1. There may be more than one "WXXX" frame in each tag, +but only one with the same description. +
+<Header for 'User defined URL link frame', ID: "WXXX"> | |
Text encoding | $xx |
Description | <text string according to encoding> $00 (00) |
URL | <text string> |
+Since there might be a lot of people contributing to an audio file in +various ways, such as musicians and technicians, the 'Text +information frames' are often insufficient to list everyone involved +in a project. The 'Involved people list' is a frame containing the +names of those involved, and how they were involved. The body simply +contains a terminated string with the involvement directly followed +by a terminated string with the involvee followed by a new +involvement and so on. There may only be one "IPLS" frame in each +tag. +
+<Header for 'Involved people list', ID: "IPLS"> | |
Text encoding | $xx |
People list strings | <text strings according to encoding> |
+This frame is intended for music that comes from a CD, so that the CD +can be identified in databases such as the CDDB. The frame +consists of a binary dump of the Table Of Contents, TOC, from the CD, +which is a header of 4 bytes and then 8 bytes/track on the CD plus 8 +bytes for the 'lead out' making a maximum of 804 bytes. The offset to +the beginning of every track on the CD should be described with a +four bytes absolute CD-frame address per track, and not with absolute +time. This frame requires a present and valid "TRCK" frame, even if +the CD's only got one track. There may only be one "MCDI" frame in +each tag. +
+<Header for 'Music CD identifier', ID: "MCDI"> | |
CD TOC | <binary data> |
+This frame allows synchronisation with key events in a song or sound. +The header is: +
<Header for 'Event timing codes', ID: "ETCO"> | |
Time stamp format | $xx |
+Where time stamp format is: +
+ $01 Absolute time, 32 bit sized, using MPEG frames as unit
+ $02 Absolute time, 32 bit sized, using milliseconds as unit
+
+Abolute time means that every stamp contains the time from the +beginning of the file. +
+Followed by a list of key events in the following format: +
Type of event | $xx |
Time stamp | $xx (xx ...) |
+The 'Time stamp' is set to zero if directly at the beginning of the +sound or after the previous event. All events should be sorted in +chronological order. The type of event is as follows: +
$00 | padding (has no meaning) |
$01 | end of initial silence |
$02 | intro start |
$03 | mainpart start |
$04 | outro start |
$05 | outro end |
$06 | verse start |
$07 | refrain start |
$08 | interlude start |
$09 | theme start |
$0A | variation start |
$0B | key change |
$0C | time change |
$0D | momentary unwanted noise (Snap, Crackle & Pop) |
$0E | sustained noise |
$0F | sustained noise end |
$10 | intro end |
$11 | mainpart end |
$12 | verse end |
$13 | refrain end |
$14 | theme end |
$15-$DF | reserved for future use |
$E0-$EF | not predefined sync 0-F |
$F0-$FC | reserved for future use |
$FD | audio end (start of silence) |
$FE | audio file ends |
$FF | one more byte of events follows (all the following bytes with the value $FF have the same function) |
+Terminating the start events such as "intro start" is not required. +The 'Not predefined sync's ($E0-EF) are for user events. You might +want to synchronise your music to something, like setting of an +explosion on-stage, turning on your screensaver etc. +
+There may only be one "ETCO" frame in each tag.
+ + ++To increase performance and accuracy of jumps within a MPEG +audio file, frames with timecodes in different locations in the file +might be useful. The ID3v2 frame includes references that the +software can use to calculate positions in the file. After the frame +header is a descriptor of how much the 'frame counter' should +increase for every reference. If this value is two then the first +reference points out the second frame, the 2nd reference the 4th +frame, the 3rd reference the 6th frame etc. In a similar way the +'bytes between reference' and 'milliseconds between reference' points +out bytes and milliseconds respectively. +
+Each reference consists of two parts; a certain number of bits, as +defined in 'bits for bytes deviation', that describes the difference +between what is said in 'bytes between reference' and the reality and +a certain number of bits, as defined in 'bits for milliseconds +deviation', that describes the difference between what is said in +'milliseconds between reference' and the reality. The number of bits +in every reference, i.e. 'bits for bytes deviation'+'bits for +milliseconds deviation', must be a multiple of four. There may only +be one "MLLT" frame in each tag. +
<Header for 'Location lookup table', ID: "MLLT"> | |
MPEG frames between reference | $xx xx |
Bytes between reference | $xx xx xx |
Milliseconds between reference | $xx xx xx |
Bits for bytes deviation | $xx |
Bits for milliseconds dev. | $xx |
+Then for every reference the following data is included; +
Deviation in bytes | %xxx.... |
Deviation in milliseconds | %xxx.... |
+For a more accurate description of the tempo of a musical piece this +frame might be used. After the header follows one byte describing +which time stamp format should be used. Then follows one or more +tempo codes. Each tempo code consists of one tempo part and one time +part. The tempo is in BPM described with one or two bytes. If the +first byte has the value $FF, one more byte follows, which is added +to the first giving a range from 2 - 510 BPM, since $00 and $01 is +reserved. $00 is used to describe a beat-free time period, which is +not the same as a music-free time period. $01 is used to indicate one +single beat-stroke followed by a beat-free period. +
+The tempo descriptor is followed by a time stamp. Every time the +tempo in the music changes, a tempo descriptor may indicate this for +the player. All tempo descriptors should be sorted in chronological +order. The first beat-stroke in a time-period is at the same time as +the beat description occurs. There may only be one "SYTC" frame in +each tag. +
<Header for 'Synchronised tempo codes', ID: "SYTC"> | |
Time stamp format | $xx |
Tempo data | <binary data> |
+Where time stamp format is: +
+ $01 Absolute time, 32 bit sized, using MPEG frames as unit
+ $02 Absolute time, 32 bit sized, using milliseconds as unit
+
+Abolute time means that every stamp contains the time from the +beginning of the file. +
+ + ++This frame contains the lyrics of the song or a text transcription of +other vocal activities. The head includes an encoding descriptor and +a content descriptor. The body consists of the actual text. The +'Content descriptor' is a terminated string. If no descriptor is +entered, 'Content descriptor' is $00 (00) only. Newline characters +are allowed in the text. There may be more than one 'Unsynchronised +lyrics/text transcription' frame in each tag, but only one with the +same language and content descriptor. +
<Header for 'Unsynchronised lyrics/text transcription', ID: "USLT"> | |
Text encoding | $xx |
Language | $xx xx xx |
Content descriptor | <text string according to encoding> $00 (00) |
Lyrics/text | <full text string according to encoding> |
+This is another way of incorporating the words, said or sung lyrics, +in the audio file as text, this time, however, in sync with the +audio. It might also be used to describing events e.g. occurring on a +stage or on the screen in sync with the audio. The header includes a +content descriptor, represented with as terminated textstring. If no +descriptor is entered, 'Content descriptor' is $00 (00) only. +
<Header for 'Synchronised lyrics/text', ID: "SYLT"> | |
Text encoding | $xx |
Language | $xx xx xx |
Time stamp format | $xx |
Content type | $xx |
Content descriptor | <text string according to encoding> $00 (00) |
Encoding: | $00 | ISO-8859-1 character set is used => $00 + is sync identifier. |
$01 | Unicode character set is used => $00 00 is + sync identifier. |
Content type: | $00 | is other |
$01 | is lyrics | |
$02 | is text transcription | |
$03 | is movement/part name (e.g. "Adagio") | |
$04 | is events (e.g. "Don Quijote enters the stage") | |
$05 | is chord (e.g. "Bb F Fsus") | |
$06 | is trivia/'pop up' information |
+Time stamp format is: +
+ $01 Absolute time, 32 bit sized, using MPEG frames as unit
+ $02 Absolute time, 32 bit sized, using milliseconds as unit
+
+Abolute time means that every stamp contains the time from the +beginning of the file. +
+The text that follows the frame header differs from that of the +unsynchronised lyrics/text transcription in one major way. Each +syllable (or whatever size of text is considered to be convenient by +the encoder) is a null terminated string followed by a time stamp +denoting where in the sound file it belongs. Each sync thus has the +following structure: +
Terminated text to be synced (typically a syllable) | |
Sync identifier (terminator to above string) | $00 (00) |
Time stamp | $xx (xx ...) |
+The 'time stamp' is set to zero or the whole sync is omitted if +located directly at the beginning of the sound. All time stamps +should be sorted in chronological order. The sync can be considered +as a validator of the subsequent string. +
+Newline ($0A) characters are allowed in all "SYLT" frames and should +be used after every entry (name, event etc.) in a frame with the +content type $03 - $04. +
+A few considerations regarding whitespace characters: Whitespace +separating words should mark the beginning of a new word, thus +occurring in front of the first syllable of a new word. This is also +valid for new line characters. A syllable followed by a comma should +not be broken apart with a sync (both the syllable and the comma +should be before the sync).
+An example: The "USLT" passage
+"Strangers in the night" $0A "Exchanging glances"
+would be "SYLT" encoded as:
++ "Strang" $00 xx xx "ers" $00 xx xx " in" $00 xx xx " the" $00 xx xx + " night" $00 xx xx 0A "Ex" $00 xx xx "chang" $00 xx xx "ing" $00 xx + xx "glan" $00 xx xx "ces" $00 xx xx +
+There may be more than one "SYLT" frame in each tag, but only one +with the same language and content descriptor.
+ + ++This frame is indended for any kind of full text information that +does not fit in any other frame. It consists of a frame header +followed by encoding, language and content descriptors and is ended +with the actual comment as a text string. Newline characters are +allowed in the comment text string. There may be more than one +comment frame in each tag, but only one with the same language and +content descriptor. +
<Header for 'Comment', ID: "COMM"> | |
Text encoding | $xx |
Language | $xx xx xx |
Short content descrip. | <text string according to encoding> $00 (00) |
The actual text | <full text string according to encoding> |
+This is a more subjective function than the previous ones. It allows +the user to say how much he wants to increase/decrease the volume on +each channel while the file is played. The purpose is to be able to +align all files to a reference volume, so that you don't have to +change the volume constantly. This frame may also be used to balance +adjust the audio. If the volume peak levels are known then this could +be described with the 'Peak volume right' and 'Peak volume left' +field. If Peakvolume is not known these fields could be left zeroed +or, if no other data follows, be completely omitted. There may only +be one "RVAD" frame in each tag. +
<Header for 'Relative volume adjustment', ID: "RVAD"> | |
Increment/decrement | %00xxxxxx |
Bits used for volume descr. | $xx |
Relative volume change, right | $xx xx (xx ...) |
Relative volume change, left | $xx xx (xx ...) |
Peak volume right | $xx xx (xx ...) |
Peak volume left | $xx xx (xx ...) |
+In the increment/decrement field bit 0 is used to indicate the right +channel and bit 1 is used to indicate the left channel. 1 is +increment and 0 is decrement. +
+The 'bits used for volume description' field is normally $10 (16 +bits) for MPEG 2 layer I, II and III and MPEG 2.5. This value +may not be $00. The volume is always represented with whole bytes, +padded in the beginning (highest bits) when 'bits used for volume +description' is not a multiple of eight. +
+This datablock is then optionally followed by a volume definition for +the left and right back channels. If this information is appended to +the frame the first two channels will be treated as front channels. +In the increment/decrement field bit 2 is used to indicate the right +back channel and bit 3 for the left back channel. +
Relative volume change, right back | $xx xx (xx ...) |
Relative volume change, left back | $xx xx (xx ...) |
Peak volume right back | $xx xx (xx ...) |
Peak volume left back | $xx xx (xx ...) |
+If the center channel adjustment is present the following is appended +to the existing frame, after the left and right back channels. The +center channel is represented by bit 4 in the increase/decrease +field. +
Relative volume change, center | $xx xx (xx ...) |
Peak volume center | $xx xx (xx ...) |
+If the bass channel adjustment is present the following is appended +to the existing frame, after the center channel. The bass channel is +represented by bit 5 in the increase/decrease field. +
Relative volume change, bass | $xx xx (xx ...) |
Peak volume bass | $xx xx (xx ...) |
+This is another subjective, alignment frame. It allows the user to +predefine an equalisation curve within the audio file. There may only +be one "EQUA" frame in each tag. +
<Header of 'Equalisation', ID: "EQUA"> | |
Adjustment bits | $xx |
+The 'adjustment bits' field defines the number of bits used for +representation of the adjustment. This is normally $10 (16 bits) for +MPEG 2 layer I, II and III and MPEG 2.5. This value may not be +$00. +
+This is followed by 2 bytes + ('adjustment bits' rounded up to the +nearest byte) for every equalisation band in the following format, +giving a frequency range of 0 - 32767Hz: +
Increment/decrement | %x (MSB of the Frequency) |
Frequency | (lower 15 bits) |
Adjustment | $xx (xx ...) |
+The increment/decrement bit is 1 for increment and 0 for decrement. +The equalisation bands should be ordered increasingly with reference +to frequency. All frequencies don't have to be declared. The +equalisation curve in the reading software should be interpolated +between the values in this frame. Three equal adjustments for three +subsequent frequencies. A frequency should only be described once in +the frame. +
+ + ++Yet another subjective one. You may here adjust echoes of different +kinds. Reverb left/right is the delay between every bounce in ms. +Reverb bounces left/right is the number of bounces that should be +made. $FF equals an infinite number of bounces. Feedback is the +amount of volume that should be returned to the next echo bounce. $00 +is 0%, $FF is 100%. If this value were $7F, there would be 50% volume +reduction on the first bounce, 50% of that on the second and so on. +Left to left means the sound from the left bounce to be played in the +left speaker, while left to right means sound from the left bounce to +be played in the right speaker. +
+'Premix left to right' is the amount of left sound to be mixed in the +right before any reverb is applied, where $00 id 0% and $FF is 100%. +'Premix right to left' does the same thing, but right to left. +Setting both premix to $FF would result in a mono output (if the +reverb is applied symmetric). There may only be one "RVRB" frame in +each tag. +
<Header for 'Reverb', ID: "RVRB"> | |
Reverb left (ms) | $xx xx |
Reverb right (ms) | $xx xx |
Reverb bounces, left | $xx |
Reverb bounces, right | $xx |
Reverb feedback, left to left | $xx |
Reverb feedback, left to right | $xx |
Reverb feedback, right to right | $xx |
Reverb feedback, right to left | $xx |
Premix left to right | $xx |
Premix right to left | $xx |
+This frame contains a picture directly related to the audio file. +Image format is the MIME type and subtype for the image. In +the event that the MIME media type name is omitted, "image/" will be +implied. The "image/png" or "image/jpeg" picture format +should be used when interoperability is wanted. Description is a +short description of the picture, represented as a terminated +textstring. The description has a maximum length of 64 characters, +but may be empty. There may be several pictures attached to one file, +each in their individual "APIC" frame, but only one with the same +content descriptor. There may only be one picture with the picture +type declared as picture type $01 and $02 respectively. There is the +possibility to put only a link to the image file by using the 'MIME +type' "-->" and having a complete URL instead of picture data. +The use of linked files should however be used sparingly since there +is the risk of separation of files. +
<Header for 'Attached picture', ID: "APIC"> | |
Text encoding | $xx |
MIME type | <text string> $00 |
Picture type | $xx |
Description | <text string according to encoding> $00 (00) |
Picture data | <binary data> |
Picture type: | $00 | Other |
$01 | 32x32 pixels 'file icon' (PNG only) | |
$02 | Other file icon | |
$03 | Cover (front) | |
$04 | Cover (back) | |
$05 | Leaflet page | |
$06 | Media (e.g. lable side of CD) | |
$07 | Lead artist/lead performer/soloist | |
$08 | Artist/performer | |
$09 | Conductor | |
$0A | Band/Orchestra | |
$0B | Composer | |
$0C | Lyricist/text writer | |
$0D | Recording Location | |
$0E | During recording | |
$0F | During performance | |
$10 | Movie/video screen capture | |
$11 | A bright coloured fish | |
$12 | Illustration | |
$13 | Band/artist logotype | |
$14 | Publisher/Studio logotype |
+In this frame any type of file can be encapsulated. After the header, +'Frame size' and 'Encoding' follows 'MIME type' represented as +as a terminated string encoded with ISO-8859-1. The +filename is case sensitive and is encoded as 'Encoding'. Then follows +a content description as terminated string, encoded as 'Encoding'. +The last thing in the frame is the actual object. The first two +strings may be omitted, leaving only their terminations. There may be more than one "GEOB" +frame in each tag, but only one with the same content descriptor. +
<Header for 'General encapsulated object', ID: "GEOB"> | |
Text encoding | $xx |
MIME type | <text string> $00 |
Filename | <text string according to encoding> $00 (00) |
Content description | |
Encapsulated object | <binary data> |
+This is simply a counter of the number of times a file has been +played. The value is increased by one every time the file begins to +play. There may only be one "PCNT" frame in each tag. When the +counter reaches all one's, one byte is inserted in front of the +counter thus making the counter eight bits bigger. The counter must +be at least 32-bits long to begin with. +
<Header for 'Play counter', ID: "PCNT"> | |
Counter | $xx xx xx xx (xx ...) |
+The purpose of this frame is to specify how good an audio file is. +Many interesting applications could be found to this frame such as a +playlist that features better audiofiles more often than others or it +could be used to profile a person's taste and find other 'good' files +by comparing people's profiles. The frame is very simple. It contains +the email address to the user, one rating byte and a four byte play +counter, intended to be increased with one for every time the file is +played. The email is a terminated string. The rating is 1-255 where +1 is worst and 255 is best. 0 is unknown. If no personal counter is +wanted it may be omitted. When the counter reaches all one's, one +byte is inserted in front of the counter thus making the counter +eight bits bigger in the same away as the play counter ("PCNT"). +There may be more than one "POPM" frame in each tag, but only one +with the same email address. +
<Header for 'Popularimeter', ID: "POPM"> | |
Email to user | <text string> $00 |
Rating | $xx |
Counter | $xx xx xx xx (xx ...) |
+Sometimes the server from which a audio file is streamed is aware of +transmission or coding problems resulting in interruptions in the +audio stream. In these cases, the size of the buffer can be +recommended by the server using this frame. If the 'embedded info +flag' is true (1) then this indicates that an ID3 tag with the +maximum size described in 'Buffer size' may occur in the audiostream. +In such case the tag should reside between two MPEG frames, if +the audio is MPEG encoded. If the position of the next tag is known, +'offset to next tag' may be used. The offset is calculated from the +end of tag in which this frame resides to the first byte of the +header in the next. This field may be omitted. Embedded tags are +generally not recommended since this could render unpredictable +behaviour from present software/hardware. +
+For applications like streaming audio it might be an idea to embed +tags into the audio stream though. If the clients connects to +individual connections like HTTP and there is a possibility to begin +every transmission with a tag, then this tag should include a +'recommended buffer size' frame. If the client is connected to a +arbitrary point in the stream, such as radio or multicast, then the +'recommended buffer size' frame should be included in every tag. +Every tag that is picked up after the initial/first tag is to be +considered as an update of the previous one. E.g. if there is a +"TIT2" frame in the first received tag and one in the second tag, +then the first should be 'replaced' with the second. +
+The 'Buffer size' should be kept to a minimum. There may only be one +"RBUF" frame in each tag. +
<Header for 'Recommended buffer size', ID: "RBUF"> | |
Buffer size | $xx xx xx |
Embedded info flag | %0000000x |
Offset to next tag | $xx xx xx xx |
+This frame indicates if the actual audio stream is encrypted, and by +whom. Since standardisation of such encrypion scheme is beyond this +document, all "AENC" frames begin with a terminated string with a +URL containing an email address, or a link to a location where an +email address can be found, that belongs to the organisation +responsible for this specific encrypted audio file. Questions +regarding the encrypted audio should be sent to the email address +specified. If a $00 is found directly after the 'Frame size' and the +audiofile indeed is encrypted, the whole file may be considered +useless. +
+After the 'Owner identifier', a pointer to an unencrypted part of the +audio can be specified. The 'Preview start' and 'Preview length' is +described in frames. If no part is unencrypted, these fields should +be left zeroed. After the 'preview length' field follows optionally a +datablock required for decryption of the audio. There may be more +than one "AENC" frames in a tag, but only one with the same 'Owner +identifier'. +
<Header for 'Audio encryption', ID: "AENC"> | |
Owner identifier | <text string> $00 |
Preview start | $xx xx |
Preview length | $xx xx |
Encryption info | <binary data> |
+To keep space waste as low as possible this frame may be used to link +information from another ID3v2 tag that might reside in another audio +file or alone in a binary file. It is recommended that this method is +only used when the files are stored on a CD-ROM or other +circumstances when the risk of file seperation is low. The frame +contains a frame identifier, which is the frame that should be linked +into this tag, a URL field, where a reference to the file where +the frame is given, and additional ID data, if needed. Data should be +retrieved from the first tag found in the file to which this link +points. There may be more than one "LINK" frame in a tag, but only +one with the same contents. A linked frame is to be considered as +part of the tag and has the same restrictions as if it was a physical +part of the tag (i.e. only one "RVRB" frame allowed, whether it's +linked or not). +
<Header for 'Linked information', ID: "LINK"> | |
Frame identifier | $xx xx xx |
URL | <text string> $00 |
ID and additional data | <text string(s)> |
+Frames that may be linked and need no additional data are "IPLS", +"MCID", "ETCO", "MLLT", "SYTC", "RVAD", "EQUA", "RVRB", "RBUF", the +text information frames and the URL link frames. +
+The "TXXX", "APIC", "GEOB" and "AENC" frames may be linked with +the content descriptor as additional ID data. +
+The "COMM", "SYLT" and "USLT" frames may be linked with three bytes +of language descriptor directly followed by a content descriptor as +additional ID data. +
+ + ++This frame delivers information to the listener of how far into the +audio stream he picked up; in effect, it states the time offset of +the first frame in the stream. The frame layout is: +
<Head for 'Position synchronisation', ID: "POSS"> | |
Time stamp format | $xx |
Position | $xx (xx ...) |
+Where time stamp format is: +
+$01 Absolute time, 32 bit sized, using MPEG frames as unit
+$02 Absolute time, 32 bit sized, using milliseconds as unit
+
+and position is where in the audio the listener starts to receive, +i.e. the beginning of the next frame. If this frame is used in the +beginning of a file the value is always 0. There may only be one +"POSS" frame in each tag. +
+ + ++This frame contains a brief description of the terms of use and +ownership of the file. More detailed information concerning the legal +terms might be available through the "WCOP" frame. Newlines are +allowed in the text. There may only be one "USER" frame in a tag. +
<Header for 'Terms of use frame', ID: "USER"> | |
Text encoding | $xx |
Language | $xx xx xx |
The actual text | <text string according to encoding> |
+The ownership frame might be used as a reminder of a made transaction +or, if signed, as proof. Note that the "USER" and "TOWN" frames are +good to use in conjunction with this one. The frame begins, after the +frame ID, size and encoding fields, with a 'price payed' field. The +first three characters of this field contains the currency used for +the transaction, encoded according to ISO-4217 alphabetic +currency code. Concatenated to this is the actual price payed, as a +numerical string using "." as the decimal separator. Next is an 8 +character date string (YYYYMMDD) followed by a string with the name +of the seller as the last field in the frame. There may only be one +"OWNE" frame in a tag. +
<Header for 'Ownership frame', ID: "OWNE"> | |
Text encoding | $xx |
Price payed | <text string> $00 |
Date of purch. | <text string> |
Seller | <text string according to encoding> |
+This frame enables several competing offers in the same tag by +bundling all needed information. That makes this frame rather complex +but it's an easier solution than if one tries to achieve the same +result with several frames. The frame begins, after the frame ID, +size and encoding fields, with a price string field. A price is +constructed by one three character currency code, encoded according +to ISO-4217 alphabetic currency code, followed by a +numerical value where "." is used as decimal seperator. In the price +string several prices may be concatenated, seperated by a "/" +character, but there may only be one currency of each type. +
+The price string is followed by an 8 character date string in the +format YYYYMMDD, describing for how long the price is valid. After +that is a contact URL, with which the user can contact the seller, +followed by a one byte 'received as' field. It describes how the +audio is delivered when bought according to the following list: +
$00 | Other |
$01 | Standard CD album with other songs |
$02 | Compressed audio on CD |
$03 | File over the Internet |
$04 | Stream over the Internet |
$05 | As note sheets |
$06 | As note sheets in a book with other sheets |
$07 | Music on other media |
$08 | Non-musical merchandise |
+Next follows a terminated string with the name of the seller followed +by a terminated string with a short description of the product. The +last thing is the ability to include a company logotype. The first of +them is the 'Picture MIME type' field containing information about +which picture format is used. In the event that the MIME media type +name is omitted, "image/" will be implied. Currently only "image/png" +and "image/jpeg" are allowed. This format string is followed by the +binary picture data. This two last fields may be omitted if no +picture is to attach. +
<Header for 'Commercial frame', ID: "COMR"> | |
Text encoding | $xx |
Price string | <text string> $00 |
Valid until | <text string> |
Contact URL | <text string> $00 |
Received as | $xx |
Name of seller | <text string according to encoding> $00 (00) |
Description | <text string according to encoding> $00 (00) |
Picture MIME type | <string> $00 |
Seller logo | <binary data> |
+To identify with which method a frame has been encrypted the +encryption method must be registered in the tag with this frame. The +'Owner identifier' is a null-terminated string with a URL +containing an email address, or a link to a location where an email +address can be found, that belongs to the organisation responsible +for this specific encryption method. Questions regarding the +encryption method should be sent to the indicated email address. The +'Method symbol' contains a value that is associated with this method +throughout the whole tag. Values below $80 are reserved. The 'Method +symbol' may optionally be followed by encryption specific data. There +may be several "ENCR" frames in a tag but only one containing the +same symbol and only one containing the same owner identifier. The +method must be used somewhere in the tag. See section 3.3.1, flag j +for more information. +
<Header for 'Encryption method registration', ID: "ENCR"> | |
Owner identifier | <text string> $00 |
Method symbol | $xx |
Encryption data | <binary data> |
+This frame enables grouping of otherwise unrelated frames. This can +be used when some frames are to be signed. To identify which frames +belongs to a set of frames a group identifier must be registered in +the tag with this frame. The 'Owner identifier' is a null-terminated +string with a URL containing an email address, or a link to a +location where an email address can be found, that belongs to the +organisation responsible for this grouping. Questions regarding the +grouping should be sent to the indicated email address. The 'Group +symbol' contains a value that associates the frame with this group +throughout the whole tag. Values below $80 are reserved. The 'Group +symbol' may optionally be followed by some group specific data, e.g. +a digital signature. There may be several "GRID" frames in a tag but +only one containing the same symbol and only one containing the same +owner identifier. The group symbol must be used somewhere in the tag. +See section 3.3.1, flag j for more information. +
<Header for 'Group ID registration', ID: "GRID"> | |
Owner identifier | <text string> $00 |
Group symbol | $xx |
Group dependent data | <binary data> |
+This frame is used to contain information from a software producer +that its program uses and does not fit into the other frames. The +frame consists of an 'Owner identifier' string and the binary data. +The 'Owner identifier' is a null-terminated string with a URL +containing an email address, or a link to a location where an email +address can be found, that belongs to the organisation responsible +for the frame. Questions regarding the frame should be sent to the +indicated email address. The tag may contain more than one "PRIV" +frame but only with different contents. It is recommended to keep the +number of "PRIV" frames as low as possible. +
<Header for 'Private frame', ID: "PRIV"> | |
Owner identifier | <text string> $00 |
The private data | <binary data> |
+The only purpose of the 'unsynchronisation scheme' is to make the +ID3v2 tag as compatible as possible with existing software. There is +no use in 'unsynchronising' tags if the file is only to be processed +by new software. Unsynchronisation may only be made with MPEG 2 layer +I, II and III and MPEG 2.5 files. +
+Whenever a false synchronisation is found within the tag, one zeroed +byte is inserted after the first false synchronisation byte. The +format of a correct sync that should be altered by ID3 encoders is as +follows: +
+%11111111 111xxxxx +
+And should be replaced with: +
+%11111111 00000000 111xxxxx +
+This has the side effect that all $FF 00 combinations have to be +altered, so they won't be affected by the decoding process. Therefore +all the $FF 00 combinations have to be replaced with the $FF 00 00 +combination during the unsynchronisation. +
+To indicate usage of the unsynchronisation, the first bit in 'ID3 +flags' should be set. This bit should only be set if the tag +contains a, now corrected, false synchronisation. The bit should +only be clear if the tag does not contain any false synchronisations. +
+Do bear in mind, that if a compression scheme is used by the encoder, +the unsynchronisation scheme should be applied *afterwards*. When +decoding a compressed, 'unsynchronised' file, the 'unsynchronisation +scheme' should be parsed first, decompression afterwards. +
+If the last byte in the tag is $FF, and there is a need to eliminate +false synchronisations in the tag, at least one byte of padding +should be added. +
+ + ++Copyright © Martin Nilsson 1998. All Rights Reserved. +
+This document and translations of it may be copied and furnished to +others, and derivative works that comment on or otherwise explain it +or assist in its implementation may be prepared, copied, published +and distributed, in whole or in part, without restriction of any +kind, provided that a reference to this document is included on all +such copies and derivative works. However, this document itself may +not be modified in any way and reissued as the original document. +
+The limited permissions granted above are perpetual and will not be revoked. +
+This document and the information contained herein is provided on an +"AS IS" basis and THE AUTHORS DISCLAIMS ALL WARRANTIES, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF +THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED +WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. +
+ + + +[CDDB] Compact Disc Data Base
+<url:http://www.cddb.com>
+ + +[ID3v2] Martin Nilsson, "ID3v2 informal standard".
+<url:http://www.id3.org/id3v2-00.txt>
+ + +[ISO-639-2] ISO/FDIS 639-2.
+Codes for the representation of names of languages, Part 2: Alpha-3 code. Technical committee / subcommittee: TC 37 / SC 2
[ISO-4217] ISO 4217:1995.
+Codes for the representation of currencies and funds. Technical committee / subcommittee: TC 68
[ISO-8859-1] ISO/IEC DIS 8859-1.
+8-bit single-byte coded graphic character sets, Part 1: Latin alphabet No. 1. Technical committee / subcommittee: JTC 1 / SC 2
[ISRC] ISO 3901:1986
+International Standard Recording Code (ISRC). Technical committee / subcommittee: TC 46 / SC 9
[JFIF] JPEG File Interchange Format, version 1.02
+<url:http://www.w3.org/Graphics/JPEG/jfif.txt>
+ + +[MIME] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996.
+<url:ftp://ftp.isi.edu/in-notes/rfc2045.txt>
+ + +[MPEG] ISO/IEC 11172-3:1993.
+Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s, Part 3: Audio. Technical committee / subcommittee: JTC 1 / SC 29
+ and
+ISO/IEC 13818-3:1995
+Generic coding of moving pictures and associated audio information, Part 3: Audio. Technical committee / subcommittee: JTC 1 / SC 29
+ and
+ISO/IEC DIS 13818-3
+Generic coding of moving pictures and associated audio information, Part 3: Audio (Revision of ISO/IEC 13818-3:1995)
[PNG] Portable Network Graphics, version 1.0
+<url:http://www.w3.org/TR/REC-png-multi.html>
+ + +[UNICODE] ISO/IEC 10646-1:1993.
+Universal Multiple-Octet Coded Character Set (UCS), Part 1: Architecture and Basic Multilingual Plane. Technical committee / subcommittee: JTC 1 / SC 2
<url:http://www.unicode.org>
+ + +[URL] T. Berners-Lee, L. Masinter & M. McCahill, "Uniform Resource Locators (URL).", RFC 1738, December 1994.
+<url:ftp://ftp.isi.edu/in-notes/rfc1738.txt>
+ + +[ZLIB] P. Deutsch, Aladdin Enterprises & J-L. Gailly, "ZLIB Compressed Data Format Specification version 3.3", RFC 1950, May 1996.
+<url:ftp://ftp.isi.edu/in-notes/rfc1950.txt>
+ + + +
+The following genres is defined in ID3v1
++ 0.Blues + 1.Classic Rock + 2.Country + 3.Dance + 4.Disco + 5.Funk + 6.Grunge + 7.Hip-Hop + 8.Jazz + 9.Metal + 10.New Age + 11.Oldies + 12.Other + 13.Pop + 14.R&B + 15.Rap + 16.Reggae + 17.Rock + 18.Techno + 19.Industrial + 20.Alternative + 21.Ska + 22.Death Metal + 23.Pranks + 24.Soundtrack + 25.Euro-Techno + 26.Ambient + 27.Trip-Hop + 28.Vocal + 29.Jazz+Funk + 30.Fusion + 31.Trance + 32.Classical + 33.Instrumental + 34.Acid + 35.House + 36.Game + 37.Sound Clip + 38.Gospel + 39.Noise + 40.AlternRock + 41.Bass + 42.Soul + 43.Punk + 44.Space + 45.Meditative + 46.Instrumental Pop + 47.Instrumental Rock + 48.Ethnic + 49.Gothic + 50.Darkwave + 51.Techno-Industrial + 52.Electronic + 53.Pop-Folk + 54.Eurodance + 55.Dream + 56.Southern Rock + 57.Comedy + 58.Cult + 59.Gangsta + 60.Top 40 + 61.Christian Rap + 62.Pop/Funk + 63.Jungle + 64.Native American + 65.Cabaret + 66.New Wave + 67.Psychadelic + 68.Rave + 69.Showtunes + 70.Trailer + 71.Lo-Fi + 72.Tribal + 73.Acid Punk + 74.Acid Jazz + 75.Polka + 76.Retro + 77.Musical + 78.Rock & Roll + 79.Hard Rock ++ |
+The following genres are Winamp extensions
++ 80.Folk + 81.Folk-Rock + 82.National Folk + 83.Swing + 84.Fast Fusion + 85.Bebob + 86.Latin + 87.Revival + 88.Celtic + 89.Bluegrass + 90.Avantgarde + 91.Gothic Rock + 92.Progressive Rock + 93.Psychedelic Rock + 94.Symphonic Rock + 95.Slow Rock + 96.Big Band + 97.Chorus + 98.Easy Listening + 99.Acoustic +100.Humour +101.Speech +102.Chanson +103.Opera +104.Chamber Music +105.Sonata +106.Symphony +107.Booty Bass +108.Primus +109.Porn Groove +110.Satire +111.Slow Jam +112.Club +113.Tango +114.Samba +115.Folklore +116.Ballad +117.Power Ballad +118.Rhythmic Soul +119.Freestyle +120.Duet +121.Punk Rock +122.Drum Solo +123.A capella +124.Euro-House +125.Dance Hall + |
+Written by +
+Martin Nilsson
+Rydsvägen 246 C. 30
+S-584 34 Linköping
+Sweden
+
+Email: nilsson@id3.org +
+ ++Edited by +
+Dirk Mahoney
+57 Pechey Street
+Chermside Q
+Australia 4032
+
+Email: dirk@id3.org +
+
+Johan Sundström
+Alsättersgatan 5 A. 34
+S-584 35 Linköping
+Sweden
+
+Email: johan@id3.org +
+ + \ No newline at end of file diff --git a/doc/id3/id3v2_blocks.gif b/doc/id3/id3v2_blocks.gif new file mode 100755 index 0000000..153027e Binary files /dev/null and b/doc/id3/id3v2_blocks.gif differ diff --git a/doc/id3/mpeghdr-19991222.htm b/doc/id3/mpeghdr-19991222.htm new file mode 100755 index 0000000..b690c98 --- /dev/null +++ b/doc/id3/mpeghdr-19991222.htm @@ -0,0 +1,769 @@ + + + + + + +This is a brief and informal document targeted to those who want to deal +with the MPEG format. If you are one of them, you probably already know what +is MPEG audio. If not, jump to http://www.mp3.com/ or http://www.layer3.org/ where you will find +more details and also more links. This document does not cover compression and +decompression algorithm. + +
NOTE: You cannot just search the Internet and find the MPEG audio specs. It +is copyrighted and you will have to pay quite a bit to get the Paper. That's why +I made this. Information I got is gathered from the Internet, and mostly originate +from program sources I found available for free. Despite my intention to always +specify the information sources, I am not able to do it this time. Sorry, I did +not maintain the list. :-( +
These are not a decoding specs, it just informs you how to read the MPEG headers and the MPEG TAG. MPEG Version 1, 2 and 2.5 and Layer I, II +and III are supported, the MP3 TAG (ID3v1 and ID3v1.1) also.. Those of you +who use Delphi may find MPGTools Delphi unit (freeware source) +useful, it is where I implemented this stuff. + +
I do not claim information presented in this document is accurate. At first +I just gathered it from different sources. It was not an easy task but I needed +it. Later, I received lots of comments as feedback when I published this document. +I think this last release is highly accurate due to comments and corrections I +received. +
This document is last updated on December 22, 1999. +
MPEG Audio Compression Basics + +
This is one of many methods to compress audio in digital form trying to consume +as little space as possible but keep audio quality as good as possible. MPEG compression +showed up as one of the best achievements in this area. +
This is a lossy compression, which means, you will certainly loose some audio +information when you use this compression methods. But, this lost can hardly be +noticed because the compression method tries to control it. By using several quite +complicate and demanding mathematical algorithms it will only loose those parts +of sound that are hard to be heard even in the original form. This leaves more +space for information that is important. This way you can compress audio up to +12 times (you may choose compression ratio) which is really significant. Due to +its quality MPEG audio became very popular. +
MPEG standards MPEG-1, MPEG-2 and MPEG-4 are known but this document covers +first two of them. There is an unofficial MPEG-2.5 which is rarely used. It is +also covered. +
MPEG-1 audio (described in ISO/IEC 11172-3) describes three Layers of audio coding with the following properties: +
MPEG-2 audio (described in ISO/IEC 13818-3) has two extensions to MPEG-1, usually referred as MPEG-2/LSF and MPEG-2/Multichannel. +
MPEG-2/LSF has the following properties: +
MPEG-2/Multichannel has the following properties: +
An MPEG audio file is built up from smaller parts called frames. Generally, +frames are independent items. Each frame has its own header and audio informations. +There is no file header. Therefore, you can cut any part of MPEG file and play +it correctly (this should be done on frame boundaries but most applications will +handle incorrect headers). For Layer III, this is not 100% correct. Due to internal +data organization in MPEG version 1 Layer III files, frames are often dependent +of each other and they cannot be cut off just like that. +
When you want to read info about an MPEG file, it is usually enough to find +the first frame, read its header and assume that the other frames are the same +This may not be always the case. Variable bitrate MPEG files may use so called +bitrate switching, which means that bitrate changes according to the content of +each frame. This way lower bitrates may be used in frames where it will not reduce +sound quality. This allows making better compression while keeping high quality +of sound. +
The frame header is constituted by the very first four bytes (32bits) in a +frame. The first eleven bits (or first twelve bits, see below about frame sync) +of a frame header are always set and they are called "frame sync". Therefore, +you can search through the file for the first occurence of frame sync (meaning +that you have to find a byte with a value of 255, and followed by a byte with +its three (or four) most significant bits set). Then you read the whole header +and check if the values are correct. You will see in the following table the exact +meaning of each bit in the header, and which values may be checked for validity. +Each value that is specified as reserved, invalid, bad, or not allowed should +indicate an invalid header. Remember, this is not enough, frame sync can be easily +(and very frequently) found in any binary file. Also it is likely that MPEG file +contains garbage on it's beginning which also may contain false sync. Thus, you +have to check two or more frames in a row to assure you are really dealing with +MPEG audio file. +
Frames may have a CRC check. The CRC is 16 bits long +and, if it exists, it follows the frame header. After the CRC comes the audio +data. You may calculate the length of the frame and use it if you need to read +other headers too or just want to calculate the CRC of the frame, to compare +it with the one you read from the file. This is actually a very good method to +check the MPEG header validity. + +
Here is "graphical" presentation of the header content. Characters +from A to M are used to indicate different fields. In the table, you can see +details about the content of each field. +
+ +AAAAAAAA AAABBCCD EEEEFFGH IIJJKLMM + + + +
Sign | Length (bits) | Position (bits) | Description | +||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
A | 11 | (31-21) | Frame sync (all bits set) | +||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
B | 2 | (20,19) | MPEG Audio version ID +00 - MPEG Version 2.5 01 - reserved 10 - MPEG Version 2 (ISO/IEC 13818-3) 11 - MPEG Version 1 (ISO/IEC 11172-3) + Note: MPEG Version 2.5 is not official standard. Bit No 20 in frame header +is used to indicate version 2.5. Applications that do not support this MPEG version +expect this bit always to be set, meaning that frame sync (A) is twelve bits long, +not eleve as stated here. Accordingly, B is one bit long (represents only bit +No 19). I recommend using methodology presented here, since this allows you to +distinguish all three versions and keep full compatibility. + |
+||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
C | 2 | (18,17) | +Layer description +00 - reserved +01 - Layer III +10 - Layer II +11 - Layer I |
+||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
D | 1 | (16) | +Protection bit +0 - Protected by CRC (16bit crc follows header) +1 - Not protected |
+||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
E | 4 | (15,12) | Bitrate index +
+NOTES: All values are in kbps MPEG files may have variable bitrate (VBR). This means that bitrate in the file may change. I have learned about two used methods: + More about VBR you may find on Xing Tech +site + For Layer II there are some combinations of bitrate and mode which are not +allowed. Here is a list of allowed combinations. +
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
F | 2 | (11,10) | +Sampling rate frequency index (values are in Hz)
+
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
G | 1 | (9) | +Padding bit +0 - frame is not padded +1 - frame is padded with one extra slot + +Padding is used to fit the bit rates exactly. For an example: 128k 44.1kHz layer II uses a lot of 418 bytes and some of 417 bytes long frames to get the exact 128k bitrate. For Layer I slot is 32 bits long, for Layer II and Layer III slot is 8 bits long. + + + + How to calculate frame length + + First, let's distinguish two terms frame size and frame length. Frame size +is the number of samples contained in a frame. It is constant and always 384 samples +for Layer I and 1152 samples for Layer II and Layer III. Frame length is length +of a frame when compressed. It is calculated in slots. One slot is 4 bytes long +for Layer I, and one byte long for Layer II and Layer III. When you are reading +MPEG file you must calculate this to be able to find each consecutive frame. Remember, +frame length may change from frame to frame due to padding or bitrate switching. + Read the BitRate, SampleRate and Padding of the frame header. + For Layer I files us this formula: + FrameLengthInBytes = (12 * BitRate / SampleRate + Padding) * 4 + For Layer II & III files use this formula: + FrameLengthInBytes = 144 * BitRate / SampleRate + Padding + Example: | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
H | 1 | (8) | +Private bit. It may be freely used for specific needs of an application, i.e. if it has to trigger some application specific events. | +||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
I | 2 | (7,6) | +Channel Mode +00 - Stereo +01 - Joint stereo (Stereo) +10 - Dual channel (Stereo) +11 - Single channel (Mono) |
+||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
J | 2 | (5,4) | +Mode extension (Only if Joint stereo)
+ Mode extension is used to join informations that are of no use for stereo effect, thus reducing needed resources. These bits are dynamically determined by an encoder in Joint stereo mode. + + Complete frequency range of MPEG file is divided in subbands There are 32 subbands. For Layer I & II these two bits determine frequency range (bands) where intensity stereo is applied. For Layer III these two bits determine which type of joint stereo + +is used (intensity stereo or m/s stereo). Frequency range is determined within decompression algorythm. + +
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
K | 1 | (3) | +Copyright +0 - Audio is not copyrighted +1 - Audio is copyrighted |
+||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
L | 1 | (2) | +Original +0 - Copy of original media +1 - Original media |
+||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
M | 2 | (1,0) | +Emphasis +00 - none +01 - 50/15 ms +10 - reserved +11 - CCIT J.17 |
+
The TAG is used to describe the MPEG Audio file. It contains information +about artist, title, album, publishing year and genre. There is some extra +space for comments. It is exactly 128 bytes long and is located at very end of +the audio data. You can get it by reading the last 128 bytes of the MPEG audio +file. + +
+AAABBBBB BBBBBBBB BBBBBBBB BBBBBBBB
+BCCCCCCC CCCCCCCC CCCCCCCC CCCCCCCD
+DDDDDDDD DDDDDDDD DDDDDDDD DDDDDEEE
+EFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFG
+
+
+
Sign | Length (bytes) | Position +(bytes) | Description |
A | 3 | (0-2) | +Tag identification. Must contain 'TAG' if tag exists and is +correct. | +
B | 30 | (3-32) | Title |
C | 30 | (33-62) | Artist |
D | 30 | (63-92) | Album |
E | 4 | (93-96) | Year |
F | 30 | (97-126) | Comment |
G | 1 | (127) | Genre |
The specification asks for all fields to be padded with null character +(ASCII 0). However, not all applications respect this (an example is WinAmp +which pads fields with <space>, ASCII 32). + +
There is a small change proposed in ID3v1.1 structure. The last byte +of the Comment field may be used to specify the track number of a song in an +album. It should contain a null character (ASCII 0) if the information is +unknown. + +
Genre is a numeric field which may have one of the following values: + +
0 | +'Blues' | +20 | +'Alternative' | +40 | +'AlternRock' | +60 | +'Top 40' | +
1 | +'Classic Rock' | +21 | +'Ska' | +41 | +'Bass' | +61 | +'Christian Rap' | +
2 | +'Country' | +22 | +'Death Metal' | +42 | +'Soul' | +62 | +'Pop/Funk' | +
3 | +'Dance' | +23 | +'Pranks' | +43 | +'Punk' | +63 | +'Jungle' | +
4 | +'Disco' | +24 | +'Soundtrack' | +44 | +'Space' | +64 | +'Native American' | +
5 | +'Funk' | +25 | +'Euro-Techno' | +45 | +'Meditative' | +65 | +'Cabaret' | +
6 | +'Grunge' | +26 | +'Ambient' | +46 | +'Instrumental Pop' | +66 | +'New Wave' | +
7 | +'Hip-Hop' | +27 | +'Trip-Hop' | +47 | +'Instrumental Rock' | +67 | +'Psychadelic' | +
8 | +'Jazz' | +28 | +'Vocal' | +48 | +'Ethnic' | +68 | +'Rave' | +
9 | +'Metal' | +29 | +'Jazz+Funk' | +49 | +'Gothic' | +69 | +'Showtunes' | +
10 | +'New Age' | +30 | +'Fusion' | +50 | +'Darkwave' | +70 | +'Trailer' | +
11 | +'Oldies' | +31 | +'Trance' | +51 | +'Techno-Industrial' | +71 | +'Lo-Fi' | +
12 | +'Other' | +32 | +'Classical' | +52 | +'Electronic' | +72 | +'Tribal' | +
13 | +'Pop' | +33 | +'Instrumental' | +53 | +'Pop-Folk' | +73 | +'Acid Punk' | +
14 | +'R&B' | +34 | +'Acid' | +54 | +'Eurodance' | +74 | +'Acid Jazz' | +
15 | +'Rap' | +35 | +'House' | +55 | +'Dream' | +75 | +'Polka' | +
16 | +'Reggae' | +36 | +'Game' | +56 | +'Southern Rock' | +76 | +'Retro' | +
17 | +'Rock' | +37 | +'Sound Clip' | +57 | +'Comedy' | +77 | +'Musical' | +
18 | +'Techno' | +38 | +'Gospel' | +58 | +'Cult' | +78 | +'Rock & Roll' | +
19 | +'Industrial' | +39 | +'Noise' | +59 | +'Gangsta' | +79 | +'Hard Rock' | +
80 | +'Folk' | +92 | +'Progressive Rock' | +104 | +'Chamber Music' | +116 | +'Ballad' | +
81 | +'Folk-Rock' | +93 | +'Psychedelic Rock' | +105 | +'Sonata' | +117 | +'Poweer Ballad' | +
82 | +'National Folk' | +94 | +'Symphonic Rock' | +106 | +'Symphony' | +118 | +'Rhytmic Soul' | +
83 | +'Swing' | +95 | +'Slow Rock' | +107 | +'Booty Brass' | +119 | +'Freestyle' | +
84 | +'Fast Fusion' | +96 | +'Big Band' | +108 | +'Primus' | +120 | +'Duet' | +
85 | +'Bebob' | +97 | +'Chorus' | +109 | +'Porn Groove' | +121 | +'Punk Rock' | +
86 | +'Latin' | +98 | +'Easy Listening' | +110 | +'Satire' | +122 | +'Drum Solo' | +
87 | +'Revival' | +99 | +'Acoustic' | +111 | +'Slow Jam' | +123 | +'A Capela' | +
88 | +'Celtic' | +100 | +'Humour' | +112 | +'Club' | +124 | +'Euro-House' | +
89 | +'Bluegrass' | +101 | +'Speech' | +113 | +'Tango' | +125 | +'Dance Hall' | +
90 | +'Avantgarde' | +102 | +'Chanson' | +114 | +'Samba' | ++ | + |
91 | +'Gothic Rock' | +103 | +'Opera' | +115 | +'Folklore' | ++ | + |
Any other value should be considered as 'Unknown' + |
This is new proposed TAG format which is different than ID3v1 and ID3v1.1. +Complete tech specs for it may be found at http://www.id3.org/. +
Created on September 1998. by Predrag
+Supurovic.
+Thanks to Jean for debugging and polishing
+of this document, Peter
+Luijer, Guwani, Rob Leslie and Franc Zijderveld
+for valuable comments and corrections.
© 1998, 1999 Copyright by DataVoyage
+This document may be changed. Check http://www.dv.co.yu/mpgscript/mpeghdr.htm
+for updates.
+You may use it freely. Distribution is allowed only in unaltered form. If you
+can help me make it more accurate, please do.
+