nowplaying-node

Informal standard M. Nilsson Document: id3v2.3.0.txt 3rd February 1999 ID3 tag version 2.3.0 Status of this document This document is an informal standard and replaces the ID3v2.2.0 standard [ID3v2]. 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. Abstract This document describes the ID3v2.3.0, which is a more developed version of the ID3v2 informal standard [ID3v2] (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. 1. Table of contents 2. Conventions in this document 3. ID3v2 overview 3.1. ID3v2 header 3.2. ID3v2 extended header 3.3. ID3v2 frames overview 3.3.1. Frame header flags 3.3.2. Default flags 4. Declared ID3v2 frames 4.1. Unique file identifier 4.2. Text information frames 4.2.1. Text information frames - details 4.2.2. User defined text information frame 4.3. URL link frames 4.3.1. URL link frames - details 4.3.2. User defined URL link frame 4.4. Involved people list 4.5. Music CD Identifier 4.6. Event timing codes 4.7. MPEG location lookup table 4.8. Synced tempo codes 4.9. Unsychronised lyrics/text transcription 4.10. Synchronised lyrics/text 4.11. Comments 4.12. Relative volume adjustment 4.13. Equalisation 4.14. Reverb 4.15. Attached picture 4.16. General encapsulated object 4.17. Play counter 4.18. Popularimeter 4.19. Recommended buffer size 4.20. Audio encryption 4.21. Linked information 4.22. Position synchronisation frame 4.23. Terms of use 4.24. Ownership frame 4.25. Commercial frame 4.26. Encryption method registration 4.27. Group identification registration 4.28. Private frame 5. The 'unsynchronisation scheme' 6. Copyright 7. References 8. Appendix A. Appendix A - Genre List from ID3v1 9. Author's Address 2. Conventions in this document 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. 3. ID3v2 overview 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 [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. 3.1. ID3v2 header 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. 3.2. ID3v2 extended header 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 3.3. ID3v2 frame overview 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 [ISO-8859-1] characters in the range $20 - $FF. Such strings are represented as <text string>, or <full text string> if newlines are allowed, in the frame descriptions. All Unicode strings [UNICODE] use 16-bit unicode 2.0 (ISO/IEC 10646-1:1993, UCS-2). Unicode strings must begin with the Unicode BOM ($FF FE or $FE FF) to identify the byte order. All numeric strings and URLs [URL] 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 [ISO-639-2]. All URLs [URL] 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. 3.3.1. Frame header flags 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 [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. 3.3.2. Default flags 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. AENC, 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. 4. Declared ID3v2 frames The following frames are declared in this draft. 4.21 AENC Audio encryption 4.15 APIC Attached picture 4.11 COMM Comments 4.25 COMR Commercial frame 4.26 ENCR Encryption method registration 4.13 EQUA Equalization 4.6 ETCO Event timing codes 4.16 GEOB General encapsulated object 4.27 GRID Group identification registration 4.4 IPLS Involved people list 4.21 LINK Linked information 4.5 MCDI Music CD identifier 4.7 MLLT MPEG location lookup table 4.24 OWNE Ownership frame 4.28. PRIV Private frame 4.17 PCNT Play counter 4.18 POPM Popularimeter 4.22 POSS Position synchronisation frame 4.19 RBUF Recommended buffer size 4.12 RVAD Relative volume adjustment 4.14 RVRB Reverb 4.10 SYLT Synchronized lyric/text 4.8 SYTC Synchronized tempo codes 4.2.1 TALB Album/Movie/Show title 4.2.1 TBPM BPM (beats per minute) 4.2.1 TCOM Composer 4.2.1 TCON Content type 4.2.1 TCOP Copyright message 4.2.1 TDAT Date 4.2.1 TDLY Playlist delay 4.2.1 TENC Encoded by 4.2.1 TEXT Lyricist/Text writer 4.2.1 TFLT File type 4.2.1 TIME Time 4.2.1 TIT1 Content group description 4.2.1 TIT2 Title/songname/content description 4.2.1 TIT3 Subtitle/Description refinement 4.2.1 TKEY Initial key 4.2.1 TLAN Language(s) 4.2.1 TLEN Length 4.2.1 TMED Media type 4.2.1 TOAL Original album/movie/show title 4.2.1 TOFN Original filename 4.2.1 TOLY Original lyricist(s)/text writer(s) 4.2.1 TOPE Original artist(s)/performer(s) 4.2.1 TORY Original release year 4.2.1 TOWN File owner/licensee 4.2.1 TPE1 Lead performer(s)/Soloist(s) 4.2.1 TPE2 Band/orchestra/accompaniment 4.2.1 TPE3 Conductor/performer refinement 4.2.1 TPE4 Interpreted, remixed, or otherwise modified by 4.2.1 TPOS Part of a set 4.2.1 TPUB Publisher 4.2.1 TRCK Track number/Position in set 4.2.1 TRDA Recording dates 4.2.1 TRSN Internet radio station name 4.2.1 TRSO Internet radio station owner 4.2.1 TSIZ Size 4.2.1 TSRC ISRC (international standard recording code) 4.2.1 TSSE Software/Hardware and settings used for encoding 4.2.1 TYER Year 4.2.2 TXXX User defined text information frame 4.1 UFID Unique file identifier 4.23 USER Terms of use 4.9 USLT Unsychronized lyric/text transcription 4.3.1 WCOM Commercial information 4.3.1 WCOP Copyright/Legal information 4.3.1 WOAF Official audio file webpage 4.3.1 WOAR Official artist/performer webpage 4.3.1 WOAS Official audio source webpage 4.3.1 WORS Official internet radio station homepage 4.3.1 WPAY Payment 4.3.1 WPUB Publishers official webpage 4.3.2 WXXX User defined URL link frame 4.1. Unique file identifier 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 [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 "<a href="http://www.id3.org/dummy/ufid.html">http://www.id3.org/dummy/ufid.html</a>" 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> 4.2. Text information frames 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> 4.2.1. Text information frames - details TALB The 'Album/Movie/Show title' frame is intended for the title of the recording(/source of sound) which the audio in the file is taken from. TBPM The 'BPM' frame contains the number of beats per minute in the mainpart of the audio. The BPM is an integer and represented as a numerical string. TCOM The 'Composer(s)' frame is intended for the name of the composer(s). They are seperated with the "/" character. TCON The 'Content type', which previously was stored as a one byte numeric value only, is now a numeric string. You may use one or several of the types as ID3v1.1 did or, since the category list would be impossible to maintain with accurate and up to date categories, define your own. References to the ID3v1 genres can be made by, as first byte, enter "(" followed by a number from the genres list (appendix A.) and ended with a ")" character. This is optionally followed by a refinement, e.g. "(21)" or "(4)Eurodisco". Several references can be made in the same frame, e.g. "(51)(39)". If the refinement should begin with a "(" character it should be replaced with "((", e.g. "((I can figure out any genre)" or "(55)((I think...)". The following new content types is defined in ID3v2 and is implemented in the same way as the numerig content types, e.g. "(RX)". RX Remix CR Cover TCOP The 'Copyright message' frame, which must begin with a year and a space character (making five characters), is intended for the copyright holder of the original sound, not the audio file itself. The absence of this frame means only that the copyright information is unavailable or has been removed, and must not be interpreted to mean that the sound is public domain. Every time this field is displayed the field must be preceded with "Copyright " (C) " ", where (C) is one character showing a C in a circle. TDAT The 'Date' frame is a numeric string in the DDMM format containing the date for the recording. This field is always four characters long. TDLY The 'Playlist delay' defines the numbers of milliseconds of silence between every song in a playlist. The player should use the "ETC" frame, if present, to skip initial silence and silence at the end of the audio to match the 'Playlist delay' time. The time is represented as a numeric string. TENC The 'Encoded by' frame contains the name of the person or organisation that encoded the audio file. This field may contain a copyright message, if the audio file also is copyrighted by the encoder. TEXT The 'Lyricist(s)/Text writer(s)' frame is intended for the writer(s) of the text or lyrics in the recording. They are seperated with the "/" character. TFLT The 'File type' frame indicates which type of audio this tag defines. The following type and refinements are defined: 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 but other types may be used, not for these types though. This is used in a similar way to the predefined types in the "TMED" frame, but without parentheses. If this frame is not present audio type is assumed to be "MPG". TIME The 'Time' frame is a numeric string in the HHMM format containing the time for the recording. This field is always four characters long. TIT1 The 'Content group description' frame is used if the sound belongs to a larger category of sounds/music. For example, classical music is often sorted in different musical sections (e.g. "Piano Concerto", "Weather - Hurricane"). TIT2 The 'Title/Songname/Content description' frame is the actual name of the piece (e.g. "Adagio", "Hurricane Donna"). TIT3 The 'Subtitle/Description refinement' frame is used for information directly related to the contents title (e.g. "Op. 16" or "Performed live at Wembley"). TKEY The 'Initial key' frame contains the musical key in which the sound starts. It is represented as a string with a maximum length of three characters. The ground keys are represented with "A","B","C","D","E", "F" and "G" and halfkeys represented with "b" and "#". Minor is represented as "m". Example "Cbm". Off key is represented with an "o" only. TLAN The 'Language(s)' frame should contain the languages of the text or lyrics spoken or sung in the audio. The language is represented with three characters according to ISO-639-2. If more than one language is used in the text their language codes should follow according to their usage. TLEN The 'Length' frame contains the length of the audiofile in milliseconds, represented as a numeric string. TMED The 'Media type' frame describes from which media the sound originated. This may be a text string or a reference to the predefined media types found in the list below. References are made within "(" and ")" and are optionally followed by a text refinement, e.g. "(MC) with four channels". If a text refinement should begin with a "(" character it should be replaced with "((" in the same way as in the "TCO" frame. Predefined refinements is appended after the media type, e.g. "(CD/A)" or "(VID/PAL/VHS)". 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) TOAL The 'Original album/movie/show title' frame is intended for the title of the original recording (or source of sound), if for example the music in the file should be a cover of a previously released song. TOFN The 'Original filename' frame contains the preferred filename for the file, since some media doesn't allow the desired length of the filename. The filename is case sensitive and includes its suffix. TOLY The 'Original lyricist(s)/text writer(s)' frame is intended for the text writer(s) of the original recording, if for example the music in the file should be a cover of a previously released song. The text writers are seperated with the "/" character. TOPE The 'Original artist(s)/performer(s)' frame is intended for the performer(s) of the original recording, if for example the music in the file should be a cover of a previously released song. The performers are seperated with the "/" character. TORY The 'Original release year' frame is intended for the year when the original recording, if for example the music in the file should be a cover of a previously released song, was released. The field is formatted as in the "TYER" frame. TOWN The 'File owner/licensee' frame contains the name of the owner or licensee of the file and it's contents. TPE1 The 'Lead artist(s)/Lead performer(s)/Soloist(s)/Performing group' is used for the main artist(s). They are seperated with the "/" character. TPE2 The 'Band/Orchestra/Accompaniment' frame is used for additional information about the performers in the recording. TPE3 The 'Conductor' frame is used for the name of the conductor. TPE4 The 'Interpreted, remixed, or otherwise modified by' frame contains more information about the people behind a remix and similar interpretations of another existing piece. TPOS The 'Part of a set' frame is a numeric string that describes which part of a set the audio came from. This frame is used if the source described in the "TALB" frame is divided into several mediums, e.g. a double CD. The value may be extended with a "/" character and a numeric string containing the total number of parts in the set. E.g. "1/2". TPUB The 'Publisher' frame simply contains the name of the label or publisher. TRCK The 'Track number/Position in set' frame is a numeric string containing the order number of the audio-file on its original recording. This may be extended with a "/" character and a numeric string containing the total numer of tracks/elements on the original recording. E.g. "4/9". TRDA The 'Recording dates' frame is a intended to be used as complement to the "TYER", "TDAT" and "TIME" frames. E.g. "4th-7th June, 12th June" in combination with the "TYER" frame. TRSN The 'Internet radio station name' frame contains the name of the internet radio station from which the audio is streamed. TRSO The 'Internet radio station owner' frame contains the name of the owner of the internet radio station from which the audio is streamed. TSIZ The 'Size' frame contains the size of the audiofile in bytes, excluding the ID3v2 tag, represented as a numeric string. TSRC The 'ISRC' frame should contain the International Standard Recording Code [ISRC] (12 characters). TSSE The 'Software/Hardware and settings used for encoding' frame includes the used audio encoder and its settings when the file was encoded. Hardware refers to hardware encoders, not the computer on which a program was run. TYER The 'Year' frame is a numeric string with a year of the recording. This frames is always four characters long (until the year 10000). 4.2.2. User defined text information frame This frame is intended for one-string text information concerning the audiofile in a similar way to the other "T"-frames. The frame body consists of a description of the string, represented as a terminated string, followed by the actual string. There may be more than one "TXXX" frame in each tag, but only one with the same description. <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> 4.3. URL link frames 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 [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> 4.3.1. URL link frames - details WCOM The 'Commercial information' frame is a URL pointing at a webpage with information such as where the album can be bought. There may be more than one "WCOM" frame in a tag, but not with the same content. WCOP The 'Copyright/Legal information' frame is a URL pointing at a webpage where the terms of use and ownership of the file is described. WOAF The 'Official audio file webpage' frame is a URL pointing at a file specific webpage. WOAR The 'Official artist/performer webpage' frame is a URL pointing at the artists official webpage. There may be more than one "WOAR" frame in a tag if the audio contains more than one performer, but not with the same content. WOAS The 'Official audio source webpage' frame is a URL pointing at the official webpage for the source of the audio file, e.g. a movie. WORS The 'Official internet radio station homepage' contains a URL pointing at the homepage of the internet radio station. WPAY The 'Payment' frame is a URL pointing at a webpage that will handle the process of paying for this file. WPUB The 'Publishers official webpage' frame is a URL pointing at the official wepage for the publisher. 4.3.2. User defined URL link frame This frame is intended for URL [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 [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> 4.4. Involved people list 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> 4.5. Music CD identifier This frame is intended for music that comes from a CD, so that the CD can be identified in databases such as the CDDB [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> 4.6. Event timing codes 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 [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. 4.7. MPEG location lookup table To increase performance and accuracy of jumps within a MPEG [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.... 4.8. Synchronised tempo codes 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 [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. 4.9. Unsychronised lyrics/text transcription 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> 4.10. Synchronised lyrics/text 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 [ISO-8859-1] character set is used => $00 is sync identifier. $01 Unicode [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 [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. 4.11. Comments 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> 4.12. Relative volume adjustment 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 [MPEG] 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 ...) 4.13. Equalisation 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 [MPEG] 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) Adjus