configure.ac: Check for optional dependency on zlib for id3demux

Original commit message from CVS:
* configure.ac:
Check for optional dependency on zlib for id3demux

* gst/id3demux/Makefile.am:
* gst/id3demux/gstid3demux.c: (gst_gst_id3demux_get_type),
(gst_id3demux_base_init), (gst_id3demux_class_init),
(gst_id3demux_reset), (gst_id3demux_init), (gst_id3demux_dispose),
(gst_id3demux_add_srcpad), (gst_id3demux_remove_srcpad),
(gst_id3demux_trim_buffer), (gst_id3demux_chain),
(gst_id3demux_set_property), (gst_id3demux_get_property),
(id3demux_get_upstream_size), (gst_id3demux_srcpad_event),
(gst_id3demux_read_id3v1), (gst_id3demux_read_id3v2),
(gst_id3demux_sink_activate), (gst_id3demux_src_activate_pull),
(gst_id3demux_src_checkgetrange), (gst_id3demux_read_range),
(gst_id3demux_src_getrange), (gst_id3demux_change_state),
(gst_id3demux_pad_query), (gst_id3demux_get_query_types),
(simple_find_peek), (simple_find_suggest),
(gst_id3demux_do_typefind), (gst_id3demux_send_tag_event),
(plugin_init):
* gst/id3demux/gstid3demux.h:
* gst/id3demux/id3tags.c: (read_synch_uint),
(id3demux_read_id3v1_tag), (id3demux_read_id3v2_tag),
(id3demux_id3v2_frame_hdr_size), (convert_fid_to_v240),
(id3demux_id3v2_frames_to_tag_list):
* gst/id3demux/id3tags.h:
* gst/id3demux/id3v2.4.0-frames.txt:
* gst/id3demux/id3v2.4.0-structure.txt:
* gst/id3demux/id3v2frames.c: (id3demux_id3v2_parse_frame),
(parse_comment_frame), (parse_text_identification_frame),
(id3v2_tag_to_taglist), (parse_split_strings):
All new LGPL id3 demuxer. Can use zlib for compressed frames,
otherwise it discards them. Works on my test files.

* gst/wavparse/gstwavparse.c: (gst_wavparse_loop):
Don't send EOS to a non-existing srcpad
The debug category can be static

1 files changed, 1734 insertions, 0 deletions

diff --git a/gst/id3demux/id3v2.4.0-frames.txt b/gst/id3demux/id3v2.4.0-frames.txt
new file mode 100644
index 00000000..74a21bed
--- /dev/null
+++ b/gst/id3demux/id3v2.4.0-frames.txt
@@ -0,0 +1,1734 @@
+$Id$
+
+Informal standard                                             M. Nilsson
+Document: id3v2.4.0-frames.txt                         1st November 2000
+
+
+                  ID3 tag version 2.4.0 - Native Frames
+
+Status of this document
+
+   This document is an informal standard and replaces the ID3v2.3.0
+   standard [ID3v2]. A formal standard will use another revision number
+   even if the content is identical to 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 frames natively supported by ID3v2.4.0,
+   which is a revised version of the ID3v2 informal standard [ID3v2.3.0]
+   version 2.3.0. The ID3v2 offers a flexible way of storing audio meta
+   information within audio file itself. The information may be
+   technical information, such as equalisation curves, as well as title,
+   performer, copyright etc.
+
+   ID3v2.4.0 is meant to be as close as possible to ID3v2.3.0 in order
+   to allow for implementations to be revised as easily as possible.
+
+
+1.   Table of contents
+
+   2.   Conventions in this document
+   3.   Default flags
+   4.   Declared ID3v2 frames
+     4.1.   Unique file identifier
+     4.2.   Text information frames
+       4.2.1.   Identification frames
+       4.2.2.   Involved persons frames
+       4.2.3.   Derived and subjective properties frames
+       4.2.4.   Rights and license frames
+       4.2.5.   Other text frames
+       4.2.6.   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.   Music CD Identifier
+     4.5.   Event timing codes
+     4.6.   MPEG location lookup table
+     4.7.   Synced tempo codes
+     4.8.   Unsynchronised lyrics/text transcription
+     4.9.  Synchronised lyrics/text
+     4.10.  Comments
+     4.11.  Relative volume adjustment (2)
+     4.12.  Equalisation (2)
+     4.13.  Reverb
+     4.14.  Attached picture
+     4.15.  General encapsulated object
+     4.16.  Play counter
+     4.17.  Popularimeter
+     4.18.  Recommended buffer size
+     4.19.  Audio encryption
+     4.20.  Linked information
+     4.21.  Position synchronisation frame
+     4.22.  Terms of use
+     4.23.  Ownership frame
+     4.24.  Commercial frame
+     4.25.  Encryption method registration
+     4.26.  Group identification registration
+     4.27.  Private frame
+     4.28.  Signature frame
+     4.29.  Seek frame
+     4.30.  Audio seek point index
+   5.   Copyright
+   6.   References
+   7.   Appendix
+     A.   Appendix A - Genre List from ID3v1
+   8.   Author's Address
+
+
+2.   Conventions in this document
+
+   Text within "" is a text string exactly as it appears in a tag.
+   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 the ID3v2 main structure document
+   [ID3v2-strct]. 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 "0123456789" only.
+
+   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
+   document are to be interpreted as described in RFC 2119 [KEYWORDS].
+
+
+3.   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.
+
+       ASPI, AENC, ETCO, EQU2, MLLT, POSS, SEEK, SYLT, SYTC, RVA2, TENC,
+       TLEN
+
+    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.
+
+  4.19  AENC Audio encryption
+  4.14  APIC Attached picture
+  4.30  ASPI Audio seek point index
+
+  4.10  COMM Comments
+  4.24  COMR Commercial frame
+
+  4.25  ENCR Encryption method registration
+  4.12  EQU2 Equalisation (2)
+  4.5   ETCO Event timing codes
+
+  4.15  GEOB General encapsulated object
+  4.26  GRID Group identification registration
+
+  4.20  LINK Linked information
+
+  4.4   MCDI Music CD identifier
+  4.6   MLLT MPEG location lookup table
+
+  4.23  OWNE Ownership frame
+
+  4.27  PRIV Private frame
+  4.16  PCNT Play counter
+  4.17  POPM Popularimeter
+  4.21  POSS Position synchronisation frame
+
+  4.18  RBUF Recommended buffer size
+  4.11  RVA2 Relative volume adjustment (2)
+  4.13  RVRB Reverb
+
+  4.29  SEEK Seek frame
+  4.28  SIGN Signature frame
+  4.9   SYLT Synchronised lyric/text
+  4.7   SYTC Synchronised tempo codes
+
+  4.2.1 TALB Album/Movie/Show title
+  4.2.3 TBPM BPM (beats per minute)
+  4.2.2 TCOM Composer
+  4.2.3 TCON Content type
+  4.2.4 TCOP Copyright message
+  4.2.5 TDEN Encoding time
+  4.2.5 TDLY Playlist delay
+  4.2.5 TDOR Original release time
+  4.2.5 TDRC Recording time
+  4.2.5 TDRL Release time
+  4.2.5 TDTG Tagging time
+  4.2.2 TENC Encoded by
+  4.2.2 TEXT Lyricist/Text writer
+  4.2.3 TFLT File type
+  4.2.2 TIPL Involved people list
+  4.2.1 TIT1 Content group description
+  4.2.1 TIT2 Title/songname/content description
+  4.2.1 TIT3 Subtitle/Description refinement
+  4.2.3 TKEY Initial key
+  4.2.3 TLAN Language(s)
+  4.2.3 TLEN Length
+  4.2.2 TMCL Musician credits list
+  4.2.3 TMED Media type
+  4.2.3 TMOO Mood
+  4.2.1 TOAL Original album/movie/show title
+  4.2.5 TOFN Original filename
+  4.2.2 TOLY Original lyricist(s)/text writer(s)
+  4.2.2 TOPE Original artist(s)/performer(s)
+  4.2.4 TOWN File owner/licensee
+  4.2.2 TPE1 Lead performer(s)/Soloist(s)
+  4.2.2 TPE2 Band/orchestra/accompaniment
+  4.2.2 TPE3 Conductor/performer refinement
+  4.2.2 TPE4 Interpreted, remixed, or otherwise modified by
+  4.2.1 TPOS Part of a set
+  4.2.4 TPRO Produced notice
+  4.2.4 TPUB Publisher
+  4.2.1 TRCK Track number/Position in set
+  4.2.4 TRSN Internet radio station name
+  4.2.4 TRSO Internet radio station owner
+  4.2.5 TSOA Album sort order
+  4.2.5 TSOP Performer sort order
+  4.2.5 TSOT Title sort order
+  4.2.1 TSRC ISRC (international standard recording code)
+  4.2.5 TSSE Software/Hardware and settings used for encoding
+  4.2.1 TSST Set subtitle
+  4.2.2 TXXX User defined text information frame
+
+  4.1   UFID Unique file identifier
+  4.22  USER Terms of use
+  4.8   USLT Unsynchronised 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 provide more information relevant to the content.
+   Since standardisation of such a database is beyond this document, all
+   UFID frames begin with an 'owner identifier' field. It is 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
+   "http://www.id3.org/dummy/ufid.html" should be used for tests. 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 often 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. All text
+   information frames supports multiple strings, stored as a null
+   separated list, where null is reperesented by the termination code
+   for the charater encoding. 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 4.2.6.>
+     Text encoding                $xx
+     Information                  <text string(s) according to encoding>
+
+
+4.2.1.   Identification frames
+
+  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").
+
+  TALB
+   The 'Album/Movie/Show title' frame is intended for the title of the
+   recording (or source of sound) from which the audio in the file is
+   taken.
+
+  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.
+
+  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 number of tracks/elements on the original
+   recording. E.g. "4/9".
+
+  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".
+
+  TSST
+   The 'Set subtitle' frame is intended for the subtitle of the part of
+   a set this track belongs to.
+
+  TSRC
+   The 'ISRC' frame should contain the International Standard Recording
+   Code [ISRC] (12 characters).
+
+
+4.2.2.   Involved persons frames
+
+  TPE1
+   The 'Lead artist/Lead performer/Soloist/Performing group' is
+   used for the main artist.
+
+  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.
+
+  TOPE
+   The 'Original artist/performer' frame is intended for the performer
+   of the original recording, if for example the music in the file
+   should be a cover of a previously released song.
+
+  TEXT
+   The 'Lyricist/Text writer' frame is intended for the writer of the
+   text or lyrics in the recording.
+
+  TOLY
+   The 'Original lyricist/text writer' frame is intended for the
+   text writer of the original recording, if for example the music in
+   the file should be a cover of a previously released song.
+
+  TCOM
+   The 'Composer' frame is intended for the name of the composer.
+
+  TMCL
+   The 'Musician credits list' is intended as a mapping between
+   instruments and the musician that played it. Every odd field is an
+   instrument and every even is an artist or a comma delimited list of
+   artists.
+
+  TIPL
+   The 'Involved people list' is very similar to the musician credits
+   list, but maps between functions, like producer, and names.
+
+  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.
+
+
+4.2.3.   Derived and subjective properties frames
+
+  TBPM
+   The 'BPM' frame contains the number of beats per minute in the
+   main part of the audio. The BPM is an integer and represented as a
+   numerical string.
+
+  TLEN
+   The 'Length' frame contains the length of the audio file in
+   milliseconds, represented as a numeric string.
+
+  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", e.g. "Dbm" $00. Off key is represented with an
+   "o" only.
+
+  TLAN
+   The 'Language' 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 [ISO-639-2]. If more than one
+   language is used in the text their language codes should follow
+   according to the amount of their usage, e.g. "eng" $00 "sve" $00.
+
+  TCON
+   The 'Content type', which ID3v1 was stored as a one byte numeric
+   value only, is now a string. You may use one or several of the ID3v1
+   types as numerical strings, or, since the category list would be
+   impossible to maintain with accurate and up to date categories,
+   define your own. Example: "21" $00 "Eurodisco" $00
+
+   You may also use any of the following keywords:
+   
+     RX  Remix
+     CR  Cover
+
+  TFLT
+   The 'File type' frame indicates which type of audio this tag defines.
+   The following types and refinements are defined:
+
+     MIME   MIME type follows
+     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 Quantisation
+     PCM    Pulse Code Modulated audio
+
+   but other types may be used, but 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".
+
+  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. Example:
+   "VID/PAL/VHS" $00.
+
+    DIG    Other digital media
+      /A    Analogue transfer from media
+
+    ANA    Other analogue media
+      /WAC  Wax cylinder
+      /8CA  8-track tape cassette
+
+    CD     CD
+      /A    Analogue transfer from media
+      /DD   DDD
+      /AD   ADD
+      /AA   AAD
+
+    LD     Laserdisc
+
+    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    Analogue transfer from media
+
+    DAT    DAT
+      /A    Analogue 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, non-linear, 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    Analogue transfer from media
+
+    DVD    DVD
+      /A    Analogue 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)
+
+  TMOO
+   The 'Mood' frame is intended to reflect the mood of the audio with a
+   few keywords, e.g. "Romantic" or "Sad".
+
+
+4.2.4.   Rights and license frames
+
+  TCOP
+   The 'Copyright message' frame, in which the string 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 audio 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.
+
+  TPRO
+   The 'Produced notice' frame, in which the string must begin with a
+   year and a space character (making five characters), is intended for
+   the production copyright holder of the original sound, not the audio
+   file itself. The absence of this frame means only that the production
+   copyright information is unavailable or has been removed, and must
+   not be interpreted to mean that the audio is public domain. Every
+   time this field is displayed the field must be preceded with
+   "Produced " (P) " ", where (P) is one character showing a P in a
+   circle.
+
+  TPUB
+   The 'Publisher' frame simply contains the name of the label or
+   publisher.
+
+  TOWN
+   The 'File owner/licensee' frame contains the name of the owner or
+   licensee of the file and it's contents.
+
+  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.
+
+4.2.5.   Other text frames
+
+  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.
+
+  TDLY
+   The 'Playlist delay' defines the numbers of milliseconds of silence
+   that should be inserted before this audio. The value zero indicates
+   that this is a part of a multifile audio track that should be played
+   continuously.
+
+  TDEN
+   The 'Encoding time' frame contains a timestamp describing when the
+   audio was encoded. Timestamp format is described in the ID3v2
+   structure document [ID3v2-strct].
+
+  TDOR
+   The 'Original release time' frame contains a timestamp describing
+   when the original recording of the audio was released. Timestamp
+   format is described in the ID3v2 structure document [ID3v2-strct].
+
+  TDRC
+   The 'Recording time' frame contains a timestamp describing when the
+   audio was recorded. Timestamp format is described in the ID3v2
+   structure document [ID3v2-strct].
+
+  TDRL
+   The 'Release time' frame contains a timestamp describing when the
+   audio was first released. Timestamp format is described in the ID3v2
+   structure document [ID3v2-strct].
+
+  TDTG
+   The 'Tagging time' frame contains a timestamp describing then the
+   audio was tagged. Timestamp format is described in the ID3v2
+   structure document [ID3v2-strct].
+
+  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.
+
+  TSOA
+   The 'Album sort order' frame defines a string which should be used
+   instead of the album name (TALB) for sorting purposes. E.g. an album
+   named "A Soundtrack" might preferably be sorted as "Soundtrack".
+
+  TSOP
+   The 'Performer sort order' frame defines a string which should be
+   used instead of the performer (TPE2) for sorting purposes.
+
+  TSOT
+   The 'Title sort order' frame defines a string which should be used
+   instead of the title (TIT2) for sorting purposes.
+
+
+4.2.6.   User defined text information frame
+
+   This frame is intended for one-string text information concerning the
+   audio file 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
+   text string is followed by a string termination, 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", except for "WXXX". 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 webpage for the publisher.
+
+
+4.3.2.   User defined URL link frame
+
+   This frame is intended for URL [URL] links concerning the audio file
+   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.   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. When this frame is used the presence of a valid "TRCK" frame is
+   REQUIRED, even if the CD's only got one track. It is recommended that
+   this frame is always added to tags originating from CDs. There may
+   only be one "MCDI" frame in each tag.
+
+     <Header for 'Music CD identifier', ID: "MCDI">
+     CD TOC                <binary data>
+
+
+4.5.   Event timing codes
+
+   This frame allows synchronisation with key events in the audio. 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
+
+   Absolute 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 MUST 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  main part 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  main part end
+     $12  verse end
+     $13  refrain end
+     $14  theme end
+     $15  profanity
+     $16  profanity end
+
+     $17-$DF  reserved for future use
+
+     $E0-$EF  not predefined synch 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 $FF have the same function)
+
+   Terminating the start events such as "intro start" is OPTIONAL. The
+   'Not predefined synch's ($E0-EF) are for user events. You might want
+   to synchronise your music to something, like setting off an explosion
+   on-stage, activating a screensaver etc.
+
+   There may only be one "ETCO" frame in each tag.
+
+
+4.6.   MPEG location lookup table
+
+   To increase performance and accuracy of jumps within a MPEG [MPEG]
+   audio file, frames with time codes in different locations in the file
+   might be useful. This ID3v2 frame includes references that the
+   software can use to calculate positions in the file. After the frame
+   header follows a descriptor of how much the 'frame counter' should be
+   increased 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....
+
+
+4.7.   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 MUST 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
+
+   Absolute time means that every stamp contains the time from the
+   beginning of the file.
+
+
+4.8.   Unsynchronised 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>
+
+
+4.9.   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 text string. 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)
+
+   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
+                   $07 is URLs to webpages
+                   $08 is URLs to images
+
+   Time stamp format:
+
+     $01  Absolute time, 32 bit sized, using MPEG [MPEG] frames as unit
+     $02  Absolute time, 32 bit sized, using milliseconds as unit
+
+   Absolute 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 characters are allowed in all "SYLT" frames and MUST 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.
+
+
+4.10.   Comments
+
+   This frame is intended 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>
+
+
+4.11.   Relative volume adjustment (2)
+
+   This is a more subjective frame than the previous ones. It allows the
+   user to say how much he wants to increase/decrease the volume on each
+   channel when 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. The volume adjustment is encoded as a fixed point decibel
+   value, 16 bit signed integer representing (adjustment*512), giving
+   +/- 64 dB with a precision of 0.001953125 dB. E.g. +2 dB is stored as
+   $04 00 and -2 dB is $FC 00. There may be more than one "RVA2" frame
+   in each tag, but only one with the same identification string.
+
+     <Header for 'Relative volume adjustment (2)', ID: "RVA2">
+     Identification          <text string> $00
+
+   The 'identification' string is used to identify the situation and/or
+   device where this adjustment should apply. The following is then
+   repeated for every channel
+
+     Type of channel         $xx
+     Volume adjustment       $xx xx
+     Bits representing peak  $xx
+     Peak volume             $xx (xx ...)
+
+
+   Type of channel:  $00  Other
+                     $01  Master volume
+                     $02  Front right
+                     $03  Front left
+                     $04  Back right
+                     $05  Back left
+                     $06  Front centre
+                     $07  Back centre
+                     $08  Subwoofer
+
+   Bits representing peak can be any number between 0 and 255. 0 means
+   that there is no peak volume field. The peak volume field is always
+   padded to whole bytes, setting the most significant bits to zero.
+
+
+4.12.   Equalisation (2)
+
+   This is another subjective, alignment frame. It allows the user to
+   predefine an equalisation curve within the audio file. There may be
+   more than one "EQU2" frame in each tag, but only one with the same
+   identification string.
+
+     <Header of 'Equalisation (2)', ID: "EQU2">
+     Interpolation method  $xx
+     Identification        <text string> $00
+
+   The 'interpolation method' describes which method is preferred when
+   an interpolation between the adjustment point that follows. The
+   following methods are currently defined:
+
+     $00  Band
+          No interpolation is made. A jump from one adjustment level to
+          another occurs in the middle between two adjustment points.
+     $01  Linear
+          Interpolation between adjustment points is linear.
+
+   The 'identification' string is used to identify the situation and/or
+   device where this adjustment should apply. The following is then
+   repeated for every adjustment point
+
+     Frequency          $xx xx
+     Volume adjustment  $xx xx
+
+   The frequency is stored in units of 1/2 Hz, giving it a range from 0
+   to 32767 Hz.
+
+   The volume adjustment is encoded as a fixed point decibel value, 16
+   bit signed integer representing (adjustment*512), giving +/- 64 dB
+   with a precision of 0.001953125 dB. E.g. +2 dB is stored as $04 00
+   and -2 dB is $FC 00.
+
+   Adjustment points should be ordered by frequency and one frequency
+   should only be described once in the frame.
+
+
+4.13.   Reverb
+
+   Yet another subjective frame, with which you can 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
+
+
+4.14.   Attached picture
+
+   This frame contains a picture directly related to the audio file.
+   Image format is the MIME type and subtype [MIME] for the image. In
+   the event that the MIME media type name is omitted, "image/" will be
+   implied. The "image/png" [PNG] or "image/jpeg" [JFIF] picture format
+   should be used when interoperability is wanted. Description is a
+   short description of the picture, represented as a terminated
+   text string. 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 [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. label 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
+
+
+4.15.   General encapsulated object
+
+   In this frame any type of file can be encapsulated. After the header,
+   'Frame size' and 'Encoding' follows 'MIME type' [MIME] represented as
+   as a terminated string encoded with ISO 8859-1 [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. MIME type is
+   always an ISO-8859-1 text string. 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    <text string according to encoding> $00 (00)
+     Encapsulated object    <binary data>
+
+
+4.16.   Play counter
+
+   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 ...)
+
+
+4.17.   Popularimeter
+
+   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 audio files 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 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 ...)
+
+
+4.18.   Recommended buffer size
+
+   Sometimes the server from which an 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 audio
+   stream. In such case the tag should reside between two MPEG [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.
+
+   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
+
+
+4.19.   Audio encryption
+
+   This frame indicates if the actual audio stream is encrypted, and by
+   whom. Since standardisation of such encryption 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
+   audio file 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
+   data block 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>
+
+
+4.20.   Linked information
+
+   To keep information duplication 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 separation is low. The
+   frame contains a frame identifier, which is the frame that should be
+   linked into this tag, a URL [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 xx
+     URL                     <text string> $00
+     ID and additional data  <text string(s)>
+
+   Frames that may be linked and need no additional data are "ASPI",
+   "ETCO", "EQU2", "MCID", "MLLT", "OWNE", "RVA2", "RVRB", "SYTC", the
+   text information frames and the URL link frames.
+
+   The "AENC", "APIC", "GEOB" and "TXXX" frames may be linked with
+   the content descriptor as additional ID data.
+
+   The "USER" frame may be linked with the language field as additional
+   ID data.
+   
+   The "PRIV" frame may be linked with the owner identifier 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.
+
+
+4.21.   Position synchronisation frame
+
+   This frame delivers information to the listener of how far into the
+   audio stream he picked up; in effect, it states the time offset from
+   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.
+
+
+4.22.   Terms of use frame
+
+   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 be more than one 'Terms of use' frame
+   in a tag, but only one with the same 'Language'.
+
+     <Header for 'Terms of use frame', ID: "USER">
+     Text encoding        $xx
+     Language             $xx xx xx
+     The actual text      <text string according to encoding>
+
+
+4.23.   Ownership frame
+
+   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 paid' field. The
+   first three characters of this field contains the currency used for
+   the transaction, encoded according to ISO 4217 [ISO-4217] alphabetic
+   currency code. Concatenated to this is the actual price paid, 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 paid        <text string> $00
+     Date of purch.    <text string>
+     Seller            <text string according to encoding>
+
+
+4.24.   Commercial frame
+
+   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 [ISO-4217] alphabetic currency code, followed by a
+   numerical value where "." is used as decimal separator. In the price
+   string several prices may be concatenated, separated 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 attached. There may be more than one 'commercial frame' in
+   a tag, but no two may be identical.
+
+     <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>
+
+
+4.25.   Encryption method registration
+
+   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 [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, in the range $80-F0. All other values 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 the description of the frame encryption flag in the ID3v2
+   structure document [ID3v2-strct] for more information.
+
+     <Header for 'Encryption method registration', ID: "ENCR">
+     Owner identifier    <text string> $00
+     Method symbol       $xx
+     Encryption data     <binary data>
+
+
+4.26.   Group identification registration
+
+   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 [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, in the range $80-F0. All other values 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 the description of the frame grouping flag
+   in the ID3v2 structure document [ID3v2-strct] for more information.
+
+     <Header for 'Group ID registration', ID: "GRID">
+     Owner identifier      <text string> $00
+     Group symbol          $xx
+     Group dependent data  <binary data>
+
+
+4.27.   Private frame
+
+   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 [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.
+
+     <Header for 'Private frame', ID: "PRIV">
+     Owner identifier      <text string> $00
+     The private data      <binary data>
+
+
+4.28.   Signature frame
+
+   This frame enables a group of frames, grouped with the 'Group
+   identification registration', to be signed. Although signatures can
+   reside inside the registration frame, it might be desired to store
+   the signature elsewhere, e.g. in watermarks. There may be more than
+   one 'signature frame' in a tag, but no two may be identical.
+
+     <Header for 'Signature frame', ID: "SIGN">
+     Group symbol      $xx
+     Signature         <binary data>
+
+
+4.29.   Seek frame
+
+   This frame indicates where other tags in a file/stream can be found.
+   The 'minimum offset to next tag' is calculated from the end of this
+   tag to the beginning of the next. There may only be one 'seek frame'
+   in a tag.
+
+   <Header for 'Seek frame', ID: "SEEK">
+   Minimum offset to next tag       $xx xx xx xx
+
+
+4.30.   Audio seek point index
+
+   Audio files with variable bit rates are intrinsically difficult to
+   deal with in the case of seeking within the file. The ASPI frame
+   makes seeking easier by providing a list a seek points within the
+   audio file. The seek points are a fractional offset within the audio
+   data, providing a starting point from which to find an appropriate
+   point to start decoding. The presence of an ASPI frame requires the
+   existence of a TLEN frame, indicating the duration of the file in
+   milliseconds. There may only be one 'audio seek point index' frame in
+   a tag.
+
+     <Header for 'Seek Point Index', ID: "ASPI">
+     Indexed data start (S)         $xx xx xx xx
+     Indexed data length (L)        $xx xx xx xx
+     Number of index points (N)     $xx xx
+     Bits per index point (b)       $xx
+
+   Then for every index point the following data is included;
+
+     Fraction at index (Fi)          $xx (xx)
+
+   'Indexed data start' is a byte offset from the beginning of the file.
+   'Indexed data length' is the byte length of the audio data being
+   indexed. 'Number of index points' is the number of index points, as
+   the name implies. The recommended number is 100. 'Bits per index
+   point' is 8 or 16, depending on the chosen precision. 8 bits works
+   well for short files (less than 5 minutes of audio), while 16 bits is
+   advantageous for long files. 'Fraction at index' is the numerator of
+   the fraction representing a relative position in the data. The
+   denominator is 2 to the power of b.
+
+   Here are the algorithms to be used in the calculation. The known data
+   must be the offset of the start of the indexed data (S), the offset
+   of the end of the indexed data (E), the number of index points (N),
+   the offset at index i (Oi). We calculate the fraction at index i
+   (Fi).
+
+   Oi is the offset of the frame whose start is soonest after the point
+   for which the time offset is (i/N * duration).
+
+   The frame data should be calculated as follows:
+
+     Fi = Oi/L * 2^b    (rounded down to the nearest integer)
+
+   Offset calculation should be calculated as follows from data in the
+   frame:
+
+     Oi = (Fi/2^b)*L    (rounded up to the nearest integer)
+
+
+5.  Copyright
+
+   Copyright (C) Martin Nilsson 2000. 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.
+
+
+6.   References
+
+   [CDDB] Compact Disc Data Base
+
+      <url:http://www.cddb.com>
+
+   [ID3v2.3.0] Martin Nilsson, "ID3v2 informal standard".
+
+      <url:http://www.id3.org/id3v2.3.0.txt>
+
+   [ID3v2-strct] Martin Nilsson,
+   "ID3 tag version 2.4.0 - Main Structure"
+   
+      <url:http//www.id3.org/id3v2.4.0-structure.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>
+
+   [KEYWORDS] S. Bradner, 'Key words for use in RFCs to Indicate
+   Requirement Levels', RFC 2119, March 1997.
+
+      <url:ftp://ftp.isi.edu/in-notes/rfc2119.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>
+
+   [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>
+
+
+7.   Appendix
+
+
+A.   Appendix A - Genre List from ID3v1
+
+   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
+
+
+8.   Author's Address
+
+   Written by
+
+     Martin Nilsson
+     Rydsvägen 246 C. 30
+     SE-584 34 Linköping
+     Sweden
+
+     Email: nilsson@id3.org