From 373dc625f82b47096893add42c4472e4a57ab7eb Mon Sep 17 00:00:00 2001 From: Aki Date: Wed, 9 Feb 2022 22:23:03 +0100 Subject: Moved third-party libraries to a separate subdirectory --- vorbis/doc/v-comment.html | 285 ---------------------------------------------- 1 file changed, 285 deletions(-) delete mode 100644 vorbis/doc/v-comment.html (limited to 'vorbis/doc/v-comment.html') diff --git a/vorbis/doc/v-comment.html b/vorbis/doc/v-comment.html deleted file mode 100644 index aad5e88..0000000 --- a/vorbis/doc/v-comment.html +++ /dev/null @@ -1,285 +0,0 @@ - - - - - -Ogg Vorbis Documentation - - - - - - - -

- -

Ogg Vorbis I format specification: comment field and header specification

- -

Overview

- -

The Vorbis text comment header is the second (of three) header -packets that begin a Vorbis bitstream. It is meant for short, text -comments, not arbitrary metadata; arbitrary metadata belongs in a -separate logical bitstream (usually an XML stream type) that provides -greater structure and machine parseability.

- -

The comment field is meant to be used much like someone jotting a -quick note on the bottom of a CDR. It should be a little information to -remember the disc by and explain it to others; a short, to-the-point -text note that need not only be a couple words, but isn't going to be -more than a short paragraph. The essentials, in other words, whatever -they turn out to be, eg:

- -

-"Honest Bob and the Factory-to-Dealer-Incentives, _I'm Still Around_, -opening for Moxy Früvous, 1997" -

- -

Comment encoding

- -

Structure

- -

The comment header logically is a list of eight-bit-clean vectors; the -number of vectors is bounded to 2^32-1 and the length of each vector -is limited to 2^32-1 bytes. The vector length is encoded; the vector -contents themselves are not null terminated. In addition to the vector -list, there is a single vector for vendor name (also 8 bit clean, -length encoded in 32 bits). For example, the 1.0 release of libvorbis -set the vendor string to "Xiph.Org libVorbis I 20020717".

- -

The comment header is decoded as follows:

- -

-  1) [vendor_length] = read an unsigned integer of 32 bits
-  2) [vendor_string] = read a UTF-8 vector as [vendor_length] octets
-  3) [user_comment_list_length] = read an unsigned integer of 32 bits
-  4) iterate [user_comment_list_length] times {
-
-       5) [length] = read an unsigned integer of 32 bits
-       6) this iteration's user comment = read a UTF-8 vector as [length] octets
-
-     }
-
-  7) [framing_bit] = read a single bit as boolean
-  8) if ( [framing_bit] unset or end of packet ) then ERROR
-  9) done.
-

- -

Content vector format

- -

The comment vectors are structured similarly to a UNIX environment variable. -That is, comment fields consist of a field name and a corresponding value and -look like:

- -

-comment[0]="ARTIST=me"; 
-comment[1]="TITLE=the sound of Vorbis"; 
-

- -

A case-insensitive field name that may consist of ASCII 0x20 through -0x7D, 0x3D ('=') excluded. ASCII 0x41 through 0x5A inclusive (A-Z) is -to be considered equivalent to ASCII 0x61 through 0x7A inclusive -(a-z).
The field name is immediately followed by ASCII 0x3D ('='); -this equals sign is used to terminate the field name.
0x3D is followed by the 8 bit clean UTF-8 encoded value of the -field contents to the end of the field.

- -

Field names

- -

Below is a proposed, minimal list of standard field names with a -description of intended use. No single or group of field names is -mandatory; a comment header may contain one, all or none of the names -in this list.

- -

TITLE: Track/Work name
VERSION: The version field may be used to differentiate multiple -versions of the same track title in a single collection. -(e.g. remix info)
ALBUM: The collection name to which this track belongs
TRACKNUMBER: The track number of this piece if part of a specific larger collection or album
ARTIST: The artist generally considered responsible for the work. In popular music -this is usually the performing band or singer. For classical music it would be -the composer. For an audio book it would be the author of the original text.
PERFORMER: The artist(s) who performed the work. In classical music this would be the -conductor, orchestra, soloists. In an audio book it would be the actor who did -the reading. In popular music this is typically the same as the ARTIST and -is omitted.
COPYRIGHT: Copyright attribution, e.g., '2001 Nobody's Band' or '1999 Jack Moffitt'
LICENSE: License information, eg, 'All Rights Reserved', 'Any -Use Permitted', a URL to a license such as a Creative Commons license -("www.creativecommons.org/blahblah/license.html") or the EFF Open -Audio License ('distributed under the terms of the Open Audio -License. see http://www.eff.org/IP/Open_licenses/eff_oal.html for -details'), etc.
ORGANIZATION: Name of the organization producing the track (i.e. -the 'record label')
DESCRIPTION: A short text description of the contents
GENRE: A short text indication of music genre
DATE: Date the track was recorded
LOCATION: Location where track was recorded
CONTACT: Contact information for the creators or distributors of the track. -This could be a URL, an email address, the physical address of -the producing label.
ISRC: ISRC number for the track; see the -ISRC intro page for more information on ISRC numbers.

- -

Implications

- -

Field names should not be 'internationalized'; this is a -concession to simplicity not an attempt to exclude the majority of -the world that doesn't speak English. Field contents, -however, use the UTF-8 character encoding to allow easy representation -of any language.
We have the length of the entirety of the field and restrictions on -the field name so that the field name is bounded in a known way. Thus -we also have the length of the field contents.
Individual 'vendors' may use non-standard field names within -reason. The proper use of comment fields should be clear through -context at this point. Abuse will be discouraged.
There is no vendor-specific prefix to 'nonstandard' field names. -Vendors should make some effort to avoid arbitrarily polluting the -common namespace. We will generally collect the more useful tags -here to help with standardization.
Field names are not required to be unique (occur once) within a -comment header. As an example, assume a track was recorded by three -well know artists; the following is permissible, and encouraged: -
```
-              ARTIST=Dizzy Gillespie 
-              ARTIST=Sonny Rollins 
-              ARTIST=Sonny Stitt 
-
```

- -

Encoding

- -

The comment header comprises the entirety of the second bitstream -header packet. Unlike the first bitstream header packet, it is not -generally the only packet on the second page and may not be restricted -to within the second bitstream page. The length of the comment header -packet is (practically) unbounded. The comment header packet is not -optional; it must be present in the bitstream even if it is -effectively empty.

- -

The comment header is encoded as follows (as per Ogg's standard -bitstream mapping which renders least-significant-bit of the word to be -coded into the least significant available bit of the current -bitstream octet first):

- -

Vendor string length (32 bit unsigned quantity specifying number of octets)
Vendor string ([vendor string length] octets coded from beginning of string -to end of string, not null terminated)
Number of comment fields (32 bit unsigned quantity specifying number of fields)
Comment field 0 length (if [Number of comment fields]>0; 32 bit unsigned -quantity specifying number of octets)
Comment field 0 ([Comment field 0 length] octets coded from beginning of -string to end of string, not null terminated)
Comment field 1 length (if [Number of comment fields]>1...)...

- -

This is actually somewhat easier to describe in code; implementation of the above -can be found in vorbis/lib/info.c:_vorbis_pack_comment(),_vorbis_unpack_comment()

- -

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