TOC 
Network Working GroupS. Pfeiffer
Internet-DraftC. Parker
Expires: June 30, 2004A. Pang
 CSIRO
 December 31, 2003

The Continuous Media Markup Language (CMML), Version 2.0

draft-pfeiffer-cmml-01

Status of this Memo

This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 except that the right to produce derivative works is not granted.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt.

The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html.

This Internet-Draft will expire on June 30, 2004.

Copyright Notice

Copyright (C) The Internet Society (2003). All Rights Reserved.

Abstract

This specification defines the Continuous Media Markup Language (CMML), version 2.0, an XML-based[1] markup language for time-continuous data. It is a sister document to the specification of the Annodex[12] annotation, indexing and hyperlinking format for time-continuous data. Its tags provide for the creation of structured and unstructured annotations as well as hyperlinks and addressable named anchor points for clips of time-continuous data. As well as enabling the creation and storage of such meta data in XML files, the CMML is an authoring language for Annodex[12] streams through its import tags. The tag names in use in CMML are similar to the ones in XHTML[3].

At this point in time, the right to produce derivative works is not granted to the IETF as the authors are uncertain about the necessity to create a working group. The specification is not encumbered by patents. The Annodex format is protected by a trade mark to prevent the use of the term "Annodex" for any related but non-conformant and therefore non-interoperable technology. Conformant technology is encouraged to use the term "Annodex" when refering to the file format.

Notice the change to CMML 2.0 from the previous version of this Internet-Draft, replacing CMML 1.0.



Table of Contents

1.  Introduction
2.  The CMML data types
2.1  ContentType
2.2  URIs
2.3  Internationalisation support
2.4  Time specifications
3.  The preamble and the 'cmml' root element
4.  The cmml 'stream' tag
4.1  The 'import' tag
4.2  The 'param' tag
5.  The cmml 'head' element
5.1  The 'title' element
5.2  The 'base' element
5.3  The 'meta' element
6.  The cmml 'clip' tag
6.1  The 'meta' element
6.2  The 'a' element
6.3  The 'img' element
6.4  The 'desc' element
7.  The encoding of CMML to Annodex format bitstreams
7.1  Encoding the 'stream' tag
7.2  Encoding the preamble and the 'cmml' tag
7.3  Encoding the 'head' tag
7.4  Encoding the 'clip' tags
8.  MIME media type registration for 'text/cmml'
8.1  URI addressing into CMML files
8.1.1  Query parameters for use with the http protocol server-side
8.1.2  Fragment identifiers for use with the http protocol client-side
9.  Security considerations
§  References
§  Authors' Addresses
A.  CMML DTD
B.  An example CMML document
C.  Definitions of terms and abbreviations
D.  Glossary of acronyms
E.  Acknowledgements
§  Intellectual Property and Copyright Statements




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1. Introduction

Please note that this document assumes that the reader has a fluent working knowledge of XML[1], HTML[2], XHTML[3] and the World Wide Web. Basic knowledge about the Annodex[12] format is also assumed.

Time-continuous data in the Annodex format contains XML-based annotations and hyperlinking information that enables it to be browsed by client applications, and crawled and indexed by search engines. The Continuous Media Markup Language CMML is a simple markup language for authoring and storing the XML data to be multiplexed with the time-continuous data given in binary bitstreams. This process eventually creates Annodex format bitstreams.

The format of the CMML derives much from XHTML. Yet, instead of enabling the annotation of textual documents, it enables creation of mark-up for time-continuous documents.

The CMML can describe one or several time-continuous data bitstreams. It is used to create all the tags required for authoring the annotation information for the Annodex format. It therefore contains the same tags as the annotation bitstream in Annodex format, which are the "head" and the "clip" tags. In addition, it may contain a stream tag, which is required for identifying and synchronising one or several input bitstreams that will be multiplexed together with the annotations for the creation of one coherent Annodex format bitstream.

The following picture illustrates the multiplexing activity schematically; in reality the stream tag is not preserved and some attributes are also made irrelevant during multiplexing. Details of how CMML markup is encoded in an Annodex bitstream are given later in this document.

   ----------
   |stream  | CMML
   ---------- instance
   | head   | document
   ----------
   | clip_1 |     ----------------------------------------------------
   ----------     | data bitstream in packets                        |
   | ...    |     ----------------------------------------------------
   ----------          |
   | clip_n |          |
   ----------          |
       |               |
       ------->-<-------
               |          Multiplexing
               |
               v
   ----------------------------------------------------------------------
   |stream|head|clip_1|  data packets         |clip_2| data packets  ...
   ----------------------------------------------------------------------
	  

The file extension of CMML files is ".cmml". This document also applies for registration of the mime-type "text/cmml" for CMML files with IANA. In the meantime, "text/x-cmml" will be used.

The CMML is technically fully specified through its DTD as given in the Appendix. The semantic meaning of each of the tags, their content and their attributes is specified in the following sections. The Appendix also contains an example of a CMML (instance) document.



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2. The CMML data types

At the beginning of the CMML DTD, several parameter entities are defined that are used throughout the DTD as data types. This section gives a brief overview of them and refers to the relevant standards in which they are defined.

2.1 ContentType

A "ContentType" specifies the media type and subtype of a document as defined in RFC 2045[7]. It is used to specify the type of content than one input time-continuous bitstream contains.

2.2 URIs

A "URI" is a character string that conforms to the specification of the Uniform Resource Identifier as defined in RFC 2396[4]. A URI generally points to a Web resource. The URI time interval specification[11] is supported for CMML and Annodex files. Also, direct addressing of clips as specified in the MIME type application part of this document is supported for CMML and Anndex files.

2.3 Internationalisation support

The "LanguageCode" defines a collection of constant strings that each identify a specific language as defined in RFC 1766[6]. It is used to provide internationalisation support. To that end, the i18n entity draws together a language given by a "LanguageCode" with the directionality of that language in "dir" given either as ltr (left-to-right) or rtl (right-to-left). "ltr" is the default.

2.4 Time specifications

There are three different time specifications in use in CMML: "Timestamp", "Playbacktime" and "UTCtime".

A "Timestamp" is generally a name-value pair which defines a time point. The time point value is interpreted according to the time scheme given in the name. If the name is ommitted, it defaults to "npt:". At least the following time specifications are defined:

The formal specifications for the time schemes are:

"npt:" NPT time with a second or subsecond basis

Specification as BNF:

npt-spec    =  "npt:" npt-time
npt-time    =  npt-sec | npt-hhmmss
npt-sec     =   1*DIGIT [ "." *DIGIT ]
npt-hhmmss  =   npt-hh ":" npt-mm ":" npt-ss [ "." *DIGIT ]
npt-hh      =   1*DIGIT
npt-mm      =   1*2DIGIT
npt-ss      =   1*2DIGIT
        

"smpte-24:" SMPTE time with a 24 fps basis

"smpte-24-drop:" SMPTE time with a 24/1.001 fps basis

"smpte-25:" SMPTE time with a 25 fps basis

"smpte-30:" SMPTE time with a 30 fps basis

"smpte-30-drop:" SMPTE time with a 30/1.001 fps basis

"smpte-50:" SMPTE time with a 50 fps basis

"smpte-60:" SMPTE time with a 60 fps basis

"smpte-60-drop:" SMPTE time with a 60/1.001 fps basis

Specification as BNF:

smpte-spec  = smpte-type ":" smpte-time
smpte-type  = "smpte-24" | "smpte-24-drop" | "smpte-25" |
              "smpte-30" | "smpte-30-drop" | "smpte-50" |
              "smpte-60" | "smpte-60-drop"
smpte-time  =  1*2DIGIT ":" 1*2DIGIT ":" 1*2DIGIT [ ":" 1*2DIGIT ]
        

"clock:" UTC time with a second or subsecond basis

Specification as BNF:

utc-spec    = "clock:" utc-time
utc-time    =   utc-date "T" utc-hhmmss "Z"
utc-date    =   8DIGIT
utc-hhmmss  =   6DIGIT [ "." *DIGIT ]
        

The "Playbacktime" entity is a data type that just specifies a SMPTE or a NPT time. It is therefore equal to the Timestamp entity without the UTC specification.

The "UTCtime" entity is a data type that just specifies a UTC time without an identifier. UTC time is specified as in the Timestamp entity, but without the "clock:" identifier.



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3. The preamble and the 'cmml' root element

A CMML file is an XML instance document of the CMML DTD. An example is given in the Appendix. It starts with the usual xml directive and the DTD specification (see http://www.w3.org/TR/REC-xml#sec-prolog-dtd). The following is an example preamble:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!DOCTYPE cmml SYSTEM "cmml.dtd">
	    

The attribute "standalone" is set to "yes" when the only DTD that is used for the instance document is cmml.dtd. The encoding format specifies the character encoding that is used for the values of the attributes and elements of the CMML file. E.g. for languages that are non-latin based, such as most Arab and Asian languages, a simple character encoding like US-ASCII does not cover all the characters. The default "UTF-8" charset can accommodate for any and all.

After the preamble, the CMML tag follows. A CMML file has a "cmml" tag as the root element. It embraces all the other tags.

<!ELEMENT cmml (stream?, head, clip*)>
<!ATTLIST cmml
  %i18n;
  id          ID             #IMPLIED
  xmlns       %URI;          #FIXED 'http://www.annodex.net/cmml'
  >
	    

The "cmml" tag encloses at most one "stream" element, exactly one "head" element, and as many "clip" elements as the document author requires. A "clip" element describes a section of the to be created Annodex bitstream. The Annodex bistream is created by multiplexing the bitstreams given in the "src" attributes of the "import" tags of the "stream" element together with the CMML annotations in a time-synchronous manner, as specified in the Annodex format[12].

Attributes of the "cmml" element are the usual xml root tag attributes: the internationalisation attributes "lang" and "dir", an identifier "id" and a fixed namespace "xmlns".

The internationalisation attributes specify the default language (language and directionality) of the complete CMML document. If not given, the language default adheres to the same rules as HTML, where the setting of the HTTP "Content-Language" header may specify the default language of a HTML document received over HTTP, or ultimately the user agent defaults and user preferences set the language. (see http://www.w3.org/TR/REC-html40/struct/dirlang.html)



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4. The cmml 'stream' tag

The "stream" element contains information that is used for authoring Annodex format[12] bitstreams from existing time-continuous data. It thus describes the input time-continuous bitstreams that are to be multiplexed together on authoring the Annodex format bitstreams. Additional tags or attributes describe other features of the Annodex bitstream such as the time mappings for the start of the file.

<!ELEMENT stream (import*)>
<!ATTLIST stream
  id          ID             #IMPLIED
  timebase    %Playbacktime; "0"
  utc         %UTCtime;      #IMPLIED
  >
	    

The "stream" element has no text attributes and thus internationalisation attributes are not required. The "id" attribute follows the default language specified in the "cmml" element.

The "timebase" attribute contains a playback time in seconds associated with the first data packet of the Annodex bitstream. All other times in the CMML file MUST be calculated relative to this timebase. For example, a timebase of 300 seconds npt for a video file implies that the first frame is related to a play time of 300 seconds, and a clip with a start time of 350 seconds is to be included 50 seconds into the Annodex bitstream. If no timebase (or no stream tag) is given, the timebase defaults to 0 npt. The timebase can be given as a SMPTE or NPT time, but not as a utc time.

The "utc" attribute associates a calendar date and a wall-clock time with the timebase. It therefore provides a mapping of the timebase to a real-world clock time and is given as a UTC time. If it is omitted, the start attribute in the import tag, and the start and end attributes in clip tags MUST NOT be specified as UTC times.

The content model of the "stream" tag then proposes an arbitrary number of input bitstreams. These are described one by one in the "import" element.

4.1 The 'import' tag

A "import" tag contains information on one of the input bitstreams for the multiplexing process. It may also contain additional parameters to set up the Annodex encoder for each import bitstream.

<!ELEMENT import (param*)>
<!ATTLIST import
  %i18n;
  id          ID             #IMPLIED
  granulerate CDATA          #IMPLIED
  contenttype %ContentType;  #IMPLIED
  src         %URI;          #REQUIRED
  start       %Timestamp;    "0"
  end         %Timestamp;    #IMPLIED
  title       CDATA          #IMPLIED
  >
	    

The relevant bitstream (fragment) is referenced through the "src" attribute. The src is a URI and may thus also contain a time interval specification in URIs which narrows down the input file to that given subpart. That resource is multiplexed into the Annodex format bitstream starting at the time given in the "start" attribute and ending at the latest at the time given in the "end" attribute. The "start" and "end" attributes are interpreted relative to the timeline of the Annodex format bitstream.

The internationalisation attributes provide the language of the import element's and the contained param tags' attribute values, such as the "id" attributes and the "title" attribute.

The "granulerate" attribute contains the base temporal resolution in Hz of the input bitstream refered in the "src" attribute. It depends on the encoding format of the input bitstream and typically contains the framerate for video (e.g. 25 frames/sec) and the samplerate for audio (e.g. 44100 samples/sec), but may contain any rational number given with an integer denominator larger than 1 sec (e.g. 25 frames on 2 seconds). Each bitstream has its own granulerate dependent on its specific encoding. This attribute is implied as it can be determined automatically during the multiplexing process when the headers of the encoded media bitstream contain this information. For bitstreams without header, such as uncompressed audio, the author of the CMML file can provide the granulerate to the multiplexer in this attribute.

The "contenttype" attribute specifies the media type[7] of the input bitstream refered in the "src" attribute. It is optional as the media type can often be derived from the file name or file header of the media source during multiplexing.

The "src" attribute specifies a URI to the input bitstream. Commonly used URI schemes are "file" and "http". For specifying temporal subsets of the input bitstream, use the time interval specification for URIs[11].

The "start" attribute specifies a time in the output Annodex bitstream at which the media bitstream will be inserted. This time is specified with respect to the "timebase" attribute given in the "stream" element.

The "end" attribute specifies a time in the output Annodex bitstream at which the media bitstream will stop at the latest. This time is also specified with respect to the "timebase" attribute given in the "stream" element. This attribute is not required when the full bitstream is used.

The optional "title" attribute provides a chance to jot down a human readable comment on the source bitstream. This may e.g. be used in authoring applications for a more human readable display than the "id" tag which is really a key for identifying elements uniquely.

The content model of the "import" tag then allows an arbitrary number of "param" tags to add as many descriptive parameter values to the mulitplexing activity as necessary.

4.2 The 'param' tag

A "param" tag is empty, but its attributes contain a name-value pair for describing the input bitstream in the parent "import" element. It inherits its internationalisation from that element, too, to avoid overhead. The "param" element is declared as follows:

<!ELEMENT param EMPTY>
<!ATTLIST param
  id          ID             #IMPLIED
  name        CDATA          #REQUIRED
  value       CDATA          #REQUIRED
  >
	    


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5. The cmml 'head' element

The CMML "head" element contains annotation information on the complete Annodex bitstream, for whose creation the CMML file is used. It therefore contains header-type information such as a title, and meta information describing the bitstream.

The "head" element is declared as the following:

<!ELEMENT head (meta*,
                ((title, meta*, (base, meta*)?) |
                 (base, meta*, (title, meta*)?)))>
<!ATTLIST head
  %i18n;
  id          ID             #IMPLIED
  profile     %URI;          #IMPLIED
  >
	    

The "head" tag must contain a "title" tag. It may contain one "base" tag before or after the "title" tag and any number of "meta" tags at any position.

The "%i18n;" attribute specifies the base language of the "head" tag's attribute values.

The value of the "profile" attribute is a space-separated list of base URIs specifying locations of "meta" tag schemes such as the Dublin Core (see http://dublincore.org/). These schemes may be used in the "meta" elements of the "head" or the "clip" tags.

5.1 The 'title' element

The "title" tag gives a descriptive title for the Annodex bitstream. The "title" element is declared as the following:

<!ELEMENT title (#PCDATA)>
<!ATTLIST title
  id          ID       #IMPLIED
  %i18n;
>
	    

The "%i18n;" attribute specifies the base language of the "title" text.

5.2 The 'base' element

The "base" element defines the base URI of the Annodex bitstream. All relative URIs of the bitstream get interpreted relative to this base. The "base" element is empty, but its attributes contain the base URI. It is declared as follows:

<!ELEMENT base EMPTY>
<!ATTLIST base
  id      ID       #IMPLIED
  href    %URI;    #REQUIRED
>
	    

The "href" attribute contains the base URI. If the "base" element is omitted, the base URI of the Annodex bitstream is derived from the address through which the Annodex bitstream is accessed.

5.3 The 'meta' element

The "meta" element in the "head" element defines structured annotations for the complete Annodex bitstream. A "meta" element is empty, but its attributes contain the name-value pairs of a structured annotation. The "meta" element is declared as follows:

<!ELEMENT meta EMPTY>
<!ATTLIST meta
  %i18n;
  id       ID       #IMPLIED
  name     NMTOKEN  #IMPLIED
  content  CDATA    #REQUIRED
  scheme   CDATA    #IMPLIED
>
	    

The "%i18n;" attribute specifies the language of the meta attribute and content texts.

The "name" attribute identifies a property name. It does not list legal values for this attribute.

The "content" attribute specifies a property's value. It does not list legal values for this attribute.

The "scheme" attribute names a scheme to be used to interprete the property's value. The scheme can be located via the "profile" attribute in the "head" element.



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6. The cmml 'clip' tag

A CMML file typically contains a number of sections given through "clip" tags. The CMML "clip" tag contains information about a section of the Annodex bitstream. This is expressed in a number of elements and attributes annotating, indexing, and hyperlinking the section. The "start" and "end" attributes are used to give the insertion time for the clip into the Annodex bitstream.

<!ELEMENT clip (meta*, a?, img?, desc?)>
<!ATTLIST clip
  %i18n;
  id          ID             #IMPLIED
  track       CDATA          "default"
  start       %Timestamp;    #REQUIRED
  end         %Timestamp;    #IMPLIED
  >
	    

Any number of "meta" elements may appear in a clip, and at most one "a" element, one "img" element, and one "desc" element. Though "meta", "a", "img", and "desc" tag are given in a specific order in the DTD, their order is actually random.

A "clip" element defines a unique identifying name for the clip in its "id" attribute. This name can be used in URIs that point either to the CMML file or the Annodex bitstream created from it, and allow to point straight at the clip. This may either be done as a URI fragment or URI query specification.

The "%i18n;" attribute specifies the base language for all the clip's attribute values and content elements.

The "track" attribute specifies the track that this clip belongs to. An annotation track is a set of clips that belong together from a semantic point of view. Clips in the same track must not overlap temporally. A default track must be available always. This track is the one a client (such as a Web browser plugin) will display by default. Other annotation tracks may be created by the document author to describe a more specific content. An example use are different annotation tracks for each speaker in an audio recording of a meeting or tracks of different languages.

The "start" and "end" attributes specify the time range during which the clip element is defined. This time range is specified with respect to the "timebase" and "utc" attributes given in the "stream" tag. If the "stream" tag does not contain a "utc" specification, "start" and "end" times are not allowed to be given in UTC time. "start" is a required attribute because a clip without a start time is useless. "end" is optional and only required where clips cannot continue on to the following clip.

6.1 The 'meta' element

The "meta" element is specified above in the "head" section. While a "meta" element in the "head" tag provides meta information for the complete Annodex bitstream, the "meta" elements in a "clip" tag only provide meta information for the clip.

6.2 The 'a' element

The "a" element specifies a link to a related Web resource together with some information on that related resource. The "a" element definition is very closely related to the xhtml "a" element definition with a reduced number of attributes as they make sense for time-continuous data.

<!ELEMENT a (#PCDATA)>
<!ATTLIST a
  %i18n;
  id          ID             #IMPLIED
  class       CDATA          #IMPLIED
  href        %URI;          #REQUIRED
  >
	    

The internationalisation attributes specify the language of the anchor's attribute values and of the anchor text.

The "class" attribute allows to override style sheet defaults for this anchor instance.

The "href" attribute specifies the location of a Web resource given through a URI. It thus defines a link between the current clip and a resource which the author believes to be connected closely to this clip's content. This might be a html page or another Annodex bitstream clip or an image etc. An "a" element without a "href" attribute is illegal and should be flagged or ignored.

The text contained in an "a" element (i.e. the anchor text) gives a short textual description of the link specified through the "href" attribute. It explains why the connection between the current clip and the destination URI is made. It may e.g. encourage the viewer to follow the link to "Get more information on blah".

6.3 The 'img' element

The "img" element specifies a link to a representative image for the clip. This image should be quite small as it is the representative image (known as "keyframe") for the current clip. This image may be used to visually summarise the content of the clip when a link to it is displayed, e.g. by a search engine or in a table of contents. The "img" element definition is very closely related to the xhtml "img" element definition with a reduced number of attributes as they make sense for time-continuous data.

<!ELEMENT img EMPTY>
<!ATTLIST img
  %i18n;
  id          ID             #IMPLIED
  src         %URI;          #REQUIRED
  alt         CDATA          #IMPLIED
  >
	    

The "src" attribute specifies the location of an image on the Web given through a URI.

The "alt" attribute specifies alternative text to be displayed instead of the image as required e.g. for accessibility.

6.4 The 'desc' element

The "desc" tag contains a human readable, textual description of the content of the clip. The "desc" element is declared as the following:

<!ELEMENT desc  (#PCDATA)>
<!ATTLIST desc
  %i18n;
  id          ID       #IMPLIED
>
	    

For extracting a short text from the "desc" element as needs to be displayed in a table of contents or as caption, the first few characters of the description will be taken. It is therefore recommended to place a short meaningful summary sentence at the beginning of the description when authoring annotations.

The internationalisation attributes specify the language of the text in the description.



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7. The encoding of CMML to Annodex format bitstreams

As CMML is an authoring format for Annodex bitstreams, there is a simple way to map the annotations and meta information contained in a CMML instance document to the annotation bitstream and header fields of an Annodex format bitstream. Please be aware that some of the encoding rules given here are a MUST, and others a SHOULD. As the binary header format for the annotation and media bitstreams provide for an extensible list of message header fields, an encoder MAY however add some or all of the non-used tags in there and even add others. For this section a detailed understanding of the Annodex format bitstream[12] is necessary.

The "head" and "clip" tags of a CMML document are mapped as codec data into the annotation bitstream of an Annodex bitstream, where the "head" tag is regarded as a secondary header. Thus, the rest of the information in a CMML file, i.e. the "stream" tag, the "cmml" tag and the preamble information, MUST be handled as binary header type information. Header type information in Annodex is generally regarded as non-human readable information, therefore by default language and directionality information will not be encoded. The character set used in the Annodex header fields is UTF-8, but the mandatory header fields are all covered by US-ASCII code points and for the optional ones it is recommended to do the same as much as possible. User defined optional message header fields MUST follow the naming standard given in RFC2822.

7.1 Encoding the 'stream' tag

A CMML instance document contains in its "stream" tag information that is relevant to the authoring process of Annodex format bitstreams.

The "stream" tag itself finds no representation in the Annodex bitstream. Rather, it contains both, information on the complete Annodex bitstream, and information on the different input documents. The first is information that finds a representation in the Annodex bos page, which is the very first bos page in an Annodex bitstream. The second is information used during the encoding process of each media bitstream and may find entry into the AnxData bos page of the respective media bitstream.

Here is a list of the attribute values of the "stream" tag and how they are being used:

id: not used, as this attribute is only used to enable addressing of the stream tag the XML way (e.g. XPath). It is not relevant for the encoded bitstream and will therefore be lost on encoding.

timebase: this attribute MUST be represented in the Annodex bos page in the fields "Timebase numerator" and "Timebase denominator".

utc: this attribute MUST be represented in the Annodex bos page in the field "utc".

Here is a list of the attribute values of the "import" tag and how they are being used:

id: this attribute SHOULD be represented in the media bos page of the respecitve media bitstream as a message header field with name "ID", as it signifies a short identifying machine-readable string for the import media bitstream.

lang, dir: not used, as these attributes signify the language and directionality of the human readable texts in the stream tag which are not acquired into the Annodex bitstream.

granulerate: this attribute MUST be represented in the media bos page in the fields "Granule rate numerator" and "Granule rate denominator". The encoder MUST however ascertain that the values are corrected with the exact granule rate that was used during creation of the Annodex bitstream.

contenttype: this attribute MUST be represented in the media bos page as a message header field with name "Content-type", as it signifies the MIME type of the media bitstream, providing for a decoding hint.

src: not used, as this attribute only points to the location of the import media bitstream and is thus pure authoring information.

start, end: not used, as this attribute only specifies the segment of the import media bitstream that is to be used during authoring.

title: not used, as this attribute provides a human readable comment on the import bitstream for authoring purposes.

Here is a list of the attribute values of the "param" tag list and how they are being used:

id: not used, as this attribute is only used to enable addressing of the param tag the XML way (e.g. XPath). It is not relevant for the encoded bitstream and will therefore be lost on encoding.

name, value: these attributes MAY be represented in the media bos page of the respecitve media bitstream as a message header field with the given name-value pair. These are highly dependent on the type of media bitstream handled and it therefore depends on the encoding tool to make a selection of the parameters acquired. E.g. lets regard an audio bitstream containing speech in a specific language. This language MAY be identified during CMML authoring as a param element with "Content-Language" name, and acquired into the media bitstream message header field of the same name.

7.2 Encoding the preamble and the 'cmml' tag

While the "stream" tag contained meta data on the different input media bitstreams, the preamble and the "cmml" tag contain meta data on the annotation bitstream and therefore end up in the AnxData bos page of the annotation bitstream.

Here is a list of the attribute values of the preamble and how they are being acquired:

xml version: without loss of generality, for simplicity this is fixed to version "1.0" for the current versions of CMML 2.0 and Annodex 2.0. Therefore, this attribute does not get represented in the Annodex bitstream and MUST be auto recreated during ripping of annotations out of the Annodex bitstream.

xml encoding: this attribute MUST be represented in the annotation bos page as a message header field with name "Content-type" and the encoding format being the charset value following "text/x-cmml;" (or "text/cmml;" after IANA registration of the MIME type).

xml standalone: this is fixed to "yes" for the current versions of CMML 2.0 and Annodex 2.0. There is a need to explore how to include data of general xml documents that conform to a different DTD into CMML and ultimately Annodex. Until then, standalone is fixed to "yes" and does not get represented in the Annodex bitstream, but MUST be auto recreated during ripping of annotations out of it.

DOCTYPE declaration: this is fixed to <!DOCTYPE cmml SYSTEM "cmml.dtd"> and thus again does not get represented in the Annodex bitstream but MUST be auto recreated during ripping.

Here is a list of the attribute values of the "cmml" tag and how they are being acquired:

id: this attribute SHOULD be represented in the bos page of the annotation bitstream as a message header field with name "ID", as it signifies a short identifying machine-readable string for the annotation bitstream (in analogy to the id field of the import tags).

lang, dir: these attributes MUST be represented in the bos page of the annotation bitstream as message header fields with name "Content-Language" and "Content-Dir".

xmlns: this attribute is fixed to "http://www.annodex.net/cmml" and thus does not get represented in the Annodex bitstream but must be auto recreated during ripping.

7.3 Encoding the 'head' tag

The CMML "head" tag is printed as a string into the first secondary header page of the annotation bitstream. Thus, the value of the field named "number of secondary header pages" in the bos page of the annotation bitstream will be 1, unless the "head" tag turns out to be too big for one Ogg page (i.e. larger than about 64K).

Note that the encoding process must ensure that newline characters are represented as LF (or "\n" in C) only. As some systems represent the new line as CR LF combinations (or "\r\n" in C), the encoding process MAY need to strip out the CR character.

7.4 Encoding the 'clip' tags

The "clip" tags are the real content of an annotation bitstream. Their "start" and "end" attributes only exist for authoring purposes and are not copied into the annotation bitstream to avoid contradictory doubly represented information as their position in the stream already represents this timing information.

A "clip" tag is encoded with all tags (except for the "start" and "end" attributes) as a string printed into a clip page in the annotation bitstream. The "clip" tag's "start" attribute tells the Annodex encoder at what time to insert the clip page into the bitstream. Its "end" attribute (if present) leads to the creation of another clip page at the given end time in the Annodex bitstream, unless another clip page starts on the same track beforehand. This clip page contains an empty "clip" tag, i.e. a "clip" tag without "meta", "a", "img" or "desc" elements and no attribute values except for a copy of the "track" attribute from the original "clip" tag.

Again, the encoding process must ensure that newline characters are represented as LF (or "\n" in C) only.



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8. MIME media type registration for 'text/cmml'

This section contains the registration information for the 'text/cmml' media type. While this media type is not approved by the IANA, 'text/x-cmml' may be used to identify CMML instance documents.

To: ietf-types@iana.org

Subject: Registration of MIME media type 'text/cmml'

MIME media type name: text

MIME subtype name: cmml

Required parameters: none

Optional parameters: charset (as in the text/xml media type[8]).

Encoding Considerations: as appropriate for the charset and the transport mechanism (see text/xml media type[8]).

Security considerations: see next section.

Interoperability considerations: CMML is a free specification that is independent of any media encoding format. It is designed to provide interoperability with existing XML tools and systems. Its specification is not patented and can be implemented by third parties without patent considerations.

Additional information:

  • Magic numbers: none. However, CMML files start with the XML preamble as any XML document[8]) and will also have the string '<cmml' near the beginning of the file.
  • File extension: .cmml
  • Macintosh File Type Code: "TEXT"
  • Intended usage: COMMON
  • 8.1 URI addressing into CMML files

    There are two ways of hyperlinking via URIs into CMML files: via specification of a temporal interval or via specification of a clip. Both of these ways of addressing are supported for URI queries and URI fragments on CMML files.

    8.1.1 Query parameters for use with the http protocol server-side

    For the purposes of URI queries on CMML files, it is assumed that the query string takes the format of a CGI query string. The Common Gateway Interface, or CGI, is a standard for external gateway programs to interface with information servers such as HTTP servers (see http://hoohoo.ncsa.uiuc.edu/cgi/). This query string is expected to be interpreted by the HTTP server to return a valid CMML file that differs from the original CMML file only by reducing the set of clip tags to the specified interval.

    Addressing of temporal intervals of CMML files is possible through specification of temporal query intervals in URIs[11]. An example is the following URI: http://www.blah.au/sample.cmml?t="npt:4" , which relates to the last clip whose start time is just before the given temporal offset and all the clips thereafter.

    Addressing of a clip is possible through specification of the clip's id attribute value. An example is the following URI: http://www.blah.au/sample.cmml?id="dolphin" , which relates to the clip whose id attribute value is "dolphin". Note that id attribute values of all elements have to be unique throughout a XML file (and thus also throughout a CMML file).

    8.1.2 Fragment identifiers for use with the http protocol client-side

    For the purposes of URI fragment specifications on CMML files, it is assumed that the fragment gets interpreted by the HTTP client after the retrieval action. The HTTP client is expected to restrict the usage of the resource to the specified interval.

    Addressing of temporal intervals of CMML files is possible through specification of temporal fragments in URIs[11] An example is the following URI: http://www.blah.au/sample.cmml#npt:4 . This then relates to the last clip whose start time is just before the given temporal offset and all the clips thereafter. This may e.g. be useful to do a zoom into a retrieved CMML resource.

    The values of the id attribute of the clip tags can be used for addressing media clips directly through fragment identifiers as in http://www.blah.au/sample.cmml#dolphin.



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    9. Security considerations

    As CMML is a markup language created by using XML, the same security considerations that apply to XML[8], apply to CMML.

    As the CMML is an authoring language for Annodex format bitstreams, there is no executable code attached to this language. The implementation of a multiplexer to actually create an Annodex bitstream must be careful when handling input bitstreams, which are binary data.



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    References

    [1] World Wide Web Consortium, "Extensible Markup Language (XML) 1.0", W3C XML, October 2000.
    [2] World Wide Web Consortium, "HTML 4.01 Specification", W3C HTML, December 1999.
    [3] World Wide Web Consortium, "XHTML(TM) 1.0 The Extensible Hyper Text Markup Language", W3C XHTML, January 2000.
    [4] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998.
    [5] Schulzrinne, H., Rao, A. and R. Lanphier, "Real Time Streaming Protocol (RTSP)", RFC 2326, April 1998.
    [6] Alvestrand, H., "Tags for the Identification of Languages", RFC 1766, March 1995.
    [7] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996.
    [8] Whitehead, E. and M. Murata, "XML Media Types", RFC 2376, July 1998.
    [9] The Society of Motion Picture and Television Engineers, "SMPTE STANDARD for Television, Audio and Film - Time and Control Code", ANSI 12M-1999, September 1999.
    [10] ISO, TC154., "Data elements and interchange formats -- Information interchange -- Representation of dates and times", ISO 8601, 2000.
    [11] Pfeiffer, S., Parker, C. and A. Pang, "Specifying time intervals in URI queries and fragments of time-based Web resources (BCP) (work in progress)", I-D draft-pfeiffer-temporal-fragments-02.txt, December 2003.
    [12] Pfeiffer, S., Parker, C. and A. Pang, "The Annodex annotation and indexing format for time-continuous data files, Version 1.0 (work in progress)", I-D draft-pfeiffer-annodex-01.txt, December 2003.


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    Authors' Addresses

      Silvia Pfeiffer
      Commonwealth Scientific and Industrial Research Organisation CSIRO, Australia
      Locked Bag 17
      North Ryde, NSW 2113
      Australia
    Phone:  +61 2 9325 3141
    EMail:  Silvia.Pfeiffer@csiro.au
    URI:  http://www.ict.csiro.au/
      
      Conrad D. Parker
      Commonwealth Scientific and Industrial Research Organisation CSIRO, Australia
      Locked Bag 17
      North Ryde, NSW 2113
      Australia
    Phone:  +61 2 9325 3133
    EMail:  Conrad.Parker@csiro.au
    URI:  http://www.ict.csiro.au/
      
      Andre T. Pang
      Commonwealth Scientific and Industrial Research Organisation CSIRO, Australia
      Locked Bag 17
      North Ryde, NSW 2113
      Australia
    Phone:  +61 2 9325 3156
    EMail:  Andre.Pang@csiro.au
    URI:  http://www.ict.csiro.au/


     TOC 

    Appendix A. CMML DTD

    <!--
    
       Continuous Media Markup Language CMML version 2.0 DTD
       Authoring language for ANNODEX(TM) media.
    
       Namespace = http://www.annodex.net/cmml
    
       Copyright (c) 2001 
       Commonwealth Scientific and Industrial Research Organisation
       (CSIRO), Australia.
       All Rights Reserved. 
    
       This DTD module is identified by the PUBLIC and SYSTEM identifiers:
    
       PUBLIC "-//CSIRO//DTD CMML 2.0//EN"
       SYSTEM "http://www.annodex.net/DTD/cmml_2_0.dtd"
    
       $Revision: 2.0 $
       $Date: 2003/12/06 24:00:00 $
    -->
    
    <!-- **************************** -->
    <!-- Definition of Imported Names -->
    <!-- **************************** -->
    
    <!-- media type, as per [RFC2045] -->
    <!ENTITY % ContentType "CDATA">
     
    <!-- a Uniform Resource Identifier, see [RFC2396] -->
    <!ENTITY % URI "CDATA">
    
    <!-- a language code, as per [RFC1766] -->
    <!ENTITY % LanguageCode "NMTOKEN">
    
    <!-- internationalization attributes
      xml:lang    language code (as per XML 1.0 spec)
      dir          direction for weak/neutral text
    -->
    <!ENTITY % i18n
     "lang        %LanguageCode; #IMPLIED
      dir         (ltr|rtl)      #IMPLIED"
      >
    
    <!-- timestamps similar to [RFC2326] 
     "smpte-24:" SMPTE time with a 24 fps basis
     "smpte-24-drop:" SMPTE time with a 24/1.001 fps basis
     "smpte-25:" SMPTE time with a 25 fps basis
     "smpte-30:" SMPTE time with a 30 fps basis
     "smpte-30-drop:" SMPTE time with a 30/1.001 fps basis
     "smpte-50:" SMPTE time with a 50 fps basis
     "smpte-60:" SMPTE time with a 60 fps basis
     "smpte-60-drop:" SMPTE time with a 60/1.001 fps basis
     "npt:" npt-time
     "clock:" utc-time
    
     Playbacktime is specified as a smpte-time 
     or npt-time only.
    
     UTCtime is specified as in [RFC2326], but
     without the "clock" identifier
    -->
    <!ENTITY % Timestamp    "CDATA">
    <!ENTITY % Playbacktime "CDATA">
    <!ENTITY % UTCtime      "CDATA">
    
    
    <!-- **************************** -->
    <!-- Document Structure           -->
    <!-- **************************** -->
    
    <!-- ROOT ELEMENT: -->
    <!-- cmml tag containing sequence of head and a tags -->
    <!-- =============================================== -->
    <!-- i18n  = the default language for the whole document including
                 the id tag of the cmml element -->
    <!-- xmlns = namespace of the cmml tags -->
    <!ELEMENT cmml (stream?, head, clip*)>
    <!ATTLIST cmml
      %i18n;
      id          ID             #IMPLIED
      xmlns       %URI;          #FIXED 'http://www.annodex.net/cmml'
      >
    
    
    <!-- **************************** -->
    <!-- Definition of stream element -->
    <!-- **************************** -->
    
    <!-- STREAM tag providing timing information for the ANNODEX file -->
    <!-- (will be stored in the binary headers of the ANX bitstreams) -->
    <!-- ============================================================ -->
    <!-- (has no text attributes and thus no i18n; id tag follows default 
          language specified in cmml tag) -->
    <!-- timebase   = base time associated with the first frame of the media 
                      document from which subsequent time references (such as 
                      in clip tags) will be taken relative to -->
    <!-- utc        = a mapping of the first frame to clock time; 
                      specifications of utc time offsets into the document as
                      in a URI will be taken relative to this -->
    <!ELEMENT stream (import*)>
    <!ATTLIST stream
      id          ID             #IMPLIED
      timebase    %Playbacktime; "0"
      utc         %UTCtime;      #IMPLIED
      >
    
    <!-- IMPORT tag giving descriptions on an input bitstream (empty content) -->
    <!-- ==================================================================== -->
    <!-- i18n        = the language of the import tag's and the contained param
                       tags' attribute values -->
    <!-- granulerate = the base temporal resolution of the bitstream (e.g.
                       its framerate for video or samplerate for audio) -->
    <!-- contenttype = encoding format of the input document (a MIME type and
                       a character encoding separated by semicolon) -->
    <!-- src         = URI to the media document -->
    <!-- start       = the start time of the media bitstream specified
                       in src -->
    <!-- end         = the end time of the media bitstream specified
                       in src -->
    <!-- title       = human readable comment on the import bitstream -->
    <!ELEMENT import (param*)>
    <!ATTLIST import 
      %i18n;
      id          ID             #IMPLIED
      granulerate CDATA          #IMPLIED
      contenttype %ContentType;  #IMPLIED
      src         %URI;          #REQUIRED
      start       %Timestamp;    "0"
      end         %Timestamp;    #IMPLIED
      title       CDATA          #IMPLIED
      >
    
    <!-- PARAM description tags of an input bitstream (empty content)   -->
    <!-- (name-value pairs e.g. comments on recording quality or so)    -->
    <!-- ============================================================== -->
    <!-- (internationalisation inherited from the parent import tag)    -->
    <!-- name  = identifies a property name; does not list legal values for this 
                 attribute --> 
    <!-- value = specifies a property's value; does not list legal values for 
                   this attribute -->
    <!ELEMENT param EMPTY>
    <!ATTLIST param
      id          ID             #IMPLIED
      name        CDATA          #REQUIRED
      value       CDATA          #REQUIRED
      >
    
    
    <!-- **************************** -->
    <!-- Definition of document head  -->
    <!-- **************************** -->
    
    <!-- head tag containing description of a specific media document -->
    <!-- ============================================================ -->
    <!-- i18n    = the base language of the head's attribute values and text 
                   content -->
    <!-- profile = space-separated list of URIs to locate meta tag schemes -->
    <!ELEMENT head (meta*,
                    ((title, meta*, (base, meta*)?) |
    		 (base, meta*, (title, meta*)?)))>
    <!ATTLIST head
      %i18n;
      id          ID             #IMPLIED
      profile     %URI;          #IMPLIED
      >
    
    <!-- TITLE tag giving descriptive title of the media document  -->
    <!-- ========================================================= -->
    <!-- i18n  = the language of the title text -->
    <!ELEMENT title (#PCDATA)>
    <!ATTLIST title 
      %i18n;
      id          ID             #IMPLIED
      >
    
    <!-- BASE URI of the document (empty content) --> 
    <!-- ======================================== -->
    <!-- (internationalisation inherited from the parent head tag) -->
    <!-- href = URI associated with the document; all relative URI references
                get interpreted relative to this base -->
    <!ELEMENT base EMPTY>
    <!ATTLIST base
      id          ID             #IMPLIED
      href        %URI;          #REQUIRED
      >
    
    <!-- META description tags of the document (empty content) -->
    <!-- ===================================================== -->
    <!-- i18n    = the language of the meta attributes -->
    <!-- name    = identifies a property name; does not list legal values for this 
                   attribute --> 
    <!-- content = specifies a property's value; does not list legal values for 
                   this attribute -->
    <!-- scheme  = names a scheme to be used to interpret the property's value 
                   (see the profiles tag in the head element for locating these) -->
    <!ELEMENT meta EMPTY>
    <!ATTLIST meta
      %i18n;
      id          ID             #IMPLIED
      name        NMTOKEN        #IMPLIED
      content     CDATA          #REQUIRED
      scheme      CDATA          #IMPLIED
      >
    
    <!-- ************************** -->
    <!-- Definition of clip tags    -->
    <!-- ************************** -->
    
    <!-- Clip tag containing information for a specific fragment -->
    <!-- ======================================================= -->
    <!-- though meta, a, img and desc are given in specific order
         here, their order is acutally random -->
    <!-- i18n     = the base language of the clip's attribute values and 
                    of its content elements -->
    <!-- id       = name of the clip used in URI clip references -->
    <!-- track    = defines different sets of clip tags; clip tags of same 
                    type cannot overlap temporally -->
    <!-- start    = specifies the start time of the clip; specified in 
                    time relative to the timebase of the header 
                    [NOT INCLUDED IN ANNODEX DOCUMENT] -->
    <!-- end      = specifies the end time of the clip; specified in 
                    time relative to the timebase of the header 
                    [NOT INCLUDED IN ANNODEX DOCUMENT] -->
    <!ELEMENT clip (meta*, a?, img?, desc?)>
    <!ATTLIST clip
      %i18n;
      id          ID             #IMPLIED
      track       CDATA          "default"
      start       %Timestamp;    #REQUIRED
      end         %Timestamp;    #IMPLIED
      >
    
    <!-- A tag containing information for a specific clip -->
    <!-- ================================================ -->
    <!-- a tag contains anchor text being a textual description of the link 
         between the current element (the source anchor) and the destination
         anchor given by the href attribute -->
    <!-- i18n     = language of the anchor's attribute values and anchor text -->
    <!-- class    = overriding style sheet defaults for this instance -->
    <!-- href     = specifies the location of a Web resource, thus defining a 
                    link between the current element (the source anchor) and the 
                    destination anchor given by this attribute -->
    <!ELEMENT a (#PCDATA)>
    <!ATTLIST a
      %i18n;
      id          ID             #IMPLIED
      class       CDATA          #IMPLIED
      href        %URI;          #REQUIRED
      >
    
    <!-- IMG tag to include a representative image for the clip -->
    <!-- ====================================================== -->
    <!-- i18n = language of the image's attribute values        -->
    <!-- src  = reference to the image                          -->
    <!-- alt  = alternative text for the image (accessibility)  -->
    <!ELEMENT img EMPTY>
    <!ATTLIST img
      %i18n;
      id          ID             #IMPLIED
      src         %URI;          #REQUIRED
      alt         CDATA          #IMPLIED
      >
    
    <!-- DESC human-readable, textual description of the clip (annotation) -->
    <!-- ================================================================= -->
    <!-- i18n = language of the data in the description -->
    <!ELEMENT desc (#PCDATA)>
    <!ATTLIST desc
      %i18n;
      id          ID             #IMPLIED
      >
    	  


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    Appendix B. An example CMML document

    <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
    <!DOCTYPE cmml SYSTEM "cmml.dtd">
    
    <cmml lang="en">
    
    <stream timebase="0">
      <import contenttype="video/mpeg" src="fish.mpg" start="0"/>
    </stream>
    
    <head>
      <title>Types of fish</title>
      <meta name="Producer" content="Joe Ordinary"/>
      <meta name="DC.Author" content="Joe's friend"/>
    </head>
    
    <clip id="intro" start="0">
      <a href="http://www.blah.au/fish.html">Read more about fish</a>
      <desc>This is the introduction to the film Joe made about fish.</desc>
    </clip>
    
    <clip id="dolphin" start="npt:3.5" end="npt:5:5.9">
      <img src="dolphin.jpg"/>
      <desc>Here, Joe caught sight of a dolphin in the ocean.</desc>
      <meta name="Subject" content="dolphin"/>
    </clip>
    
    <clip id="goldfish" start="npt:5:5.9">
      <a href="http://www.blah.au/morefish.anx?id=goldfish">More video clips on goldfish.</a>
      <img src="http://www.blah.au/goldfish.jpg"/>
      <desc>Joe has a fishtank at home with many colourful fish. The common goldfish is one of them and Joe's favourite. Here are some fabulous pictures he has taken of them.</desc>
      <meta name="Location" content="Joe's fishtank"/>
      <meta name="Subject" content="goldfish"/>
    </clip>
    
    </cmml>
    
    	    


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    Appendix C. Definitions of terms and abbreviations

    Mark-up:
    XML tags and their content used to describe a document.
    Annotating:
    The task of authoring mark-up for a document thus creating a Web resources.
    Hyperlinking:
    The task of linking from one Web resource to another. When a link contains a fragment offset into a resource, this is called "deep hyperlinking".
    Clip:
    A section of a time-continuous document covering some temporal interval.
    Indexing:
    The task of identifying index points or clips for time-continuous documents.
    Annotation track:
    A set of clips representing semantically correlated annotations of a time-continuous resource.
    Annodex bitstream:
    A specific file format for storing annotation, hyperlinking, and indexing information in annotation tracks and multiplexed together with the time-continuous documents they describe.
    Bitstream:
    A sequence of data containing samples of a time-continous document.
    Time-continuous document:
    A file containing time-sampled data in a temporally sequential manner.


     TOC 

    Appendix D. Glossary of acronyms

    Annodex:
    Annotated and indexed bitstream format.
    CMML:
    Continuous Media Markup Language.
    DTD:
    Document Type Declaration.
    XML:
    eXtensible Markup Language.
    Web:
    World Wide Web.
    URI:
    Unified Resource Identifier.


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    Appendix E. Acknowledgements

    The authors greatly acknowledge the contributions of Zentaro Kavanagh, Andrew Nesbit and Simon Lai in developing this specification.



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    Intellectual Property Statement

    Full Copyright Statement

    Acknowledgment