Synchronized Multimedia Integration Language
REC-smil-19980615
Synchronized Multimedia Integration Language (SMIL) 1.0 Specification
W3C Recommendation 15-June-1998
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About this Document
This document has been prepared by the Synchronized Multimedia Working Group
(WG) of the World Wide Web Consortium. The WG included the following individuals:
Stephan Bugaj, Lucent/Bell Labs
Dick Bulterman, CWI
Bruce Butterfield, RealNetworks
Wo Chang, NIST
Guy Fouquet, Alcatel
Christian Gran, GMD
Mark Hakkinen, The Productivity Works
Lynda Hardman, CWI
Peter Hoddie, Apple
Klaus Hofrichter, GMD
Philipp Hoschka, W3C
Jack Jansen, CWI
George Kerscher, DAISY Consortium
Rob Lanphier, RealNetworks
Nabil Layaïda, INRIA
Stephanie Leif, RealNetworks
Sjoerd Mullender, CWI
Didier Pillet, CNET/DSM
Anup Rao, Netscape
Lloyd Rutledge, CWI
Patrick Soquet, Havas
Warner ten Kate, Philips
Jacco van Ossenbruggen, CWI
Michael Vernick, Lucent/Bell Labs
Jin Yu, DEC
Acknowledgments:
In addition to the working group members,
the following people contributed to the SMIL effort: Bert Bos (W3C), Dan
Connolly (W3C), Patrick Deunhouwer (Philips), Martin Dürst (W3C), Al
Gilman, Håkon Lie (W3C), Chris Lilley (W3C), Curtis Reynolds
(RealNetworks), Michael Riesman, Curtis Reynolds (RealNetworks), Henning
Schulzrinne (Columbia University) and Koga Youichirou (W3C).
Editor:
Philipp Hoschka, W3C
hoschka@w3.org
Abstract
This document specifies version 1 of the Synchronized Multimedia Integration
Language (SMIL 1.0, pronounced "smile"). SMIL allows integrating a set of
independent multimedia objects into a synchronized multimedia presentation.
Using SMIL, an author can
describe the temporal behavior of the presentation
describe the layout of the presentation on a screen
associate hyperlinks with media objects
This specification is structured as follows: Section 1 presents the specification
approach. Section 2 defines the "smil" element. Section 3 defines the elements
that can be contained in the head part of a SMIL document. Section
4 defines the elements that can be contained in the body part of a SMIL document.
In particular, this Section defines the time model used in SMIL. Section
5 describes the SMIL DTD.
Status of this Document
This document was edited in place on 15 sept 2015, to fix a broken link in the above "latest version".
This document has been reviewed by W3C Members and other interested parties
and has been endorsed by the Director as a W3C Recommendation. It is a stable
document and may be used as reference material or cited as a normative reference
from another document. W3C's role in making the Recommendation is to draw
attention to the specification and to promote its widespread deployment.
This enhances the functionality and interoperability of the Web.
Comments on this Recommendation may be sent to the
public mailing list
www-smil@w3.org
Available languages
The English version of this specification is the only normative version.
However, for translations in other languages see
Errata
The list of known errors in this specification is available at
Table of Contents
1 Specification Approach
2 The smil Element
3 The Document Head
3.1 The head Element
3.2 The layout Element
3.3 SMIL Basic Layout Language
3.3.1 The region Element
3.3.2 The root-layout Element
3.4 The meta Element
4 The Document Body
4.1 The body Element
4.2 Synchronization Elements
4.2.1 The par Element
4.2.2 The seq Element
4.2.3 Media Object Element
: The ref, animation,
audio, img, video, text and textstream elements
4.2.4 SMIL Time Model
4.2.4.1 Time Model Values
4.2.4.2 Determining Values of Model Values
for SMIL 1.0 Elements
4.3 The switch Element
4.4 Test Attributes
4.5 Hyperlinking
Elements
4.5.1 The a Element
4.5.2 The anchor Element
5 SMIL DTD
5.1 Relation to XML
5.2 DTD
Appendix
Extending SMIL 1.0
Using SMIL 1.0 as an Extension
1 Specification Approach
SMIL documents are XML 1.0 documents
[XML10]
. The
reader is expected to be familiar with the concepts and terms defined in
XML 1.0.
This specification does not rely on particular features defined in URLs that
cannot potentially be expressed using URNs. Therefore, the more generic term
URI
[URI]
is used throughout the specification.
The syntax of SMIL documents is defined by the DTD in
Section
5.2
. The syntax of an attribute value that cannot be defined using the
DTD notation is defined together with the first element using an attribute
that can contain the attribute value. The syntax of such attribute values
is defined using the Extended Backus-Naur Form (EBNF) defined in the XML
1.0 specification.
An element definition is structured as follows: First, all attributes of
the element are defined in alphabetical order. An attribute is defined in
the following way: If the attribute is used by an element for the first time
in the specification, the semantics of the attribute are defined. If the
attribute has already been used by another element, the specification refers
to the definition of the attribute in the first element that used it. The
definition of element attributes is followed by the definition of any attribute
values whose syntax cannot be defined using the DTD notation. The final
section in an element definition specifies the element content.
2 The
smil
Element
Element Attributes
The "smil" element can have the following attribute:
id
This attribute uniquely identifies an element within a document. Its value
is an XML identifier.
Element Content
The "smil" element can contain the following children:
body
Defined in
Section 4.1
head
Defined in
Section 3.1
3 The Document Head
3.1
The
head
Element
The "head" element contains information that is not related to the temporal
behavior of the presentation.
Element Attributes
The "head" element can have the following attribute:
id
Defined in
Section 2
Element Content
The "head" element can contain the following children:
layout
Defined in
Section 3.2
meta
Defined in
Section 3.4
switch
Defined in
Section 4.3
The "head" element may contain any number of "meta" elements and either a
"layout" element or a "switch" element.
3.2
The
layout
Element
The "layout" element determines how the elements in the document's body are
positioned on an abstract rendering surface (either visual or acoustic).
If a document contains no layout element, the positioning of the body elements
is implementation-dependent.
A SMIL document can contain multiple alternative layouts by enclosing several
layout elements within a "switch" element (defined in
Section
4.3
). This can be used for example to describe the document's layout
using different layout languages.
The following example shows how CSS2 can be used as alternative to the SMIL
basic layout language (defined in
Section 3.3
):
[region="r"] { top: 20px; left: 20px }
(note that in this example, both layout alternatives result in the same layout)
Element Attributes
id
Defined in
Section 2
type
This attribute specifies which layout language is used in the layout element.
If the player does not understand this language, it must skip all content
up until the next "" tag. The default value of the type attribute
is "text/smil-basic-layout".
Element Content
If the type attribute of the layout element has the value
"text/smil-basic-layout", it can contain the following elements:
region
Defined in
Section 3.3.1
root-layout
Defined in
Section 3.3.2
If the type attribute of the "layout" element has another value, the element
contains character data.
3.3 SMIL Basic Layout Language
This section defines a basic layout language for SMIL. SMIL basic layout
is consistent with the visual rendering model defined in CSS2, it reuses
the formatting properties defined by the CSS2 specification, and newly introduces
the "fit" attribute
[CSS2]
. The reader is expected
to be familiar with the concepts and terms defined in CSS2.
SMIL basic layout only controls the layout of media object elements (defined
in
Section 4.2.3
). It is illegal to use SMIL
basic layout for other SMIL elements.
The type identifier for SMIL basic layout is "text/smil-basic-layout".
Fixed Property Values
The following stylesheet defines the values of the CSS2 properties "display"
and "position" that are valid in SMIL basic layout. These property values
are fixed:
a {display:block}
anchor {display:block}
animation {display: block;
position: absolute}
body {display: block}
head {display: none}
img {display: block;
position: absolute}
layout {display: none}
meta {display: none}
par {display: block}
region {display: none}
ref {display: block;
position: absolute}
root-layout {display: none}
seq {display: block}
smil {display: block}
switch {display:block}
text {display: block;
position: absolute}
textstream {display: block;
position: absolute}
video {display: block;
position: absolute}
Note that as a result of these definitions, all absolutely positioned elements
(animation, img, ref, text, textstream and video) are contained within a
single containing block defined by the content content edge of the root element
(smil).
Default Values
SMIL basic layout defines default values for all layout-related attributes.
These are consistent with the initial values of the corresponding properties
in CSS2.
If the author wants to select the default layout values for
all
media object elements in a document, the document must contain an empty layout
element of type "text/smil-basic-layout" such as:
3.3.1
The
region
Element
The region element controls the position, size and scaling of media object
elements.
In the following example fragment, the position of a text element is set
to a 5 pixel distance from the top border of the rendering window:
Element Attributes
The "region" element can have the following attributes:
background-color
The use and definition of this attribute are identical to the "background-color"
property in the CSS2 specification, except that SMIL basic layout does not
require support for "system colors".
If the background-color attribute is absent, the background is transparent.
fit
This attribute specifies the behavior if the intrinsic height and width of
a visual media object differ from the values specified by the height and
width attributes in the "region" element. This attribute does not have a
1-1 mapping onto a CSS2 property, but can be simulated in CSS2.
This attribute can have the following values:
fill
Scale the object's height and width independently so that the content just
touches all edges of the box.
hidden
If the intrinsic height (width) of the media object element is smaller than
the height (width) defined in the "region" element, render the object starting
from the top (left) edge and fill up the remaining height (width) with the
background color.
If the intrinsic height (width) of the media object element is greater than
the height (width) defined in the "region" element, render the object starting
from the top (left) edge until the height (width) defined in the "region"
element is reached, and clip the parts of the object below (right of) the
height (width).
meet
Scale the visual media object while preserving its aspect ratio until its
height or width is equal to the value specified by the height or width
attributes, while none of the content is clipped. The object's left top corner
is positioned at the top-left coordinates of the box, and empty space at
the left or bottom is filled up with the background color.
scroll
A scrolling mechanism should be invoked when the element's rendered contents
exceed its bounds.
slice
Scale the visual media object while preserving its aspect ratio so that its
height or width are equal to the value specified by the height and width
attributes while some of the content may get clipped. Depending on the exact
situation, either a horizontal or a vertical slice of the visual media object
is displayed. Overflow width is clipped from the right of the media object.
Overflow height is clipped from the bottom of the media object.
The default value of "fill" is "hidden".
height
The use and definition of this attribute are identical to the "height"
property in the CSS2 specification. Attribute values can be "percentage"
values, and a variation of the "length" values defined in CSS2. For "length"
values, SMIL basic layout only supports pixel units as defined in CSS2. It
allows to leave out the "px" unit qualifier in pixel values (the "px" qualifier
is required in CSS2).
id
Defined in
Section 2
A region element is applied to a positionable element by setting the
region
attribute of the positionable element to the id
value of the region.
The "id" attribute is required for "region" elements.
left
The use and definition of this attribute are identical to the "left"
property in the CSS2 specification. Attribute values have the same restrictions
as the attribute values of the "height" attribute.
The default value is zero.
skip-content
This attribute is introduced for future extensibility of SMIL (see
Appendix
). It is interpreted in the following two
cases:
If a new element is introduced in a future version of SMIL, and this
element allows SMIL 1.0 elements as element content, the "skip-content" attribute
controls whether this content is processed by a SMIL 1.0 player.
If an empty element in SMIL version 1.0 becomes non-empty in a future SMIL
version, the "skip-content" attribute controls whether this content is ignored
by a SMIL 1.0 player, or results in a syntax error.
If the value of the "skip-content" attribute is "true", and one of the cases
above apply, the content of the element is ignored. If the value is "false",
the content of the element is processed.
The default value for "skip-content" is "true".
title
This attribute offers advisory information about the element for which it
is set. Values of the title attribute may be rendered by user agents in a
variety of ways. For instance, visual browsers frequently display the title
as a "tool tip" (a short message that appears when the pointing device pauses
over an object).
It is strongly recommended that all "region" elements have
a "title" attribute with a meaningful description. Authoring tools should
ensure that no element can be introduced into a SMIL document without this
attribute.
top
The use and definition of this attribute are identical to the "top"
property in the CSS2 specification. Attribute values have the same restrictions
as the attribute values of the "height" attribute.
The default value is zero.
width
The use and definition of this attribute are identical to the "width"
property in the CSS2 specification. Attribute values have the same restrictions
as the attribute values of the "height" attribute.
z-index
The use and definition of this attribute are identical to the "z-index"
property in the CSS2 specification, with the following exception:
If two boxes
generated by elements A and B have
the same stack level, then
If the display of an element A starts later than the display of an element
B, the box of A is stacked on top of the box of B (temporal order).
If the display of the elements starts at the same time, and an element A
occurs later in the SMIL document text than an element B, the box of A is
stacked on top of the box of B (document tree order as defined in CSS2).
Element Content
"region" is an empty element.
3.3.2 The
root-layout
element
The "root-layout" element determines the value of the layout properties of
the root element, which in turn determines the size of the viewport, e.g.
the window in which the SMIL presentation is rendered.
If a document contains more than one "root-layout" element, this is an error,
and the document should not be displayed.
Element Attributes
The "root-layout" element can have the following attributes:
background-color
Defined in
Section 3.3.1
height
Defined in
Section 3.3.1
Sets the height of the root element. Only length values are allowed.
id
Defined in
Section 2
skip-content
Defined in
Section 3.3.1
title
Defined in
Section 3.3.1
width
Defined in
Section 3.3.1
Sets the width of the root element. Only length values are allowed.
Element Content
"root-layout" is an empty element.
3.4 The
meta
Element
The "meta" element can be used to define properties of a document (e.g.,
author, expiration date, a list of key words, etc.) and assign values to
those properties. Each "meta" element specifies a single property/value pair.
Element Attributes
The "meta" element can have the following attributes:
content
This attribute specifies the value of the property defined in the meta
element.
The "content" attribute is required for "meta" elements.
id
Defined in
Section 2
name
This attribute identifies the property defined in the meta
element.
The "name" attribute is required for "meta" elements.
skip-content
Defined in
Section 3.3.1
The list of properties is open-ended. This specification defines the following
properties:
base
The value of this property determines the base URI for all relative URIs
used in the document.
pics-label or PICS-Label
The value of this property specifies a valid rating label for the document
as defined by PICS
[PICS]
title
The value of this property contains the title of the presentation.
Element Content
"meta" is an empty element.
4 The Document Body
4.1
The
body
Element
The "body" element contains information that is related to the temporal and
linking behavior of the document. It implicitly defines a "seq" element (defined
in Section 4.2.2, see Section 4.2.4 for a definition of the temporal semantics
of the "body" element).
Element Attributes
The "body" element can have the following attribute:
id
Defined in
Section 2
Element Content
The "body" element can contain the following children:
Defined in
Section 4.5.1
animation
Defined in
Section 4.2.3
audio
Defined in
Section 4.2.3
img
Defined in
Section 4.2.3
par
Defined in
Section 4.2.1
ref
Defined in
Section 4.2.3
seq
Defined in
Section 4.2.2
switch
Defined in
Section 4.3
text
Defined in
Section 4.2.3
textstream
Defined in
Section 4.2.3
video
Defined in
Section 4.2.3
4.2
Synchronization Elements
4.2.1
The
par
Element
The children of a par element can overlap in time. The textual order of
appearance of children in a par has no significance for the timing of their
presentation.
Element Attributes
The "par" element can have the following attributes:
abstract
A brief description of the content contained in the element.
author
The name of the author of the content contained in the element.
begin
This attribute specifies the time for the explicit begin of an element. See
Section 4.2.4
for a definition of its semantics.
The attribute can contain the following two types of values:
delay-value
A delay value is a clock-value measuring presentation time. Presentation
time advances at the speed of the presentation. It behaves like the timecode
shown on a counter of a tape-deck. It can be stopped, decreased or increased
either by user actions, or by the player itself.
The semantics of a delay value depend on the element's first ancestor that
is a synchronization element (i.e. ancestors that are "a" or "switch" elements
are ignored):
If this ancestor is a "par" element, the value defines a delay from the effective
begin of that element (see Figure 4.1).
If this ancestor is a "seq" element (defined in
Section
4.2.2
), the value defines a delay from the effective end of the first
lexical predecessor that is a synchronization element (see Figure 4.2).
event-value
The element begins when a certain event occurs (see Figure 4.3). Its value
is an element-event (see Definition below).
The element generating the event must be "in scope". The set of "in scope"
elements S is determined as follows:
Take all children from the element's first ancestor that is a synchronization
element and add them to S.
Remove all "a" and "switch" elements from S. Add the children of all "a"
elements to S, unless they are "switch" elements.
The resulting set S is the set of "in scope" elements.
Figure 4.1: Using a delay value within a "par" element
Figure 4.2: Using a delay value within a "seq" element
Figure 4.3: Synchronization attribute with element event value
The copyright notice of the content contained in the element.
dur
This attribute specifies the explicit duration of an element. See
Section 4.2.4
for a definition of its semantics.
The attribute value can be a clock value, or the string "indefinite".
end
This attribute specifies the explicit end of an element. See
Section 4.2.4
for a definition of its semantics.
The attribute can contain the same types of attribute values as the "begin"
attribute.
endsync
For a definition of the semantics of this attribute, see
Section 4.2.4
. The attribute can have the
following values:
first
For a definition of the semantics of this value, see
Section 4.2.4
id-ref
This attribute value has the following syntax:
id-ref ::= "id(" id-value ")"
where "id-value" must be a legal XML identifier.
For a definition of the semantics of this value, see
Section 4.2.4
last
For a definition of the semantics of this value, see
Section 4.2.4
The default value of "endsync" is "last".
id
Defined in
Section 2
region
This attribute specifies an abstract rendering surface (either visual or
acoustic) defined within the layout section of the document. Its value must
be an XML identifier. If no rendering surface with this id is defined in
the layout section, the values of the formatting properties of this element
are determined by the default layout.
The "region" attribute on "par" elements cannot be used by the basic layout
language for SMIL defined in this specification. It is added for completeness,
since it may be required by other layout languages.
repeat
For a definition of the semantics of this attribute, see
Section 4.2.4
. The attribute value can be
an integer, or the string "indefinite". The default value is 1.
system-bitrate
Defined in
Section 4.4
system-captions
Defined in
Section 4.4
system-
language
Defined in
Section 4.4
system-overdub-or-caption
Defined in
Section 4.4
system-required
Defined in
Section 4.4
system-
screen
-size
Defined in
Section 4.4
system-screen-depth
Defined in
Section 4.4
title
Defined in
Section 3.3.1
It is strongly recommended that all "par" elements have a "title" attribute
with a meaningful description. Authoring tools should ensure that no element
can be introduced into a SMIL document without this attribute.
Note on Synchronization between Children
The accuracy of synchronization between the children in a parallel group
is implementation-dependent. Take the example of synchronization in case
of playback delays, i.e. the behavior when
the
"par" element contains two or more continuous media types such as audio or
video, and one of them experiences a delay.
A player can show the following synchronization behaviors:
hard synchronization
The player synchronizes the children in the "par" element to a common clock
(see Figure 4.4 a)).
soft synchronization
Each child of the "par" element has its own clock, which runs independently
of the clocks of other children in the "par" element (see Figure 4.4 b)).
a) hard synchronization: Delay in video: Either the audio is stopped,
or some video frames are dropped. The exact behavior is
implementation-dependent
b) soft synchronization
Figure 4.4: Effect of a delay on playout schedule for players using different
synchronization policies
Attribute Values
clock value
Clock values have the following syntax:
Clock-val ::= Full-clock-val | Partial-clock-val | Timecount-val
Full-clock-val ::= Hours ":" Minutes ":" Seconds ("." Fraction)?
Partial-clock-val ::= Minutes ":" Seconds ("." Fraction)?
Timecount-val ::= Timecount ("." Fraction)?
("h" | "min" | "s" | "ms")? ; default is "s"
Hours ::= 2DIGIT; any positive number
Minutes ::= 2DIGIT; range from 00 to 59
Seconds ::= 2DIGIT; range from 00 to 59
Fraction ::= DIGIT+
Timecount ::= DIGIT+
2DIGIT ::= DIGIT DIGIT
DIGIT ::= [0-9]
The following are examples of legal clock values:
Full clock value: 02:30:03 = 2 hours, 30 minutes and 3 seconds
Partial clock value: 02:33 = 2 minutes and 33 seconds
Timecount values:
3h = 3 hours
45min = 45 minutes
30s = 30 seconds
5ms = 5 milliseconds
A fraction x with n digits represents the following value:
x * 1/10**n
Examples:
00.5s = 5 * 1/10 seconds = 500 milliseconds
00:00.005 = 5 * 1/1000 seconds = 5 milliseconds
element-event value
An
element event
value specifies a particular event in a synchronization
element.
An element event has the following syntax:
Element-event ::= "id(" Event-source ")(" Event ")"
Event-source ::= Id-value
Event ::= "begin" | Clock-val | "end"
The following events are defined:
begin
This event is generated at an element's effective begin.
Example use:
begin="id(x)(begin)"
clock-val
This event is generated when a clock associated with an element reaches a
particular value. This clock starts at 0 at the element's effective begin.
For "par" and "seq" elements, the clock gives the presentation time elapsed
since the effective begin of the element. For media object elements, the
semantics are implementation-dependent. The clock may either give presentation
time elapsed since the effective begin, or it may give the media time of
the object. The latter may differ from the presentation time that elapsed
since the object's display was started e.g. due to rendering or network delays,
and is the recommended approach.
It is an error to use a clock value that exceeds the value of the effective
duration of the element generating the event.
Example use:
begin="id(x)(45s)"
end
This event is generated at the element's effective end.
Example use:
begin="id(x)(end)"
Element Content
The par element can contain the following children:
Defined in
Section 4.5.1
animation
Defined in
Section 4.2.3
audio
Defined in
Section 4.2.3
img
Defined in
Section 4.2.3
par
Defined in
Section 4.2.1
ref
Defined in
Section 4.2.3
seq
Defined in
Section 4.2.2
switch
Defined in
Section 4.3
text
Defined in
Section 4.2.3
textstream
Defined in
Section 4.2.3
video
Defined in
Section 4.2.3
All of these elements may appear multiple times as direct children of a par
element.
4.2.2
The
seq
Element
The children of a "seq" element form a temporal sequence.
Attributes
The seq element can have the following attributes:
abstract
Defined in
Section 4.2.1
author
Defined in
Section 4.2.1
begin
Defined in
Section 4.2.1
Defined in
Section 4.2.1
dur
Defined in
Section 4.2.1
end
Defined in
Section 4.2.1
id
Defined in
Section 2
region
Defined in
Section 4.2.1
The region attribute on "seq" elements cannot be used by the basic layout
language for SMIL defined in this specification. It is added for completeness,
since it may be required by other layout languages.
repeat
Defined in
Section 4.2.1
system-bitrate
Defined in
Section 4.4
system-captions
Defined in
Section 4.4
system-
language
Defined in
Section 4.4
system-overdub-or-caption
Defined in
Section 4.4
system-required
Defined in
Section 4.4
system-
screen
-size
Defined in
Section 4.4
system-screen-depth
Defined in
Section 4.4
title
Defined in
Section 3.3.1
It is strongly recommended that all "seq" elements have a "title" attribute
with a meaningful description. Authoring tools should ensure that no element
can be introduced into a SMIL document without this attribute.
Element Content
The seq element can contain the following children:
Defined in
Section 4.5.1
animation
Defined in
Section 4.2.3
audio
Defined in
Section 4.2.3
img
Defined in
Section 4.2.3
par
Defined in
Section 4.2.1
ref
Defined in
Section 4.2.3
seq
Defined in
Section 4.2.2
switch
Defined in
Section 4.3
text
Defined in
Section 4.2.3
textstream
Defined in
Section 4.2.3
video
Defined in
Section 4.2.3
4.2.3
Media Object Elements: The
ref
animation
audio,img
video,text
and
textstream
elements
The media object elements allow the inclusion of media objects into a SMIL
presentation. Media objects are included by reference (using a URI).
There are two types of media objects: media objects with an intrinsic duration
(e.g. video, audio) (also called "continuous media"), and media objects without
intrinsic duration (e.g. text, image) (also called "discrete media").
Anchors and links can be attached to visual media objects, i.e. media objects
rendered on a visual abstract rendering surface.
When playing back a media object, the player must not derive the exact type
of the media object from the name of the media object element. Instead, it
must rely solely on other sources about the type, such as type information
contained in the "type" attribute, or the type information communicated by
a server or the operating system.
Authors, however, should make sure that the group into which of the media
object falls (animation, audio, img, video, text or textstream) is reflected
in the element name. This is in order to increase the readability of the
SMIL document. When in doubt about the group of a media object, authors should
use the generic "ref" element.
Element Attributes
Media object elements can have the following attributes:
abstract
Defined in
Section 4.2.1
alt
For user agents that cannot display a particular media-object, this attribute
specifies alternate text.
It is strongly recommended that all
media object elements have an "alt" attribute with a meaningful description.
Authoring tools should ensure that no element can be introduced into a SMIL
document without this attribute.
author
Defined in
Section 4.2.1
begin
Defined in
Section 4.2.1
clip-begin
The clip-begin attribute specifies the beginning of a sub-clip of a continuous
media object as offset from the start of the media object.
Values in the clip-begin attribute have the following syntax:
Clip-time-value ::= Metric "=" ( Clock-val | Smpte-val )
Metric ::= Smpte-type | "npt"
Smpte-type ::= "smpte" | "smpte-30-drop" | "smpte-25"
Smpte-val ::= Hours ":" Minutes ":" Seconds
[ ":" Frames [ "." Subframes ]]
Hours ::= 2DIGIT
Minutes ::= 2DIGIT
Seconds ::= 2DIGIT
Frames ::= 2DIGIT
Subframes ::= 2DIGIT
The value of this attribute consists of a metric specifier, followed by a
time value whose syntax and semantics depend on the metric specifier. The
following formats are allowed:
SMPTE Timestamp
SMPTE time codes
[SMPTE]
can be used for frame-level
access accuracy. The metric specifier can have the following values:
smpte
smpte-30-drop
These values indicate the use of the "SMPTE 30 drop" format with 29.97 frames
per second. The "frames" field in the time value can assume the values 0
through 29. The difference between 30 and 29.97 frames per second is handled
by dropping the first two frame indices (values 00 and 01) of every minute,
except every tenth minute.
smpte-25
The "frames" field in the time specification can assume the values 0 through
24.
The time value has the format hours:minutes:seconds:frames.subframes. If
the frame value is zero, it may be omitted. Subframes are measured in
one-hundredth of a frame.
Examples:
clip-begin="smpte=10:12:33:20"
Normal Play Time
Normal Play Time expresses time in terms of SMIL clock values. The metric
specifier is "npt", and the syntax of the time value is identical to the
syntax of SMIL clock values.
Examples:
clip-begin="npt=123.45s"
clip-begin="npt=12:05:35.3
clip-end
The clip-end attribute specifies the end of a sub-clip of a continuous media
object (such as audio, video or another presentation) that should be played.
It uses the same attribute value syntax as the clip-begin
attribute.
If the value of the "clip-end" attribute exceeds the duration of the
media object, the value is ignored, and the clip end is set equal to the
effective end of the media object.
Defined in
Section 4.2.1
dur
Defined in
Section 4.2.1
end
Defined in
Section 4.2.1
fill
For a definition of the semantics of this attribute, see Section 4.2.4. The
attribute can have the values "remove" and "freeze".
id
Defined in
Section 2
longdesc
This attribute specifies a link (URI) to a long description of a media object.
This description should supplement the short description provided using the
alt attribute. When the media-object has associated anchors, this attribute
should provide information about the anchor's contents.
region
Defined in
Section 4.2.1
src
The value of the src attribute is the URI of the media object.
system-bitrate
Defined in
Section 4.4
system-captions
Defined in
Section 4.4
system-
language
Defined in
Section 4.4
system-overdub-or-caption
Defined in
Section 4.4
system-required
Defined in
Section 4.4
system-
screen
-size
Defined in
Section 4.4
system-screen-depth
Defined in
Section 4.4
title
Defined in
Section 3.3.1
It is strongly recommended that all media object elements have a "title"
attribute with a meaningful description. Authoring tools should ensure that
no element can be introduced into a SMIL document without this attribute.
type
MIME type of the media object referenced by the "src" attribute.
Element Content
Media Object Elements can contain the following element:
anchor
Defined in
Section 4.5.2
4.2.4 SMIL Time Model
4.2.4.1 Time Model Values
In the following discussion, the term "element" refers to synchronization
elements only.
For each element we define the implicit, explicit, desired, and effective
begin, duration, and end.
The effective begin/duration/end specify what the reader of the document
will perceive.
The implicit, explicit, and desired values are auxiliary values used to define
the effective values.
The rules for calculating each of these values for the elements defined in
SMIL 1.0 are described in the next section.
Each element in SMIL has an
implicit begin
Each element can be assigned an
explicit begin
by adding a "begin"
attribute to the element:
begin = "
value of explicit-begin
It is an error if the explicit begin is earlier than the implicit begin of
the element.
Each element in SMIL has an
implicit end
Each element can be assigned an
explicit end
by adding an "end"
attribute to the element:
end = "
value of explicit-end
The
implicit duration
of an element is the difference between the
implicit end and the implicit begin.
Each element in SMIL can be assigned an
explicit duration
by adding
a "dur" attribute to the element:
dur = "
value of explicit-duration
The
desired begin
of an element is equal to the explicit begin if
one is given, otherwise the desired begin is equal to the implicit begin.
Each element has a
desired end
The
desired duration
of an element is the difference between the
desired end and the desired begin.
Each element has an
effective begin
Each element has an
effective end
. (Note: the effective end of a
child element can never be later than the effective end of its parent.)
The
effective duration
of an element is the difference between the
effective end and the effective begin.
4.2.4.2 Determining Time Model Values for SMIL
1.0 Elements
This section defines how time model values are calculated for the synchronization
elements of SMIL 1.0 in cases that are not covered by the rules in
Section 4.2.4.1
Determining the
implicit begin
of an element
The implicit begin of the first child of the "body" element is when the document
starts playing. When this is falls outside the scope of this document.
The implicit begin of a child of a "par" element is equal to the effective
begin of the "par" element.
The implicit begin of the first child of a "seq" element is equal to the
effective begin of the "seq" element.
The implicit begin of any other child of a "seq" element is equal to the
desired end time of the previous child of the "seq" element.
Determining the
implicit end
of an element
The first description that matches the element is the one that is to be used:
An element with a "repeat" attribute with value "indefinite" has an implicit
end immediately after its effective begin.
An element with a "repeat" attribute with a value other than "indefinite"
has an implicit end equal to the implicit end of a seq element with the stated
number of copies of the element without "repeat" attribute as children.
A media object element referring to a continuous media object has an implicit
end equal to the sum of the effective begin of the element and the intrinsic
duration of the media object.
A media object element referring to a discrete media object such as text
or image has an implicit end immediately after its effective begin.
A "seq" element has an implicit end equal to the desired end of its last
child.
A "par" element has an implicit end that depends on the value of the "endsync"
attribute. The implicit end is equal to the sum of the effective begin of
the "par" element and the implicit duration which is derived as follows:
If the value of the "endsync" attribute is "last", or if the "endsync" attribute
is missing, the implicit duration of the "par" element is the maximum of
the desired durations of its children.
If the value of the "endsync" attribute is "first", the implicit duration
of the "par" element is the minimum of the desired durations of its children.
If the value of the "endsync" attribute is an id-ref, the implicit duration
of the "par" element is equal to the desired duration of the child referenced
by the "id-ref".
Determining the
desired end
of an element
If the element has both an explicit duration and an explicit end, the desired
end is the minimum of:
the sum of the desired begin and the explicit duration; and
the explicit end.
If the element has an explicit duration but no explicit end, the desired
end is the sum of the desired begin and the explicit duration.
If the element has an explicit end but no explicit duration, the desired
end is equal to the explicit end
Otherwise, the desired end is equal to the implicit end.
Determining the
desired begin
of an element
The desired begin of an element is determined by using rule 7 in
Section 4.2.4.1
Determining the
effective begin
of an element
The
effective begin
of an element is equal to the desired begin
of the element, unless the effective end of the parent element is earlier
than this time, in which case the element is not shown at all.
Determining the
effective end
of an element
The effective end of the last child of the body element is player-dependent.
The effective end is at least as late as the desired end, but whether it
is any later is implementation-dependent.
The effective end of the child of a "par" element can be derived as follows:
If the child has a "fill" attribute, and the value of the "fill" attribute
is "freeze", the effective end of the child element is equal to the effective
end of the parent.
The last state of the element is retained on the screen until the
effective end of the element.
If the child has a "fill" attribute, and the value of the "fill" attribute
is "remove", the effective end of the child element is the minimum of the
effective end of the parent and the desired end of the child element.
If the child element has no "fill" attribute, the effective end of the child
depends on whether or not the child has an explicit duration or end.
If the child has an explicit duration or end, the effective end is determined
as if the element had a "fill" attribute with value "remove".
If the child has neither an explicit duration nor an explicit end, the effective
end is determined as if the element had a "fill" attribute with value "freeze".
The effective end of the last child of a "seq" element is derived in the
same way as the effective end of a child of a "par" element.
The effective end of any other child of a "seq" element can be derived as
follows:
If the child has a "fill" attribute, and the value of the "fill" attribute
is "freeze", the effective end of the child element is equal to the effective
begin of the next element
If the child has a "fill" attribute, and the value of the "fill" attribute
is "remove", the effective end of the child element is the minimum of the
effective begin of the next element and the desired end of the next child
element.
If the child element has no "fill" attribute, the effective end of the child
depends on whether or not the child has an explicit duration or end.
If the child has an explicit duration or end, the effective end is determined
as if the element had a fill attribute with value "remove".
If the child has neither an explicit duration nor an explicit end, the effective
end is determined as if the element had a fill attribute with value "freeze".
4.3
The
switch
Element
The switch element allows an author to specify a set of alternative elements
from which only one acceptable element should be chosen. An element is acceptable
if the element is a SMIL 1.0 element, the media-type can be decoded, and
all of the test-attributes (see
Section 4.4
) of the element
evaluate to "true".
An element is selected as follows: the player evaluates the elements in the
order in which they occur in the switch element. The first acceptable element
is selected at the exclusion of all other elements within the switch.
Thus, authors should order the alternatives from the most desirable to the
least desirable. Furthermore, authors should place a relatively fail-safe
alternative as the last item in the
within the switch is chosen (unless this is explicitly not desired).
Implementations should NOT arbitrarily pick an object within a
Note that http URIs provide for content-negotiation, which may be an alternative
to using the "switch" element in some cases.
Attributes
The switch element can have the following attributes:
id
Defined in
Section 2
title
Defined in
Section 3.3.1
It is strongly recommended that all switch elements have a "title"
attribute with a meaningful description Authoring tools should ensure that
no element can be introduced into a SMIL document without this attribute.
Element Content
If the "switch" element is used as a direct or indirect child of a "body"
element, it can contain the following children:
Defined in
Section 4.5.1
animation
Defined in
Section 4.2.3
audio
Defined in
Section 4.2.3
img
Defined in
Section 4.2.3
par
Defined in
Section 4.2.1
ref
Defined in
Section 4.2.3
seq
Defined in
Section 4.2.2
switch
Defined in
Section 4.3
text
Defined in
Section 4.2.3
textstream
Defined in
Section 4.2.3
video
Defined in
Section 4.2.3
All of these elements may appear multiple times as children of a "switch"
element.
If the "switch" element is used within a "head" element, it can contain the
following child:
layout
Defined in
Section 3.2
Multiple layout elements may occur within the switch element.
4.4
Test
Attributes
This specification defines a list of test attributes that can be added to
any synchronization element, and that test system capabilities and settings.
Conceptually, these attributes represent boolean tests. When one of the
test attributes specified for an element evaluates to "false", the element
carrying this attribute is ignored.
Within the list below, the concept of "user preference" may show up. User
preferences are usually set by the playback engine using a preferences dialog
box, but this specification does not place any restrictions on how such
preferences are communicated from the user to the SMIL player.
The following test attributes are defined in SMIL 1.0:
system-bitrate
This attribute specifies the approximate bandwidth, in bits per second available
to the system. The measurement of bandwidth is application specific, meaning
that applications may use sophisticated measurement of end-to-end connectivity,
or a simple static setting controlled by the user. In the latter case, this
could for instance be used to make a choice based on the users connection
to the network. Typical values for modem users would be 14400, 28800, 56000
bit/s etc. Evaluates to "true" if the available system bitrate is equal to
or greater than the given value. Evaluates to "false" if the available system
bitrate is less than the given value.
The attribute can assume any integer value greater than 0. If the value exceeds
an implementation-defined maximum bandwidth value, the attribute always evaluates
to "false".
system-captions
This attribute allows authors to distinguish between a redundant text equivalent
of the audio portion of the presentation (intended for a audiences such as
those with hearing disabilities or those learning to read who want or need
this information) and text intended for a wide audience. The attribute can
has the value "on" if the user has indicated a desire to see closed-captioning
information, and it has the value "off" if the user has indicated that they
don't wish to see such information. Evaluates to "true" if the value is "on",
and evaluates to "false" if the value is "off".
system-
language
The attribute value is a comma-separated list of language names as defined
in [RFC1766].
Evaluates to "true" if one of the languages indicated by user preferences
exactly equals one of the languages given in the value of this parameter,
or if one of the languages indicated by
user preferences exactly equals a prefix of one of the languages given in
the value of this parameter such that the first tag character following the
prefix is "-".
Evaluates to "false" otherwise.
Note: This use of a prefix matching rule does not imply that language tags
are assigned to languages in such a way that it is always true that if a
user understands a language with a certain tag, then this user will also
understand all languages with tags for which this tag is a prefix.
The prefix rule simply allows the use of prefix tags if this is the case.
Implementation note: When making the choice of linguistic preference available
to the user, implementors should take into account the fact that users are
not familiar with the details of language matching as described above, and
should provide appropriate guidance. As an example, users may assume that
on selecting "en-gb", they will be served any kind of English document if
British English is not available. The user interface for setting user preferences
should guide the user to add "en" to get the best matching behavior.
Multiple languages MAY be listed for content that is intended for multiple
audiences. For example, a rendition of the "Treaty of Waitangi", presented
simultaneously in the original Maori and English versions, would call for:
However, just because multiple languages are present within the object on
which the system-language test attribute is placed, this does not mean that
it is intended for multiple linguistic audiences. An example would be a
beginner's language primer, such as "A First Lesson in Latin," which is clearly
intended to be used by an English-literate audience. In this case, the
system-language test attribute should only include "en".
Authoring note: Authors should realize that if several alternative language
objects are enclosed in a "switch", and none of them matches, this may lead
to situations such as a video being shown without any audio track. It is
thus recommended to include a "catch-all" choice at the end of such a switch
which is acceptable in all cases.
system-overdub-or-caption
This attribute is a setting which determines if users prefer overdubbing
or captioning when the option is available. The attribute can have the values
"caption" and "overdub". Evaluates to "true" if the user preference matches
this attribute value. Evaluates to "false" if they do not match.
system-required
This attribute specifies the name of an extension. Evaluates to "true" if
the extension is supported by the implementation, otherwise, this evaluates
to "false". In a future version of SMIL, this attribute value will be an
XML namespace
[NAMESPACES]
system-
screen
-size
Attribute values have the following syntax:
screen-size-val ::= screen-height"X"screen-width
Each of these is a pixel value, and must be an integer value greater than
0. Evaluates to "true" if the SMIL playback engine is capable of displaying
a presentation of the given size. Evaluates to "false" if the SMIL playback
engine is only capable of displaying a smaller presentation.
system-screen-depth
This attribute specifies the depth of the screen color palette in bits required
for displaying the element. The value must be greater than 0. Typical values
are
, 8, 24 .... Evaluates to "true" if the SMIL
playback engine is capable of displaying images or video with the given color
depth. Evaluates to "false" if the SMIL playback engine is only capable of
displaying images or video with a smaller color depth.
Examples
1) Choosing between content with different bitrate
In a common scenario, implementations may wish to allow for selection via
a "system-bitrate" parameter on elements. The media player evaluates each
of the "choices" (elements within the switch) one at a time, looking for
an acceptable bitrate given the known characteristics of the link between
the media player and media server.
...
...
...
........
...
2) Choosing between audio resources with different bitrate
The elements within the switch may be any combination of elements. For instance,
one could merely be specifying an alternate audio track:
...
...
3) Choosing between audio resources in different languages
In the following example, an audio resource is available both in French and
in English. Based on the user's preferred language, the player can choose
one of these audio resources.
...
...
4) Choosing between content written for different screens
In the following example, the presentation contains alternative parts designed
for screens with different resolutions and bit-depths. Depending on the
particular characteristics of the screen, the player can choose one of the
alternatives.
...
........
...
...
...
5) Distinguishing caption tracks from stock tickers
In the following example, captions are shown only if the user wants captions
on.
...
...
6) Choosing the language of overdub and caption tracks
In the following example, a French-language movie is available with English,
German, and Dutch overdub and caption tracks. The following SMIL segment
expresses this, and switches on the alternatives that the user prefers.
...
...
4.5
Hyperlinking Elements
The link elements allows the description of navigational links between objects.
SMIL provides only for in-line link elements. Links are limited to
uni-directional single-headed links (i.e. all links have exactly one source
and one destination resource). All links in SMIL are actuated by the user.
Handling of Links in Embedded Documents
Due to its integrating nature, the presentation of a SMIL document may involve
other (non-SMIL) applications or plug-ins. For example, a SMIL browser may
use an HTML plug-in to display an embedded HTML page. Vice versa, an HTML
browser may use a SMIL plug-in to display a SMIL document embedded in an
HTML page.
In such presentations, links may be defined by documents at different levels
and conflicts may arise. In this case, the link defined by the containing
document should take precedence over the link defined by the embedded object.
Note that since this might require communication between the browser and
the plug-in, SMIL implementations may choose not to comply with this
recommendation.
If a link is defined in an embedded SMIL document, traversal of the link
affects only the embedded SMIL document.
If a link is defined in a non-SMIL document which is embedded in a SMIL document,
link traversal can only affect the presentation of the embedded document
and not the presentation of the containing SMIL document. This restriction
may be released in future versions of SMIL.
Addressing
SMIL supports name fragment identifiers and the '#' connector. This means
that SMIL supports locators as currently used in HTML (e.g. it uses locators
of the form "http://foo.com/some/path#anchor1").
Linking to SMIL Fragments
A locator that points to a SMIL document may contain a fragment part (e.g.
identifies one of the elements within the referenced SMIL document. If a
link containing a fragment part is followed, the presentation should start
as if the user had fast-forwarded the presentation represented by the destination
document to the effective begin of the element designated by the fragment.
The following special cases can occur:
The element addressed by the link has a "repeat" attribute.
If the value of the "repeat" attribute is N, all N repetitions of the element
are played.
If the value of the "repeat" attribute is "indefinite", playback ends according
to the rules defined for repeat value "indefinite".
The element addressed by the link is contained within another element that
contains a "repeat" attribute.
If the value of the "repeat" attribute is N, playback starts at the beginning
of the element addressed by the link, followed by N-1 repetitions of the
element containing the "repeat" attribute.
If the value of the "repeat" attribute is "indefinite", playback starts at
the beginning of the element addressed by the link. Playback ends according
to the rules defined for repeat value "indefinite".
The element addressed by the link is content of a "switch" element: It is
forbidden to link to elements that are the content of "switch" elements.
4.5.1
The
Element
The functionality of the "a" element is very similar to the functionality
of the "a" element in HTML 4.0
[HTML40]
. SMIL
adds an attribute "show" that controls the temporal behavior
of the source when the link is followed. For synchronization purposes, the
"a" element is transparent, i.e. it does not influence the synchronization
of its child elements. "a" elements may not be nested. An "a" element must
have an
href
attribute.
Attributes
The "a" element can have the following attributes:
id
Defined in
Section 2
href
This attribute contains the URI of the link's
destination.
The "href" attribute is required for "a" elements.
show
This attribute controls the behavior of the source document containing the
link when the link is followed. It can have one of the following values:
"replace": The current presentation is paused at its current state and is
replaced by the destination resource. If the player offers a history mechanism,
the source presentation resumes from the state in which it was paused when
the user returns to it.
"new": The presentation of the destination resource starts in a new context,
not affecting the source resource.
"pause": The source presentation is paused at its current state, and the
destination resource starts in a new context. When the display of the destination
resource ends, the source presentation resumes from the state in which it
was paused.
The default value of "show" is "replace".
title
Defined in
Section 3.3.1
It is strongly recommended that all "a" elements have a "title" attribute
with a meaningful description. Authoring tools should ensure that no element
can be introduced into a SMIL document without this attribute.
Element Content
The "a" element can contain the following children:
animation
Defined in
Section 4.2.3
audio
Defined in
Section 4.2.3
img
Defined in
Section 4.2.3
par
Defined in
Section 4.2.1
ref
Defined in
Section 4.2.3
seq
Defined in
Section 4.2.2
switch
Defined in
Section 4.3
text
Defined in
Section 4.2.3
textstream
Defined in
Section 4.2.3
video
Defined in
Section 4.2.3
Examples
Example 1
The link starts up the new presentation replacing the presentation that was
playing.
In the example, the second line can be replaced by a reference to any valid
subtree of an SMIL presentation.
Example 2
The link starts up the new presentation in addition to the presentation that
was playing.
For example, this allows a SMIL player to spawn off an HTML browser.
Example 3
The link starts up the new presentation and pauses the presentation that
was playing.
Example 4
The following example contains a link from an element in one presentation
A to the middle of another presentation B. This would play presentation B
starting from the effective begin of the element with id "next".
Presentation A:
Presentation B (http://www.cwi.nl/presentation):
...
^^^^^^^^^
...
4.5.2 The
anchor
Element
The functionality of the "a" element is restricted in that it only allows
associating a link with a complete media object. HTML image maps have
demonstrated that it is useful to associate links with spatial subparts of
an object. The anchor element realizes similar functionality for SMIL:
The anchor element allows associating a link destination to spatial and temporal
subparts of a media object, using the "href" attribute (in contrast, the
"a" element only allows associating a link with a complete media object).
The anchor element allows making a subpart of the media object the destination
of a link, using the "id" attribute.
The anchor element allows breaking up an object into spatial subparts, using
the "coords" attribute.
The anchor element allows breaking up an object into temporal subparts, using
the "begin" and "end" attributes. The values of the begin and end attributes
are relative to the beginning of the media object.
Attributes
The anchor element can have the following attributes:
begin
Defined in
Section 4.2.1
coords
The value of this attribute specifies a rectangle within the display area
of a visual media object. Syntax and semantics of this attribute are similar
to the coords attribute in HTML image maps, when the link is associated with
a rectangular shape. The rectangle is specified by four length values: The
first two values specify the coordinates of the upper left corner of the
rectangle.The second two values specify the coordinates of the lower right
corner of the rectangle. Coordinates are relative to the top left corner
of the visual media object (see Figure 4.5). If a coordinate is specified
as a percentage value, it is relative to the total width or height of the
media object display area.
An attribute with an erroneous coords value is ignored (right-x smaller or
equal to left-x, bottom-y smaller or equal to top-y). If the rectangle defined
by the coords attribute exceeds the area covered by the media object, exceeding
height and width are clipped at the borders of the media object.
Values of the coords attribute have the following syntax:
coords-value ::= left-x "," top-y "," right-x "," bottom-y
Figure 4.5: Semantics of "coords" attribute
end
Defined in
Section 4.2.1
id
Defined in
Section 2
show
Defined in
Section 4.5.1
skip-content
Defined in
Section 3.3.1
title
Defined in
Section 3.3.1
It is strongly recommended that all anchor elements have a "title"
attribute with a meaningful description. Authoring tools should ensure that
no element can be introduced into a SMIL document without this attribute.
Examples
1) Associating links with spatial subparts
In the following example, the screenspace taken up by a video clip is split
into two sections. A different link is associated with each of these sections.
2) Associating links with temporal subparts
In the following example, the duration of a video clip is split into two
subintervals. A different link is associated with each of these subintervals.
3) Jumping to a subpart of an object
The following example contains a link from an element in one presentation
A to the middle of a video object contained in another presentation B. This
would play presentation B starting from second 5 in the video (i.e. the
presentation would start as if the user had fast-forwarded the whole presentation
to the point at which the designated fragment in the "CoolStuff" video begins).
Presentation A:
Presentation B:
4) Combining different uses of links
The following example shows how the different uses of associated links can
be used in combination.
Presentation A:
Presentation B:
5 SMIL DTD
5.1
Relation to XML
A SMIL 1.0 document may optionally contain a document type declaration,
which names the document type definition (DTD) in use for the document.
For SMIL, the document type declaration should look as follows (the double
quotes can be replaced by single quotes):
"http://www.w3.org/TR/REC-smil/SMIL10.dtd">
The XML 1.0 specification provides a way to extend the DTD using the
element, for instance to add a new set of entity definitions.
Authors must not use this feature with SMIL since many SMIL players will
not support it.
The following is illegal in SMIL:
"http://www.w3.org/TR/REC-smil/SMIL10.dtd" [
"-//Acme Corp//ENTITIES Corporate Symbols//EN"
"http://www.acme.com/corp_symbols.xml"
%AcmeCorpSymbols;
]>
5.2 DTD
%title-attr;
abstract CDATA #IMPLIED
author CDATA #IMPLIED
copyright CDATA #IMPLIED
">
%id-attr;
%id-attr;
type CDATA "text/smil-basic-layout"
height CDATA #IMPLIED
width CDATA #IMPLIED
background-color CDATA #IMPLIED
">
%id-attr;
%title-attr;
%viewport-attrs;
left CDATA "0"
top CDATA "0"
z-index CDATA "0"
fit (hidden|fill|meet|scroll|slice) "hidden"
%skip-attr;
%id-attr;
%title-attr;
%viewport-attrs;
%skip-attr;
name NMTOKEN #REQUIRED
content CDATA #REQUIRED
%skip-attr;
begin CDATA #IMPLIED
end CDATA #IMPLIED
">
system-bitrate CDATA #IMPLIED
system-language CDATA #IMPLIED
system-required NMTOKEN #IMPLIED
system-screen-size CDATA #IMPLIED
system-screen-depth CDATA #IMPLIED
system-captions (on|off) #IMPLIED
system-overdub-or-caption (caption|overdub) #IMPLIED
">
fill (remove|freeze) 'remove'
">
%id-attr;
%desc-attr;
endsync CDATA "last"
dur CDATA #IMPLIED
repeat CDATA "1"
region IDREF #IMPLIED
%sync-attributes;
%system-attribute;
%id-attr;
%desc-attr;
dur CDATA #IMPLIED
repeat CDATA "1"
region IDREF #IMPLIED
%sync-attributes;
%system-attribute;
%id-attr;
%title-attr;
%id-attr;
%desc-attr;
region IDREF #IMPLIED
alt CDATA #IMPLIED
longdesc CDATA #IMPLIED
src CDATA #IMPLIED
type CDATA #IMPLIED
dur CDATA #IMPLIED
repeat CDATA '1'
%fill-attribute;
%sync-attributes;
%system-attribute;
">
clip-begin CDATA #IMPLIED
clip-end CDATA #IMPLIED
">
%id-attr;
%title-attr;
href CDATA #REQUIRED
show (replace|new|pause) 'replace'
">
%smil-link-attributes;
%skip-attr;
%smil-link-attributes;
%sync-attributes;
coords CDATA #IMPLIED
References
[CSS2]
"Cascading Style Sheets, level 2", B. Bos, H. Lie, C. Lilley, I. Jacobs,
12 May 1998.
Available at
[HTML40]
"HTML 4.0 Specification", D. Raggett, A. Le Hors, I. Jacobs, 24 April 1998.
Available at
[ISO/IEC 10646]
ISO (International Organization for Standardization). ISO/IEC 10646-1993
(E). Information technology -- Universal Multiple-Octet Coded Character Set
(UCS) -- Part 1: Architecture and Basic Multilingual Plane. [Geneva]:
International Organization for Standardization, 1993 (plus amendments AM
1 through AM 7).
[NAMESPACES]
"Namespaces in XML", T. Bray, D. Hollander, A. Layman, 27 March 1998
W3C working draft. Available at
[PICS]
"PICS 1.1 Label Distribution -- Label Syntax and Communication Protocols",
31 October 1996, T. Krauskopf, J. Miller, P. Resnick, W. Trees
Available at
[RFC1738]
"Uniform Resource Locators", T. Berners-Lee, L. Masinter, and M. McCahill,
December 1994.
Available at
ftp://ftp.isi.edu/in-notes/rfc1738.txt
[RFC1766]
"Tags for the Identification of Languages", H. Alvestrand, March 1995.
Available at
ftp://ftp.isi.edu/in-notes/rfc1766.txt
[RFC1808]
"Relative Uniform Resource Locators", R. Fielding, June 1995.
Available at
ftp://ftp.isi.edu/in-notes/rfc1808.txt
[RFC2045]
"Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet
Message Bodies", N. Freed and N. Borenstein, November 1996.
Available at
ftp://ftp.isi.edu/in-notes/rfc2045.txt
. Note that this RFC obsoletes
RFC1521, RFC1522, and RFC1590.
[SMPTE]
"Time and Control Codes for 24, 25 or 30 Frame-Per-Second Motion-Picture
Systems - RP 136-1995". Society of Motion Picture & Television
Engineers.
[URI]
"Uniform Resource Identifiers (URI): Generic Syntax and Semantics", T.
Berners-Lee, R. Fielding, L. Masinter, 4 March 1998.
Available at
This is a work in progress that is expected to update
[RFC1738]
and
[RFC1808]
[XML10]
"Extensible Markup Language (XML) 1.0", T. Bray, J. Paoli, C.M. Sperberg-McQueen,
editors, 10 February 1998.
Available at
Appendix
Extending SMIL 1.0
(non-normative)
In the future, SMIL 1.0 may be extended by another W3C recommendation, or
by private extensions.
For these extensions, it is recommended that the following rules are obeyed:
All elements introduced in extensions must have a "skip-content" attribute
(defined in Section 3.3.1) if it should be possible that their content is
processed by SMIL 1.0 players.
Private extensions must be introduced using the syntax of the XML namespace
specification.
It is recommended that SMIL 1.0 players are prepared to handle documents
that contain extension that obey these two rules.
Extensions should be handled using an XML namespace mechanism, once such
a mechanism becomes a W3C recommendation. In the rest of the section, the
syntax and semantics for XML namespaces defined in the W3C note [NAMESPACE]
will be used for demonstration purposes only.
The following cases can occur:
The document contains a namespace declaration for the SMIL 1.0 specification
that defines an empty prefix. In this case, non-SMIL 1.0 elements and attributes
are only allowed in a document if they are declared using an XML namespace.
The document may not contain a document type declaration for SMIL 1.0. If
it does, it is invalid.
In the following example, the element "new:a" is a legal extension. The elements
"mytags:a" and "b" are syntax errors, since they are not declared using an
XML namespace.
...
...
...
The document contains no document type declaration, it contains a document
type declaration for a SMIL version higher than 1.0, or it contains a namespace
declaration for a SMIL specification with a version higher than 1.0. For
a SMIL 1.0 player to be able to recognize such a namespace declaration, it
is recommended that the URI of future SMIL versions starts with
for example be a version number.
In this case, a SMIL 1.0 player should assume that it is processing a SMIL
document with a version number higher than 1.0.
The following cases can occur:
Unknown element
Unknown elements are ignored
An unknown element may contain content that consists of SMIL 1.0 elements.
Whether such content is ignored or processed depends on the value of the
"skip-content" attribute. If the attribute is set to "true", or the attribute
is absent, the content is not processed. If it is set to "false", the content
is processed.
Content in Element that was declared "Empty"
A future version of SMIL may allow content in elements that are declared
as "empty" in SMIL 1.0.
Whether this content is ignored or not depends on the value of the "skip-content"
attribute of the formerly empty element. If the attribute is set to "true",
the content is not processed. If it is set to "false", the content is processed.
Unknown Attribute
Unknown attributes are ignored.
Unknown Attribute Value
Attributes with unknown attribute values are ignored.
The document contains a document type declaration for SMIL 1.0. In this case,
it may not contain any non-SMIL 1.0 elements, even if they are declared using
XML namespaces. This is because such extensions would render the document
invalid.
Using SMIL 1.0 as an Extension
When the XML namespace mechanism is used to include SMIL elements and attributes
in other XML-based documents, it is recommended to use the following namespace
identifier: