7 3GPP SMIL Language Profile definition
26.2463GPP3GPP SMIL language profileRelease 17Transparent end-to-end Packet-switched Streaming Service (PSS)TS
3GPP SMIL is based on SMIL 2.0 Basic language profile [7]. This chapter defines the content model and integration semantics of the included modules where they differ from those defined by SMIL Basic.
7.1 Content Control Modules
3GPP SMIL includes the content control functionality of the BasicContentControl, SkipContentControl and PrefetchControl modules of SMIL 2.0. PrefetchControl is not part of SMIL Basic and is an additional module in this profile.
All BasicContentControl attributes listed in the module specification shall be supported. Annex B extends the SMIL 2.0 BasicContentControl specification [7] by additional definitions on the systemComponent test attribute.
Note: The SMIL specification [7] defines that all functionality of PrefetchControl module is optional. This mean that even although PrefetchControl is mandatory user agents may implement semantics of PrefetchControl module only partially or not to implement them at all.
PrefetchControl module adds the prefetch element to the content model of SMIL Basic body, switch, par and seq elements. The prefetch element has the attributes defined by the PrefetchControl module (mediaSize, mediaTime and bandwidth), the src attribute, the BasicContentControl attributes and the skip-content attribute.
7.2 Layout Module
3GPP SMIL includes the BasicLayout module of SMIL 2.0 for spatial layout. The module is part of SMIL Basic.
Default values of the width and height attributes for root-layout shall be the dimensions of the device display area.
7.3 Linking Module
3GPP SMIL includes the SMIL 2.0 BasicLinking and LinkingAttributes modules for providing hyperlinks between documents and document fragments. The BasicLinking module is from SMIL Basic.
When linking to destinations outside the current document, implementations may ignore values "play" and "pause" of the ‘sourcePlaystate’ attribute and values "new" and "pause" of the ‘show’ attribute, instead using the semantics of values "stop" and "replace" respectively. When the values of ‘sourcePlaystate’ and ‘show’ are ignored the player may also ignore the ‘sourceLevel’ attribute since it is of no use then
7.4 Media Object Modules
3GPP SMIL includes the media elements from the SMIL 2.0 BasicMedia module and attributes from the MediaAccessibility, MediaDescription and MediaClipping modules. MediaAccessibility, MediaDescription and MediaClipping modules are additions in this profile to the SMIL Basic.
MediaClipping module adds to the profile the ability to address sub-clips of continuous media. MediaClipping module adds ‘clipBegin‘ and ‘clipEndยด(and for compatibility ‘clip-begin‘ and ‘clip-end‘) attributes to all media elements.
MediaAccessibility module provides basic accessibility support for media elements. New attributes ‘alt‘, ‘longdesc‘ and ‘readIndex‘ are added to all media elements by this module. MediaDescription module is included by the MediaAccessibility module and adds ‘abstract‘, ‘author‘ and ‘copyright‘ attributes to media elements.
MediaParameter module allows passing additional parameters to the rendering of a media object. This specification extends the SMIL 2.0 specification [7] by defining some values for the ‘name’ and ‘value‘ attributes of MediaParameter module and the expected behaviour of a 3GPP SMIL player when these are used:
A 3GPP SMIL player should render the content as specified whenever one of the following name value pairs are encoded as a parameter to a media object of one of the listed MIME types:
NOTE: The behaviour of the 3GPP SMIL player is undefined for all other cases.
|
MIME type of the media object |
value of the ‘name’ attribute |
value of the ‘value’ attribute |
Intended rendering of the media content. |
|
application/text, application/xhtml+xml, application/vnd.wap.xhtml+xml |
color or foreground-color |
Any legal value for the CSS2 color attribute [8] (eg. "#ff000", "red") |
The text document is rendered with the given (default) color. Note: Attribute name="foreground-color" is included for compatibility. |
|
application/text, application/xhtml+xml, application/vnd.wap.xhtml+xml |
font-size or textsize |
Any legal value for the CSS2 font-size attribute [8] (e.g. "medium", "12pt") |
The text document is rendered with the given (default) text size. The size values are interpreted as in CSS2 [8], Note: Attribute name="fontsize" is included for compatibility. |
7.5 Metainformation Module
The MetaInformation module of SMIL 2.0 is included to the profile. This module is addition in this profile to the SMIL Basic and provides a way to include descriptive information about the document content into the document.
This module adds meta and metadata elements to the content model of SMIL Basic head element.
7.6 Structure Module
The Structure module defines the top-level structure of the document. It is included by SMIL Basic.
7.7 Timing and Synchronization modules
The timing modules included in the 3GPP SMIL are BasicInlineTiming, MinMaxTiming, BasicTimeContainers, RepeatTiming and EventTiming. The EventTiming module is an addition in this profile to the SMIL Basic.
For ‘begin’ and ‘end’ attributes either single offset-value or single event-value shall be allowed. Offsets shall not be supported with event-values.
Event timing attributes that reference invalid IDs (for example elements that have been removed by the content control) shall be treated as being indefinite.
Supported event names and semantics shall be as defined by the SMIL 2.0 Language Profile. All user agents shall be able to raise the following event types:
– activateEvent;
– beginEvent;
– endEvent.
The following SMIL 2.0 Language event types should be supported:
– focusInEvent;
– focusOutEvent;
– inBoundsEvent;
– outOfBoundsEvent;
– repeatEvent.
User agents shall ignore unknown event types and not treat them as errors.
Events do not bubble and shall be delivered to the associated media or timed elements only.
When using delivery mechanisms such as streaming, the setup time, connection time and buffering time shall be excluded from the computation of the simple duration.
7.8 Transition Effects Module
3GPP SMIL profile includes the SMIL 2.0 BasicTransitions module to provide a framework for describing transitions between media elements.
Note: The SMIL specification [7] defines that all functionality of BasicTransitions module is optional: "Transitions are hints to the presentation. Implementations must be able to ignore transitions if they so desire and still play the media of the presentation". This mean that even although the BasicTransitions module is mandatory user agents may implement semantics of the BasicTransitions module only partially or not to implement them at all. Content authors should use transitions in their SMIL presentation where this appears useful. User agents that fully support the semantics of the Basic Transitions module will render the presentation with the specified transitions. All other user agents will leave out the transitions but present the media content correctly.
User agents that implement the semantics of this module should implement at least the following transition effects described in SMIL 2.0 specification [7]:
– barWipe;
– irisWipe;
– clockWipe;
– snakeWipe;
– pushWipe;
– slideWipe;
– fade;
A user agent should implement the default subtype of these transition effects.
A user agent that implements the semantics of this module shall at least support transition effects for non-animated image media elements. For purposes of the Transition Effects modules, two media elements are considered overlapping when they occupy the same region.
BasicTransitions module adds attributes ‘transIn’ and ‘transOut’ to the media elements of the Media Objects modules, and value "transition" to the set of legal values for the ‘fill’ attribute of the media elements. It also adds transition element to the content model of the head element.