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11. The SMIL 2.1 Time Manipulations Module

Editor for SMIL 2.1:
Thierry MICHEL, W3C
Editor for SMIL 2.0:
Patrick Schmitz, Microsoft

Table of contents

11.1 Introduction

This module introduces new attributes for advanced manipulation of time behavior, such as controlling the speed or rate of time for an element. These time manipulations are especially suited to animation and non-linear or discrete media. Not all continuous media types will fully support time manipulations. For example, streaming MPEG 1 video will not generally support backwards play. A fallback mechanism is described for these kinds of media.

Four new attributes add support for time manipulations to SMIL timing modules, including control over the speed of an element, and support for acceleration and deceleration.  The impact on overall timing and synchronization is described. A definition is provided for reasonable fallback mechanisms for media players that cannot support the time manipulations.

An accessibility requirement for control of the playback speed is related to the speed control, but may also be controlled through some other mechanism such as DOM interfaces. 

11.2 Relation to SMIL 2.0

The SMIL 2.1 specification leaves the Time Manipulations Module unchanged.
Please refer to the former SMIL 2.0 Time Manipulations Module [SMIL20-timemanipulations] for information about semantics, elements and attributes allowing advanced manipulation of time behavior in SMIL presentationss.

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