set_video_attribute_value ‐ Dynamic modification of the video properties
This action is used to modify the values associated with attributes in a video property. If the attribute values contain parenthesized expressions, they are dynamically evaluated as numerical expressions and their values are replaced in the attribute value strings. The string value of the operator attribute is an operator string. The values of the operator must be "=", "=", "+=", "-=", "*=", or "/=". The child node is a video element that contains at least one attribute and its associated value.
The attributes of the child node are called source attributes. The target node must have video properties. In this case, the values of the source attributes are used to modify the values of the corresponding attributes in the target video properties.
For instance if the source element has attributes begin and end that define the begin and end time of video playing, and if the operator is "=", the source values define the begin and end time of the target video property. The other operators respectively correspond to addition, substraction, multiplication, and division of the target values by the source values. The attributes of the target element that are not instantiated in the source video element (the child node) are not modified by this action.
The following element must occur in set_video_attribute_value: one video property element.
The target node must have video properties.
The example below defines an action that starts immediately the playing of the video file associated with a target node and stops it after 10000 time units.
<set_video_attribute_value operator="="> <video begin="now" end="(now + 10000)"/> </set_video_attribute_value>