Inside Macintosh: QuickTime Reference

Media Object Attributes

composite-mode: Specifies how to composite a visual media element with other visual media elements behind it. Its value is a combination of a text string identifying the mode and an optional semicolon and second parameter, which will vary depending on the mode itself. The composite-mode SMIL attribute is equivalent to the graphics mode property of a Movie's Media. Possible modes are:
- copy, none, direct: Specifies a direct copy. The default composite mode for most image formats.
- blend;percent : Specifies a weighted blend between the image and the background, with a required percent integer value (i.e., "50%") specifying the blend weight. 0% means complete transparency, 100% complete opacity.
- transparent-color;color: Specifies that all pixels of a particular color within the image should be treated as transparent, similar to transparency in GIF files [GIF89]. It accepts a second parameter, color, which specifies the color to be rendered as transparent. The color parameter may be any valid color specification supported by Cascading Style Sheets Level 2 ⁴.
- alpha, straight-alpha, premultiplied-white-alpha, premultiplied-black-alpha: Specify that the image has an internal alpha channel which should be used when compositing. Alpha and straight-alpha refer to a separate alpha component; the premultiplied modes refer to an image which has been premultiplied with the alpha against a white or black background, respectively.
- straight-alpha-blend: Specifies that the image has an internal alpha channel as a separate component, and that when compositing the alpha weight should also be multiplied by a percentage blend value, which is specified by a second parameter, similar to the second parameter in blend mode.
Example usage:
<imgsrc="test.png"qt:composite-mode="alpha"/>
immediate-instantiation: Performs the same function as the identically named attribute for the <smil> root element, though affecting only this particular media object instead of the entire presentation. Example usage:
<imgsrc="bkgimage.png"qt:immediate-instantiation="true"/>
bitrate: Specifies the bitrate at which a media object would need to be transmitted in order to play back in real time. It is used in conjunction with immediate-instantiation, in order to give QuickTime enough information to decide how far in advance it should attempt to read a delayed-instantiation media object in order to provide seamless playback. Possible values are positive integers, in units of bits-per-second. Example usage:
<videosrc="stream56k.mov"qt:bitrate="56000"qt:immediate-instantiation="true"/>
system-mime-type-supported: Specifies to the player the MIME type that needs to be supported in order to be able to play back this particular media-object. Though similar, at first blush, to the type attribute, this is intended to be used in conjunction with the switch element in SMIL, in a similar fashion as the other system attributes, such as system bitrate and system screen definitions. Possible values are character strings matching a valid MIME type. Example usage is:
<switch> <imgsrc="qt.mov"qt:system-mime-type-supported="video/quicktime"/> <imgsrc="someotherformat.suffix"qt:system-mime-type-supported= "some-other/ format's-mime-type"/>
attach-timebase: Defaults to "true", which slaves the timebase of the child movie to the parent's. This means that play/pause controls will control the child movie as well as the parent. Setting it to "false" unlinks the timebase, which is useful for interactivity operations, especially when using the SMIL <par> tag. Note that when doing this, you need to provide some other way to control the child movie, presumably through the use of actions. Example usage:
<imgsrc="movie2.mov" qt:attach-timebase="true"/>
chapter: Specifies to the player a chapter name to attach to this particular media object, which then may be used by the player to provide a higher-level navigation UI than a simple linear control. Valid values are any character string, and example usage is:
<imgsrc="movie1.mov"qt:chapter="chap1"/>

Inside Macintosh: QuickTime Reference