The dynsrc attribute

Use the dynsrc attribute extension in the <img> tag to reference an AVI movie for inline display by Internet Explorer. Its required value is the URL of the movie file enclosed in quotation marks. For example, this text displays the tag and attribute for an AVI movie file entitled intro.avi:

<img dynsrc="movies/intro.avi">

The browser sets aside a video viewport in the HTML display window and plays the movie, with audio if it’s included in the clip and if your computer is able to play audio. Internet Explorer treats dynsrc movies similar to inline images: in line with current body content and according to the dimension of the video frame. And, like common images, the dynsrc referenced movie file gets displayed immediately after download from the server. You may change those defaults and add some user controls with other attributes, as described below.

Because all other browsers currently ignore the special Internet Explorer attributes for movies, they may become confused by an <img> tag that does not contain the otherwise required src attribute and an image URL. We recommend that you include the src attribute and a valid image file URL in all <img> tags, including those that reference a movie for Internet Explorer users. The other browsers display the still image in place of the movie; Internet Explorer does the reverse and plays the movie, but does not display the image. Note that the order of attributes does not matter. For example:

<img dynsrc="movies/intro.avi" src="pics/mvstill.gif">

Internet Explorer loads and plays the AVI movie intro.avi; other graphical browsers will load and display the mvstill.gif image instead.

The controls attribute

Normally, Internet Explorer plays a movie inside a framed viewport once, without any visible user controls. The user may restart, stop, and continue the movie by clicking inside that viewport with the mouse. Use the controls attribute (no value) to add visible controls to the movie viewport so that the user may, with the mouse, play, fast-forward, reverse, stop, and pause the movie, like on a VCR. If the movie clip includes a sound track, Internet Explorer provides an audio volume control as well. For example:

<img dynsrc="movies/intro.avi" controls src="pics/mvstill.gif">

adds the various playback controls to the video window of the intro.avi movie clip, as shown in Figure 5.19.

The loop attribute

Internet Explorer normally plays a movie clip from beginning to end once after download. The loop attribute for the movie <img> tag lets you have the clip play repeatedly for an integer number of times set by the attribute’s value, or forever if the value is infinite. The user may still cut the loop short by clicking on the movie image, by pressing the stop button, if given controls (see previous), or by moving on to another document.

The following intro.avi movie clip will play from beginning to end, then restart at the beginning and play through to the end nine more times:

<img dynsrc="movies/intro.avi" loop=10 src="pics/mvstill.gif">

Whereas the following movie will play over and over again, incessantly:

<img dynsrc="movies/intro.avi" loop=infinite src="pics/mvstill.gif">

Looping movies aren’t necessarily meant to annoy. Some special effects animations, for instance, are a sequence of repeated frames or segments. Rather than string the redundant segments into one, long movie that extends its download time, simply loop the single, compact frame or segment.

The start attribute

Normally, an Internet Explorer movie clip starts playing as soon as it’s downloaded. You can modify that behavior with the start attribute in the movie’s <img> tag. By setting its value to mouseover, you delay playback until the user passes the mouse pointer over the movie viewport. The other valid start attribute value, fileopen, is the default: start playback just after download. It is included because both values may be combined in the start attribute to cause the movie to automatically playback once after download, and then whenever the user passes the mouse over its viewport. Add a value-separating comma, with no intervening spaces, or else enclose them in quotes, when combining the start attribute values.

For example, our by-now-infamous intro.avi movie will play once when its host HTML document is loaded by the user, and whenever he or she passes the mouse over the movie’s viewport:

<img dynsrc="movies/intro.avi" start="fileopen,mouseover"
     src="pics/mvstill.gif">