for a business reasons I need to overly Flash video player with HTML content. This requires the WMODE to be set as “opaque”.
However Flash Player Engineering Tinic Uro warns us over lower performance and couple years ago he even mentioned serious instability and Adobe TechNote 15523 states “the WMODE parameter is supported only on some browser/Flash Player version combinations“.
In addition there is whole bunch of bugs associated directly with the WMODE option (search for “wmode” and “opaque” in Adobe Flash Player Bug and Issue Management System)
To my knowledge even YouTube tries to avoid using the WMODE “opaque” at any cost, just have a look at the design of the account drop down menu above expanded video.
My question is:
Do you have any experience with lower performance, bugs or instability regarding Flash video and WMODE “opaque”? Can you share any good reading on this topic?
Yes, wmode opaque can hinder performance. “transparent” is even worse. However,
1) It’s not as bad as it was a while ago (when sometimes it wouldn’t work at all).
2) Most importantly, performance hit is only on certain situations. I have ran into two different situations: a) you have a part of your SWF that is being redraw, and that part of the SWF (dirty rectangle) is close to some HTML content. This forces the browser to redraw the HTML content every time the SWF part is redrawn, thus losing performance; and b) user events like a mouse rolling over a button that is close to HTML content can also be a problem… the browser seems to lose a few frames every time you move the mouse (to determine what’s below the cursor, maybe?) so if you have a quick rollover (say, something that takes 0.3s) it’s very easy to notice the animation ‘lagging’ as you move the mouse and it loses some frames.
Point is, if you can avoid situations where you are interacting with animated content below the HTML area, or if you can disable the HTML content sometimes, using opaque is ok.
Performance also vary between browsers, so be sure to test well.