Flash StageQuality.LOW causes strange jiggling, anyone know why?

Question

We have a cpu-intesive Flash app that needs to run at StageQuality.HIGH if possible due to how much better it looks. On slower machines we kick it down to StageQuality.LOW, but it causes the entire app to look horrible - the images and even sprites "jiggle".

Here's a link to a 20s movie showing the problem. It has to be seen to understand "jiggling".

http://cloud.tourbuzz.net.s3.amazonaws.com/tmp/Flash%20Low%20Quality%20Jiggling.mov

Anyone have any idea what's going on? I can understand if LQ mode doesn't anti-alias, but the actual Sprites jumping around is unacceptable. Can't tell if it's me or a bug or what.

Answer 1

The only thing I can think of is that, in low quality mode, it's turning on pixel snapping? It shouldn't cause this kind of stutter, unless the elements that are jiggling were moving in sub-pixel increments in the normal course of your app, so that when pixel snapping gets toggled on, it's making that very subtle movement much more 'jiggly'.

http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/flash/display/Bitmap.html#pixelSnapping