Hang/delay starting up multiple USB cameras?

Question

This one has been going on for a while, but it's been inonsistent in behavior with different computers and different configurations.
Our Flex application uses two cameras, user selectable from our interface.  I've got a stripped down version of the code (done as a web app from Flash Builder) that I've pasted below.  It has two dropdowns to select the cameras, and a preview display area for the selected camera.
It appears that, depending on the USB bus configuration and where the cameras are, it will either work correctly or hang for an indeterminate amount of time (usually over 30 seconds) when a second USB camera is selected.  I've been able to reproduce this fairly consistently if both cameras are plugged into a hub.  On other computers in our office, it will work with the cameras plugged into one set of ports but hang when one of the cameras is moved to another port.
Another note, if I leave the camera in default mode (320x240, 15FPS) everything seems to work consistently.  If I leave the resolution at 320x240 and change the frame rate to 30FPS, it also works.  However, if I change the resolution to 640x480, it will have the delay.
Any suggestions on this?  Yes, we need to have both cameras, and yes they need to be 640x480.
<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
               xmlns:s="library://ns.adobe.com/flex/spark"
               xmlns:mx="library://ns.adobe.com/flex/mx"
               minWidth="955" minHeight="600"
               creationComplete="onInit(event)">
    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, value objects) here -->
    </fx:Declarations>
    <fx:Script>
        <![CDATA[
            import mx.collections.ArrayList;
            import mx.events.FlexEvent;
            import spark.events.IndexChangeEvent;
            [Bindable] private var cameraList:ArrayList;
            protected function onInit(event:FlexEvent):void {
                cameraList = new ArrayList(Camera.names);
            protected function onCamera1Change(event:IndexChangeEvent):void {
                var cam:Camera = Camera.getCamera(event.newIndex.toString());
                cam.setMode(640, 480, 15);
                cam1Preview.attachCamera(cam);
            protected function onCamera2Change(event:IndexChangeEvent):void {
                var cam:Camera = Camera.getCamera(event.newIndex.toString());
                cam.setMode(640, 480, 15);
                cam2Preview.attachCamera(cam);
        ]]>
    </fx:Script>
    <s:HGroup width="100%" height="100%" paddingTop="10" paddingBottom="10" paddingLeft="10" paddingRight="10" gap="10">
        <s:VGroup width="100%" height="100%" horizontalAlign="center" gap="10">
            <s:Label text="Camera 1"/>
            <s:DropDownList id="cam1List" dataProvider="{cameraList}" change="onCamera1Change(event)" width="100%"/>
            <mx:VideoDisplay id="cam1Preview" width="320" height="240"/>
        </s:VGroup>
        <s:VGroup width="100%" height="100%" horizontalAlign="center" gap="10">
            <s:Label text="Camera 2"/>
            <s:DropDownList id="cam2List" dataProvider="{cameraList}" change="onCamera2Change(event)" width="100%"/>
            <mx:VideoDisplay id="cam2Preview" width="320" height="240"/>
        </s:VGroup>
    </s:HGroup>
</s:Application>

Answer 1

Dear everyXnewXday,
I'm as mystified as you are. This sounds exactly like my issue. Have you tried starting up in Verbose mode (hold down cmd-V on startup)? This will give you a running log of events that occur during startup, and may indicate where errors are occurring that the operating system has to resolve or work around in order to proceed. I'm no expert in interpreting this information, though, which is why I posted this question in the event others have ideas about how to reduce the amount of computational "red tape."
Do you have many external drives or other peripherals connected to your computer? One thing I have noticed in the startup sequence is that the OS has some difficulty recognizing or mounting some of them (in particular, a Seagate FreeAgent USB drive). Not sure if this is a driver issue, but I believe I have the most current drivers for all my external drives.
- K725