Camera Eventually stops connecting possibly caused by a handle leak

Question

Can somebody tell me how to write an app that display a picture of the webcam on screen, change the size of video shown and remove it from the screen without the camera eventually not displaying and the created handles being left behind.
From my investigation any camera with the usbvideo.sys driver is affected, which will be at least 50% of webcams out there.
Sometimes air locks up and becomes unresponsive / sometimes it just stops displaying the camera, it depends upon the camera.
Tested with lots of different cameras on Windows 7 and 8 with lots of versions of the Air/Flex Frameworks.
Heres a simple app to test it.
<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009"
    xmlns:s="library://ns.adobe.com/flex/spark"
    xmlns:mx="library://ns.adobe.com/flex/mx"
    creationComplete="windowedapplication1_creationCompleteHandler(event)">
  <fx:Script>
  <![CDATA[
  import mx.collections.ArrayList;
  import mx.events.FlexEvent;
  import spark.events.IndexChangeEvent;
  private var camera:Camera;
  [Bindable]
  private var cams:ArrayList;
  private var video:Video;
  [Bindable]
  private var autoInProgress:Boolean;
  [Bindable]
  private var totalAttempts:int = 0;
  private var currentAttempts:int = 0;
  protected function windowedapplication1_creationCompleteHandler(event:FlexEvent):void
  cams = new ArrayList(Camera.names);
  protected function selectedCamera_changeHandler(event:IndexChangeEvent):void
  camera = Camera.getCamera(selectedCamera.selectedIndex.toString());
  if (camera)
  camera.setMode(640, 480, 30);
  private function start() : void {
  currentAttempts = 0;
  autoInProgress = true;
  if (resizeTest.selected) {
  addVideoAndAttachCamera();
  resize();
  else {
  attachDetach();
  private function addVideoAndAttachCamera() : void {
  if (camera) {
  video = new Video(camera.width, camera.height);
  videoContainer.addChild(video);
  video.attachCamera(camera);
  private function detachCameraAndRemoveVideo() : void {
  video.attachCamera(null);
  video.clear();
  videoContainer.removeChild(video);
  video = null;
  private function attachDetach() : void {
  ++ currentAttempts;
  ++ totalAttempts;
  if (camera) {
  addVideoAndAttachCamera();
  memoryUsage.text = "System Memory Usage: " + (System.totalMemory).toString() + "bytes";
  setTimeout(function():void {
  detachCameraAndRemoveVideo();
  if (currentAttempts < int(attempts.selectedItem)) {
  attachDetach();
  else {
  autoInProgress = false;
  }, int(delay.selectedItem));
  private function resize() : void {
  ++ currentAttempts;
  ++ totalAttempts;
  if (camera) {
  camera.setMode(640, 480, 30);
  memoryUsage.text = "System Memory Usage: " + (System.totalMemory).toString() + "bytes";
  setTimeout(function():void {
  if (currentAttempts < int(attempts.selectedItem)) {
  resize();
  else {
  detachCameraAndRemoveVideo();
  autoInProgress = false;
  }, int(delay.selectedItem));
  ]]>
  </fx:Script>
  <s:VGroup>
  <s:HGroup>
  <s:Label enabled="{!autoInProgress}" text="Camera" />
  <s:ComboBox enabled="{!autoInProgress}"
  id="selectedCamera"
  dataProvider="{cams}"
  change="selectedCamera_changeHandler(event)"/>
  <s:Label id="memoryUsage" />
  <s:Label text="{totalAttempts}" />
  </s:HGroup>
  <s:HGroup>
  <s:Label text="Auto Connect/Disconnect" enabled="{!autoInProgress}" />
  <s:ComboBox id="attempts" enabled="{!autoInProgress}" selectedIndex="1">
  <mx:ArrayCollection>
  <fx:String>1</fx:String>
  <fx:String>5</fx:String>
  <fx:String>10</fx:String>
  <fx:String>50</fx:String>
  <fx:String>75</fx:String>
  <fx:String>100</fx:String>
  <fx:String>500</fx:String>
  <fx:String>1000</fx:String>
  <fx:String>5000</fx:String>
  <fx:String>10000</fx:String>
  </mx:ArrayCollection>
  </s:ComboBox>
  <s:Label text="times" enabled="{!autoInProgress}" />
  <s:CheckBox id="resizeTest" label="Resize Test?" />
  <s:Button enabled="{!autoInProgress}" click="start()" label="Start" />
  </s:HGroup>
  <s:HGroup>
  <s:Label text="Delay" enabled="{!autoInProgress}" />
  <s:ComboBox id="delay" enabled="{!autoInProgress}" selectedIndex="1">
  <mx:ArrayCollection>
  <fx:String>1000</fx:String>
  <fx:String>1500</fx:String>
  <fx:String>2000</fx:String>
  <fx:String>3000</fx:String>
  </mx:ArrayCollection>
  </s:ComboBox>
  </s:HGroup>
  <mx:UIComponent id="videoContainer" width="640" height="480" />
  </s:VGroup>
</s:WindowedApplication>
The resizeTest checkbox shows that you can make the camera lockup just by repetitively calling cam.setMode().
I have submitted a bug into the bugbase.  Bug#3850401 - Handle leak with video.attachCamera leading to inoperable camera

Answer 1

Avrom,
I have never seeb this error before.
It certainly looks like an OC4J issue. Please try to get an answer on this in the OC4J forum.
Steven Davelaar,
JHeadstart Team.