CaptureDevice is an Adobe Air Native Extension for video capturing from cameras. It supports Windows (Direct Show) and Mac (QTkit), is able to handle multiple cameras and updates only on new frame.

Sample

package 
{
    import flash.display.Bitmap;
    import flash.display.BitmapData;
    import flash.display.Sprite;
    import flash.display.StageAlign;
    import flash.display.StageScaleMode;
    import flash.events.Event;
    import flash.events.MouseEvent;
    import flash.geom.Point;
    import flash.text.TextField;
    import flash.text.TextFormat;
    import ru.inspirit.asfeat.capture.CaptureDevice;
    import ru.inspirit.asfeat.capture.CaptureDeviceInfo;

    /**
     * Simple Demo App
     * @author Eugene Zatepyakin
     */
    [SWF(frameRate='30',backgroundColor='0xFFFFFF')]
    public final class Main extends Sprite 
    {
        public var captDevs:Vector.;
        public var captLabs:Vector.;
        public var _txt:TextField;

        public var scrBitmap:Bitmap;
        public var scr_bmp:BitmapData;

        public var dev_info:String;

        public function Main():void 
        {
            stage.scaleMode = StageScaleMode.NO_SCALE;
            stage.align = StageAlign.TOP_LEFT;

            scr_bmp = new BitmapData(800, 600, false, 0xFFFFFF);
            scrBitmap = new Bitmap(scr_bmp, 'auto', true);
            addChild(scrBitmap);

            //
            _txt = new TextField();
            _txt.width = 200;
            _txt.multiline = true;
            _txt.autoSize = 'left';
            _txt.background = true;
            _txt.backgroundColor = 0xffffff;
            _txt.x = 320;
            _txt.y = 240;

            addChild(_txt);
            //

            initCapture();
        }

        protected function createCaptLab(capt:CaptureDevice):TextField
        {
            var lab:TextField;

            var fmt:TextFormat = new TextFormat('_sans',9, 0xffffff,false,false,false,null,null,'left',4,6);

            lab = new TextField();
            lab.background = true;
            lab.backgroundColor = 0x0;
            lab.autoSize = 'left';
            lab.selectable = false;                                                   
            lab.text = capt.name.toUpperCase()  + ' // ' + capt.width + 'x'+capt.height;
            lab.setTextFormat(fmt);

            lab.addEventListener(MouseEvent.CLICK, onLabClick);

            return lab;
        }
        private function onLabClick(e:MouseEvent):void
        {
            var lab:TextField = e.currentTarget as TextField;
            var ind:int = captLabs.indexOf(lab);
            if(ind >= 0 && ind < captDevs.length)
            {
                var capt:CaptureDevice = captDevs[ind];
                if(capt.isCapturing)
                {
                    capt.stop();
                } else {
                    capt.start();
                }
            }
        }

        protected function initCapture():void
        {
            CaptureDevice.initialize();

            dev_info = '';
            dev_info += 'CaptureInterface init: ' + CaptureDevice.available + 'n';

            var dev_inf:Vector. = CaptureDevice.getDevices(false);
            captDevs = new Vector.();
            captLabs = new Vector.();

            var capt:CaptureDevice;
            var lab:TextField;

            var n:int = dev_inf.length;
            for (var i:int = 0; i < n; ++i)
            {
                var dev:CaptureDeviceInfo = dev_inf[i];
                dev_info += 'Device[' + i + ']: ' + '{ name: '+ dev.name + ', connected: ' + dev.connected +', available: ' + dev.available +' }n';
                dev_info += 'ttrying to init: ';

                try 
                {
                    capt = new CaptureDevice(dev.name, 320, 240);
                    capt.addEventListener('CAPTURE_DEVICE_LOST', onDeviceLost);

                    lab = createCaptLab(capt);

                    captLabs.push(lab);
                    addChild(lab);

                    captDevs.push(capt);
                    dev_info += 'OK';
                }
                catch (err:Error)
                {
                    dev_info += 'failed :(';
                }

                dev_info += 'n';
            }

            // dirty test of dispose method
            /*
            setTimeout(function():void
            {
                captDevs[1].dispose();
                removeChild(captLabs[1]);
                captDevs.splice(1, 1);
                captLabs.splice(1, 1);
            }, 5000);
            */

            if (captDevs.length)
            {
                addEventListener(Event.ENTER_FRAME, updateFrame);
            }

            _txt.text = dev_info;
        }

        private function onDeviceLost(e:Event):void 
        {
            var capt:CaptureDevice = e.currentTarget as CaptureDevice;

            // please be carefull
            // this causes app hand on Mac but works on Windows
            capt.dispose();

            var n:int = captDevs.length;
            for (var i:int = 0; i < n; ++i)
            {
                if (captDevs[i].id == capt.id)
                {
                    captDevs.splice(i, 1);

                    captLabs[i].removeEventListener(MouseEvent.CLICK, onLabClick);
                    removeChild(captLabs[i]);
                    captLabs.splice(i,  1);

                    break;
                }
            }

            capt.removeEventListener('CAPTURE_DEVICE_LOST', onDeviceLost);

            e.stopImmediatePropagation();
        }

        private function updateFrame(e:Event):void 
        {
            var n:int = captDevs.length;
            var capt:CaptureDevice;
            var lab:TextField;
            var isNewFrame:Boolean;
            var pt:Point = new Point();

            var sw:Number = stage.stageWidth;
            var sh:Number = stage.stageHeight;

            var _str:String = 'n';
            for (var i:int = 0; i < n; ++i)             {                 capt = captDevs[i];                 isNewFrame = capt.requestFrame(CaptureDevice.GET_FRAME_BITMAP);                 //isNewFrame = capt.requestFrame(CaptureDevice.GET_FRAME_RAW_BYTES);                 //isNewFrame = capt.requestFrame(CaptureDevice.GET_FRAME_RAW_BYTES | CaptureDevice.GET_FRAME_BITMAP);                                  _str += 'device[' + capt.name + '] update ' + isNewFrame + 'n';                                  if(isNewFrame)                 {                     pt.x = 320*(i%2);                     pt.y = 240*(i>>1);

                    scr_bmp.copyPixels(capt.bmp, capt.bmp.rect, pt);
                    /*
                    var raw:ByteArray = capt.raw;
                    raw.position = 0;
                    var size:int = capt.width * capt.height;
                    var cols:Vector. = new Vector.(capt.width * capt.height);
                    for (var j:int = 0; j < size; ++j)
                    {
                        var _r:uint = raw.readUnsignedByte();
                        var _g:uint = raw.readUnsignedByte();
                        var _b:uint = raw.readUnsignedByte();
                        cols[j] = _r << 16 | _g << 8 | _b;
                    }
                    scr_bmp.setVector(new Rectangle(pt.x + 320, pt.y, capt.width, capt.height), cols);
                    */

                    lab = captLabs[i];
                    lab.x = pt.x;
                    lab.y = pt.y;
                }
            }

            _txt.text = dev_info + _str;
        }

    }

}