求救！！！高手们帮帮忙，关于flex视频拍照设置图片大小问题！

在flex里把图片设置320*240可以正常保存，可是我要给图片设置640*480就保存不了。
flex代码：<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" width="1024" height="768" creationComplete="initApp()" backgroundColor="#A6C9E2">
<mx:Style>
Alert{font-size:12px;}
</mx:Style>
<mx:Script>
<![CDATA[
import mx.events.CloseEvent;
import mx.rpc.events.FaultEvent;
import mx.rpc.events.ResultEvent;
import mx.controls.Alert;
import mx.core.Application;

private static const DEFAULT_CAMERA_WIDTH:Number = 640; //摄像头显示宽度
private static const DEFAULT_CAMERA_HEIGHT:Number = 480; //摄像头显示高度
private var DEFAULT_WEBSERVICE_URL:String = ""; //WebService地址
private var str:String;
private var widthcur:uint = 640;
private var heightcur:uint = 480;
private var m_camera:Camera; //定义一个摄像头
private var m_localVideo:Video; //定义一个本地视频
private var m_pictureBitmapData:BitmapData //定义视频截图
[Bindable]
private var m_pictureData:String;

private function initApp():void
{
t_btn_Shooting.enabled = false;
t_ban_Save.enabled = false;
initCamera();
DEFAULT_WEBSERVICE_URL = "http://localhost:8080/FlexHttpService/onLineTakePhotoServlet";
t_ws_SavePicture.url=DEFAULT_WEBSERVICE_URL;
}

//初始化摄像头
private function initCamera():void
{
m_camera = Camera.getCamera();
if(m_camera != null)
{
m_camera = Camera.getCamera();
m_camera.addEventListener(StatusEvent.STATUS,__onCameraStatusHandler);
m_camera.setMode(widthcur,heightcur,30);
m_localVideo = new Video();
m_localVideo.width = DEFAULT_CAMERA_WIDTH;
m_localVideo.height = DEFAULT_CAMERA_HEIGHT;
m_localVideo.attachCamera(m_camera);
t_vd_Video.addChild(m_localVideo);
}
else
{
Alert.show("没有找到摄像头，是否重新查找。","提示：",Alert.OK|Alert.NO,this,__InitCamera);
return;
}
}

//拍照按钮事件，进行视频截图
private function SnapshotPicture():void
{
m_pictureBitmapData = new BitmapData(DEFAULT_CAMERA_WIDTH,DEFAULT_CAMERA_HEIGHT);
m_pictureBitmapData.draw(t_vd_Video,new Matrix());

var m_pictureBitmap:Bitmap = new Bitmap(m_pictureBitmapData);
t_img_Picture.addChild(m_pictureBitmap);

t_panel_Picture.visible = true;
t_ban_Save.enabled = true;
}

//保存按钮事件，保存视频截图
//通过WebService保存
private function SavePicture():void
{
m_pictureData = "";
for(var i:int = 0; i < DEFAULT_CAMERA_WIDTH; i++)
{
for(var j:int = 0; j < DEFAULT_CAMERA_HEIGHT; j++)
{
if(m_pictureData.length > 0)
{
m_pictureData += "," + m_pictureBitmapData.getPixel32(i,j).toString();
}
else
{
m_pictureData = m_pictureBitmapData.getPixel32(i,j).toString();
}
}
}

var params:URLVariables = new URLVariables();
params.width = DEFAULT_CAMERA_WIDTH;
params.height = DEFAULT_CAMERA_HEIGHT;
params.bitmap_data = m_pictureData;
t_ws_SavePicture.send(params);
}

//检测摄像头权限事件
private function __onCameraStatusHandler(event:StatusEvent):void
{
if(!m_camera.muted)
{
t_btn_Shooting.enabled = true;
}
else
{
Alert.show("无法链接到活动摄像头，是否重新检测。","提示：",Alert.OK|Alert.NO,this,__InitCamera);
}
m_camera.removeEventListener(StatusEvent.STATUS,__onCameraStatusHandler);
}

//当摄像头不存在，或连接不正常时重新获取
private function __InitCamera(event:CloseEvent):void
{
if(event.detail == Alert.OK)
{
initApp();
}
}

//WebService保存图片成功事件
private function __onSavePictureResult(event:ResultEvent):void
{
//trace(event.result);
if(event.result.toString() != "保存失败")
{
str = event.result.toString();

Alert.show("保存成功,是否关闭窗口？","提示",3,this,__onAlertCloseHandler);
}
else
{
Alert.show(event.result.toString(),"提示",Alert.OK);
}
}

//连接WebService失败事件
private function __onSavePictureFault(event:FaultEvent):void
{
//Alert.show(event.fault.toString(),"提示",Alert.OK);
Alert.show("连接服务器失败。","提示",Alert.OK);
}
private function CanelPicture():void
{
t_panel_Picture.visible = false;
}
//保存图片成功后的弹出窗口确认事件
private function __onAlertCloseHandler(event:CloseEvent):void
{
if(event.detail == Alert.YES)
{
ExternalInterface.call("setValueToField",str);
}
}
]]>
</mx:Script>
<mx:HTTPService id="t_ws_SavePicture" showBusyCursor="true" method="POST" useProxy="false" result="__onSavePictureResult(event)" fault="__onSavePictureFault(event)"/>
<mx:Panel x="73" y="6" width="662" height="572" layout="absolute" title="视频拍照" fontSize="12">
<mx:VideoDisplay id="t_vd_Video" width="640" height="480" x="10" y="6"  />
<mx:VideoDisplay id="t_vd_Video1" width="640" height="480" x="4" y="4" visible="false"/>
<mx:ControlBar horizontalAlign="right">
<mx:Button id="t_btn_Shooting" label="拍照" click="SnapshotPicture()"/>
</mx:ControlBar>
</mx:Panel>

<mx:Panel id="t_panel_Picture" x="180" y="5" width="662" height="572" layout="absolute" title="拍照图片" fontSize="12" visible="false">
<mx:Image id="t_img_Picture" x="2" y="5" width="640" height="480"/>
<mx:ControlBar   horizontalAlign="right">
<mx:Button id="t_ban_Save" label="保存" click="SavePicture()" />
<mx:Button id="t_ban_Canel" label="取消" click="CanelPicture()" />
</mx:ControlBar>
</mx:Panel>
</mx:Application>javaservlet代码import java.awt.Color;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.*;
public class onLineTakePhotoServlet extends HttpServlet {private static final long serialVersionUID = 1L;
    
public void doGet(HttpServletRequest request, HttpServletResponse response)    
throws ServletException, IOException {    
processRequest(request, response);    
}    
  
public void doPost(HttpServletRequest request, HttpServletResponse response)    
 throws ServletException, IOException {    
processRequest(request, response);    
}    

public void processRequest(HttpServletRequest request, HttpServletResponse response)    throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");   
        response.setHeader("Pragma", "No-cache");   
        response.setHeader("Cache-Control", "no-cache");   
        response.setDateHeader("Expires", 0);   
  
        String bitmap_data = request.getParameter("bitmap_data");   
        int width = Integer.parseInt(request.getParameter("width"));   
        int height = Integer.parseInt(request.getParameter("height"));   
        BufferedImage img = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);   
try {   
            int w = width;   
            int h = height;   
            int[] pixels = new int[w * h];   
            String[] m_tempPics = bitmap_data.split(",");   
            for (int x = 0; x < w; x++) {   
                for (int y = 0; y < h; y++) {   
                    long pic_argb = (long) Long.parseLong(m_tempPics[x * h + y]);   
                    int a = (int) (pic_argb >> 24 & 0xFF);   
                    int r = (int) (pic_argb >> 16 & 0xFF);   
                    int g = (int) (pic_argb >> 8 & 0xFF);   
                    int b = (int) (pic_argb & 0xFF);   
                    pixels[y * w + x] = new Color(r, g, b, a).getRGB();   
                }   
            }   
            img.setRGB(0, 0, w, h, pixels, 0, w);   
            img.flush();   
            ByteArrayOutputStream bao = new ByteArrayOutputStream();   
            ImageIO.write(img, "jpg", bao);   
            byte[] data = bao.toByteArray();  
            String filePath = request.getRealPath("/uploads/photo");
            //判断路径是否存在,若不存在则创建路径
            File upDir = new File(filePath);
            if (!upDir.exists())
            {
                upDir.mkdir();
            }
            //生成随机文件名
            String saveName = UUID.randomUUID().toString(); ;
            String fileName = saveName + ".jpg";
            //写图片
            File f = new File(filePath+"\\" + fileName);
     DataOutputStream dos = new DataOutputStream(new FileOutputStream(f));
     dos.write(data);
     dos.flush();
     dos.close();
     response.setContentType("text/xml");   
            response.getWriter().write("/uploads/photo/" + fileName);   
        }
        catch(Exception ex)
        {
         response.setContentType("text/xml");   
            response.getWriter().write("保存失败");   
        }
}}