您可以在 Flash 实例之间传递 Camera 和 Microphone 对象吗？

Question

我正在开发一个 HTML5 应用程序，该应用程序需要与 Flash 交互以访问本地媒体（例如，网络摄像头和麦克风），并在远程浏览器之间传输音频-视频。但在这个应用程序中，我需要将本地网络摄像头显示在屏幕的一部分上，并由远程网络摄像头显示中的各种 HTML 元素隔开。我很确定这意味着我需要运行多个 Flash 应用程序实例。但我认为您一次只能抓取一个网络摄像头实例，这意味着我需要能够在 Flash 实例之间共享这些网络摄像头和麦克风对象：一个显示本地网络摄像头，另一个与远程网络摄像头。有可能这样做吗？例如，我可以通过 ExternalInterface 将我的 Camera 和 Microphone 实例传递给 JavaScript，然后将它们传递回我的 Flash 对象的单独实例吗？

换句话说，我正在考虑创建一个如下所示的 ActionScript 类（当然要简化很多）：

public class MediaController
{

    public function MediaController()
    {
        ExternalInterface.addCallback('getUserMedia', this.getUserMedia);
        ExternalInterface.addCallback('getCamera', this.getCamera);
        ExternalInterface.addCallback('setCamera', this.setCamera);
        ExternalInterface.addCallback('getMicrophone', this.getMicrophone);
        ExternalInterface.addCallback('setMicrophone', this.setMicrophone);
    }

    private var _mic:Microphone;
    private var _cam:Camera;

    public function getUserMedia()
    {
      _mic = Microphone.getMicrophone();
        _cam = Camera.getCamera();
    }

    public function getCamera():Camera
    {
        return this._cam;
    }

    public function setCamera(cam:Camera):void
    {
        this._cam = cam;
    }

    public function getMicrophone():Microphone
    {
        return this._mic;
    }

    public function setMicrophone(mic:Microphone):void
    {
        this._mic = mic;
    }
}

我会像这样在 JavaScript 中检索它们：

var localUser = $('#localUser')[0];
localUser.getUserMedia();
var mic = localUser.getMicrophone();
var cam = localUser.getCamera();

然后将它们传递回实际与远程用户进行通信的实例，如下所示：

var remoteUser = $('#remoteUser')[0];
remoteUser.setMicrophone(mic);
remoteUser.setCamera(cam);

这样做有什么已知的陷阱吗？有没有更好的方法来处理这个？ （在你问之前，是的，在没有其他建议的情况下，我打算编写这个代码，我会让每个人都知道我发现了什么 - 只是想知道在我得到之前是否有任何已知的陷阱或替代方案开始了。:-)

Answer 1

您不能通过ExternalInterface 将Camera 和Microphone 等对象传递给Javascript。当您使用ExternalInterface 与 Javascript 进行通信时，您传递的任何数据都将被编组为 XML 格式。所以到那时，相机/麦克风不再是 Flash Camera 和 Microphone 对象。

您可能会发现，在某些浏览器/操作系统中，尝试同时从两个不同的 SWF 访问同一个摄像头是可行的。但是，在其他情况下它失败了。我在两个完全不相关的网站访问相机时看到了这种行为。

SWF 可以使用 LocalConnection 类相互通信，尽管我从未尝试过使用摄像头或麦克风进行类似的操作。

Answer 2

对于它的价值，这是我最终采用的方法（或多或少），它有效。复杂，而且有点脆，但很有效：

// A typical 1:1 communication will involve four instances of the FlashMediaObject class:
// Instance1 (Initiator Sender): Displays local video, streams local video out to Instance4
// Instance2 (Initiator Receiver): Receives and displays video from Instance3
// Instance3 (Responder Sender): Displays local video, streams local video out to Instance2
// Instance4 (Responder Receiver): Receives and displays video from Instance1

// The workflow needs to go something like this:
// (1) Both: Room.onSessionAdded():     
//          SignalR makes both the JS clients for both the Initiator and the Responder aware of each other (i.e., their SessionId's).
// (2) Initiator: writeLocalMediaElement() -> fmo1.Connect():
//          Instance1 connects to Adobe's rtmfp service, gets its nearId, and passes it up to JS.
// (3) Responder: writeLocalMediaElement() -> fmo3.connect():
//          Instance3 connects to Adobe's rtmfp service, gets its peerId, and passes it up to JS.
// (4) Responder: prepareForCall() -> fmo4.connect():           
//          Instance4 connects to Adobe's rtmfp service, gets its peerId, and passes it up to JS.
// (5) Initiator: call() -> prepareForCall() -> fmo2.Connect():
//          Instance2 connects to Adbobe's rtmfp service, gets its nearId, and passes it up to JS.
// (6) Initiator: call() -> server.flashOffer():
//          The Initiator's JS controller contacts the Responder's JS (via SignalR), and passes it the two rtmfp ID's.
// (7) Responder: handleFlashOffer() -> fmo3.call():            
//          The Responder's JS controller passes the peerId for Instance2 (Initiator Receiver) to Instance3 (Responder Sender).
//          Instance3 begins publishing its video to Instance 2.
// (8) Responder: handleFlashOffer() -> fmo4.prepareForCall():
//          The Responder's JS controller passes the peerId for Instance1 (Initiator Sender) to Instance4 (Responder Receiver)
//          Instance4 prepares to receive a call from Instance1.
// (10) Responder: handleFlashOffer() -> server.flashAnswer():  
//          The Responder's JS controller contacts the Initiator's JS (via SignalR), and passes it the two peer ID's.
// (11) Initiator: handleFlashAnswer() -> fmo1.call():
//          The Initiator's JS controller passes the peerId for Instance4 (Responder Receiver) to Instance1 (Initiator Sender).
//          Instance1 connects to Instance4 and begins streaming video.
// (12) Initiator: handleFlashAnswer() -> fmo2.prepareForCall()
//          The Responder's JS controller passes the peerID for Instance3 (Responder Sender) to Instance2
//          Instance2 prepares to receive video from Instance3
// (9) Initiator: fmo2.onCall():
//          Instance2 begins playing video from Instance3.
// (13) Responder: fmo4.onCall():
//          Instance4 begins playing video from Instance1