Alexa-音频播放器。播放问题在Echo Show Now Playing屏幕上显示内容

我在理解如何在音频播放器“正在播放”屏幕内的回声显示上显示图像时遇到问题。

我正在播放一个音频文件,希望在“正在播放”屏幕上显示图像。我能得到的最接近的代码是下面的代码,它在音频开始前显示图像和标题,但随后立即消失,回声显示转到没有背景图像和元数据的“正在播放”屏幕。我觉得我已经很接近了,但是我不知道如何更新“正在播放”屏幕,而不是之前的屏幕。

这是代码的一部分(按上述方式工作):

var handlers = {
  'LaunchRequest': function() {
   this.emit('PlayStream');        
   },

'PlayStream': function() {
 let builder = new Alexa.templateBuilders.BodyTemplate1Builder();
 let template = builder.setTitle('Test Title')
    .setBackgroundImage(makeImage('https://link_to_my_image.png'))
    .setTextContent(makePlainText('Test Text'))
    .build();

 this.response.speak('OK.').

 audioPlayerPlay(
    'REPLACE_ALL', 
    stream.url, 
    stream.url, 
    null, 
    0)
    .renderTemplate(template);

 this.emit(':responseReady');  
 }

我一直在看这一页 https://developer.amazon.com/docs/custom-skills/audioplayer-interface-reference.html 但无法理解如何将页面上的结构转换为我的代码。我假设,从页面上的代码来看:

{
  "type": "AudioPlayer.Play",
  "playBehavior": "valid playBehavior value such as ENQUEUE",
  "audioItem": {
    "stream": {
      "url": "https://url-of-the-stream-to-play",
      "token": "opaque token representing this stream",
      "expectedPreviousToken": "opaque token representing the previous stream",
      "offsetInMilliseconds": 0
    },
    "metadata": {
      "title": "title of the track to display",
      "subtitle": "subtitle of the track to display",
      "art": {
        "sources": [
          {
            "url": "https://url-of-the-album-art-image.png"
          }
        ]
      },
      "backgroundImage": {
        "sources": [
          {
            "url": "https://url-of-the-background-image.png"
          }
        ]
      }
    }
  }
}

我需要得到这个部分:

"metadata": {
          "title": "title of the track to display",
          "subtitle": "subtitle of the track to display",
          "art": {
            "sources": [
              {
                "url": "https://url-of-the-album-art-image.png"
              }
            ]
          },

进入我的代码块:

audioPlayerPlay(
        'REPLACE_ALL', 
        streamInfo.url, 
        streamInfo.url, 
        null, 
        0)
        .renderTemplate(template);

(可能会失去 .renderTemplate(template); 部分原因是它只会在“正在播放”屏幕加载之前短暂闪烁。

关于如何实现这个目标有什么想法吗?

更新:

我在index.js中添加了以下内容:

var metadata = { 
    title: "title of the track to display",
    subtitle: "subtitle of the track to display",
    art: { 
        sources: {
            url: "https://url-of-the-album-art-image.png"
            } 
        }
    };

并对音频播放器进行了如下修改:

audioPlayerPlay(
    'REPLACE_ALL', 
    stream.url, 
    stream.url, 
    null, 
    0,
    metadata)
    .renderTemplate(template);

并修改responseBuilder.js,如下所示:

audioPlayerPlay(behavior, url, token, expectedPreviousToken, offsetInMilliseconds, metadata) {
    const audioPlayerDirective = {
        type : DIRECTIVE_TYPES.AUDIOPLAYER.PLAY,
        playBehavior: behavior,
        audioItem: {
            stream: {
                url: url,
                token: token,
                expectedPreviousToken: expectedPreviousToken,
                offsetInMilliseconds: offsetInMilliseconds,   
                metadata : metadata 
            }
        }
    };

    this._addDirective(audioPlayerDirective);
    return this;
}

但我还是没有在“正在播放”屏幕上显示任何内容。