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开始使用 IMA DAI SDK

借助 IMA SDK，您可以轻松将多媒体广告集成到您的网站和应用中。IMA SDK 可从任何符合 VAST 标准的广告服务器请求广告，并管理您应用中的广告播放。借助 IMA DAI SDK，应用可以针对广告和内容视频（VOD 或直播内容）发出流式传输请求。然后，SDK 会返回一个合并的视频串流，这样您就不必在应用中管理广告视频和内容视频之间的切换。

选择您感兴趣的 DAI 解决方案

本指南演示了如何使用适用于 Roku 的 IMA DAI SDK 播放 DAI Pod Serving 直播或 VOD 直播。

IMA DAI Pod Serving 概览

使用 IMA DAI 实现广告连播投放涉及两个主要 SDK 组件，本指南将对此进行演示：

StreamRequest.createPodLiveStreamRequest()/StreamRequest.createPodVodStreamRequest()：创建一个对象，用于定义向 Google 广告服务器发送的数据流请求。这些请求会指定网络代码，Pod Live ima.StreamRequest 还需要一个自定义资产密钥和一个可选的 API 密钥。
StreamManager：用于处理视频串流与 IMA DAI SDK 之间的通信的对象，例如触发跟踪 ping 和将串流事件转发给发布商。

此外，您还需要向清单操作服务器发出请求，以检索要供应用显示的直播清单。具体流程可能会因视频技术合作伙伴 (VTP) 而异。

前提条件

请仔细阅读我们的兼容性页面，确保您的预期用例受支持。
下载我们的 Roku 示例播放器代码。
将示例播放器代码部署到 Roku 设备，以验证您的开发设置是否有效。

播放视频

提供的示例视频播放器可直接播放内容视频。将示例播放器部署到 Roku 设备，以确保您的开发环境设置正确。

将视频播放器转换为 IMA DAI 流式播放器

请按照以下步骤实现流式播放器。

创建 Sdk.xml

将一个名为 Sdk.xml 的新文件添加到项目中 MainScene.xml 旁边，并添加以下样板代码：

Sdk.xml

<?xml version = "1.0" encoding = "utf-8" ?>

  <component name = "imasdk" extends = "Task">
  <interface>
  </interface>
  <script type = "text/brightscript">
  <![CDATA[
    ' Your code goes here.
  ]]>
  </script>
  </component>

在本指南中，您需要修改这两个文件（MainScene.xml 和 Sdk.xml）。

加载 IMA DAI SDK 框架

如需加载框架，请将以下代码添加到 manifest 和 Sdk.xml：

清单

bs_libs_required=googleima3

Sdk.xml

<?xml version = "1.0" encoding = "utf-8" ?>

  <component name = "imasdk" extends = "Task">
  <interface>
  </interface>
  <script type = "text/brightscript">
  <![CDATA[
  Library "IMA3.brs"
  ]]>
  </script>
  </component>

初始化 IMA DAI SDK

加载 IMA 动态广告插播流的第一步是加载并初始化 IMA DAI SDK。以下代码会初始化 IMA DAI SDK 脚本。

Sdk.xml

<?xml version="1.0" encoding="utf-8" ?>

  <component name="IMASDKTask" extends="Task">
  <interface>
    <field id="IMASDKInitialized" type="Boolean" />
    <field id="errors" type="stringarray" />
  </interface>
  <script type = "text/brightscript">
  <![CDATA[
    Library "IMA3.brs"
    sub init()
      m.top.functionName = "runThread"
    end sub

    sub runThread()
      if not m.top.IMASDKInitialized
        initializeIMASDK()
      end if
    end sub

    sub initializeIMASDK()
        if m.sdk = invalid
          m.sdk = New_IMASDK()
        end if
        m.top.IMASDKInitialized = true
    end sub
  ]]>
  </script>
  </component>

现在，在 MainScene.xml 中启动此任务，并移除加载内容流的调用。

MainScene.xml

<?xml version="1.0" encoding="utf-8" ?>

<component extends="Scene" initialFocus="myVideo" name="MainScene">
  <script type="text/brightscript">
  <![CDATA[
  function init()
    m.video = m.top.findNode("myVideo")
    m.video.notificationinterval = 1
    runIMASDKTask()
  end function

  function runIMASDKTask()
    m.IMASDKTask = createObject("roSGNode", "IMASDKTask")
    m.IMASDKTask.observeField("IMASDKInitialized", "handleIMASDKInitialized")
    m.IMASDKTask.observeField("errors", "handleIMASDKErrors")

    m.IMASDKTask.control = "RUN"
  end function

  sub handleIMASDKInitialized()

    ' Follow your manifest manipulator (VTP) documentation to register a user
    ' streaming session if needed.

  end sub

  sub handleIMASDKErrors(message as object)
    print "------ IMA DAI SDK failed  ------"
    if message <> invalid and message.getData() <> invalid
      print "IMA DAI SDK Error ";message.getData()
    end if
  end sub
  ]]>
  </script>
  <children>
    <Video height="720" id="myVideo" visible="false" width="1280"/>
  </children>
</component>

创建 IMA 流式播放器

接下来，您需要使用现有的 roVideoScreen 创建 IMA 流式播放器。

直播连播投放

对于直播，此流式播放器会实现三个回调方法：streamInitialized、adBreakStarted 和 adBreakEnded。

此外，在加载数据流时停用跳转播放。这样可以防止用户在前贴片广告开始播放的那一刻（广告插播时间点已启动事件触发之前）跳过。

Sdk.xml

<?xml version="1.0" encoding="utf-8" ?>

  <component name="IMASDKTask" extends="Task">
  <interface>
    <field id="IMASDKInitialized" type="Boolean" />
    <field id="errors" type="stringarray" />
    <field id="urlData" type="assocarray" />
    <field id="adPlaying" type="Boolean" />
    <field id="videoNode" type="Node" />
  </interface>

  <script type="text/brightscript">
  ...
  sub runThread()
    if not m.top.IMASDKInitialized
      initializeIMASDK()
    end if

    setupPlayerCallbacks()
  end sub
  ...
  sub initializeIMASDK()
    if m.ima = invalid
      ima = New_IMASDK()
      ima.initSdk()
      m.ima = ima
    end if
    m.top.IMASDKInitialized = true
  end sub

  sub setupPlayerCallbacks()
    m.player = m.ima.createPlayer()
    m.player.top = m.top

    m.player.streamInitialized = function(urlData)
      m.top.videoNode.enableTrickPlay = false
      m.top.urlData = urlData
    end function

    m.player.adBreakStarted = function(adBreakInfo)
      print "------ Ad break started ------"
      m.top.adPlaying = true
      m.top.videoNode.enableTrickPlay = false
    end function

    m.player.adBreakEnded = function(adBreakInfo)
      print "------ Ad break ended ------"
      m.top.adPlaying = false
      m.top.videoNode.enableTrickPlay = true
    end function

  end sub
  </script>
...
</component>

VOD 视频流广告连播投放

对于 VOD 串流，此流式播放器会实现四个回调方法：streamInitialized、loadUrl、adBreakStarted 和 adBreakEnded。在 streamInitialized 回调中，请务必调用 StreamManager.loadThirdPartyStream()。否则，SDK 将不会触发 loadUrl 函数。

在此步骤中，您还需要使用在 loadAdPodStream() 中获取的串流 ID 向视频技术合作伙伴 (VTP) 请求串流网址。然后，使用广告连播清单和 VTP 返回的所有字幕调用 StreamManager.loadThirdPartyStream()。

同时在加载视频流时停用特技播放。这样可以防止用户在前贴片广告开始播放后立即跳过该广告，即在“广告插播开始”事件触发之前。

Sdk.xml

<?xml version="1.0" encoding="utf-8" ?>

  <component name="IMASDKTask" extends="Task">
  <interface>
    <field id="IMASDKInitialized" type="Boolean" />
    <field id="errors" type="stringarray" />
    <field id="adStitchedStreamInfo" type="assocarray" />
    <field id="adPlaying" type="Boolean" />
    <field id="videoNode" type="Node" />
    <field id="streamParameters" type="assocarray" />
  </interface>

  <script type="text/brightscript">
  ...
  sub runThread()
    if not m.top.IMASDKInitialized
      initializeIMASDK()
    end if

    setupPlayerCallbacks()
  end sub
  ...
  sub initializeIMASDK()
    if m.ima = invalid
      ima = New_IMASDK()
      ima.initSdk()
      m.ima = ima
    end if
    m.top.IMASDKInitialized = true
  end sub

  sub loadThirdPartyStream(adStitchedManifest as string, subtitleConfig as dynamic)
    m.streamManager.loadThirdPartyStream(adStitchedManifest, subtitleConfig)
  end sub

  sub setupPlayerCallbacks()
    m.player = m.ima.createPlayer()
    m.player.top = m.top

    m.player.streamInitialized = function(urlData)
      adStitchedManifest = m.top.streamParameters.VTPManifest.replace("[[STREAMID]]", urlData.streamId)
      loadThirdPartyStream(adStitchedManifest, m.top.streamParameters.subtitleConfig)
    end function

    m.player.loadUrl = function(streamInfo)
      m.top.adStitchedStreamInfo = streamInfo
    end function

    m.player.adBreakStarted = function(adBreakInfo)
      print "------ Ad break started ------"
      m.top.adPlaying = true
      m.top.videoNode.enableTrickPlay = false
    end function

    m.player.adBreakEnded = function(adBreakInfo)
      print "------ Ad break ended ------"
      m.top.adPlaying = false
      m.top.videoNode.enableTrickPlay = true
    end function

  end sub
  </script>
...
</component>

创建和执行直播或 VOD 连播服务流请求

有了流播放器后，您可以创建和执行流请求。此示例包含存储在 m.testPodServingStream 中的 Pod 服务流数据。

直播广告连播投放

在 m.testPodServingStream 对象中，存储 Google Ad Manager 需要用来识别相关数据流的参数，例如广告资源网代码和自定义素材资源键。此外，还应存储用于访问清单操纵服务器的清单网址。在这种情况下，需要在返回数据流请求后，将 Google 数据流 ID 添加到清单网址。

为了支持 AdUI（例如“广告选项”图标），您还必须在请求中传递指向包含内容视频的节点的引用。

MainScene.xml

function init()
  m.video = m.top.findNode("myVideo")
  m.video.notificationinterval = 1
  m.testPodServingStream = {
    title: "Test live stream for DAI Pod Serving",
    assetKey: "test-live-stream",
    networkCode: "your-network-code",
    manifest: "https://.../master.m3u8?stream_id=[[STREAMID]]",
    apiKey: ""
  }
  runIMASDKTask()
end function

function runIMASDKTask()
  m.IMASDKTask = createObject("roSGNode", "IMASDKTask")

  m.IMASDKTask.streamParameters = m.testPodservingStream
  m.IMASDKTask.videoNode = m.video

  m.IMASDKTask.observeField("IMASDKInitialized", "handleIMASDKInitialized")
  m.IMASDKTask.observeField("errors", "handleIMASDKErrors")

  m.IMASDKTask.control = "RUN"
end function

Sdk.xml

<interface>
  <field id="IMASDKInitialized" type="Boolean" />
  <field id="errors" type="stringarray" />
  <field id="urlData" type="assocarray" />
  <field id="adPlaying" type="Boolean" />
  <field id="videoNode" type="Node" />
  <field id="streamParameters" type="assocarray" />
</interface>

...

sub runThread()
  if not m.top.IMASDKInitialized
    initializeIMASDK()
  end if

  setupPlayerCallbacks()
  loadAdPodStream()
end sub

sub loadAdPodStream()
  request = m.ima.CreatePodLiveStreamRequest(m.top.streamParameters.assetKey, m.top.streamParameters.networkCode, m.top.streamParameters.apiKey)

  ' Set the player object so that the request can trigger the player's
  ' callbacks at stream initialization or playback events.
  request.player = m.player

  ' Set the video node for the IMA DAI SDK to create ad UI as its child nodes.
  request.adUiNode = m.top.video

  requestResult = m.ima.requestStream(request)
  if requestResult <> invalid
    print "Error requesting stream ";requestResult
    return
  end if

  m.streamManager = invalid
  while m.streamManager = invalid
    sleep(50)
    m.streamManager = m.ima.getStreamManager()
  end while

  if m.streamManager = invalid
    errors = CreateObject("roArray", 1, True)
    invalidStreamManagerError = "Invalid stream manager"
    print invalidStreamManagerError
    errors.push(invalidStreamManagerError)
    m.top.errors = errors
    return
  end if

  if m.streamManager["type"] <> invalid and m.streamManager["type"] = "error"
    errors = CreateObject("roArray", 1, True)
    print "Stream request returns an error. " ; m.streamManager["info"]
    errors.push(m.streamManager["info"])
    m.top.errors = errors
    return
  end if

  setupStreamManager()
  m.streamManager.start()
end sub

VOD 视频流广告连播投放

在 m.testPodServingStream 对象中，您可存储视频流请求中使用的广告联盟代码，以便 Google Ad Manager 可以提供视频流 ID。此外，还应在清单操作服务器上存储用于访问特定于用户的清单的清单网址。

为了能够支持 AdUI，例如 adChoices 图标，您还必须在请求中传递对包含内容视频的节点的引用。

MainScene.xml

sub init()
  m.video = m.top.findNode("myVideo")
  m.video.notificationinterval = 1
  m.testPodServingStream = {
    title: "Pod Serving VOD Stream",
    networkCode: "your-network-code",
    VTPManifest: "https://.../manifest.m3u8?gam-stream-id=[[STREAMID]]",
    subtitleConfig: []
  }
  runIMASDKTask()
end sub

sub runIMASDKTask()
  m.IMASDKTask = createObject("roSGNode", "IMASDKTask")

  m.IMASDKTask.streamParameters = m.testPodservingStream
  m.IMASDKTask.videoNode = m.video

  m.IMASDKTask.observeField("IMASDKInitialized", "handleIMASDKInitialized")
  m.IMASDKTask.observeField("errors", "handleIMASDKErrors")

  m.IMASDKTask.control = "RUN"
end sub

Sdk.xml

sub runThread()
  if not m.top.IMASDKInitialized
    initializeIMASDK()
  end if

  setupPlayerCallbacks()
  loadAdPodStream()
end sub

sub loadAdPodStream()
  request = m.ima.CreatePodVodStreamRequest(m.top.streamParameters.networkCode)

  ' Set the player object so that the request can trigger the player
  ' callbacks at stream initialization or playback events.
  request.player = m.player

  ' Set the video node for the IMA DAI SDK to create ad UI as its child nodes.
  request.adUiNode = m.top.video

  requestResult = m.ima.requestStream(request)
  if requestResult <> invalid
    print "Error requesting stream ";requestResult
    return
  end if

  m.streamManager = invalid
  while m.streamManager = invalid
    sleep(50)
    m.streamManager = m.ima.getStreamManager()
  end while

  if m.streamManager = invalid
    errors = CreateObject("roArray", 1, True)
    invalidStreamManagerError = "Invalid stream manager"
    print invalidStreamManagerError
    errors.push(invalidStreamManagerError)
    m.top.errors = errors
    return
  end if

  if m.streamManager["type"] <> invalid and m.streamManager["type"] = "error"
    errors = CreateObject("roArray", 1, True)
    print "Stream request returns an error. " ; m.streamManager["info"]
    errors.push(m.streamManager["info"])
    m.top.errors = errors
    return
  end if

  setupStreamManager()
  m.streamManager.start()
end sub

添加事件监听器并启动数据流

直播广告连播投放

请求视频流后，只需进行几项操作：添加事件监听器以跟踪广告进度，以及将 Roku 消息转发到 SDK。请务必将所有消息转发给 SDK，以确保正确播放广告。否则会导致广告观看次数报告不当。

在此步骤中，您还需要添加一个函数，用于将 [[STREAMID]] 宏替换为串流 ID，并将已完成的清单请求网址传递给视频播放器。此实现会在此步骤中获取串流 ID，但根据您的 VTP 集成，此 ID 可能在此步骤之前可用。

MainScene.xml

function runIMASDKTask()
  m.IMASDKTask = createObject("roSGNode", "IMASDKTask")

  m.IMASDKTask.streamParameters = m.testPodservingStream
  m.IMASDKTask.videoNode = m.video

  m.IMASDKTask.observeField("IMASDKInitialized", "handleIMASDKInitialized")
  m.IMASDKTask.observeField("errors", "handleIMASDKErrors")
  m.sdkTask.observeField("adStitchedStreamInfo", "loadAdStitchedStream")

  m.sdkTask.control = "RUN"
end function

sub loadAdStitchedStream(message as object)
  print "Ad pod stream information ";message
  adPodStreamInfo = message.getData()
  manifest = m.testPodservingStream.manifest.Replace("[[STREAMID]]", adPodStreamInfo.streamId)
  playStream(manifest, adPodStreamInfo.format)
end sub

sub playStream(url as string, format as string)
  vidContent = createObject("RoSGNode", "ContentNode")
  vidContent.url = url
  vidContent.title = m.testPodservingStream.title
  vidContent.streamformat = format
  m.video.content = vidContent
  m.video.setFocus(true)
  m.video.visible = true
  m.video.control = "play"
  m.video.EnableCookies()
end sub

Sdk.xml

sub runThread()
  if not m.top.IMASDKInitialized
    initializeIMASDK()
  end if

  setupPlayerCallbacks()
  loadAdPodStream()
  if m.streamManager <> invalid
    runLoop()
  end if
end sub

sub runLoop()
  m.top.videoNode.timedMetaDataSelectionKeys = ["*"]

  ' IMPORTANT: Failure to listen to the position and timedmetadata fields
  ' could result in ad impressions not being reported.
  m.port = CreateObject("roMessagePort")
  m.top.videoNode.observeField("position", m.port)
  m.top.videoNode.observeField("timedMetaData", m.port)
  m.top.videoNode.observeField("timedMetaData2", m.port)
  m.top.videoNode.observeField("state", m.port)

  while True
    msg = wait(1000, m.port)
    if m.top.videoNode = invalid
      print "exiting"
      exit while
    end if

    m.streamManager.onMessage(msg)
    currentTime = m.top.videoNode.position
    if currentTime > 3 And not m.top.adPlaying
      m.top.videoNode.enableTrickPlay = true
    end if
  end while
end sub

sub setupStreamManager()
  m.streamManager.addEventListener(m.sdk.AdEvent.ERROR, errorCallback)
  m.streamManager.addEventListener(m.sdk.AdEvent.START, startCallback)
  m.streamManager.addEventListener(m.sdk.AdEvent.FIRST_QUARTILE, firstQuartileCallback)
  m.streamManager.addEventListener(m.sdk.AdEvent.MIDPOINT, midpointCallback)
  m.streamManager.addEventListener(m.sdk.AdEvent.THIRD_QUARTILE, thirdQuartileCallback)
  m.streamManager.addEventListener(m.sdk.AdEvent.COMPLETE, completeCallback)
end sub

sub startCallback(ad as object)
  print "Callback from SDK -- Start called - "
end sub

sub firstQuartileCallback(ad as object)
  print "Callback from SDK -- First quartile called - "
end sub

sub midpointCallback(ad as object)
  print "Callback from SDK -- Midpoint called - "
end sub

sub thirdQuartileCallback(ad as object)
  print "Callback from SDK -- Third quartile called - "
end sub

sub completeCallback(ad as object)
  print "Callback from SDK -- Complete called - "
end sub

function errorCallback(error as object)
  print "Callback from SDK -- Error called - " ; error
  m.errorState = True
end function

VOD 视频流广告连播投放

请求数据流后，您只需完成以下几项操作：添加事件监听器以跟踪广告进度，并将 Roku 消息转发给 SDK。请务必将所有消息转发给 SDK，以确保广告正确播放。否则，系统将无法正确报告广告观看次数。

MainScene.xml

sub runIMASDKTask()
  m.IMASDKTask = createObject("roSGNode", "IMASDKTask")

  m.IMASDKTask.streamParameters = m.testPodservingStream
  m.IMASDKTask.videoNode = m.video

  m.IMASDKTask.observeField("IMASDKInitialized", "handleIMASDKInitialized")
  m.IMASDKTask.observeField("errors", "handleIMASDKErrors")
  m.sdkTask.observeField("adStitchedStreamInfo", "loadAdStitchedStream")

  m.sdkTask.control = "RUN"
end sub

sub loadAdStitchedStream(message as object)
  print "Ad pod stream information ";message
  adPodStreamInfo = message.getData()
end sub

sub playStream(url as string, format as string, subtitleConfig as object)
  vidContent = createObject("RoSGNode", "ContentNode")
  vidContent.title = m.testPodservingStream.title
  vidContent.url = url
  vidContent.subtitleConfig = subtitleConfig
  vidContent.streamformat = format
  m.video.content = vidContent
  m.video.setFocus(true)
  m.video.visible = true
  m.video.control = "play"
  m.video.EnableCookies()
end sub

Sdk.xml

sub runThread()
  if not m.top.IMASDKInitialized
    initializeIMASDK()
  end if

  setupPlayerCallbacks()
  loadAdPodStream()
  if m.streamManager <> invalid
    runLoop()
  end if
end sub

sub runLoop()
  m.top.videoNode.timedMetaDataSelectionKeys = ["*"]

  ' IMPORTANT: Failure to listen to the position and timedmetadata fields
  ' could result in ad impressions not being reported.
  m.port = CreateObject("roMessagePort")
  m.top.videoNode.observeField("position", m.port)
  m.top.videoNode.observeField("timedMetaData", m.port)
  m.top.videoNode.observeField("timedMetaData2", m.port)
  m.top.videoNode.observeField("state", m.port)

  while True
    msg = wait(1000, m.port)
    if m.top.videoNode = invalid
      exit while
    end if

    m.streamManager.onMessage(msg)
    currentTime = m.top.videoNode.position
    if currentTime > 3 and not m.top.adPlaying
      m.top.videoNode.enableTrickPlay = true
    end if
  end while
end sub

sub setupStreamManager()
  m.streamManager.addEventListener(m.sdk.AdEvent.ERROR, errorCallback)
  m.streamManager.addEventListener(m.sdk.AdEvent.START, startCallback)
  m.streamManager.addEventListener(m.sdk.AdEvent.FIRST_QUARTILE, firstQuartileCallback)
  m.streamManager.addEventListener(m.sdk.AdEvent.MIDPOINT, midpointCallback)
  m.streamManager.addEventListener(m.sdk.AdEvent.THIRD_QUARTILE, thirdQuartileCallback)
  m.streamManager.addEventListener(m.sdk.AdEvent.COMPLETE, completeCallback)
end sub

sub startCallback(ad as object)
  print "Callback from SDK -- Start called - "
end sub

sub firstQuartileCallback(ad as object)
  print "Callback from SDK -- First quartile called - "
end sub

sub midpointCallback(ad as object)
  print "Callback from SDK -- Midpoint called - "
end sub

sub thirdQuartileCallback(ad as object)
  print "Callback from SDK -- Third quartile called - "
end sub

sub completeCallback(ad as object)
  print "Callback from SDK -- Complete called - "
end sub

sub errorCallback(error as object)
  print "Callback from SDK -- Error called - " ; error
  m.errorState = True
end sub