直播预提取

IMA SDK 可用于通过直播和视频点播创收。 对于直播,您需要为每个广告插播时间点发出新的广告请求。 错开这些请求,确保不会让所有观看者同时请求广告,导致广告服务器无法运行。

为帮助完成此任务,IMA SDK 具有 AdsRequest.liveStreamPrefetchSeconds 属性。此属性用于指定在您调用 AdsLoader.requestAds() 后,SDK 在与广告服务器通信之前应等待的最大秒数。实际请求时间是随机的。例如,如果您将 AdsRequest.liveStreamPrefetchSeconds 设置为 30,在您调用 AdsLoader.requestAds() 以实际向服务器发出请求后,SDK 会等待 0 到 30 秒。

直播预提取的实际运用

我们建议在广告插播结束后立即预提取下一个广告插播时间点。 这样可以确保预取窗口具有最长的时间长度。假设您的广告插播时间点之间有 5 分钟的间隔时间。广告插播结束后,您可以请求将预提取时长设置为 290 秒(5 分钟减去 10 秒,以确保在预提取窗口结束时发送的请求有足够的时间进行解析)的下一个广告插播时间点:

Objective-C


- (void)adsManager:(IMAAdsManager *)adsManager didReceiveAdEvent:(IMAAdEvent *)event {

  ...

  switch (event.type) {

    ...

    case kIMAAdEvent_ALL_ADS_COMPLETED:

      IMAAdsRequest *request = [[IMAAdsRequest alloc]
             initWithAdTagUrl: self.adTagUrl
           adDisplayContainer: self.adDisplayContainer
         avPlayerVideoDisplay: self.avPlayerVideoDisplay
        pictureInPictureProxy: self.pictureInPictureProxy
                  userContext: nil];

      // set a delay between the end of the last ad
      // in the last request, and the first ad from
      // the new request
      Float64 adGap = 30;
      // make sure the request occurs at least five
      // seconds before starting the new set of ads
      request.liveStreamPrefetchSeconds = adGap - 5;
      [self.adsLoader requestAdsWithRequest:request];
      // start new ads after adGap seconds have elapsed
      dispatch_after(dispatch_time(DISPATCH_TIME_NOW, adGap * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
        [adsManager start];
      });

      break;

    ...

  }

  ...

}

Swift

func adsManager(_ adsManager: IMAAdsManager!, didReceive event: IMAAdEvent!) {
  switch event.type {

    ...

    case IMAAdEventType.ALL_ADS_COMPLETED:

      let request = IMAAdsRequest(
        adTagUrl: AdTagUrl,
        adDisplayContainer: adDisplayContainer,
        contentPlayhead: contentPlayhead,
        userContext: nil)

      // set a delay between the end of the last ad
      // in the last request, and the first ad from
      // the new request
      let adGap = 30
      // make sure the request occurs at least five
      // seconds before starting the new set of ads
      request.liveStreamPrefetchSeconds = adGap - 5
      adsLoader.requestAds(with: request)
      // start new ads after adGap seconds have elapsed
      DispatchQueue.main.asyncAfter(deadline: .now() + adGap) {
        adsManager.start()
      }

      break

    ...
  }
}