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# 客户端信标
<a name="ad-reporting-client-side-beaconing"></a>

借助客户端跟踪`startTimeInSeconds`元素，您可以使用 MediaTailor 来支持信标计时。

以下 JSON 响应显示了主要的信标类型：展示次数、开始次数、四分位数和完成量。

**注意**  
互动广告局 (IAB) 的《视频展示量衡量指南》规定，展示次数要求广告内容在客户端加载，并且至少要有开始向玩家呈现的时间。有关更多信息，请参阅 IAB 网站上的[数字视频广告投放模板 (VAST)](https://www.iab.com/guidelines/vast/)。

```
{
  "avails": [
    {
      "ads": [
        {
          "adId": "8104385",
          "duration": "PT15.100000078S",
          "durationInSeconds": 15.1,
          "startTime": "PT17.817798612S",
          "startTimeInSeconds": 17.817,
          "trackingEvents": [
          {
              "beaconUrls": [
                "http://exampleadserver.com/tracking?event=impression"
              ],
              "duration": "PT15.100000078S",
              "durationInSeconds": 15.1,
              "eventId": "8104385",
              "eventType": "impression",
              "startTime": "PT17.817798612S",
              "startTimeInSeconds": 17.817
            },
            {
              "beaconUrls": [
                "http://exampleadserver.com/tracking?event=start"
              ],
              "duration": "PT0S",
              "durationInSeconds": 0.0,
              "eventId": "8104385",
              "eventType": "start",
              "startTime": "PT17.817798612S",
              "startTimeInSeconds": 17.817
            },
            {
              "beaconUrls": [
                "http://exampleadserver.com/tracking?event=firstQuartile"
              ],
              "duration": "PT0S",
              "durationInSeconds": 0.0,
              "eventId": "8104386",
              "eventType": "firstQuartile",
              "startTime": "PT21.592798631S",
              "startTimeInSeconds": 21.592
            },
             {
              "beaconUrls": [
                "http://exampleadserver.com/tracking?event=midpoint"
              ],
              "duration": "PT0S",
              "durationInSeconds": 0.0,
              "eventId": "8104387",
              "eventType": "midpoint",
              "startTime": "PT25.367798651S",
              "startTimeInSeconds": 25.367
            },
            {
              "beaconUrls": [
                "http://exampleadserver.com/tracking?event=thirdQuartile"
              ],
              "duration": "PT0S",
              "durationInSeconds": 0.0,
              "eventId": "8104388",
              "eventType": "thirdQuartile",
              "startTime": "PT29.14279867S",
              "startTimeInSeconds": 29.142
            },
            {
              "beaconUrls": [
                "http://exampleadserver.com/tracking?event=complete"
              ],
              "duration": "PT0S",
              "durationInSeconds": 0.0,
              "eventId": "8104390",
              "eventType": "complete",
              "startTime": "PT32.91779869S",
              "startTimeInSeconds": 32.917
            }
          ]
        }
      ],
      "availId": "8104385",
      "duration": "PT15.100000078S",
      "durationInSeconds": 15.1,
      "startTime": "PT17.817798612S",
      "startTimeInSeconds": 17.817
    }
  ]
}
```