New Report from Wowza Evaluates 在线直播 Latency

在过去的20年里, live streaming has transitioned from nearly incomprehensible magic to a manageable experience that relies upon a well-known set of codecs, 编码器, ABR技术, 输送管道, 和球员. This allows live streaming producers to shift their focus from simply making it work to providing the best user experience, 回避问题, “什么才是最好的用户体验?" A new report from Wowza Media Systems entitled "Create the 流媒体 Experience Users Want focuses on just that for five live markets; user-generated content (UGC), 网络游戏, 体育, 新闻, 和广播. 不足为奇的是, 延迟是一个关键因素, 尽管正如报告所详述的那样, the importance of latency varies dramatically among the markets studied.

制作报告, Wowza measured the time to first frame (TTFF) and end-to-end latency (E2E) for leaders in each of the five listed markets. The report presents and analyzes the results for each market, including research into the factors critical to success in each one.

One key finding is that while faster is always better, services should be tuned for how they are used by their primary customers. 例如, 在教资会范畴内, 如下图所示, YouNow offers close to the lowest end-to-end latency, which is necessary for the interactivity critical to users. 另一方面, Facebook Live, which is primarily used for one-to-many broadcasts, 是相对较慢的端到端延迟, 但最快的时间到第一帧.

Latency results for (top to bottom): Periscope, Live.我，YouNow, Live.ly, FlurryLive, Facebook Live和Instagram.
Average time to first frame is shown in gray, and everage end-to-end latency in green.

在其他市场, 比如新闻报道, the report discusses how video quality and TTFF may be more important than E2E latency, 金融应用除外, 哪里端到端延迟是关键. 在这方面, if you’re a day trader or other fast-twitch investor, note that Bloomberg’s E2E latency exceeded 90 seconds, 远远超过路透社的16和CNN的12.

The report also reveals how E2E latency is also critical to 体育 applications, where delays longer than 10-15 seconds can lead to "spoiler alerts," where viewers read about a score or goal on Twitter before they see it in the stream. 有趣的是, the report states that while broadcast tends to have E2E latency of about 15 seconds, the live streaming apps Wowza tested had E2E latency from 9 to 101 seconds.

因为报道的重点是现场直播, 它不包括视频点播服务, 尽管该报告的作者, Wowza’s director of communications and streaming industry evangelist Chris Michaels, did state that "we do intend to re-create this study with a focus of testing more subscription-based live services."

正如大多数百家乐软件app最新版下载所认识到的那样, achieving optimal performance in one metric often degrades performance in another; it’s nearly impossible to offer the highest quality, TTFF最快, 端到端延迟最低. The discussion of this tradeoff in the various markets covered makes the report a must-read for any vendors in each space. 在更高的层次上, the individual market studies provide valuable perspective for learning the importance of TTFF and E2E latency in other markets.