smw17: id3as的Dom Robinson谈论牧行、多播和架构cdn

蒂姆Siglin: Welcome back to 流媒体 West 2017. I'm here with Dom Robinson from id3as. Dom, tell us quickly what's id3as.

Dom Robinson: Id3as是一家软件公司. We've been around for about eight years now. 非常专注于视频工作流的微服务架构交付. 大约八年前，我们把当时的路透社(Reuters)和现在的纳斯达克(Nasdaq)的视频工作流放到了云端, 这是相当大的一个, 这对他们来说是激进的举动. 节省了很多钱，我们现在每年为这些人举办35-4万场现场活动. It's all fully automated and all cloud based.

蒂姆Siglin: That's kind of the fair disclosure types of events?

Dom Robinson: Fair disclosures, corporate announcements. 这是一个周期性很强的好生意，它本身就是一个研究案例.

蒂姆Siglin: 哦，我确定. 是啊，因为每个人都想把它塞进两周的收入里

Dom Robinson: 就是这样，然后我们有三个月的时间，大量的未充分利用. They came to us, and we suggested virtualizing it. This was before anyone else was doing it at that scale. It left us with a really interesting stack. We use an unusual telecoms language, WhatsApp的工程团队或Twitter的工程团队会熟悉哪些, but most other people haven't heard of Erlang. It's really designed for developing carrier-class video workflows. It's self-healing, which is really fundamental. 我们不需要花很多时间来设计失败案例. 这就是我们作为一家小公司获得强大竞争优势的地方, 更大的公司.

蒂姆Siglin: 非常有趣，当然你是流媒体特约编辑.

Dom Robinson: 我要戴上作家的帽子.

蒂姆Siglin: 是的,完全. You and I and Eric have started SMAF, 流媒体高级论坛, which we're not really allowed to talk about here, but people can come to SMAdvancedForum.com and catch up on what we did on the show-floor today.

你有一本书， Content 交付网络: 基本面, Design, and Evolution. I'm going to hold the book up in my best Vanna White impersonation, and I'll put it here so that it's part of the close-up, 但这是内容, 交付网络, 基本面, 设计和进化. 给我简单讲讲这本书.

Dom Robinson: As an outcome of editing my first book for 威利, 高级内容交付, 流媒体, and Cloud Services with Mukaddim Pathan and Ramesh Sitaraman, 我注意到学术书籍总是关于当前的最佳实践. There was very much a competition between people to say, "This is the best way you can possibly do this,这是完全正确的. But there was a sense that people coming into the industry, moving into the sector for the first time, or moving across from a different role of responsibility, really wanted to understand streaming content delivery networks. 他们没有上下文. They didn't have a picture of the cycles in the industry and so on. 我为那本书写的章节更多的是关于这个领域的简短历史. 基本上, 我所做的是，我所做的是，我详细阐述了这一点，并将其扩展到这本书中, 这就更重要了, 在某种程度上, my voyage into the industry over 20 years.

It goes into technical detail about things like; I've got a real belief in service philosophies, 作为大多数技术决策和您应该如何构建内容交付网络之间的基本驱动因素, 流工作流程, and probably other aspect of your business workflow.

蒂姆Siglin: Let's do a slight tangent off of that. 我们会在最后回到书中，但是细胞结合，细胞混合. 这是你很早就知道的东西现在我和克里斯·诺尔顿在一个小组里我们讨论了作为一个很好的冗余来容纳以太网. 你认为这些技术的发展方向是什么?从几乎任何地方都能进行现场直播的能力来看? 过去是这样的, 如果你远程操作, if you went out into the "field," you had to roll a satellite truck. 现在大多数人会说，“哦，是的，我们可以用几个蜂窝器来做这个."

Dom Robinson: 是的, if you're very puritanical about it, the capability's been in the Linux kernel for 12 years, 甚至可能更久一点. 链路聚合控制面板，LACP，在十年前就开始做通道绑定了.

蒂姆Siglin: 这是有道理的, 因为我们这些人, like me who came out of video conferencing, 我们会对B频道进行ISDN绑定，然后用反向频道进行控制.

Dom Robinson: When I started writing for 流媒体, no one was really focused on that space six or eight years ago, so when Eric was asking me to write a little bit more about it, 我意识到仅仅谈论链接聚合或通道绑定链接聚合是不够的. 我开始创建这些层.

你有链路聚合，你只需要一个独立的调制解调器就可以做到. 它是一个路由器. You've got five different IP connections, and if you're doing little bursts of data like web data, an office can get a sense that they're all aggregated, because between all of the offices, 总是有可用性的. 如果您想要流式传输，就不能将其全部视为单个管道. 你需要做什么, 你是否需要在信号的两端进行多路复用和解路复用. 然后 you get a channel bonding link aggregator, 究竟是什么将不同的信道与远程端的对应系统连接在一起, which creates a bit of a buffer basically, 我会带着你, if you've got three one-megabyte connections, 它会把它变成, as far as everything else is concerned, 一个3兆字节的管道.

蒂姆Siglin: 如果您有DSL和电缆调制解调器，这在某些方面类似于您可以获得的家庭负载平衡器.

Dom Robinson: 是的, some of those vendors are dominant vendors. Vislink和Mushroom Networks, 那些家伙, were all about having multiple redundant pipes between offices, 并且实际上能够将它们全部用作一个管道来进行高带宽文件传输, 诸如此类的事情.然后, there's another generation on top of that, 你开始在背包和越来越多的相机顶部系统中看到的是什么.

蒂姆Siglin: Teradek, LiveU等.

Dom Robinson: 完全, 这些家伙, 他们所做的是他们实际上得到了编码的具体应用, 能否施加背压, 如果你喜欢的话, 使用链接聚合器您可以了解是否要降低视频的比特率, because your availability's gone wrong. 如果您的3mb下降到1mb, you can actually signal to the encoder, drop from 3 MB encoding to a 1 MB encoding. I call those cellmuxes, cellular multiplexes.

蒂姆Siglin: 这自然就引出了我想和你们谈的最后一个话题, 哪个是可靠的UDP, because one of the things we were talking about in this panel was, 细胞成键了. You've got the muxing as you say, 但最终, 如果网络不稳定，如果你不能很好地整合所有这些不同的服务提供商, the need to have forward error correction to have reliable UDP, 你觉得未来会怎样?

Dom Robinson: 可靠的UDP，我肯定在18年前在全球混合中使用它，在多播中. 我们对在公共消费网络中扩展多播很感兴趣, 疯狂的项目, 不同的故事, 书里有, 但基本上, 当您在此环境中使用连接推出数据包时, 也就是UDP, 但别忘了, TCP是带反向通道的UDP协议, TCP is like a specific use case of UDP. It's just a very, very good one and very established. 问题是, it's designed to be a good net citizen, 所以它在网络上共享会话，如果两个做不同事情的人试图使用相同的链接, 这对双方都公平. What's happened with a lot of the more recent entrants to the space, 他们是说, “嗯, 如果这是你的IP网络，而你不想成为别人的好公民, 然后强制UDP关闭. Saturate the links and don't have a TCP to back your network.

蒂姆Siglin: I think of TCP and cartoon terms, 奇普和戴尔, 那两只花栗鼠——“你先来。, no after you; no, 在你之后”——UDP是一种浩克进来，只是爆破.

Dom Robinson: 不顾一切地开过去. 那么问题是, 当你开始丢失数据包时, you need to have some intelligence to actually manage that. 我们在哪里建立了自己的链接聚合和贡献堆栈. I suppose something akin to what SRT's been about, 但也, our outcome's a little bit more like maybe quick, 作为一种进化, 斯皮迪. We tried to turn TCP into something that looks like UDP, rather than turn all of the TCP connections into UDP. 我们感兴趣的是经过许多路径的非常非常非常小的数据片段.

蒂姆Siglin: 这不是增加了闲聊，还是减少了闲聊?

Dom Robinson: 它还允许后退过程以许多不同的管理方式发生, and you don't have to implement a reliability protocol over the top. 这是一个可靠性协议. 它就是有效的. Particularly for the Nasdaq guys, 他们广泛使用我们为他们开发的现场编码器，因为它快速简单，他们不必考虑防火墙. It also brings link aggregation, cellular bonding as a byproduct.

蒂姆Siglin: It does that traversal, that kind of thing?

Dom Robinson: 这是TCP.

蒂姆Siglin: Because it's TCP, you’re right, fair point. All right, where can people get the book?

Dom Robinson: 去 亚马逊. That's the fastest way to get the copies delivered. 你可以去 威利.com网站，如果你在11月直接给我发信息，我也可以给你一点8折的代币.

蒂姆Siglin: The 流媒体 2017 discount. 太棒了. Thank you Dom, as always, and I like the hat.

Dom Robinson: 是的, it's for my writing role only. 回到id3as.