2023年8月9日
By 蒂姆Siglin 特约编辑
聚光灯

实时编码的关键注意事项

As more and more live streaming content is consumed on a widely disparate group of devices—including both lowerand upper-end mobile phones and tablets, as well as 智能电视s and 4K-capable set-top boxes (STBs)—the decisions around choosing a live streaming encoder have grown more complex.

Consider the fact that a large number of live streaming viewers will consume a single live event across at least two devices—whether sitting in the comfort of their living room, 在智能电视上观看大赛, 同时还可以在第二个屏幕上与“观看派对”的朋友互动, or just watching part of the event on a mobile device while in transit between work and home—and it’s easy to see that live streaming workflows are much more complex than they were even four or five years ago.

设备之间的往返

幸运的是, newer live streaming solutions have benefited from two decades of consumer-facing features added to video-on-demand (VOD) media streaming workflows. 超越了基于http的交付的标准化, 由Adobe等公司开创, Apple, 微软, 还有一些是十多年前的, 以用户为中心的VOD优势现在已成为当今大多数直播编码器平台的标准选项. 举个例子, 想想设备之间的内容往返是如何从仅限视频点播功能跃升为现在的
直播解决方案的赌注表.

The VOD roundtrip benefit addressed a consumer frustration: when VOD content viewing started on one device and was completed on another device. 消费者抱怨说，他们被迫从第二台设备的开头开始观看内容, 手动搜索，直到找到同一个地点. The advent of roundtripping content (essentially keeping track of time-based pointers in a single-users playlist that was shared between devices) allowed consumers to start watching content on one device and then seamlessly shift to another device.

在直播传输解决方案中, this roundtripping benefit is expanded to catch-up services (essentially a DVR-like functionality that allows the viewer to miss a few minutes of a game as they transition to another device, 但是“赶上”这个间隔来检查间隔中是否发生了重大事件). 一些解决方案允许完整的事件追赶(例如.g., 主要体育赛事, 包括必看的商业广告)，而其他一些则允许几分钟的最小追赶窗口.

有很多挑战, 当然, 其中一些在最近的流媒体东部2023会议上被讨论迎接直播视频点播挑战, but also new benefits as livestreamed catch-up functionality has added the ability to create on-the-fly highlight reels of key events, 然后以视频点播的形式传送.

Some content owners choose to make VOD content available to non-paying viewers as a way to entice them to subscribe or pay for an ongoing pay-per-view event. 作为一种改进，超出了典型的基于dvr的追赶服务或手动创建的高光卷轴上面提到的, 处理大型现场活动的经验带来了额外的增强.

最近, a number of companies have announced machine learning options—often using the term AI or artificial intelligence—with the intent of automating the creation and packaging of these highlight reels for live sports. 解决方案被编程来识别球的运动, 裁判的哨子, 人群怒吼, 以及关键比赛或进球的其他重要方面.

考虑到观众更有可能在多个设备上观看现场活动内容——无论是在工作中, home, 或者在位置之间的转换中——在过去几年中，编码中的表利害关系显著增加. Ensuring a high-quality origination stream from the encoder to the consumer is vital for successful live streaming—especially now that consumers are demanding catch-up functionality with content quality expectations for this functionality that rivals VOD content encodings that have the luxury of multipass encoding.

确保原创流质量:需要考虑的关键因素

那么，在尝试确保高质量的原创流时应该考虑哪些因素呢? 每个实时事件流工作流都有相似之处, 但我在下面列出了一些需要考虑的关键因素.

场地带宽: 鉴于现场活动内容消费的短暂性, 需要考虑的不仅仅是消费者交付前端的带宽问题，还有场地方面的问题. There are a number of solutions designed to assist with intermittent network availability—most based around the concept of forward error correction, which can extrapolate parts of the content even if packets are missing—but nothing guarantees a quality ingest into a modern encoder more than a rock-solid IP content acquisition network.

编码参数: 您在设置直播编码器时所做的选择对于增强消费者的观看体验也至关重要, so choosing a live streaming solution that can encode anything for very-low-bandwidth 3G mobile all the way up to 4K high-dynamic range (HDR) streams—ideally at the same time, 作为一种节省功耗和处理时间的方法，这是直播流编码和交付工作流程中的关键因素.

多个协议: Not only should the live encoder be able to handle the multiple bandwidths and resolutions required for viewers to properly experience your live event; it should also be able to handle multiple input (acquisition) and delivery (origin server) transmission protocols. 我们将在下面讨论收购, 但是在原始服务器前端, 确保最小的交付输出至少涵盖经典RTMP以及几种基于http的交付选项之一. This flexibility will both provide a redundancy of origin streams and also add flexibility as you choose a streaming delivery partner to help deliver streams to all your viewers.

可伸缩性: 除了计划你的实时事件流到达每一种类型的查看器设备-桌面, laptop, 智能电视, smartphone—the question of scalability is probably the next major concern when choosing both a live streaming encoder and streaming delivery partner. 在过去，扩大规模以满足观众需求通常被视为一种“黑色艺术”,但过去20年的活动直播已经产生了许多经验丰富的交付合作伙伴. The great thing about working with a partner is that they’ve not only been through scaling up a similar live event stream but also may have worked with the very live stream encoder you’re using, 这意味着他们可能会就如何创建最佳的原始流提出一些建议.

收购决策: 说到内容获取，最好的设备就是你手边的设备. 在某些情况下，这可能是一款高端智能手机, in others it may be a laptop—remember just how much remote production (REMI) was done during the pandemic lockdowns via business and consumer laptops—or it may be a group of high-end broadcast cameras.

输入源: 目前大多数基于硬件的直播编码器都允许通过IP(包括Wi-Fi和以太网)输入。, 以及通过标准数字视频连接(如SDI或HDMI), 其中很多都非常小巧，价格也很合理, 用于功能集选项.

软件编码器: 不想花钱买硬件编码器? 你很幸运, as the new breed of software-based online encoders offers many of the features found in hardware encoders while also providing acquisition from all sorts of low-latency, 双向视频，无论是FaceTime, Meet, Skype, 团队和其他一些人——以及平原, 旧的RTMP和新WebRTC流.

监控: 在任何事件之前和期间，监控是直播工作流的关键组成部分. 这可以采取设备上监控的形式, 基于硬件的编码器中经常包含的功能是什么, 也可以通过硬件或软件编码器解决方案提供的应用程序进行监控. 我个人使用了一个基于应用程序的监控解决方案，用于一个非常小的硬件编码器, which has ultra-low-latency monitoring that’s proven helpful in catching audio- and video-sync issues before a live event stream goes public.

额外的百家乐软件

我们只选择了你在选择直播事件流编码器时应该考虑的亮点, 但这里有一些额外的百家乐软件. Several 文章在最近 2023流媒体源手册 cover 直播选项.

除了, 这个特殊的清单部分包括一篇附带的文章, 《百家乐软件》,” which follows this one and highlights additional considerations when selecting the right encoder for your workflow; I strongly encourage readers to review that article carefully while making purchasing decisions around live stream encoders and streaming delivery service partners.

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