2019年6月6日
By 1月时特约编辑
专题文章

买家现场转码指南2019

如果你制作现场活动, the optimal workflow is to encode one stream at your event location and transport that to the cloud where it can be transcoded into a full encoding ladder, 为不同平台上的观众打包, 然后交给他们. This Buyers’ Guide discusses the categories of vendors available to provide these services.

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我将首先讨论需要考虑的基本特性列表, 然后我将确定供应商类别, 讨论它们的利弊, 然后讨论应该选择每个特定类别的用户类型.

基本特征

最基本的特性与您要生成的事件类型有关. The vast majority of events are 1 to 2 hours or shorter and can be handled by any category of supplier. 如果你正在制作全天活动或24/7流媒体, 在选择过程的早期检查该功能, 因为并非所有服务都支持这些类型的事件.

除此之外，请考虑以下选项.

代码转换

Transcoding is where the incoming stream is encoded into an encoding ladder—a range of resolutions and data rates called to enable distribution to a broad variety of target platforms over a range of connections. 大多数服务转码为H.作为基准，因为H . 264格式.264在任何地方播放，并且转码相对有效.

这里列出了一些可能很重要的问题, 取决于你的尺寸, 目标受众, 以及你发布的视频类型.

你对编码阶梯的制定有多大的控制权, 包括梯级的数量和它们的结构?
您的订阅计划是否有分辨率限制? While 720p should suffice for many bread-and-butter events (most Facebook Live events are 720p), 对于付费赛事，最好使用1080p或更大的分辨率.
除了H之外，该服务还提供哪些编解码器(如果有的话).264? Codecs like VP9 and HEVC can cut bandwidth costs and increase viewers’ quality of experience (QoE) by allowing the service to deliver higher resolution streams at the same data rate as H.264. HEVC也是大多数智能电视的首选编解码器.
Is there a per-title encoding capability that can customize transcoding configurations according to the content in the video file? 此功能在VOD编码商店中很常见, 2017年底，每个标题的实时编码出现在市场上.
该服务可以编码4K和高动态范围(HDR)视频吗?

包装

Packaging is the chunking and metadata creation necessary to support adaptive bitrate (ABR) formats like HTTP 在线直播 (HLS) and Dynamic Adaptive Streaming over HTTP (DASH). 这里的问题包括:

除HLS/DASH外，该服务还支持哪些格式? 如果你的观众是在Xbox等游戏平台上观看的, then Microsoft Smooth Streaming may be the only format that can reach these targets.
服务何时会支援通用媒体申请格式? CMAF will enable delivery to DASH and HLS players via a single set of packaged files, 哪一种能显著降低运输和储存成本. 一些旧的平台不支持CMAF, 但在2019年或2020年的某个时候, some producers may consider these platforms irrelevant and may want to cut over to CMAF.

球员

Many services supply an integrated player and/or integrate with third-party players. 这里的问题包括:

What features are supported in the integrated player, and how simple are they to implement? 你能改变颜色和品牌来匹配你的网站吗? 你能轻松地实现社交媒体整合、嵌入或评论吗?
Does the player include the service’s branding, or is there a “white label” option with no branding?
你可以使用你授权或开发的现有播放器吗? Which third-party players have integrations with the system, or will you have to create your own?

CDN

大多数服务通过内容交付网络交付, 或CDN, 旨在有效地提供高带宽视频流, 这有助于确保观众的QoE. 这里的问题包括:

该服务使用哪个CDN?
业务支持单CDN(无冗余)还是多个CDN?
如果有多个cdn，切换的模式是什么? Does the service switch when demand gets too great or when the original CDN fails, or does it monitor the quality of service (QoS) provided by each CDN in each region and use the CDN that delivers the best service within each region?

分析

Analytics are playback statistics like the number of viewers and their average viewing duration. 其他需要查找的数据点包括:

Does the service provide real-time access to encoding and delivery status to immediately identify problems so they can be resolved?
Does the service include integrations with QoE services so you can track performance indices like startup time, rebuffering比率, 平均媒体比特率, 视频启动失败?
Can the service integrate live-streaming analytics with Google Analytics or similar packages?

玩家和平台支持

大多数服务都可以打包流，以便在电脑和移动设备上观看, 但更多的平台可能意味着更多的眼球. 这里需要考虑的问题包括:

该服务还支持哪些其他平台? 相关费用是什么?
该服务是否提供支持移动设备和其他平台的sdk?
Can the service syndicate the live feed to social media platforms like Facebook Live or YouTube?

技术支持

现场活动是“必须第一次就把事情做好”的终极情形. If you haven’t felt the panic of things going south while streaming a live event, 你要么没有生产很多，要么你非常幸运. 由于许多事件都是在下班后产生的，所以有8点的支持.m. 到5点.m.星期一到星期五，可能不够. 底线是对于关键任务事件, 在活动期间，您需要方便的电话支持, 所以要检查成本和可用性.

对于不太紧急的问题, 你会想要一个充满活力的帮助台，里面有常见问题解答, 深厚的知识基础, and an active community where you can get answers from peers as well as from the service provider. It’s always useful to check these resources to gauge how current and active they are.

This table compares the categories of companies that can provide live transcoding functionality.

先进的功能

除了上面讨论的基础之外, there are several more advanced features that many live-event producers should consider.

API

应用程序编程接口, 或api, enable you to programmatically integrate your systems with those of the live-streaming service so you can automate some aspects of live event production or dump analytics from the service into your own systems. 问这些问题:

服务有API吗?
Which features of the service does it incorporate: event setup, real-time or post-event analytics?

数字版权管理和其他安全措施

数字版权管理, 或数字版权管理, 对于那些发布优质内容的人来说是必不可少的吗, 但对其他人来说可能是可取的. 您需要知道服务支持哪些drm以及如何支持它们. 例如, some larger service providers may run their own 数字版权管理 servers while others link to third-party services, 提供更多的灵活性和潜在的可负担性. 其他要检查的安全选项包括密码保护, geo-restriction, and the ability to limit which sites (if any) can embed the live event stream.

标题

大多数现场活动制作不需要字幕支持, 但如果你的, 请注意，许多较小的服务提供商不支持它们.

广告插入/收费

插入广告是让你的内容变现的一种方式, 而订阅或通过付费墙按次付费则是另外两种方式. 如果你想赚钱, forget social media delivery and check early on other categories because not all companies offer these options.

低延时

在现场事件设置中, 延迟通常是指“玻璃到玻璃”的延迟, or the delay between when the event is shot through a camera lens (the first glass) and then viewed on a computer, 移动设备, 或者电视(第二个). 如果不进行特殊调优，这个延迟很容易超过30秒或更长时间. 很多私人活动, this latency is acceptable and comes with a significant benefit—that playback will be well-buffered and robust.

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