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, packaged for your viewers on different platforms, 然后交给他们. This Buyers’ Guide discusses the categories of vendors available to provide these services.

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I’ll start by discussing the basic list of features to consider, 然后我将确定供应商类别, 讨论它们的利弊, and go over the types of users that should choose each particular category.

基本特征

The most basic feature relates to the type of event you’re producing. The vast majority of events are 1 to 2 hours or shorter and can be handled by any category of supplier. If you’re producing all-day events or 24/7 streaming, check for that functionality early in the selection process, because not all services support those types of events.

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 plays everywhere and is relatively efficient to transcode.

Here’s a list of questions that may be important, 取决于你的尺寸, 目标受众, 以及你发布的视频类型.

How much control do you have over the formulation of the encoding ladder, including the number of rungs and their configurations?
Are there any resolution limits for your subscription plan? While 720p should suffice for many bread-and-butter events (most Facebook Live events are 720p), 1080p or larger may be preferred for premium events.
Which codecs (if any) does the service offer beyond H.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 is also the codec of choice for most smart TVs.
Is there a per-title encoding capability that can customize transcoding configurations according to the content in the video file? This feature is common in VOD encoding shops, and live per-title encoding appeared on the market in late 2017.
Can the service encode 4K and high dynamic range (HDR) video?

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:

Which formats other than HLS/DASH does the service support? If your viewers watch on gaming platforms like the Xbox, then Microsoft Smooth Streaming may be the only format that can reach these targets.
When will the service support the Common Media Application Format? CMAF will enable delivery to DASH and HLS players via a single set of packaged files, which should cut delivery and storage costs significantly. 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? Can you change the color and branding to match your website? Can you easily enable social media integration, embedding, or comments?
Does the player include the service’s branding, or is there a “white label” option with no branding?
Can you use an existing player that you’ve licensed or developed? Which third-party players have integrations with the system, or will you have to create your own?

CDN

Most services deliver via a content delivery network, 或CDN, designed to efficiently deliver high-bandwidth video streams, 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?
Does the service support a single CDN (no redundancy) or multiple CDNs?
If multiple CDNs, what’s the schema for switching over? 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. Other data points to look for include the following:

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

Most services can package streams for viewing on computers and 移动设备s, but additional platforms may mean more eyeballs. Questions to consider here include the following:

What other platforms does the service support? 相关费用是什么?
Does the service provide SDKs to support 移动设备s and other platforms?
Can the service syndicate the live feed to social media platforms like Facebook Live or YouTube?

技术支持

Live events are the ultimate “must get it right the first time” situations. If you haven’t felt the panic of things going south while streaming a live event, you either haven’t produced many or you’ve been extremely lucky. Since many events are produced after hours, having support from 8 a.m. 到5点.m., Monday through Friday, probably won’t cut it. The bottom line is that for mission-critical events, you’ll need accessible telephone support during the event, 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, is essential for those publishing premium content, 但对其他人来说可能是可取的. You’ll want to know which 数字版权管理s the service supports and how it supports them. 例如, some larger service providers may run their own 数字版权管理 servers while others link to third-party services, providing more flexibility and potentially affordability. Other security options to check for include password protection, geo-restriction, and the ability to limit which sites (if any) can embed the live event stream.

标题

Most live event productions don’t require caption support, 但如果你的, be aware that many smaller service providers don’t support them.

广告插入/收费

Advertising insertion is one way to monetize your content, while subscription or pay-per-view via a paywall are two others. 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, latency typically refers to “glass-to-glass” latency, 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). Without special tuning, this latency can easily exceed 30 seconds or longer. 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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