Buyers' Guide to Cloud VOD Encoding
云视频点播编码已经从前沿发展成为主流. If you're considering a move to the cloud, or perhaps changing vendors, 本买家指南将帮助您确定最适合您的服务提供商类别, and how to differentiate between services within that category.
In this guide, 我只讨论那些以软件即服务(SaaS)或平台即服务(PaaS)的方式提供产品的公司。, 而不是那些在公共云或私有云上安装软件的公司, or for other internal computing infrastructure. 下面列出了一些问题和特性，以帮助您进行分析.
Who Are You and What Do You Want?
Several years ago, 云编码公司的产品相对同质化. Codecs and formats were limited, 带宽限制限制了大多数大容量用户上传一个相当紧凑的夹层文件用于编码到Flash或HLS格式. Over the past few years, things have changed, 现在大约有四种类型的供应商提供云编码, though things may get blurry around the edges. These are shown in Figure 1.
Figure 1. A rough taxonomy of cloud encoding vendors
Primarily encoding—Services like Amazon Elastic Transcoder, Coconut, and Qencode 主要是尽可能高效地对上传到平台的夹层文件进行编码, 并假设生产高质量产品所需的计算需求和专业知识, compatible video files.
Workflows, packaging, QC, and more—Beyond simple encoding, 这个类中的公司想要假设通常在夹层文件创建之前的工作流活动. This can include dynamic assembly, broadcast and OTT packaging, closed-caption creation and deployment, quality control, playout format support, DAI and stream conditioning, DRM and manifest manipulation, and metadata transformation. Companies like Encoding.com, Hybrik, and Telestream fall into this category.
Encoding plus这些供应商提供编码和一个或多个主要的辅助服务. For example, Bitmovin offers encoding plus analytics and a player, while Brightcove offers encoding through its wholly owned subsidiary Zencoder, a player, 以及视频分发工作流的其他元素，如服务器端广告插入. 如果你想走这条路，这两家公司都提供全面的在线视频平台.
Encoding as a component of a streaming platform-此类服务将编码作为整体分发平台的一个组件提供, which can include storage, origin server provision, and content delivery. Microsoft Azure is the best example of a PaaS, while Elemental can supply many of these components via a product or a platform.
因此，在考虑云服务时要问的第一个问题是，您希望卸载编码和分发工作流和/或基础架构的哪一部分. 然后确保您选择了一个能够提供必要服务或基础设施组件的提供者. As part of this analysis, be sure to consider whether you need live as well as VOD, since not all providers offer a live option.
The more functionality you push to the cloud, the more help you’ll likely need to get it up and running. So if you’re pushing workflows into the cloud, as compared to simple encoding, 一定要询问咨询服务的可用性和费用, both for start-up and ongoing changes.
Where Do You Want It?
第二个问题与您希望如何部署系统有关. 有些服务严格以SaaS的形式提供，这适用于许多组织. However, 如果您已经创建了自己的私有云或其他内部计算功能, you may want a solution you can install internally.
As an example, you can deploy Encoding.com在私有云上的各种虚拟化平台(OpenStack, VMware, Joyent), storage configurations (SMB, SWIFT, S3, NFS), and network configurations. In addition, Bitmovin在Kubernetes和Docker上提供了一个托管的本地编码服务，适用于VOD和live，并提供与云编码相同的功能. Bitmovin还可以运行在各种各样的虚拟化堆栈上，比如OpenStack, VMware, Mesos, DC/OS, and CoreOS as well as bare metal.
另一个有效的问题是该服务运行在哪个云平台上. 大多数大型服务在多个云平台上运行，以确保短期操作冗余，并减少对单个供应商的依赖. Most smaller customers likely wouldn’t care about these issues, but large customers may share these same concerns.
Input/Output Format Support
For several years, streaming formats have been relatively static; H.264是编解码器，而Flash、HLS或Smooth Streaming是主要的发行格式. 许多公司现在都在考虑HEVC和/或VP9, AV1将在短期内出现. On the packaging front, 通用媒体申请格式(CMAF)将在2018年及以后变得越来越重要. 您在明年左右考虑的任何供应商都应该在支持所有这些技术的计划上走得很远.
Pricing Model
Pricing is key when choosing a vendor, but price comparisons are not simple, primarily because there are multiple disparate pricing models. Most SaaS vendors offer either per-minute or per-GB pricing, which is simple to compute, but generally are the most expensive for high-volume customers. Also, 这些定价方案可能(也应该)根据软件的运行地点而变化——如果你是在云服务上运行的话, it should be one charge; if running on your own private cloud, it should be cheaper.
在估计按GB或分钟收费的服务定价时, 一定要考虑每个服务的价格操作，如转换, 从CPU的角度来看，这是非常有效的，不应该定价相同的编码. For example, Zencoder转换到HLS或DASH的费用比从头开始生产输出的费用低75%. Others charge full price for each output format, which obviously can have a huge impact on overall pricing.
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