什么是DRM?

这是我们的“是什么...?”文章, 旨在提供定义, 历史, context around significant terms and issues in the online video industry.

如果你打算从主要的美国.S. 工作室, 您需要加密该内容, which typically means that you'll have to deploy one or more digital rights management (DRM) technologies. 您将在本文中了解到, while many aspects of the migration from plug-ins like Flash and Silverlight to HTML5 playback have simplified video distribution, 这种转变使得DRM方面更加复杂, 尽管有新的服务和服务模型可以提供帮助.

在进入实现端之前, 让我们定义DRM, see what distinguishes it from other less-sophisticated content protection schemes like simple 加密. 在本质上, there are four components to DRM; digital rights to manage, 加密, 许可证管理, 以及支持drm的客户端.

管理数字版权drm技术支持广泛的商业模式, 包括购买, 订阅, 租赁, 和礼物, 通过流媒体在单个和多个平台上启用播放, 下载或侧载, provide playback restrictions that guard against or enable playing via HDMI outputs and the like.

加密,DRM technologies use 加密 to protect the content prior to or during streaming, 下载或其他转移.

许可证管理,DRMs require a DRM platform to manage the request and issuance of licenses (图1). 有些还包含域控制器, which manage the multiple user devices that can play content under a single license, metering servers that track usage data and total plays for royalty purposes.

图1. PlayReady DRM组件. 请注意，并非所有DRM技术都利用域的概念.

支持drm的播放器—The final element of DRM is a DRM-capable player that can communicate with the DRM platform and enforce all software- and hardware-related playback restrictions. 用于电脑和笔记本播放, some DRMs use an existing plugin—like Adobe Access and Flash or PlayReady and Silverlight—while other technologies, 比如谷歌都 Classic, 需要单独下载, which is one of the reasons that Google has stopped updating this technology. 稍后将详细讨论, the industry is moving from plugin-based DRM to browser-based DRM via the Media Source Extensions (MSE) and Encrypted Media Extensions (EME), 其中DRM必须集成到浏览器中.

On 移动 devices, DRM support can come from the native browser or via a downloadable app. 例如, iOS设备通过Safari浏览器支持苹果的DRM FairPlay, 但如果你是通过自定义应用发行，你也可以使用其他drm. 通常, 智能电视, 奥特盒子, other consumer electronic devices have one or more DRM technologies pre-integrated into the platform.

在深入讨论之前, let's identify the major DRM technologies and companies on the periphery that provide critical DRM-related functionality.

DRM市场

Let's start with companies supplying the actual DRM, some of which we've already discussed. 与流媒体相关的主要DRM提供商有:

Adobe黄金时段adobe的DRM最初是Access, 然后Adobe将其更名为Adobe黄金时段 DRM, 但他们后来又回到了Access. 访问主要通过Flash在浏览器中访问, 或者在Mozilla Firefox中使用HTML5, but almost exclusively for companies who are also licensing the Adobe黄金时段 platform.
Apple FairPlay Streaming (FPS)fps是苹果的DRM HTTP直播(HLS) 它可以在iOS, Apple TV和OS X的Safari上运行. Apple licenses FairPlay to content owners and some premium platform operators. DRM供应商可以提供FairPlay加密和许可, 但是它们必须从内容所有者那里获得证书, 谁又能从苹果那里得到呢.
谷歌都Widevine有两个版本:经典版, 哪些只能通过可下载播放器获得, 和模块化, 在Google Chrome和Android设备上使用HTML5. 如前所述，Classic已被弃用. Today, Modular only works with DASH, but soon may support HLS under CENC.
DivX - Now owned by Neulion, DivX has significant penetration in consumer electronics devices.
Intertrust马林-一个开放的标准DRM从马林开发者社区, 是由Intertrust创立的吗, 松下, 飞利浦, 三星, 和索尼. 还专注于消费电子设备
微软PlayReady-工作与Silverlight播放器在旧的浏览器, or with HTML5 on the latest versions of Internet Explorer (on Windows 8.1+)和Microsoft Edge. 也用于Xbox和许多其他智能电视和OTT设备.
Veramatrix VCAS—A hybrid solution for pay TV distributors that also wish to distribute to computers, 移动, 和OTT设备.

Surrounding these core DRMs are a number of distribution and technology partners/service providers. 如你所知, DRM需要许可功能, each DRM vendor provides these functions differently—some directly, 一些与第三方增值经销商网络.

许多公司还涉及DRM工作流程, from on-premise and cloud encoding vendors that encrypt the content files to player vendors that help develop video players that talk to the license servers to retrieve the decryption key and play the video file. We'll look at some of these vendors and discuss how to choose a DRM technology after taking a deeper look at how DRM works.

DRM如何工作

既然我们已经定义了DRM, 让我们快速了解一下DRM技术的一般工作原理, 从一个名为 DRM今天. The first step is to get the 加密 keys from the DRM provider or create them and upload them to the DRM platform. 这些是用来加密视频的, with the decryption key and associated metadata sent to a license server accessible by the player. This 加密 prevents playback of the content without a decryption key, 通过互联网安全地传输给最终用户.

图2. DRM的第一步是加密. (图片由DRM今天提供)

For most DRMs, external products or services can perform the 加密 and packaging shown in 图2. 例如，云编码器像编码.com can communicate with a DRM platform to acquire 加密 keys to encrypt and package the licensed content, 就像许多企业级编码器一样电影《欧洲杯在线投注赔率》英文名编码器, Wowza流媒体引擎, Telestream有利. 除了, most DRM services provide separate encoding tools to encrypt and package your video and send the key to the DRM Platform. Once encrypted, the protected content is delivered to a web server for distribution.

当客户播放内容时, the player sends the license request to the content owners' proxy which communicates with an authentication process running on the customer's website. 一旦客户的网站验证了用户对内容的权利, the proxy communicates with the DRM platform to create the license/decryption key which is then returned back down to the customer's proxy and ultimately to the user's player (图3). 在为离线播放而下载的内容的情况下, 此验证也在下载之前进行, 以及任何播放权和限制.