April 3, 2014
By Jan Ozer Contributing Editor
Featured Articles

现场编码器买家指南2014

So you’re streaming a live event at some off-site location and you’re wondering what hardware or software to buy to encode the video to send to your streaming server. Well, you’re in the right place, because that’s the subject I tackle in this Buyer’s Guide. I’ll present bite-sized chunks that should quickly help you narrow your selections. 请注意，我不会深入讨论相机编码器, 因为这些将在单独的买方指南中进行说明.

从你的服务开始

If you have your own streaming servers, your encoding options are practically unlimited. In contrast, if you’re streaming with a live streaming service, particularly Livestream，你的选择可能非常有限. So check your service provider’s website first to determine if there are any free tools that can get the job done, 任何推荐的工具, 以及任何不起作用的特定工具.

What’s Your Schema?

Whether you’re broadcasting with your own servers or a third-party service, 您必须了解自己的编码模式. That is, 你是自适应流媒体吗, 哪一种更受欢迎，但更复杂, 或者编码单个流, which is cheaper and easier but may deliver a suboptimal experience to mobile viewers or those watching on large screen LCDs.

If you’re broadcasting a single stream, pretty much any encoder will do. If you’re streaming adaptively, your encoding needs depend upon your overall encoding schema. One technique is to encode all streams on-site for transmitting to the server, 哪个是昂贵的，需要大量的出站带宽. The other is to send one stream that the service can transcode into the required number of streams. 许多硬件设备只能对单个流进行编码, 在你去购物之前，有什么重要的事情要知道. 如果您有任何特殊要求, 例如加密或封闭字幕, 早点把这些放到桌子上, 因为绝大多数字段编码器不支持它们.

视频混频器，编码器，或其他?

The first major decision relates to the functions you need your encode to perform. For example, 如果你使用多个摄像头, 你需要一个视频混频器, 其中许多还可以对单个或多个流进行编码. 在光谱的另一端, you may only need an encoder that can input a single audio/video (A/V) feed, encode it, 然后将其传输到流媒体服务器.

In between are lecture capture stations such as the Winnov Cbox P2 HD that can input multiple A/V inputs, including screens from other computers for PowerPoint and software presentations, and format them for transmitting to a streaming service or for distribution to a range of desktop and mobile devices. Similarly, video management platform vendors such as Sonic Foundry usually offer their own portable video capture systems, which you should definitely move to the top of your list when buying a portable unit to stream into these platforms.

在企业领域也是如此, where the VBrick Rich Media Studio Portable HD is an ideal solution for those producing rich media webcasts for distribution through the VBrick 企业视频架构，而思科数字媒体编码器1000 在思科数字媒体系统中功能类似. Basically, 就像直播服务一样, if you’re distributing your content through any kind of academic or enterprise distribution mechanism, you should ascertain which portable encoder the vendor offers or recommends.

你需要连接到什么?

如果你买的是硬件设备, 它显然需要连接到您的A/V设备, so identify the connection standards your field encoder needs to support and make sure it can support them, 直接或通过格式转换器. 如果你正在购买一个软件编码器或混频器/编码器, you’ll need a capture card to input your A/V streams into your computer.

If your capture station has open expansion slots, you’ll have multiple options from many vendors. 如果你有笔记本的话, you can either buy an external capture device or get an expansion device such as the Magma ExpressBox that provides an expansion slot into which you can plug a capture card. Obviously, with either option, you need to buy a capture device that can connect to your A/V sources.

选择视频混频器/编码器

如果你正在寻找一个视频混频器/编码器组合, your first major decision is between a hardware-based system such as the NewTek 或软件程序，如 Telestream Wirecast or CombiTech VidBlaster. In general, 尽管TriCaster是一台装在专用盒子里的Windows电脑, it’s thought to be more reliable than off-the-shelf software solutions because the hardware and software components are more rigorously tested, 并且该设备一般只用于现场生产, 而不是用于通用计算, 哪种方法可以最大限度地减少应用程序冲突的可能性, viruses, and wear and tear. Of course, the TC 40 (as with all TriCasters) is transportable, but not truly portable.

On the other hand, 使用Wirecast和VidBlaster, 你可以用不到1美元的价格观看直播,000, 包括捕获硬件. 提高可移植性和可靠性, Telestream has partnered with several hardware vendors to provide turnkey computer systems with Wirecast preinstalled and guaranteed compatible I/O hardware, 尽管这显然会提高整个系统的成本.

如果选择使用硬件路由, the TriCaster line is one the few that can perform mixing and general-purpose encoding chores. In particular, TriCaster’s success in the streaming space has led to very wide support from most live streaming services. In fact, TriCaster is one of the few (if not the only) third-party devices supported by Livestream. Certainly there are many other hardware video mixers available from multiple vendors, although you may also need to purchase a separate encoder in order to use them.

选择软件混频器/编码器

如果你正在寻找一个软件混频器/编码器, Wirecast (Mac/Windows) and VidBlaster are the two most prominent entries. 寻找Mac替代品的制作人应该考虑一下 BoinxTV from Boinx software, while those working on Windows can consider the Open Broadcaster Software, 哪个既是免费的又是开源的.

As between Wirecast and VidBlaster, if you’re a Mac producer, VidBlaster is out. Beyond this, 这两个程序的核心功能非常相似, and both have been around long enough for any major feature deficits to have been addressed. 最近发布的Wirecast 5具有很强的竞争力, 一个开放的界面提高易用性, 结合x264编解码器提高质量, and the ability to easily capture multiple screen regions on the Wirecast system offsetting a long-term VidBlaster advantage.