A Buyer's Guide to Portable Encoders

Live event streaming while on the road requires an encoder that's as powerful as it is portable. 在这份买方指南中, I'll detail the categories to consider when buying a portable encoder, along with factors to consider to help identify the best product for your needs. 特别, 我将讨论软件编码器, 便携式硬件编码器, 还有摄像机编码器, though exclusively for Ethernet or Wi-Fi transmission, as cellular models are covered in another Buyer's Guide.

Let's start with the two things you need to consider before buying any encoder.

服务提供者

If you're using a live streaming service provider such as Ustream or 转播画面, your first stop should be their list of compatible hardware and software programs. Most of these providers supply free software encoders that simplify connecting to the service and ensure the full use of all features, 比如自适应流. If you decide to go the hardware route and your hardware encoder isn't listed, 这可能行不通, or you may not be able to access all streaming-related features offered by that live streaming service provider.

工作流

Most live event producers want to reach multiple platforms, such as computer and mobile devices, optimally with adaptive streams that match the bandwidth and playback capabilities of their viewers. To accomplish multiple-format adaptive streaming, you'll have to encode your source into multiple files, package these files in the proper format, and create any necessary metadata files.

Relax; you don't have to do all this on your portable encoder. But you do need to plot the various stops along the way to work back to the format and quality that you do need to produce on-site. So mind the second habit of highly successful people and begin with the end in mind.

除了这两个考虑之外, each of the three types of portable encoders brings with it its own set of questions. So, rather than offer a bullet-point list of questions, we'll cover those within each of the following sections.

软件编码器

Most live event producers are drawn to software encoders because they're inexpensive (or free) and can be very powerful, with multiple programs that offer production functions such as multiple camera switching or title creation. If you already own a sufficiently powerful notebook computer and budget is your most pressing consideration, 这门课是为你准备的. Unless you're running older DV or HDV gear that you can connect to your computer via FireWire, don't forget to factor in the cost of the adapter you'll need to connect your camera gear to your notebook.

If you're streaming into the Flash infrastructure, the free Adobe Flash Live Media Encoder (FMLE), which is available for both Mac and Windows, is a natural first stop. Note that FMLE has a three-stream limit, so if your encoding tool needs to create more than three, 你得另寻他处. FMLE is also devoid of any production-oriented features such as multiple-camera switching.

If you're streaming into the Silverlight or IIS infrastructure, check out 微软表达式编码器 ($199), which can create as many streams as your notebook can support and offers rudimentary camera switching. The product is Windows-only, however; so it's a no-go if you're encoding on a Mac.

There are two product families that combine encoding with production features: Telestream Wirecast, which is cross-platform and starts at $495, and VidBlaster, which is Windows-only and starts at $195. Both families offer versions with a dizzying array of features that can dramatically enhance a live broadcast, from the aforementioned multiple camera switching and titles to adding disk-based files and screen-based or PowerPoint presentations to the live feed.

While software encoders are very popular for many producers, there are three general concerns. 第一个, while operating these programs should be well within the capabilities of most computer literate video or streaming professionals, they're probably beyond the capabilities of your average marketing or personnel administrator. 第二个, performance is obviously hardware-dependent, so if the program is installed on a substandard computer, or if performance is degraded on a particular computer by a background task, streaming may come to an abrupt halt.