A Buyer's Guide to Streaming Appliances

Sometimes all you need is a small box. Perched firmly between software-based streaming encoders -- which run on laptops or desktops -- and higher-end video mixers -- which switch seamlessly between graphics and multiple video inputs -- there's a category of encoder products we call streaming appliances.

"Appliance" is a term for a product that is self-contained, often hiding the operating system behind a simpler interface. Some streaming appliances offer access to controls via front-screen tactile buttons or touchscreens, while others provide access via webpages.

Streaming appliances often perform a simple task: encoding content to stream at predefined data rates via industry-standard codecs and formats. But a few offer additional benefits such as graphics overlays and rudimentary transitions.

In this Buyer's Guide, we'll consider a few key questions needed to determine whether a streaming appliance is the best choice. We'll also look at the options offered by streaming appliances.

Number and Type of Inputs

For a multicamera shoot, a streaming appliance is probably not going to pass muster. If, however, you only need one video source input -- say, from a single camera -- then a streaming appliance might make sense for your workflow.

Appliances come with a variety of inputs, including analog -- composite, component, Y/C -- and serial digital video -- SDI, HD-SDI, 3G-SDI. A few streaming appliances even offer DVI or HDMI inputs.

On the audio front, inputs consist of analog unbalanced connectors (RCA) or balanced (XLR), and a few also offer captive screw connectors for bare-wire connections that minimize the size of the appliance while still offering multiple audio inputs.

The latter type of connector is often found on a new breed of streaming appliance, one that has internal scaling and multiple inputs, which can be selected to switch between DVI, HDMI, or serial digital inputs. Note that this selection isn't true video switching, which takes advantage of time-base correction and a vertical interval switch to provide a seamless cut. The appliances with a selection option will show a momentary "glitch" when switched, and the codec will need to work hard to encode the glitch and resulting change of image.

Graphics Support

Streaming appliances don't have sophisticated graphics overlay capabilities, but a number of units can generate a graphic "bug" overlay in the bottom corner, via a JPEG or alpha-channeled image.

If your workflow calls, for instance, for multiple titles that need to be positioned over live shots of a number of presenters, a video switcher is often the best option.

The one other area where streaming appliances are gaining traction, when it comes to graphics, though, is the ability to offer crawls along the bottom of the screen. This feature has been added to a few appliances, mainly from manufacturers whose target markets include education, as part of the safety and alert requirements for digital signage.

Field Production

Many streaming appliances are "headless" devices, which means that they have no graphic interface beyond a 1-2 line LCD display. We've covered a few of these products in the past, noting that field production would require an external monitor, mouse, and keyboard to be able to make changes to even the simplest streaming parameters.

These units, however, can also be accessed via webpage interfaces, and a few have even added the ability to access and store basic parameters via Android or iOS device apps. The handset or tablet needs to be on both the same network and subnet, and most field locations where you use a streaming appliance won't allow you to open up ports in their firewalls just to access the controls for your appliance, so it doesn't hurt to carry a separate Wi-Fi access point (WAP) to allow access to the device. If your WAP has an Ethernet port, it can be placed on the same network, but check with the venue about its policies for "rogue" WAP devices before plugging a nonencrypted WAP into its network.