A Buyer's Guide to Streaming Appliances

Other units have a touchscreen interface. The user experience varies from appliance to appliance, and your mileage may vary depending on your comfort level in learning a new "operating system" for each appliance, but we've been pleasantly surprised with the ease of use on a handful of these products.

Most streaming appliances are designed to be rack-mounted, either via integrated "rack ears" or through the use of a separate bracket. The latter is more likely in those 1-2 rack units that take up one-third to one-fourth of a horizontal rack space.

One Encoder or Two?

Several appliances on the market have two discrete inputs, allowing a single appliance to encode two discrete input signals. The majority of these multiple-input appliances use a blade-server approach, where each encoder is fully self-contained in a shared chassis.

For multitenant (MTU) or high-density encoding requirements, the number of discrete blades can run into the double digits -- with a price point to match -- so we feel these appliances are more setup-and-forget compared to a one- or two-input unit that might be used in portable production.

Number of Outputs

For these ultraportable 1-2 input units, it's worth noting that each input is capable of more than one output. While a very limited number of streaming appliances on the market have loop-through capabilities for local display of the input signal -- good for confidence monitoring -- the majority of streaming appliances output only via an Ethernet connector.

Some appliances have two Ethernet connectors, ranging in speed from 100Mbps to 1Gbps, but the majority of ultraportable appliances rely on a single Ethernet connector.

Outputs on a streaming appliance may be better explained as number of different stream types, based on resolution or bitrate. While a streaming appliance certainly can be used as the primary streaming server, allowing multiple users to access the stream directly from the appliance, most manufacturers recommend against this. Instead, use a content delivery network (CDN) so that the limited processing power on the streaming appliance can be harnessed to output HD content up to 1080p.

A few streaming appliances offer on-board adaptive bitrate (ABR) segmenting, while others only offer multiple discrete streams at differing bitrates. In the latter case, a separate media server will need to segment the multiple live streams into an ABR format such as Apple's HLS, MPEG-DASH, or Microsoft's Smooth Streaming.

Whether your workflow calls for on-board or external ABR segmentation, a key suggestion is to test your preferred workflow -- including the number of primary streams you will need to generate and pass on to a CDN -- during the evaluation phase of a streaming appliance. I've found in testing that a single additional stream requirement, even at a low bitrate, may be too much for the appliance's processor to handle, requiring the addition of a second appliance.

Conclusion

The market for streaming appliances continues to grow, with some manufacturers reporting shipments of 10,000 or more units. Still, there is room for further expansion, including the addition of touchscreen interfaces on a number of small-form-factor and ultra-portable appliances. Processing power continues to increase, and sizes continue to shrink, making the idea of a streaming appliance attractive to whatever field production workflow challenge you might find yourself faced with.

Seven Key Questions for Streaming Appliance Purchasing Decisions

• How many video inputs do you need, and what kind -- analog, digital, SD, HD?
• Do you need balanced (XLR) audio inputs?
• Do you need graphics, titles, or crawling or rolling text?
• Can your mobile production kit include a separate monitor or computer to control the appliance?
• Would your work flow benefit from iOS or Android support for a control UI?
• How many outputs do you need?
• Do you need adaptive bitrate segmentation?