One of the biggest myths is that broadcasters need a lot of bandwidth to import good video from the field via the cell networks. It isn’t true. One modem and 500 kpbs will do the job. And many broadcasters don’t realize that the more modems you stream with, the higher your on-air latency.
As interest in live video streaming in TV news gathering increases, so, too does the misinformation about the technology. Here are some things that every broadcaster should know before they invest in a streaming solution.
A common myth about cellular streaming bandwidth
One of the biggest myths is that broadcasters need a lot of cell bandwidth to produce good video, which isn’t true. You can do it using only 500 Kbps of bandwidth from one 4G/LTE modem. This is important because the lower amount of bandwidth you use, the more likely you are to sustain your connection. Using a lower amount of bandwidth gives broadcasters more streaming time with modems that have monthly usage limits. This strategy is also important when streaming live to the Web and mobile devices — more about this below.
Little-known fact about modem interference
Cellular engineers from the cell companies agree: Cellular modems need to be kept at least eight inches apart from one another when streaming live to keep the modems from interfering with each other. When modems are placed fewer than eight inches apart, the output data rates often fall considerably. The result: Users of these systems end up not getting what they’re paying for. This is why streaming systems that allow users to physically separate the modems provide the best value and performance for the money. This is also why it’s best to find a system that allows broadcasters to use their own modems.
Growing chorus of concern about multi-modem emissions
According to the FCC, the maximum cellular SAR value a human can be exposed to at a safe level is 1.6. Each cellular modem emits an effective SAR value of about 1.1 on average. Thus, a two-modem system emits an effective SAR level of 2.2; a 4-modem system a SAR level of 4.4, and so on. When multiple modems are placed close to the body, some broadcasters have become concerned about the safety and legal liability this issue poses. Fortunately, some companies have developed a simple way to separate the modems from a user’s body in a way that also improves the performance of the modems.
It’s all about latency
Many broadcasters don’t realize that the more modems you stream with, the higher your on-air latency. Why? A streaming system is only as fast as its slowest modem. Systems that use four, six or more modems can produce a higher latency than systems with fewer modems because you have to wait for the packets of each modem to arrive at the receive end, and then it takes even more time to re-order the packets from each modem and render the video for playout. While some multi-modem solutions give broadcasters a way to reduce the latency, this feature effectively disables some of the modems to produce lower latency. Some broadcasters are just now figuring this out, and they are coming to the conclusion that they are better off buying a live streaming system that uses fewer modems to start with.
Live HD streaming
Cellular network engineers don’t want their uplinks clogged with bandwidth-consuming HD video, which requires three to four times more bandwidth than an SD stream. To maintain the integrity of the cell networks that make live streaming possible, they urge “responsible cellular streaming” — the use of as little bandwidth as possible. This strategy allows broadcasters more streaming time each month without exceeding their cellular modem bandwidth cap. HD streaming also requires the use of four or more modems, which as discussed above can add a significant amount of latency to each stream.
A growing demand for live Web and mobile video
Broadcasters realize that streaming live to air alone isn’t enough anymore. They also need to be able to stream live to the Web and mobile devices to remain competitive and to protect themselves in the event the government sells off the on-air spectrum. When streaming live to the Web, most broadcasters don’t realize that using more than about 500K of bandwidth on the uplink side is more bandwidth than many Web and mobile viewers on the downlink side can handle.
What happens then? If you set your streaming device’s encoding rate too high, a high percentage of Web and mobile viewers won’t likely see your live video because they either don’t have enough download bandwidth or because their viewing devices — laptops and/or mobile devices — don’t have enough power to render smooth video at higher streaming speeds. This is one of the main reasons why broadcasters don’t need more than two modems when streaming live —more, in this case, is just a waste of money.
A cry for a simpler cloud-based workflow
The bane of every broadcaster’s existence is opening ports on firewalls to host a live video streaming solution. Fortunately, there is a better way that allows broadcasters to stream live to TV, the Web and to mobile devices via the cloud that eliminates the need to install any streaming servers at a customer’s location. With this workflow, broadcasters can use a scan converter that converts live Web video into video that can be broadcast on air. Keeping the streaming workflow simple, at a time when staffing is at an all-time low, makes a lot of sense.
Ken Lee is the co-founder of StreamQuik, which produces a line of live video streaming solutions. He can be reached by email at [email protected]. The company also conducts live streaming Web demos every Tuesday at 11 a.m. PT at www.MyStreamCell.com/demo.