The Difference Between Zero-Delay and WiFi-Based Wireless Video
If you’re in the market for your first wireless video system or want to upgrade the one you have, you may have noticed some ambiguity in the language used to describe wireless video, what it promises, and what it actually means in production. The truth is that not all low-latency systems are created equal, so we’re going to unpack the differences, demystify the jargon, and show you how to get the most out of your wireless video workflow.
Let’s begin with the basics: The ultimate goal of wireless video is to look at a wireless monitor and see what the camera sees as it sees it. To be fair, virtually every wireless system sold by reputable vendors accomplishes the first part, “to look at a wireless monitor and see what the camera sees,” but it’s those last four words—“as it sees it”—that bear further scrutiny. In this blog post, we’ll examine what a true zero-delay system is, why you need it, how it works, and which system best fits your needs.
What Is True Zero-Delay?
What Is True Zero-Delay?
You might argue that due to the speed of light and the laws of physics, 100% zero-delay wireless video isn’t possible. And you’d be right. Sort of. There may be some quantum solution for that scenario in the future, but it wouldn’t really make a difference. Let’s be practical: If you’re shooting 24, 30, or 60 frames per second, then a wireless video delay (or “latency”) of less than a millisecond (0.001 seconds) ensures that the frame you see on your monitor’s screen is in perfect sync with the camera’s sensor. Zero frames are out of sync. Time may be fluid, but video frames are discrete moments captured at a predictable rate. Math is math, science is science, and 0.001 seconds of latency is effectively true zero-delay on any set.
Sunny Sixteen crew seamlessly monitors production on a Cine 13 utilizing the Ace 750.
Sunny Sixteen crew seamlessly monitors production on a Cine 13 utilizing the Ace 750.
WiFi vs True Zero-Delay
WiFi vs True Zero-Delay
Typical wireless video systems use a WiFi or “packet-based” approach in which video is first compressed and then transmitted over a local-only WiFi network. Compressing video into packets before transmission introduces delay, typically 2-4 frames, and lowers the image quality. This is because most decoders will store multiple packets, or decoded frames, in a buffer to smooth out the video before outputting, which creates a less robust signal and latency unsuitable for the rigorous demands of film production.
As an alternative to packet-based WiFi systems, the Amimon frame-based system, the one found in the Teradek Ace 750 and Bolt Series, is built around a unique patented chipset that uses the entire available channel capacity, removing the need for a buffer and delivering less than 1 millisecond of latency, or zero frame delay. It transmits and receives virtually lossless, uncompressed video at a high bandwidth over 5GHz and 6GHz U-NII channels for the most robust signal in any production environment.
Why is Zero-Delay Important?
Why is Zero-Delay Important?
The need for zero-delay wireless video monitoring becomes obvious on any set that requires precision focus pulling, calling out action cues, or any scenario that requires precise timing. If you’re shooting a closeup of a butterfly / animal / child / dancer with a wide-open lens and a shallow depth of field, 2-4 frames of delay on your focus puller’s monitor can ruin everyone’s day. If the director is calling stunt, choreography, or action cues from their handheld monitor, delayed frames can result in the flow of action appearing stilted and unnatural when replayed. These problems are best solved when you’re confident that your wireless video system operates with true zero delay as defined above. Zero delay also creates a more natural viewing experience at Video Village where creative stakeholders and clients can hear and see true sync between what’s happening on set and what they’re seeing on their monitors. If you’ve ever watched footage that’s a few frames out of sync, you understand how distracting it can be.
Legal Considerations
Legal Considerations
As mentioned above, there are some hidden factors you should be aware of when considering wireless systems that claim a few frame latency is good enough. Many of these seemingly great deals exceed maximum power levels and illegally trespass on DFS frequencies used by military and weather radar systems. Bargain systems do not advertise these shortcomings, so the onus is on you to research and ensure your wireless video system is fully compliant with FCC, CE, and relevant regional regulations.
Get What Works for You
Get What Works for You
If you want a system for off-set viewing that doesn’t require critical real-time functionality, there are several great WiFi solutions that measure up, including the Teradek Serv Series and Teradek TV for remote/cloud-based monitoring. But if you want to step up to true zero-delay wireless video monitoring for critical on-set decision making, consider investing in a reputable, legally-compliant Amimon system like the Teradek Ace 750.
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