Imagine the following scenario...

You’re streaming the Super Bowl and your favorite team is one touchdown away from making history. The broadcast comes back from commercial and the game is about to restart. Suddenly, your neighbors start screaming at the top of their lungs, celebrating. But why? 

The answer comes 20 seconds later when you see the star quarterback throw a perfectly timed pass that’s caught by the receiver mid-air. Touchdown. Game over. Total elation. Except you didn’t experience it in real time, your neighbors did. That’s because you have an issue with latency. Or, as some people call it, “lag” meaning the delay between when an event happens and when you actually see it. 

In this post we’ll be looking at how this digital pet peeve works, what causes transmission delays, and what are the best tools to achieve low latency.

How Does Latency Work? 

When we talk about latency, we’re talking about the delay between when a video is captured and when it’s displayed on a viewer’s device. Passing chunks of data from one place to another can take time, so small delays can build up at every step of the streaming workflow. This can range from several minutes to a matter of milliseconds. Generally speaking, there are 4 basic levels of latency: 

Typical Latency: Anywhere between 18 seconds and 30 seconds. It suits mainly non-time sensitive and non-interactive broadcasts.

Broadcast Latency (from linear TV to OTT) / Reduced Latency: Anywhere between 5 seconds and 18 seconds. Usually suited for live-streaming news and sporting events.

Low Latency: Even though there isn’t one absolute value that defines it, we generally call “low latency” anything less than 1 second. It’s the goal for every publisher as it allows for more interactive use cases. 

Ultra-Low Latency: Anything under 300 milliseconds. It’s the type of range we want to achieve in video conferencing as it ensures that video and audio data are transferred through the network with little to no disruption. 

When Is Low latency Important? Different Cases for Different Industries

The big question is: does latency always matter? Well, it depends on your application. Let’s break it all down:

BROADCASTING

Broadcast video networks have a track record of getting low latency by using workflows and streaming protocols built to scale high-quality, cost-effective experiences served to millions of concurrent viewers. 

The European Broadcast Union, for example, defines “live” as 7 seconds from glass-to-glass. This delay is often intentional as it facilitates live subtitling, closed captioning, and prevents obscenities from airing. That’s why you tend to hear bleeps during live ceremonies like the Oscars or the Grammys. 

VIDEO STREAMING

Live video experiences like sports, reality shows, breaking news and the like are powerful draws for audiences, which heightens the importance of low latency. The same applies to recorded content with its constant buffering issues (remember the spinning wheel from hell?). 

ONLINE GAMING

In FPS online gaming, high latency means your character will be killed before you even have a chance to register the danger. Thus, latency becomes high priority, more so than the actual network speed. Anything at 100 milliseconds is acceptable even though the 20-40 milliseconds range is considered optimal.

VIDEO CONFERENCING

In the case of live interactive and real time applications, latency should be nearer 200 milliseconds, or, as close to real-time as possible. Otherwise, this will happen.

What Causes Poor Latency?

Poor latency is dependent on many factors, ranging from the type of delivery chain set up to the number of video processing steps involved. Let’s take a look at some of the main causes of a frustrating high latency experience:

Network Type & Speed: The type of network used to transmit video (e.g. public internet, satellite or MPLS) impacts both latency and quality. The speed of that same network is defined by how many megabits or gigabits it can handle in the span of a second and how far it has to travel. 

Low Memory Space: In case of low disk space, the operating system will struggle to maintain RAM requirements to provide a seamless video experience. It’s like having a massive hangover and expecting to have full brain power. 

Streaming Protocols & Output Formats: The type of video protocol used for contribution and distribution formats is something you should take under consideration. Additionally, the type of error correction (meaning: the automatic correction of errors that arise from the incorrect transmission of digital data) used by your protocol to counter packet loss and jitter can also add to latency.

Multiple Routers: Routers take time to process information in the header of a packet, so when a packet transfers from router to router, the latency time gets increased. This is the difference between a direct flight and a flight with layovers. One gets you there faster simply because it doesn’t have to stop along the way.

Fiber Optic Network: In a fiber-optic network latency occurs at every stage of the fiber link travel and it keeps increasing during every conversion. Additional steps means loss of information along the way.

Wi-Fi Interference: Common causes of Wi-Fi interference include cordless landline phones, concrete walls, metal, mirrors, microwaves, baby monitors, a neighbor's own Wi-Fi, and other wireless electronics. 

Streaming Workflow: How streamlined your workflow is has great influence on latency. For example, OTT latency tends to be higher than digital TV because video needs to go through additional steps before reaching a device.

How Can Latency Be Reduced?

The truth is that there is no such thing as “zero latency” video over IP distribution since it’s  physically and digitally impossible for electrical signals to instantaneously be converted to data, transmitted over a data line, and then converted back into electrical signals at the other end. 

That said, there are several ways to minimize video latency without having to compromise on picture quality. Let’s take a look at a few options:

Focus on Bandwidth: Bandwidth efficiency is critical to low latency streaming over all-IP infrastructure, not only to reduce congestion on a network, but also to maximize cost efficiency. In order to achieve high-def video conferencing, for example, many systems require as little as 1mbps. When a network bandwidth is close to capacity, a quality-of-service can be implemented to effectively reserve bandwidth for video conferencing traffic. Prioritizing bandwidth will help reduce latency and packet loss. 

Hardwire Connections: These types of connections have much lower ping times. If your latency is over 150 milliseconds (you can measure it through a service like Speedtest), going the hardwire route will help avoid lags. Meaning, you should connect your device to your router via an Ethernet cable.

Disconnect Unnecessary Devices: If you’re downloading a large file on another laptop and streaming a video on your television, your bandwidth might not be enough for a high-quality, low latency video call. Yes, your tech is not very different from your brain when it comes to multitasking. It may be able to do multiple activities at once, but won’t do all of them well. 

Choose the Right Hardware Encoder and Decoder Combo: The latest generation of video encoders and decoders are able to maintain low latency and high picture quality while having enough processing power to use HEVC (High Efficiency Video Coding) to compress video to extremely low bitrates. 

Choose the Right Video Protocol: Different types of error correction will all introduce latency, but some more than others. Streaming protocols like Real-Time Messaging Protocol (RTMP) enable speedy video delivery using dedicated streaming servers, while HTTP-based protocols rely on regular web servers to optimize the viewing experience. The solution is to select the right video transport protocol that fits your latency needs. 

Low Latency Video Conferencing Options

Even by taking the actions listed above, you’ll typically run into latency issues when trying to conduct a video conference over Zoom or Skype. This is even more apparent when trying to run any creative collaboration workstream.

Below are some tools designed to help you overcome these challenges. 

Evercast

Evercast’s powerful real-time collaboration platform securely streams any creative workflow with uncompromising quality and ultra low latency. It’s the first virtual workflow resource that combines full video conferencing, HD live-streaming, and full-spectrum audio in a single, easy-to-use web-based platform. 

Top Features

• Ultra Low Latency Anytime, Anywhere: No matter where in the world they are, users can securely stream any creative workflow (live cameras on set, Avid, Premiere, Maya, Pro Tools, etc.) with ultra low latency and uncompromising quality. 
• Hardware Free: Evercast requires no file sharing and no proprietary or complex hardware for most use cases. Only a computer and software are required to stream, thus it is easily adopted across all stages of production, among teams large and small. 
• Collaboration with On-Screen Drawing and Time-Stamped Notes
• Streaming from Any Media Source (live camera or any creative software)
• Privacy: Evercast’s security protocol is approved by all major Hollywood studios.
• Recording: Sessions can be securely recorded and played back interactively. Each stream and webcam feed is captured individually in HD.
  

Drawbacks

• Not available on Android
  

Who Uses Evercast: Creative professionals working in film & television, game development, advertising, and more.

If you are interested in integrating Evercast into your workflow, get a demo here.