Live stream latency compared to Zoom

No matter how many live streams we’ve done or how familiar end clients are to live streaming, I’m always asked the same question quite frequently – what is the latency time and why?

Because of people’s experience with household devices such as free-to-air TV compared to online communication services such as Zoom and MS Teams, viewers are often under the illusion that all means of virtual communication are real-time and in sync.

But they are not.

Microsoft Teams, Zoom, Bluejeans, GotoMeeting, Whereby, Webinar Jam and Skype to name a few, do an amazing job keeping everyone in session, in sync. These platforms have a wonderfully engineered environment where they set the weakest connection of all attendees as the common denominator which in turn keeps everyone in sync regardless of connection strength.

With live streaming, it’s quite different with many factors contributing to the unintentional delay of the entire broadcast.

When collaborating live streaming with a Zoom session, it’s the streaming providers’ responsibility to make sure that the Zoom session attendees are not using the live stream as a reference point to the actual event.

The Zoom session is purely to engage remote presenters into the session and the live stream page caters to the live stream audience watching online which could be potentially, thousands of viewers.

While they work fantastically well in collaboration to produce an end result for the viewing audience, they are two different types of technologies that should be treated as two separate systems.

With the live streaming component, there is the upload at the broadcast venue that has to be considered. The quicker the upload, the quicker the content gets to the streaming servers and I always test with https://testmy.net/upload and https://fast.com/.

Next, the streaming servers will ingest the video stream and distribute content to the stream page and you want the servers to be located in the same country as the broadcast venue.

Finally, the viewing experience is, unfortunately, in the palms of the users connection and there are many factors that affect the broadcast latency such as connection speed, congested networks, are they in transit on a mobile device skipping from tower to tower, browser version, throttled corporate networks and VPN’s.
Live streaming latency
So when a live stream is due to start at 6 PM, all users will experience some level of latency compared to the live event at the broadcast site and for the reasons I’ve listed above, the latency time differences will be different for each viewer. All viewers will start to see the live stream between 6:00:05 to 6:00:45PM, generally.

There is an upside with the latency associated with live streaming.

The longer the time the streaming servers take to ingest the live feed and deliver reduces the viewer experiencing buffering issues. Going live on YouTube now allows a broadcaster to choose a latency time to keep the buffering issue to a minimum for viewers.

Live audience Q&A is generally text-based to the presenters which does a great job removing the “perceived latency” away from the live event and the online audience responses seem to run in sync.