Wait for it: Why World Cup live streams were often far behind live TV signals

The 2014 World Cup has broken records as the largest live event on the internet. However, this also means that countless viewers have been waking up to a painful reality of internet TV: Sometimes you just have to wait a few extra seconds to see that deciding goal, and that can be especially frustrating if your cable-watching neighbor is already loudly cheering. Or if you’re watching games with one eye on your Twitter feed, for that matter.

Throughout the Cup, there have been numerous reports on Twitter and elsewhere from soccer fans who had to deal with delays ranging anywhere from a few seconds to up to two minutes. Some people reported different latencies on varying devices, while others have seen results improve by switching from one streaming service to another. And when I watched the U.S. versus Germany game at ESPN’s booth during Google (S GOOG) I/O, the cable network had four TVs on display, all showing the game with slightly varying delays, prompting one of the attendees to ask: “Which one is more live?”

Satellite TV tends to be a few seconds behind

Latency issues during live sports games are nothing new, and not by any means exclusive to online video. Even regular live TV feeds face different types of latencies when distributed via cable, broadcast, IPTV and satellite TV services. For example, satellite viewers often report that they’re around five seconds behind cable or over-the-air broadcast signals, and multi-room set-ups that relay signals from one single cable box can even lead to delays between TVs within the same household — or sports bar, for that matter.
That kind of latency doesn’t really matter for everyday TV use, but can be enough to make a dedicated sports fan close their windows if the neighbors are watching as well and happen to get their programming from a lower-latency feed. Some of these differences can be explained through the different pathways of TV signals. Sending a live feed to a satellite and back introduces half a second of delay, compression and decompression can add a few more seconds.

HLS alone can add ten extra seconds

With online video, there are a number of additional factors that can introduce latency. On-premise encoding doesn’t add too much latency, but some streaming services instead encode their signal in the cloud, which can add a few extra seconds.
Then there are the video formats used to stream World Cup games to Apple TVs, Roku boxes and other devices: Services like ESPN’s (S DIS) WatchESPN live streaming service tend to use HLS, a format first introduced by Apple, (S AAPL) for these kinds of streams. However, HLS streams tend to introduce a delay of around ten seconds, according to an industry insider who didn’t want to be quoted on the matter.
After the transcoding, streams are sent to a content delivery network, which can introduce significant additional latency. And when the signal is streamed to the end-user, there are last-mile issues, and even issues with home routers, local Wi-Fi networks and playback devices that slow things down some more. All of this adds up to the point where internet live just isn’t quite the same as TV live.
Still, latency issues clearly haven’t stopped soccer fans from tuning in online. ESPN averaged 829,000 unique viewers and 36.9 million minutes per game through the end of the round of 16, and the USA vs. Germany match was viewed by 1.7 million concurrent viewers during peak times, making it the most popular live stream in the network’s history. A total of 2.1 million people tuned in during the semifinal match between Germany and Brazil.
Maybe sports fans have just learned to live with the delay and stopped looking at their Twitter feed while the action unfolded on TV.