Live sports have moved to the internet and are now streaming instead of being broadcast. Traditional streaming protocols have a built-in delay that challenges the experience of a live game. Amazon Prime has found a solution by combining a new protocol with a very distributed CDN.
It has been interesting to observe how professional sports have moved the transmission onto the internet instead of requiring their viewers to sit at home and watch their TV. Many still do that — the details of any sportsball game are best enjoyed on a big screen — but the games are no longer broadcast via the TV signal in the air or on the cable, but coming via the connection to the internet.
Amazon Prime Video is one of the services delivering a lot of sports — you might recall my colleague Doug Madory’s blog in 2022 about Thursday Night Football traffic, as seen in the Kentik data.
Before we dig into the Prime Video solution, what is the main challenge with moving live events from broadcast to the internet?
Flow TV (traditional television) broadcasts are transmitted using dedicated networks, such as over-the-air, cable, or satellite. In this case, the signal is sent once to all viewers, and multiple users watching the same channel do not create additional load on the network. This is because the broadcast signal is shared, and the network’s capacity is designed to handle the full audience without degradation of the signal.
Internet broadcasts rely on data packets transmitted over the internet. Each viewer receives a separate stream of data, which means that as more users watch a live event, the load on the network increases. This can lead to congestion, slower connection speeds, or buffering, particularly if the network does not have enough capacity to handle the increased demand.
So the main difference is that more viewers lead to a higher load on the network that carries the event. One consequence of the congestion that might result from the higher load is delay — which is nearly unacceptable for sportsball game events. I remember watching the World Cup in football (aka soccer for you Americans) in 2018 on the internet — in the summer with open windows. We got a good warning to pay attention the next couple of minutes when we heard the neighbors’ cheer. (My country’s team had a good run in that World Cup.)
However, this delay was not due to congestion but to the live-streaming technology needing to be more mature at the time.
Understanding adaptive bitrate streaming and its limitations
The reason for the delay — or the unsynchronized delivery of the packets that make up the live stream — is that traditional adaptive streaming protocols are based on chopping the video up into small segments. These are then encoded in several different bitrates. The playback of the files is compared to the speed of the download of the segment, and if it is slower, the client w
