Lag in streaming football matches: what latency is and how to fix it

How many times does it happen that at home we are watching a football match streaming and suddenly we hear the neighbor rejoicing before us, spoiling the goal for us in advance? There’s that delay, of 5-10 seconds, sometimes even more, which completely ruins the game for us. Football fans are now very familiar with this problem, which has been quite widespread since the matches of A league are broadcast on DAZN, which uses streaming technology for its broadcasts. But what this delay, which in technical jargon is called, depends on latency? Is there a way to fix it?

What is latency and what does it indicate

Let’s start from a fundamental premise: when we watch a match on DAZN or Prime Video in live streaming, none of us see it in real time, because there is always a delay between the moment the image of the field is captured and the moment we see it on the screen of our devices. This delay is called latency and is nothing more than a delay in network communication: it is physiological of streaming technology. Latency, however, is not the same for everyone, because there are multiple factors that determine the seconds of delay. Factors that may depend on the quality of our connection, on our device, on where we are – for example – but also on factors that do not depend on us, such as a series of slowdowns that the signal encounters on its journey from the stadium to our home.

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To understand what is the cause of the latency and the lack of contemporaneity between user and user, we need to clarify our ideas about the entire process of live streaming of a match. Let’s immediately establish a key concept: streaming technology is used to transmit video and audio via the internet and the basic principle is that multimedia files are converted into data packets. Do you know when we download a photo or video? We are doing a data download. Streaming is an evolved version of downloading, because it allows us to start viewing content even if it has not been completely downloaded. But what happens during the streaming of a live event, such as a football match? That is, video content that is created on the spot?

How it works and what it means to watch a match in live streaming

The live streaming of a match is essentially divided into four phases.

  • Phase 1: The cameras at the stadium capture the image of the field, generating RAW frames, which weigh several gigabytes and are too large to travel online.
  • Phase 2: The images end up in a central server which converts them into smaller digital files – imagine many small chopped segments – the so-called data packets. This packet flow is not unique, but is reproduced in multiple versions: that is, a copy is made for every possible resolution (4k, 1080p, 720p etc.) and for each destination device (TV, smartphone, tablet etc.). So of the same live broadcast there will be a 1080p stream for the smartphone and another 4K for the TV for example. This whole process – which is very complicated, as you can see, but actually lasts just a few seconds – is called transcoding.

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  • Phase 3: Once created, the data packets are sent to users through a distribution network called CDN. CDNs are built a bit like a highway: they serve to redistribute the flow of data packets and avoid slowdowns.
  • Phase 4: Through CDNs, data packets arrive at our device, but are not played immediately. They end up in a temporary storage called buffer. This process is called buffering.

How buffering works and what it is used for

We can imagine the buffer as a sort of reservoir in which video segments are stored. Until the buffer is filled, the live broadcast on our screen does not start. Let’s give an example: if my buffer can contain three 6-second segments, then my live broadcast will start with a latency of 18 seconds. But why do packets have to pass through this buffer? To buffer any snags that may arise throughout the journey.

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The buffer is a reserve of “spare” data packets which serves to guarantee fluid viewing even in the event of network problems. You know that damn annoying little wheel that you see when the game freezes? It means that the buffer is really empty. And this happens either because our connection is so slow that it can’t fill it, or because something went wrong with whoever is providing the service to us.

Can streaming lag be eliminated?

Can this latency technically be corrected? On the viewer’s side, with a quality connection and a more performing device the situation can be improved. At a structural level, the distribution network could be improved and compression into data packets could be speeded up (and this is up to those who provide the streaming services: the various DAZN, Prime etc.). But a certain latency will always exist, because as we said at the beginning it is physiological of streaming technology. The real challenge, in fact, is not to completely eliminate latency, but to correct that lack of contemporaneity which today ruins the beauty of live broadcasting, especially when we watch a football match. A challenge that is anything but easy.