Understanding video quality when streaming


Why does streaming video resolution sometimes go bad (and why don’t we fix it)?

It’s really frustrating when streaming video goes fuzzy and pixelated or sometimes stops playing altogether. Why does this happen, and why does it seem worse at peak times?

Starting with the basics, streaming video is delivered over the internet. Every few seconds, our streaming apps test the speed of the viewer’s internet connection and based on that we send higher or lower resolution video packets. Put simply, a slow connection generally means lower video quality and a faster connection supports higher video quality. If the speed is really slow, the video will stop altogether (the dreaded buffering spinning wheel).

My video quality was fine, but as soon as the big game started it fell apart - so the problem is clearly with your service, right? 

We plan ahead for big games and make sure we’ve got enough capacity, so no that isn’t likely to be the cause. The simplest explanation for video quality falling during high demand times is congestion downstream from our servers, and there could be a number of factors causing that.

An example of how congestion affects someone connecting via mobile is that lots of people are accessing the same mobile base station at the same time (e.g. as the game starts) and because the base station has limited capacity, the quality of the mobile connection drops.

We use world-class CDN (content distribution network) providers like Akamai, and these companies specialise in delivering the highest possible video stream to the end-user. Under extremely high load situations, even CDN companies can run into capacity constraints or can run into bottlenecks elsewhere in the system. More information on this here.

That’s rubbish! YouTube is fine but DStv Now looks terrible, so clearly the problem is with your service. 

Great point! The key here is supplying pre-recorded content is different from supplying live content. In the case of YouTube or Showmax or Netflix, shows can be stored (the technical term is ‘cached’) close to the customer. In the case of live content, we’re taking the stream from Japan and distributing it in Africa without the same ability to pre-load it as close as possible to the customer, so any bottlenecks downstream from our servers can have an impact on video quality. The other obvious difference is with YouTube or Showmax or Netflix, people aren’t all watching exactly the same thing at the same time - which presents a whole bunch of technical challenges.

So are you saying you can’t or won’t fix it?

Live streaming with huge numbers of concurrent users is a technical challenge that video services worldwide are grappling with - if it were as simple as just increasing capacity we’d most definitely have done that long ago. But we’re not backing down - we’re working with content distribution networks and others, and we are making headway.

What should I do?

To test if the issue is related to your ISP, one approach is to temporarily switch to mobile data (or to a fixed connection if you’re currently on mobile) and see if there is a change in quality. Obviously the other connection may also be congested but certainly if the quality improves you’ll have an indication that it may be worth speaking to the ISP or changing to another ISP.