What is ABR and why it is important

Feb. 26, 2016

Explained briefly, the basic aim of the following article is to answer a couple of simple questions - what is ABR, what does it do and how it affects the video streaming services. 

What is Adaptive Bitrate streaming, commonly known as ABR?

ABR is a video streaming technique which is part of HTTP streaming protocols like HLS and DASH.
It’s a technique for optimal adaptive streaming which means that the quality of the stream may depend on viewer’s device environment parameters like CPU loads, network conditions or display size. However, the end result is that the viewer watches the video with the best possible quality. 
After all, whether you’re a broadcaster or an executive in a big enterprise, you inevitably search for one thing - high stream quality. Seems very simple, but in fact it isn’t - it requires a solid amount of work, innovative solutions and the right technology.
Speaking of technology, here is an important technical detail about ABR:

For ABR to work, the encoder should create multiple aligned video outputs of different quality representations/variants for each video stream. This is a must for all ABR algorithms.


What does the ABR algorithm do?
The exceptional performance of ABR begins with identifying the state of the viewer’s network connectivity by constantly monitoring its bandwidth, CPU capacity and video display size in real time. This is a key moment, because having this data, the technology automatically adapts to any changes in the viewer’s network and playback conditions and adjusts the quality of the stream according to them.

What does this mean for the end user?
It means they will not always get the stream with the highest bitrate overall. However, they will undoubtedly get the stream with the maximum quality their device can play. When the conditions change, the video playback switches smoothly to the best quality allowed.
This adds great value to the viewer’s experience and leads us to the main reason why ABR is an important part of video streaming services- it uses less streaming resources while providing the best video stream without buffering and the fastest start time the viewer’s device can play.

Notice that the low latency and zero buffering are both part of ABR performance and are also two of the features which add most value to the streaming service.

Does this mean that ABR support should be an important part of every video player?
All in all, ABR adapts to the playback capabilities of each viewer’s device and chooses the best possible quality of the stream they can play accordingly.
This means that the player always takes the best it can from the video stream. And the ABR feature is its way of doing this because, the better the network connection is, the highest the quality of the stream it fetches is. However, if the network connection is bad or the device has lower capacities, the quality of experience will remain the same.
And if the quality of experience is what all broadcasters or enterprises seek, then yes, ABR is an important part of any streaming service and every video player.

This is why we, at Viblast, developed our own ABR algorithm implementation as a part of Viblast Player,  which takes all necessary conditions for smooth streaming into account.