AI Case Study

Netflix optimises video quality during user playback using machine learning to improve customer experience

Netflix detects changes in video streaming quality using machine learning. Optimising the tradeoff between providing high quality video with risk of having to wait for the media to rebuffer problems provides better streaming services for customers watching videos on, by adapting to changing geographic and device capabilities.


Consumer Goods And Services

Entertainment And Sports

Project Overview

"Movies and shows are often encoded at different video qualities to support different network and device capabilities. Adaptive streaming algorithms are responsible for adapting which video quality is streamed throughout playback based on the current network and device conditions (see here for an example of our colleagues’ research in this area). Can we leverage data to determine the video quality that will optimize the quality of experience? The quality of experience can be measured in several ways, including the initial amount of time spent waiting for video to play, the overall video quality experienced by the user, the number of times playback paused to load more video into the buffer (“rebuffer”), and the amount of perceptible fluctuation in quality during playback."

Reported Results

Results undisclosed


In-house: "Adaptive streaming algorithms are responsible for adapting which video quality is streamed throughout playback based on the current network and device conditions... These metrics can trade off with one another: we can choose to be aggressive and stream very high-quality video but increase the risk of a rebuffer. Or we can choose to download more video up front and reduce the rebuffer risk at the cost of increased wait time. The feedback signal of a given decision is delayed and sparse. For example, an aggressive switch to higher quality may not have immediate repercussions, but could gradually deplete the buffer and eventually lead to a rebuffer event on some occasions. This “credit assignment” problem is a well-known challenge when learning optimal control algorithms, and machine learning techniques (e.g., recent advances in reinforcement learning) have great potential to tackle these issues."


Information Technology

Quality Assurance


"Netflix streams to over 117M members worldwide. Well over half of those members live outside the United States, where there is a great opportunity to grow and bring Netflix to more consumers. Providing a quality streaming experience for this global audience is an immense technical challenge. A large portion of this is engineering effort required to install and maintain servers throughout the world, as well as algorithms for streaming content from those servers to our subscribers’ devices. ... We need to adapt our methods for these different, often fluctuating conditions to provide a high-quality experience for existing members as well as to expand in new markets.

Network quality is difficult to characterize and predict. While the average bandwidth and round trip time supported by a network are well-known indicators of network quality, other characteristics such as stability and predictability make a big difference when it comes to video streaming. A richer characterization of network quality would prove useful for analyzing networks (for targeting/analyzing product improvements), determining initial video quality and/or adapting video quality throughout playback."



Netflix describes the attributes of its data which lend themselves to solving this problem statistically and with machine learning:

* "there is sufficient data (over 117M members worldwide)
* the data is high-dimensional and it is difficult to hand-craft the minimal set of informative variables for a particular problem
* there is rich structure inherent in the data due to complex underlying phenomena (e.g., collective network usage, human preferences, device hardware capabilities)".