Netflix rolls out dynamic optimisation upgrade for improved HDR video quality

Mike Wheatley

Netflix has rolled out a quiet update that’s said to improve the video quality of 4K HDR titles in its library, using a new video encoding method called dynamic optimization.


Netflix details the update in a post on its tech blog on Medium, where it explains it implemented a new, HDR variant of the Video Multi-Method Assessment Fusion technique, which is the name it calls its primary video quality metric. With this metric, the “multi-method” part refers to a variety of objective and subjective measurements that evaluate parameters including motion and visual information fidelity, as well as detail loss.

HDR-VMAF is a collaborative effort between Netflix and Dolby Labs. The two companies carried out a range of subjective tests on 4K HDR content displayed on high-end OLED panels in calibrated conditions. According to Netflix, HDR-VMAF is a format-agnostic technique that measures quality equally and independently for both Dolby Vision and HDR10 content, calculating its scores on an “ideal display” that’s capable of representing the entire colour gamut and luminance range covered by the video signal.

One of the benefits of HDR-VMAF is it enables Netflix to transition from fixed bitrate video encoding to dynamically-optimized encodings (HDR-DO) for 4K HDR streaming. HDR-DO, as it’s known, not only ensures higher quality video content, but also brings efficiency gains, as it only uses 58% of the storage space as fixed bitrate encoding.

In the blog post, Netflix claimed a long list of improvements in its 4K HDR streaming quality, with 40% few rebuffers, higher quality video for both bandwidth-constrained and unconstrained sessions, lower initial bitrate, higher initial quality, lower play delay, less variation in the delivered video quality and lower overall internet data usage, especially for mobile devices.

The company began upgrading its 4K HDR library with HDR-DO last year, completing the process by the end of June 2023. The superior quality content is being made available to Premium subscribers only, and any Dolby Vision or HDR10 content they watch will now be optimized using the new 4K HDR picture quality metrics.

According to Netflix, users should notice the visual benefits when watching HDR content on any 4K television, though it will also deliver noticeable improvements for those watching on smartphones and tablets – many of which now support HDR.

The update brings significant benefits to Netflix Premium subscribers, who were recently subjected to yet another price hike for the company’s top tier offering, one that increased the monthly cost from £15.99 to £17.99 in the UK.. The newer price makes Netflix one of the most expensive streaming services around, but with the benefits of HDR-DO now in place, it might just be enough to convince subscribers that they’re still getting good value for their money.