Netflix Details the Tech It Uses to Optimise Quality, Size of Video Downloads

Last month, popular video streaming service Netflix announced that it will allow users to download select videos and watch them offline - a feature that had been requested by users for a long time. Now the company has detailed how it optimises downloads so that they don't end up consuming too much storage on the user's device, whilst also maintaining quality.

In order to reduce the size of the videos that are available for download on most Android devices, Netflix is making use of Google's open source video codec named VP9, as reported by Variety. The video codec used by Netflix for its streaming service is H.264/AVC but the company opted for VP9 as it allows the same video quality to be delivered for significantly less data.

However, things turned out to be much difficult for Netflix when it came to iOS devices, which don't support the VP9 video codec, as the company had to use a different codec altogether (i.e. H.264/AVC). In order to reduce file size, the company devised a technique in which it divides each video into one-to-three-minute-long segments that are further analysed by computers and encoded according to the complexity of their visuals.

Even though this technique is complicated, it allows the videos to take around 19 percent less space and effectively allow users to store more content on their iOS devices. In case of Android devices, the file size is reduced significantly by around 36 percent due to the use with VP9 codec.

The company has reportedly said that the same approach will also enable it to reduce data usage while streaming the content when it is implemented in next few months. However, as per a report by 9to5Mac, Netflix has clarified that this technique doesn't always reduce the storage size but ends up improving the video quality in those cases.

Interestingly, Netflix became the top-grossing iPhone app in the US for the first time right after the introduction of the offline download feature, as per a report by data analytics firm SensorTower. "Netflix has seen its app's revenue increasing steadily, even as it faces challenges in growing its user base in the US," the report said.