Last week, Netflix launched the one feature that binge-watchers worldwide have been wanting: support for movie downloads on mobile devices. The move is meant to help you binge on your favorite shows while you’re on the move, without worrying whether you’ve got access to a wireless network, or whether you have enough data on your cellular plan. But it turns out that Netflix also wants to help out with the obvious side-effect of downloading movies for offline viewing: killing your phone’s storage.
The easiest way to save data on downloads is to lower the resolution of movies and TV shows. But streaming giant came up with a way to save data without compromising on video quality. That means you can either download more episodes of your favorite show for less data or improve video quality for offline downloads without taking massive hits when it comes to storage.
As Variety explains, Netflix adopted a new video codec for downloads. Netflix uses Google’s open source VP9 codec that makes possible videos of the same video quality but with significantly less data. Or, you can get better video quality for the same amount of data. In either case, your storage does not take a hit.
The problem with VP9 is that it’s only used on Android but not the iPhone. Netflix has an H.264/AVC High codec to replace VP9, compared to the H.264/AVC Main is the codec it uses for streaming videos.
However, Netflix didn’t give up and used a different trick to bring the same storage-saving feature to iOS devices.
Netflix realized that different scenes in different movies need different amounts of data. The more special effects in a scene, the more data it’ll need to play on your device. To make up for the iPhone’s lack of VP9 support, Netflix decided to simply split all videos that can be downloaded on an iPhone into chunks between one and three minutes. The computer then analyzes each scene and chooses how to encode it.
These technologies (VP9 and splitting videos in short clips) help Netflix save some 36% data on average for videos that look the same to the human eye. When H.264/AVC High is in use, iPhone users would still save 19% of data. A more technical explanation is available on Netflix’s blog.
Netflix could use the same new codec technology for mobile streaming in the future, and offer better quality videos to users who are on slower internet connections.