Last week Netflix debuted offline viewing mode, something that subscribers have been wanting for a long time. With the offline mode, users were allowed to download shows and movies directly to their device to watch on the go without having to stream using WiFi or data connections. Netflix has taken steps to ensure that the downloads are as small and as efficient as possible using VP9 content encoding for downloaded content.
With streaming content Netflix is using H.264/AVC almost exclusively which helps to reduce the bandwidth needed for the streaming while keeping the shows looking good at the same time. For the downloaded content for offline viewing Netflix is using VP9 encoding. VP9 is an open source encoding format that was developed by Google, VP9 uses tech that allows the same video quality with significantly less data bandwidth required.
VP9 can also allow better quality videos for the same amount of data needed at download. The challenge is that VP9 isn’t supported by all streaming providers. VP9 is supported on Android devices and via the Chrome browser. That means iPhone users won’t get to use VP9 codec and so far Apple has given no indication that it will ever support VP9.
To get around that lack of support, Netflix is offering downloads in H.264/AVC High whereas streams are encoded in H.264/AVC Main. Netflix chooses the optimal encoding format for each title on its service after finding, for instance, that animated films are easier to encode than live-action. Netflix began optimizing encoding for each title last year and claims that change helped users on slower connections save up to 20% of their data.
Netflix says that H.264 High encoding saves 19% bandwidth compared to other encoding standards while VP9 saves 36%. Netflix wants to be clear that its encoding not only aims to save storage space on devices, but to improve video quality as well.