When Netflix rolled out its new download feature, it also quietly started using Google’s royalty-free VP9 compression format at scale on some mobile devices. VP9 is a free alternative to the costly HEVC compression format.
Google’s royalty-free VP9 format
Netflix has been testing Google’s VP9 format internally for some time but this is the first time that the company has used VP9 at mass scale. The company started using the VP9 format when it rolled out the new download function last week.
Netflix has traditionally used the MPEG4 H.264/AVC format almost exclusively (except for 4K/HDR streaming where it uses HEVC). VP9 offers several advantages, including the ability to stream at significantly lower bitrates without compromising picture quality, says Netflix. That is important because mobile devices have limited storage space for downloaded video content or data caps on mobile data connections.
- “Last month, we started re-encoding our catalog to generate the new mobile bitstreams and the effort is ongoing. The mobile encodes are being used in the brand new downloads feature. In the near future, we will also use these new bitstreams for mobile streaming to broaden the benefit for Netflix members, no matter how they’re watching,” says Netflix.
"VP9 is a free alternative to the costly HEVC format"
More importantly, VP9 is a royalty-free format developed by Google as an alternative to the costly HEVC format. VP9 also supports 4K streaming but Netflix has yet to adopt it for 4K, it seems. The latest version called VP9 Profile 2 supports HDR (High Dynamic Range).
Only viewers downloading Netflix content on newer Android devices will get the VP9-encoded video. iPhone/iPad users will get a new mobile-optimized stream in the H.264/AVC High profile. Apple has not implemented hardware support for Google’s VP9 format in its devices.
Netflix video formats
MPEG4 H.264: Have to date been used for everything, except 4K/HDR - royalty rates apply
HEVC: Used exclusively for 4K/HDR - royalty rates apply
VP9: Used to replace MPEG4 H.264 on Android mobile/tablet (only download, later streaming) - free to use
Up to 36% reduced bandwidth
Together with VP9, Netflix has also optimized its compression technique. In late 2015, Netflix started creating a separate compression for each title in its content catalogue. It now goes even further by dividing everything into 1-to-3 minute long chunks and then optimizing compression based on each separate chunk.
Combined the new initiatives can reduce bandwidth by up to 36% on average on mobile devices, as seen below. Left side is the new ‘AVC High’ that iPhone/iPad users are seeing, right side is VP9 for Android mobile users.
To be clear, the above techniques are only being used for downloaded content right now but Netflix has plans to use the same techniques for mobile streaming in “the near future”.
Netflix is also planning to use these techniques to improve picture quality for those with bandwidth to spare.
By adopting VP9 at mass scale, Netflix can bring down costs and royalty payments over time. Netflix is also member of AOM (Alliance for Open Media) together with Google, Microsoft, Amazon, and others. AOM is developing a new free and open video format based on Google’s work in video compression (VP9 and VP10) that will be called AV1.