Tuesday, December 15, 2015

Netflix optimizes quality and bandwidth by tuning compression for each title

Netlifx is already responsible for the largest part of internet traffic during evenings; but it's about to shave off a few percent of used bandwidth thanks to a new encoding optimization.

Video encoding is part technical prowess and part artistic. If you ever handled music or video encoding using lossy codecs like MP3 or MPEG4, you'll be familiarized with things like constant and variable bitrates, and target bitrates.

For a service like Netlix, you can multiply that by 100x, as for each title we need to have multiple versions encoded at different resolutions and bandwidth. That's needed because, someone may be watching a movie in a low-def TV, therefore requiring a much lower quality version of the movie; while others maybe watching in a large screen Full HD (or 4K) set, using a fiber connection and wanting the maximum quality. Then there's still those that may be watching it in a mobile device, with connection speed constantly shifting, and Netflix will do it's best to choose between the most appropriate stream for each moment.

Until now, Netflix defined these different quality levels, which allowed them to specify you'd need this amount of bandwidth to watch low-def streams; this for HD streams; and this for Full HD. But we all know not every title is alike, and it didn't make much sense the same amount of bandwidth on a cartoon as you'd use on an action movie. And hence, the per-title optimization.

This not only allows Netflix to save bandwidth, as it also of benefit for users. While using a fixed encoding would mean you'd need something like 4 or 5Mbps to watch Full HD content, with these optimizations a simpler title (like a cartoon) can be encoded in Full HD and require less then 3Mbps to be seen - allowing even customers with slower connections to watch higher quality content.

... I just find it odd that Netflix took so long to figure out this. Maybe they'd better hire some of the "pirate crews" that are masters in putting compression to good use! :)

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