Netflix’s New Video Compression Strategy

Don Melton:

The tl;dr of it all is simply that Netflix plans on scaling bitrates up and down based on the complexity of their video. So, slightly higher bitrates for busy action blockbusters and possibly lower bitrates for relatively static, flat cartoons.

Basically what we’ve all been doing for years with variable bitrate (VBR) encoding. But they’re trying to control that variance a lot more than an encoder like x264 typically allows. In fact, as near as I can tell, Netflix still plans on encoding everything with a constant bitrate (CBR), but they want to be really particular about the target number.

To do that, Netflix will transcode every one of their videos a bazillion times at different resolutions and at different bitrates, finally selecting the smallest one for a particular title that doesn’t suck visually. Seriously, their algorithm for all of this is quite clever.

★ Wednesday, 23 December 2015