In recent months, Netflix has been silently testing the new encoding scheme by sending out streams with new and improved bitrates and resolutions to randomly selected customers. The company did keep a close eye on completion rates and streaming duration, but it also wanted to make sure that all devices out in the field were able to deal with the new bitrates. Beginning with some of the most popular videos, the company aims to have a thousand re-encoded titles in its catalog by the holidays, and complete the entire process by the end of Q1 2016.
Source: Netflix’s New Tech Makes for Better-Looking, Lower-Bandwidth Streams | Variety