Google announced it has begun encoding YouTube videos in VP9, the open-source codec that offers HD and even 4K quality with lower bandwidth usage.
While VP9 uses the same basic blueprint as other codecs, there are several improvements designed to optimize image quality. The encoder, for example, prioritizes the sharpest image features, and the codec now uses "asymmetric transforms" according to the Google announcement which will help even the lowest quality scenes to look good.
VP9 decoding support is available today in the Chrome Web browser, in Android devices like the Samsung Galaxy S6, and in TVs and game consoles from Sony, LG, Sharp, and others.