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Netflix Finds x265 20% More Efficient Than VP9 (streamingmedia.com)
Reader StreamingEagle writes (edited): Netflix conducted a large-scale study comparing x264, x265 and libvpx (Google-owned VP9), under real-world conditions, and found that x265 encodes used 35.4% to 53.3% fewer bits than x264, and between 21.8% fewer bits than libvpx, when measured with Netflix's advanced VMAF assessment tool. This was the first large-scale study to use real-world encoder implementations, and a large sample size of high quality, professional content.A Netflix spokesperson explained why they did the test in the first place; "We wanted to understand the current state of the x265 and libvpx codec implementations when used to generate non-realtime encodes optimized for OTT use case. It was important to see how the codecs performed when testing on a diverse set of premium content from our catalog. This test can help us find areas of improvement for the different codecs."
This is not the case of video codecs.
Video is a huge bandwidth hog and small improvements can really make a difference. This is why we still use JPEG and MP3 but video benefits from the latest technologies. It is also why Vorbis (audio) is much more successful than Theora (video). Both are patent-free formats from xiph.org.
Additionally, with hardware improving, more advanced compression algorithms can be used. For example entropy coders are mostly a performance/ratio tradeoff and newer standards tend to use more advanced schemes. Not that these couldn't have been used before, but the hardware requirement were too steep at that time. And you can't really put "insert preferred encoding scheme here" in your standard to make it future proof, because it wouldn't be a standard. All parts have to work together. You don't want to specify a super duper filter that melts CPUs and botch the job with a crappy entropy coder, you have to balance each part to get the best of your target hardware.
A small nitpick, but sad to see a common but serious maths error in a technical article.
20% fewer bits is not equivalent to 20% more efficient, but 25% more .
Efficiency would be the reciprocal of the bitrate. A ratio of 4:5 becomes 5:4 when looked at the other way around.
If you were to halve the bitrate, it would be twice as efficient, not 50% more.
Or to put it in simple money terms, its like if two items are $100, one gets a 20% discount to $80, the other is now 25% more expensive.