YouTube now adding VP9 option to popular videos

Originally Posted by IgorC

x265_Project, you aren't an average forum member. This is serious stuff. You're developer and You've lied about 2.4x efficiency of HEVC over JPEG and lately have tried cherrypicking on results.

You're free to disagree with me, but it's another thing to call me a lier, even if you tried to soften the blow with a smiley face. I haven't lied about anything. If you want people to respond to you on a public forum like this, you need to stick to the subject (the technology), and avoid personal accusations or insults.

It's not "cherrypicking" to point out that there is a place along the RD curve where the efficiency gain of one codec is 2x or greater than another codec. That's the way RD curves work. That's why I pointed out that " the % improvement in compression efficiency varies depending on ... the quality levels being compared." Pick a different place along the 2 curves (as you tried to), and you'll see a different gain.

It's not possible quantify the efficiency gain of Codec A over Codec B in with perfect precision and get universal agreement, because the result always depends on the content, the settings (like Chroma subsampling), and the PLACE ON THE RD CURVEs (the quality level) you choose in your test. Change any variable, and you'll get a different result (especially the place on the RD curve that you're attempting to compare).

The only place along the RD curve that no one can debate is the highest quality - lossless compression. Certainly the % bit rate savings will be different for lossless quality than for typical lossy compression settings. But that doesn't mean that it isn't valid to say that "for typical lossy compression bit rates the savings is X". We could argue ad infinitum as to what bit rates are typical (what point on the RD curve we should compare). But that would be a pissing contest.

We're discussing/debating a very limited set of data from a couple of studies that are several years old, using small picture sizes (800x1280). To add more clarity and arrive at a consensus we need more data, using a wider range of content, picture sizes and quality levels, as well as the latest builds of HEVC encoders (x265, HM reference encoder, etc.).