But what does that concretely mean, "lowest bitrate or file size possible"? What do you mean by "possible"? You almost certainly mean choosing a lower bitrate

But what does that concretely mean, "lowest bitrate or file size possible"? What do you mean by "possible"? You almost certainly mean choosing a lower bitrate whose numerical perceptual quality is similar to the video encoded at a higher bitrate. Of course, x264 can do that—that's what the CRF value is. It already has technology to choose the best bitrate per GOP given its perceptual model. Even if I take everything you say at face value, your semantics, at minimum, are the snake oil. You make it sound like this perceptual compression technology doesn't exist, when it actually ships on by default in Handbrake. I think what Daiz is talking about is snake oil of the technology, not semantic, variety. So let's talk technology snake oil. Your special perceptual model might find situations where it could reduce the bitrate in a way that x264's model would disagree. But what about situations where x264's model is better? The end-user never gets to see where x264 makes a subjectively better image than your system does at a lower bitrate. In other words, quality arbitrage: you can always claim to reduce bitrate by adjusting your model to be a bit more permissive than the competition. Knowing there is no rigorous numerical way to compare two perception-optimizing compressors, you can get away with "arbitrage" bitrate reductions. Put another way, a lot of people are going to demand the wrong tests, because they don't understand the inherent contradiction of comparing two perception-optimizing compressors (like allegedly Beamr and x264's CRF model). The way I'd know if your perceptual model were in fact better is if you could show me situations where it is wrong. In other words, convert your "lowest... possible" Beamr Perceptual Model parameter to a CRF parameter. You could do it subjectively. Find me situations where x264 chooses a lower bitrate than your model. At least if your model is falsifiable, it isn't snake oil. Incidentally, Diaz did exactly this test. And your model calculate a worse bitrate than an equivalently-chosen CRF in all cases. So your model isn't snake oil—it's just bad. Perhaps we would randomize the subjective differences, but my suspicion is the default Handbrake CRF (20.0) will work better more than 50% of the time for randomized videos against a randomized audience.