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Perceptually lossless (talking head) video compression at 22kbit/s

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Re: Perceptually lossless (talking head) video compression at 22kbit/s

#81

Post by Retric »

mercutio2 wrote: post #68
Retric wrote: post #64

Earlier quoted context omitted.

Might be better if you like space opera style really soft science fiction. I really didn’t enjoy it.

Fascinating. Vinge is about the furthest from “soft” sci-fi I can think of. We must have very different definitions of what makes something soft. It’s certainly true that Vinge doesn’t spend much time on the engineering details, but I find him unusually clear on “imagine if we had this kind of impossible-now technology, but the rest of what we know about physics remained, how would people behave?” He was, after all,…

Soft vs hard is based on how closely the world tracks with modern physics/science. As such even just FTL is soft, let alone everything else that doesn’t fit.

Re: Perceptually lossless (talking head) video compression at 22kbit/s

#82

Post by unshavedyak »

ComplexSystems wrote: post #71
Ladsko wrote: post #59

Earlier quoted context omitted.

Can you propose a better term for the concept then? Perceiving something as lossless is a real world metric that has a proper use case. "Perceptually lossless" does not try to imply that it is not lossy.

The term for this is "transparency." A codec is "transparent" if people can't tell the difference between the original and the compressed version.

So it would be `transparent lossy compression`? To this layman `perceptually lossless` sounds more clear, but i understand the issue with the name.

Re: Perceptually lossless (talking head) video compression at 22kbit/s

#83

Post by unshavedyak »

Brian_K_White wrote: post #77
LeoPanthera wrote: post #13

This is very impressive, but “perceptually lossless” isn’t a thing and doesn’t make sense. It means “lossy”.

It means what it already says for itself, and does not need correcting into incorrectness. "no perceived loss" is a perfectly internally consistent and sensible concept and is actually orthogonal to whether it's actually lossless or lossy. For instance an actually lossless block of data could be perceptually lossy if displayed the wrong way. In fact, even actual lossless data is always actually lossy, and only ever "…

Similar to your points, i also expect `perceptually lossless` to be a valid term in the future with respect to AI. Ie i can imagine a compression which destroys detail, but on the opposite end it uses "AI" to reconstruct detail. Of course though, the AI is hallucinating the detail, so objectively it is lossy but perceptibly it is lossless because you cannot know which detail is incorrect if the ML is doing a good job.

In that scenario it certainly would not be `transparent` ie visually without any lossy artifacts. But your perception of it would look lossless.

The future is going to be weird.

Re: Perceptually lossless (talking head) video compression at 22kbit/s

#84

Post by unshavedyak »

bityard wrote: post #42
_ZeD_ wrote: post #18

Earlier quoted context omitted.

also are .mp3, yet they are hardly discernible from the originals

Ability to tell MP3 from the original source was always dependent on encoder quality, bitrate, and the source material. In the mid 2000's, I tried to encode all of my music as MP3. Most of it sounded just fine because pop/rock/alt/etc are busy and "noisy" by design. But some songs (particularly with few instruments, high dynamic range, and female vocals) were just awful no matter how high I cranked the bitrate. And I…

iirc there's "easy" (though i don't know them) tests to validate if the signal is lossless or not. When played over speakers for humans, at least.

I always intend to figure out how that works, because i don't feel a lot of audiophiles are actually speaking truth in many cases lol. Still, i don't know - i can't remember my sources to figure it out for myself :/

Re: Perceptually lossless (talking head) video compression at 22kbit/s

#85

Post by janandonly »

gwd wrote: post #43

This reminds me of a scene in "A Fire Upon the Deep" (1992) where they're on a video call with someone on another spaceship; but something seems a bit "off". Then someone notices that the actual bitrate they're getting from the other vessel is tiny -- far lower than they should be getting given the conditions -- and so most of what they're seeing on their own screens isn't actual video feed, but their local computer'…

I came here to reply just this exactly and found a fellow geek beat me to it. Indeed a brilliant book.

Re: Perceptually lossless (talking head) video compression at 22kbit/s

#86

Post by rini17 »

lifthrasiir wrote: post #41
rini17 wrote: post #33

Earlier quoted context omitted.

But that's mathematically impossible, to restore signal from extremely low bitrate stream with any highly bounded distortion. Perhaps only if you have highly restricted set of posible input, which online meetings aren't.

> Perhaps only if you have highly restricted set of posible input, which online meetings aren't. Are you sure? After all, you can effectively summarize meetings in a plain text which is extremely restricted in comparison to the original input. Guaranteed, exact manner of speech and motions and all subtleties should be also included to be fair, but that information is still far limited to fill the 20 kbps bandwidth. W…

Okay, did not know you measure distortion that way.

Re: Perceptually lossless (talking head) video compression at 22kbit/s

#87

Post by hinkley »

The second example shown is not perceptually lossless, unless you’re so far on the spectrum you won’t make eye contact even with a picture of a person. The reconstructed head doesn’t look in the same direction as the original.

However is does raise an interesting property in that if you are on the spectrum or have ADHD, you only need one headshot of yourself staring directly at the camera and then the capture software can stop you from looking at your taskbar or off into space.

Re: Perceptually lossless (talking head) video compression at 22kbit/s

#88

Post by hinkley »

initramfs wrote: post #47

nice feature for low bandwidth 4G cell systems. Reminds me of the video chat in Metal Gear Solid 1 https://youtu.be/59ialBNj4lE?t=21

Nice feature for many to one video conferencing as well. Though I don’t know if the organizers will agree.

Re: Perceptually lossless (talking head) video compression at 22kbit/s

#89

Post by hinkley »

manmal wrote: post #46
antiquark wrote: post #37

Not quite lossless... look at the bicycle seat behind him. When he tilts his head, the seat moves with his hair.

His gaze also doesn’t quite match.

Why is nobody noticing the eyes?? This is important!

I feel like I’m taking crazy pills.

Re: Perceptually lossless (talking head) video compression at 22kbit/s

#90

Post by hinkley »

up2isomorphism wrote: post #72

“Perceptually lossless” is an oxymoron.

You’re still listening to vinyl, arntcha?

Lossiness definitely matters when you’re doing forensics. But not for consumers.

If you just want to bop to Taylor who the fuck cares. The iPod ended that argument. Yes I can be a perfectionist, or I can have one thousand songs in my pocket. That was more than half of your collection for many people at the time.

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