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H.264 is Magic

sidbala.com

71–80 of 230 posts

Re: H.264 is Magic

#71
post #11

Earlier quoted context omitted.

Excellent! :) It would be really cool to further extend it showing actually how the various tiles are encoded and between frames, something along the lines of: http://jvns.ca/blog/2013/10/24/day-16-gzip-plus-poetry-equal... H.265 can even do deltas between blocks in the same frame, IIRC, and is excellent for still image compression too.

H.265 is my next post :)

So if H.264 is magic, what is H.265 then? :)

Re: H.264 is Magic

#72
post #68
post #21

What are directions for the future? Could neural networks become practically useful for video compression? [1] [1] http://cs.stanford.edu/people/eroberts/courses/soco/projects...

Suppose I have a table of 8-digit numbers that I need to add and subtract for various reasons. Do I A: have a child, train them how to read numbers, add, and subtract, and then have the child do it or B: use a calculator purpose built to add and subtract numbers? Neural nets are always expensive to train. You'd better be getting something from them that you can't get some other way.

Yes, you don't need the machinery of learning when you already have an algorithm you're happy with. Adding a table of numbers, I don't think anyone hopes to do much better than we already do with our circuits and computer architectures.

With video compression, I think most would agree that there might be better architectures/algorithms that we haven't stumbled upon yet. Whether specifically "neural networks" will be the shape of a better architecture, I don't know. But almost surely some meta-algorithm that can try out tons of different parameters/data-pipeline-topologies for something that vaguely resembles h.264 might find something better than h.264.

Neural nets are expensive to train. But so is designing h.264.

Re: H.264 is Magic

#73

Ugh. Comparing the file size difference between a lossless PNG and a LOSSY H.264 video of a STATIC PAGE is absurd. Calling it "300 times the amount of data," when it's a STATIC IMAGE is insulting in the extreme. It really doesn't matter if the rest of the article has insights, because you lost me already.

He clarifies right after that he got to those numbers because he used a lossless vs lossy encoder. Really should've kept reading

Re: H.264 is Magic

#74
"This concept of throwing away bits you don't need to save space is called lossy compression."

What a terrible introduction of lossy compression. This would mean that if I empty the thrash bin on my desktop, it's lossy compression.

The concept of going through all compression ideas that are used is pretty neat though.

Re: H.264 is Magic

#75
Absolutely love this:

'Suppose you have some strange coin - you've tossed it 10 times, and every time it lands on heads. How would you describe this information to someone? You wouldn't say HHHHHHHHH. You would just say "10 tosses, all heads" - bam! You've just compressed some data! Easy. I saved you hours of mindfuck lectures.'

This is a really great, simple way to explain what is otherwise a fairly complex concept to the average bear. Great work.

Re: H.264 is Magic

#76

A real fun read. Had an assignment a couple of weeks ago where we used the most k most significant singular values of matrices (from picture of Marilyn M.) to compress the image. H.264 is on a whole other level, though ;)

Now the Question is - Manson or Monroe - and which one would be easier to compress? ;)

Re: H.264 is Magic

#77
post #33
post #26

H.265 gets you twice the resolution for the same bandwidth, or the same resolution for half the bandwidth.

H.265 gets you half the file size for ten times more in royalty fees, or saving 50% of bandwidth for 1000% more in royalty.

Hilarious!

Re: H.264 is Magic

#78
post #56

Earlier quoted context omitted.

>why wouldn't any local media playback seek backwards and reconstruct the full frame? Most codecs/players do. VLC used to be criticized for being different in that regard. One possible advantage is istantaneous seeking, as there's no need to decode all the needed frames (which could amount to several seconds of video) between the nearest I-frames[1] (the complete reference pictures) and the desired one. [1]: plural,…

I try to use VLC when I can because it offers intuitive playlist support, but for high-resolution H.264 and friends I usually have to switch to Media Player Classic. VLC is willing to let my entire screen look like a blob of grey alien shit for 10 seconds instead of just taking a moment to reconstruct frames. And its hardware acceleration for newer codecs is balls. Sucks because otherwise, it's right up there with f2…

>VLC is willing to let my entire screen look like a blob of grey alien shit for 10 seconds instead of just taking a moment to reconstruct frames.

Yes, this is what I was talking about, and yes, specifically for VLC. Plus it's not like playback is so taxing that all cores are pegged at 100% during playback. When I seek, VLC should get off its ass and scramble to come up with the correct full frame then. I'll wait.

Re: H.264 is Magic

#80
> "If you don't zoom in, you would even notice the difference."

First of all, I think he meant "you would NOT even notice".

Second of all, that's the first thing I noticed. That PNG looks crystal clear. The video looks like overcompressed garbage.

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