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H.264 is Magic

sidbala.com

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Re: H.264 is Magic

#31

Post by adilparvez »

Related, how h265 works: http://forum.doom9.org/showthread.php?t=167081

This is a great overview and the techniques are similar to those of h264.

I found it invaluable to get up to speed when I had to do some work on the screen content coding extensions of hevc in Argon Streams. They are a set of bit streams to verify hevc and vp9, take a look, it is a very innovative technique:

http://www.argondesign.com/products/argon-streams-hevc/ http://www.argondesign.com/products/argon-streams-vp9/

Re: H.264 is Magic

#32

Post by tveita »

logicallee wrote: post #24
userbinator wrote: post #10

The lossy transform is important, but I think what's actually most important in video compression is getting rid of redundancy --- H.264 actually has a lossless mode in which that transform is not used, and it still compresses rather well (especially for noiseless scenes like a screencast.) You can see the difference if you compare with something like MJPEG which is essentially every frame independently encoded as a…

This is really interesting and the imgur picture you linked (with your explanation) explains it really clearly! But when seeking, why wouldn't any local media playback seek backwards and reconstruct the full frame? It's not like the partial frame after seeking is useful - I'd rather wait 2 seconds while it scrambles (i mean "hurries up") to show me a proper seek, wouldn't everyone? What was your Internet search for f…

"datamoshing" is a term I've heard for people deliberately removing I-frames, so P-frames are applied to the wrong base image.

Re: H.264 is Magic

#33

Post by ksec »

iplaw wrote: 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.

Re: H.264 is Magic

#34

Post by [deleted] »

logicallee wrote: post #24
userbinator wrote: post #10

The lossy transform is important, but I think what's actually most important in video compression is getting rid of redundancy --- H.264 actually has a lossless mode in which that transform is not used, and it still compresses rather well (especially for noiseless scenes like a screencast.) You can see the difference if you compare with something like MJPEG which is essentially every frame independently encoded as a…

This is really interesting and the imgur picture you linked (with your explanation) explains it really clearly! But when seeking, why wouldn't any local media playback seek backwards and reconstruct the full frame? It's not like the partial frame after seeking is useful - I'd rather wait 2 seconds while it scrambles (i mean "hurries up") to show me a proper seek, wouldn't everyone? What was your Internet search for f…

[deleted]

Re: H.264 is Magic

#35

Post by p0nce »

amelius wrote: 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...

Perhaps for intra-prediction. I wouldn't hold my breathe.

Re: H.264 is Magic

#36

Post by [deleted] »

amelius wrote: 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...

[deleted]

Re: H.264 is Magic

#37

Post by striking »

szemet wrote: post #9

I thought I'll learn something special about H.264, but all information here is high level and generic. For example if you replace H.264 with a much older technology like mpeg-1 (from 1993) every sentence stays correct, except this: "It is the result of 30+ years of work" :)

Sure, but also keep in mind that the technology hasn't changed much over time. Even HEVC, which causes extreme gains in compression on high-res video with minimal loss in quality, is still mostly the same algorithm as H.264 but with larger blocks, slightly more flexible coding units rather than frame-wide interpolation changes, and 35 rather than 9 directions recognized for predictions.

Re: H.264 is Magic

#38

Post by dao- »

eutectic wrote: post #20

Anyone who likes this would probably also enjoy the Daala technology demos at https://xiph.org/daala/ for a little taste of some newer, and more experimental, techniques in video compression.

Note that Daala has been discontinued in favor of AV1: https://en.wikipedia.org/wiki/AOMedia_Video_1

Previously Daala was presented as a candidate for NETVC but apparently this didn't go anywhere? https://en.wikipedia.org/wiki/NETVC

Re: H.264 is Magic

#40

Post by eutectic »

dao- wrote: post #38
eutectic wrote: post #20

Anyone who likes this would probably also enjoy the Daala technology demos at https://xiph.org/daala/ for a little taste of some newer, and more experimental, techniques in video compression.

Note that Daala has been discontinued in favor of AV1: https://en.wikipedia.org/wiki/AOMedia_Video_1 Previously Daala was presented as a candidate for NETVC but apparently this didn't go anywhere? https://en.wikipedia.org/wiki/NETVC

The demos are still neat, and some of the ideas are being used in AV1.
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