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...
H.264 is Magic
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Re: H.264 is Magic
#22I 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" :)
Also the fleeting mention of b-frames, which mpeg-1 doesn't have. And I believe mpeg-1 doesn't use 16×16 macroblocks. Still, it's a good overview of generic video compression.
Re: H.264 is Magic
#23This was a good and interesting read. Is h.264 an open standard ?
Doesn't look like it; https://en.wikipedia.org/wiki/H.264/MPEG-4_AVC > H.264 is protected by patents owned by various parties. A license covering most (but not all) patents essential to H.264 is administered by patent pool MPEG LA.[2] Commercial use of patented H.264 technologies requires the payment of royalties to MPEG LA and other patent owners. MPEG LA has allowed the free use of H.264 technologies for streaming…
It is an open standard. Anyone can purchase and implement it, and it was developed by ISO. The technologies are not royalty free in the US. Don't conflate the two. *
Edit: I emphasize this mainly because the terms have a specific meaning in standards jargon but also because it places the blame for software patent abuses on the wrong parties (the standards developers rather than the lawyers and legislators).
Re: H.264 is Magic
#24The 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 finding that imgur frame? What is this effect called?
Re: H.264 is Magic
#25Damn, lost me during the frequency part.
Re: H.264 is Magic
#26H.265 gets you twice the resolution for the same bandwidth, or the same resolution for half the bandwidth.
Re: H.264 is Magic
#27H.265 gets you twice the resolution for the same bandwidth, or the same resolution for half the bandwidth.
No, it doesn't. Though that may have been the goal, HEVC has only thus far achieved an improvement of around 25%, not 50%.
Re: H.264 is Magic
#28Wow, now tell me how H.265 works!
Re: H.264 is Magic
#29I love how you can edit photos from people to correct some skin imperfections without loosing the touch that the image is real (and not that blurred, plastic look) when you decompose it in wavelets and just edit some frequencies. Don't know in photoshop, but in Gimp there's a plugin called "wavelet decomposer" that does that.
I guess this is the plugin you are talking about? Interesting.
Re: H.264 is Magic
#30The 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…
>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, because prediction can also be bidirectional in time
The use of incomplete video frame data for artistic purposes is called "datamoshing".