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21st June 2013, 03:59 | #21 | Link |
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Thank you.
Anyway, how much gain can we really expect from CTUs dividing into CUs in practicality, rather than in theory? I found a good description of CTUs/CTBs/CUs/CBs on this PDF from the HHI, if it helps: http://iphome.hhi.de/wiegand/assets/...erformance.pdf Will 32x32 and 64x64 CTUs improve compression that much? Or will most of the gain come from the additional encoder flexibility with variable-size non-grid CUs within CTUs? Also, will the additional encoder flexibility allow for encoders which are much, much better than the bitstream format devs expected? x264 is a very good encoder for H.264, better than the H.264 devs expected, but I'm worried it's reached a point where it doesn't have any additional bitstream flexibility to allow it to improve (the x264 devs can give me an opinion on this, I'd be glad to be wrong.) TL;DR: How much difference does the additional flexibility really make? |
21st June 2013, 23:04 | #22 | Link | ||
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23rd June 2013, 08:00 | #23 | Link |
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When the trolling got cut out, we also lost a link to a blog comparing hevc and x264, which wasn't particularly interesting in itself but had a link to this recent paper which was:
https://ece.uwaterloo.ca/~z70wang/pu...ons/vpqm13.pdf The basic gist is that all the standard objective frame by frame analysis methodologies (psnr, ssim etc.) may systematically, and substantially, underrepresent the improvements in HEVC over its predecessor. Last edited by Guest; 23rd June 2013 at 12:58. Reason: make link hot |
23rd June 2013, 09:57 | #24 | Link |
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Join Date: Nov 2004
Posts: 240
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This bloke has updated his posts and says that this month he will have a new code release out:
https://code.google.com/p/x265/ Last edited by Guest; 23rd June 2013 at 12:59. Reason: make link hot |
26th June 2013, 21:03 | #26 | Link |
x264 developer
Join Date: Sep 2005
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There is something in the works, and hopefully you're hear about it soon. Keep in mind that this is going to take years to produce a good encoder if ever, just like with x264. It's not going to be ready to displace H.264 by Christmas.
I also kind of don't feel like engaging trolls, so... |
26th June 2013, 22:33 | #28 | Link | |
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Are you planning some in-depth analysis of the standard like you did with vp8 in your diary of x264 dev? |
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27th June 2013, 00:56 | #29 | Link |
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My guess it is will help some but not as much as everyone would like. HEVC is not H.264 so different enhancements might still look good but some other equivalent quality enhancement will compress much better. That's what this kind of encoder research is for
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27th June 2013, 01:00 | #30 | Link |
x264 developer
Join Date: Sep 2005
Posts: 8,666
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Years of experience gives some guidance in experimentation and optimization, but you still have to build the software in the first place and make it fast, clean, and efficient, and that alone is many developer-years of work. Applying smart algorithms and knowledge gleaned from x264 comes after that, and still, it's just guidance; H.265 is very different from H.264.
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27th June 2013, 08:46 | #31 | Link |
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I agree It will take years for a good H.265 encoder ( i.e ~50% bitrate for the same H.264 quality )
But I hope the first generation of H.265 encoder will quickly at least be as good as current H.264 encoder in bitrate/speed/quality. |
27th June 2013, 16:27 | #32 | Link |
x264 developer
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Keep in mind that it took until 2007-2008 for x264 to consistently beat Xvid (the previous generation), and H.264 came out in 2003. I don't want people to get their hopes too high, or else everyone's going to be disappointed.
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28th June 2013, 05:14 | #33 | Link |
Curious Beta Tester
Join Date: Nov 2004
Posts: 240
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Heres a group with a free HEVC software decoder for windows:
http://xhevc.com/en/hevc/decoder/download.jsp Divx have a patch out for mkvtoolknix to add their divx HEVC profiles to the toolset. They also reckon they are close to releasing a HEVC decoder and their own encoder. |
28th June 2013, 07:11 | #34 | Link | ||
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Also, I really didn't want to put the same stuff in a yet another thread (we already have HEVC general and Available HEVC/H.265 test encoders threads, as well as some other random ones...), but there is a libavcodec HEVC decoder by smarter that is by now in a pretty good condition. It has been forked by OpenHEVC, and is also developed there (in a somewhat chaotic form). OpenHEVC is then used by GPAC for their Osmo4 "mp4" player. GPAC happens to have one of the 14496-15 AMD2 (HEVC File Format, aka HEVC-in-"MP4") editors on their team, so they are currently the only ones who can implement it until the last draft is published (the newest draft currently public is from May 2012, and there seem to have been plenty of changes since). Since GPAC is not historically well known for implementing things well/correctly, no-one is copying their implementation, but instead waiting for the last draft to be published to implement it. Quote:
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28th June 2013, 15:46 | #36 | Link | |
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The topic of this thread is about HEVC decoders/encoders so its ontopic to discuss various implementations of that. I'm excited mate to hear about the libavcodec decoder and I'm a regular with ffmpeg so thats great |
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30th June 2013, 13:43 | #37 | Link | |
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Anyway, great hearing that the x264 devs have something cooking for h265, their track record speaks for itself. |
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2nd July 2013, 19:55 | #40 | Link |
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It only works in their crappy player and does not even support seeking yet.
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Tags |
decoder, encoder, h.265, hevc, open-source |
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