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18th April 2018, 10:34 | #641 | Link |
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I would say that the film grain synthesis is something that no one has really looked at yet in tests, that will be a huge advantage over HEVC.
Screenshots below are from
Src, x265, aom Frame 2: Src, x265, aom |
18th April 2018, 13:04 | #642 | Link | |
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Out of curiosity, can the synthesis part (but not the removal.) be disabled (or defeated) to see how it looks without it? |
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18th April 2018, 13:39 | #644 | Link | |
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I definitely look for the day where I no longer need to use the sharpening filter shortcuts I added to my player configuration.
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18th April 2018, 16:21 | #646 | Link | |
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I don't disable sharpening. I enable sharpening as I can't stand the smoothness of many videos. I basically have this in ~/.mpv/input.conf: Code:
k add sharpen +0.25 K add sharpen -0.25 And I already use ewa_lanczossharp for scaling.
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19th April 2018, 13:56 | #647 | Link |
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AOM AV1 v0.1.0-9264-gbce84eb0b
Built on April 19, 2018, GCC 7.3.0 Code:
https://aomedia.googlesource.com/aom |
20th April 2018, 02:35 | #648 | Link |
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HM and JM both had a rudimentary implementation of FGM, and they never made it into any of the commercial or major free encoders or decoders. I hope AV1's makes it into the wild, because that's one of the features I most sorely miss for mid-to-low bitrate encoding. There wouldn't be such a thing as "too smooth" at normal bitrates anymore; HEVC has really suffered among video enthusiasts because of that.
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20th April 2018, 13:32 | #649 | Link | |
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(BTW, It's been mentioned a bunch of times that they didn't do any performance optimizations in libaom.) |
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20th April 2018, 18:32 | #651 | Link | |
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Last edited by mzso; 20th April 2018 at 18:40. |
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20th April 2018, 21:51 | #652 | Link |
Derek Prestegard IRL
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^^ Is it just me, or does that sound extremely optimistic?
The bitstream was supposed to be frozen about 18 months ago I think? Maybe they should be a bit more conservative with timelines. Last edited by Blue_MiSfit; 20th April 2018 at 21:54. |
22nd April 2018, 08:23 | #653 | Link | |
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Should the AoM have published credible timelines, HEVC would have had ample opportunity to dodge out of the way of any expectoration. Whether they'd have actually taken advantage of those opportunities is another matter. As it currently stands, the decision facing the streaming industry is this: with the rapid uptake of UHD/HDR consumer displays (aka immediate demand), do you implement a UHD delivery system NOW using HEVC's absurd licensing, or in 3 years time using AV1's open license? That decision should be a no-brainer... if it weren't for the likes of Velos being in the HEVC patent pool. So, if the AoM were able to convince those decision makers that they need only wait 1 year (irrespective of the timeline's veracity), HEVC gets it in the eye again. |
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24th April 2018, 15:59 | #655 | Link |
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I don't think there's that many On2 employees left; I think it's more a general quality of the AV industry to overpromise and underdeliver, and Google itself is well-known for unfounded enthusiasm for eternal betas. Kind of a match made in heaven, there.
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24th April 2018, 20:20 | #656 | Link |
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Added AV1 to my comparison: https://wyohknott.github.io/video-formats-comparison/
I had to run it at cpu-used=4 to get a reasonable encode time so it's not representative of the max quality that could be obtained. You can see that the encode speed is still infinitesimal. |
25th April 2018, 07:39 | #657 | Link | |
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" It was proven that high precision mc is only effective for low resolution. Beyond 1080p, even 1/4 pel seems not very effective to justify its complexity. I remember that 1/4 pel shows 30% coding gain for famous Mobile CIF sequence (low res, complex texture, slow motion, aliasing from inadequate down sampler) but average 5-8% over various test sequences. Very high frame rate with non hierarchical structure may change the situation but it seems clear that it is highly sequence dependent tool" I remember a paper "Motion-Compensating Prediction with Fractional-Pel Accuracy", by B. Girod, 1993 . If we omit a mathematical part of the article and go to the conclusion part, it's written (in my wording): for blocks 16x16 of TV video resolution 1/4-pel motion accuracy appears to be sufficient. |
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25th April 2018, 07:46 | #658 | Link |
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AV1 enables to omit transmission of skip_flags - what's a gain in coding efficiency?
AV1 enables to omit transmission of skip flags. Indeed, there is the frame-header parameter 'skip_mode_present' and if this parameter equals to 1 then the skip flags are not signalled. The rationale is clear, if we know 'a priory' that encoding of a given frame will not produce skip blocks then it's redundant to transmit skip flags.
Let's look at the situation from another view, what's a penalty in transmission of skip flags provided that all blocks are non-skipped? Because i am not completely familiar with AV1 entropy coding process i consider AVC/HEVC arithmetic engine instead. In HEVC/AVC the maximal probability of a symbol is ~0.98 and hence the number of bits produced by encoding a symbol having the maximal probability is -log2(0.98) = ~0.02 bits. Let's suppose that we know ahead that all MBs will be no-skipped (i.e. skip_flag = 0 for each MB) and consequently the skip_flag syntax element gets maximal probability 0.98. In such case the total number of bits consumed by all skip flags is ~0.02 x Number_Mbs. For example, HD resolution frame has usually 8100 MBs (16x16 grid) and hence the total size of all skip_flag syntax elements is ~8100 x 0.02 = 162 bits. It's negligible in most cases. Probably AV1 frame level parameter 'skip_mode_present' (to disable transmission of skip flags) has a minimal impact on coding efficiency, although it increases the decoding complexity (more 'if-else'). |
25th April 2018, 15:42 | #659 | Link | |
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According to HVS research all video with PSNR above 45 dB look perceptual identical to the original. |
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27th April 2018, 07:12 | #660 | Link | |
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Quote:
Another topic: Good video to explain people what av1 is, why it was created and by whom etc. (the whole story): https://youtu.be/lEdqN22vaWs |
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