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15th October 2018, 12:32 | #6421 | Link |
Pig on the wing
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Has anybody made any recent tests with different CTU and TU sizes? I made a quick test yesterday on a 720p encode, and max CTU (and TU) 16 turned out to produce the smallest file but also looked best compared to the original frame. At CTU max 64, the frame was clearly more blurry in places where there were more small details such as hair etc.
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15th October 2018, 14:16 | #6422 | Link | |
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15th October 2018, 19:01 | #6423 | Link |
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Pushing Encoding Quality and Speed with x265
Massively Parallel Encoding from Mile-High Video Workshop videos http://mile-high.video/files/mhv2018/ |
15th October 2018, 19:27 | #6424 | Link | |
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rc: Fix rowStat computation in const-vbv It looks like it might fix a serious issue in a given RC mode, but it isn't actually self-documenting. |
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16th October 2018, 06:43 | #6426 | Link | |
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And if the band you're in starts playing different tunes I'll see you on the dark side of the Moon... |
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16th October 2018, 07:57 | #6427 | Link | |
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Still, there seems to be a lack of communication recently. I reported compiler warnings of GCC 8.x already 2 times, and nobody replied until today. Last edited by LigH; 16th October 2018 at 07:59. |
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16th October 2018, 09:22 | #6428 | Link | |
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But that's probably just me wishfully hoping for a sane AV1 encoder with proper performance, multithreading, profiles and documentation... |
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16th October 2018, 16:10 | #6429 | Link | |
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Larger CTUs are definitely helpful at lower bitrates. Comparing at high perceptual quality can bring in other subtler differences between modes. I've even been able to see a slight improvement at sub-SD resolutions using CTU 64 at very low bitrates. |
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16th October 2018, 17:02 | #6430 | Link |
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Source was 4K, downsampled to 1080p. These are the basic parameters that I've set:
Code:
--input-depth 16 --dither --profile main10 --min-keyint 5 --keyint 480 --merange 44 --splitrd-skip --preset veryslow --rc-lookahead 60 --deblock -2:-2 --no-strong-intra-smoothing --no-sao --qcomp 0.8 --aq-mode 3 --aq-strength 0.8 --ctu 64 --max-tu-size 32 --rdpenalty 1 --qg-size 16 --tu-inter-depth 4 --tu-intra-depth 4 --limit-tu 4 --limit-refs 3 --max-merge 2 --rd-refine --ref 6 --bframes 10 --crf 19 In the 1080p encode, the bitrate is as follows: CTU 64 / TU 32 - 15078 kbps CTU 32 / TU 32 - 14608 kbps CTU 32 / TU 16 - 14472 kbps Of these, CTU 32 / TU 32 resembles the original the most. It's interesting that setting TU 16 also causes distortion in the same areas as CTU 64 / TU 32. I checked areas like eyes, hair etc. which have easily some sort of distortion because there are many fine lines and things that can be compared quite easily. I've just started testing what CRF value is visually enough for 1080p so the final bitrate will probably be lower than what I got from my tests. I'd estimate CRF 20-21 would be the final value.
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16th October 2018, 17:11 | #6431 | Link | |
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Overall, that is a very idiosyncratic set of options. Nothing looks wrong (and I'd love to hear who you picked some of those!, but it's definitely outside of any combination of settings that MCW would be doing psychovisual optimization for. I'm curious about why you chose these particular settings:
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16th October 2018, 17:28 | #6432 | Link |
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My sources are just regular movies or TV series. I'll tune CRF as the last item once I've got all the rest in place.
--merange 44, basically lowering it from the default 57 which I understand is meant for 4K. For 720p, I've used 38 all the time. I think this is remains of littlepox's set of "tune film" parameters. --splitrd-skip, in my old notes, I didn't find it cause any ill effects. Do you have any specific information why it's a "bad idea"? --max-merge 2, values 3-4 tested and it caused blur. One of the things in x265 that is different from x264 - the slower presets don't mean similar quality at lower final bitrate --deblock -2:-2, no need for intense deblocking according to my tests --rdpenalty 1, trying to favour smaller blocks. --qg-size 16, tested values from 64 to 8, 16 looked best (in terms of distortion in small details again) when compared frame-by-frame. Tested with a 720p encode, so I'll need to check that also with 1080p later. --bframes 10, some video utilizes a lot of B-frames for some reason. Not a big slowdown so I've kept it at that all the time.
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16th October 2018, 17:52 | #6433 | Link | |||||||
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Anyone from MultiCoreWare care to weigh in? What's the tradeoff? Is this something that should get added to the faster presets, or default to On but off in --preset placebo? Quote:
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16th October 2018, 18:09 | #6434 | Link |
Pig on the wing
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I think the general problem is that the presets and tunings are really old. I'm quite sure things are very much different now compared to what they were when most of the parameters and settings were come up with. Also, we are still missing the most common tuning which is --tune film. I would very much like to see what the creators of the encoder think of proper settings as they should know the internal workings best.
I recall someone else also complaining about max-merge for smoothing things if the value is too big. I'll need to retest and file a bug report if it's still reproducable. It's been some time since I tested it. Will also retest deblock 0:0. When I tested it earlier, I did find it smooth things slightly so I went one notch down from the standard -1:-1 of x264's --tune film. --rdpenalty 1 is something I have not tested recently. --qg-size 16 does cause the bitrate to jump compared to 32 or 64, but it's worth it in my opinion. I had tested it with a 720p encode with quite a big filesize difference: qg-size 64 : 3147,41 kbps qg-size 32 : 3648,01 kbps qg-size 16 : 3954,23 kbps It is something I need to separately retest for 1080p. The bitrates fluctuate a lot, I'd say between 2.5 - 6 Mbps for 720p encodes. I have no specific target so I just use CRF 19. 10 B-frames because for some quite noisy sources, I noticed that 8 consecutive B-frames were being used 5-10% of the time. Setting ten usually meant that the longest sequence was used 1-2% of the time.
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And if the band you're in starts playing different tunes I'll see you on the dark side of the Moon... Last edited by Boulder; 16th October 2018 at 18:11. |
17th October 2018, 02:09 | #6436 | Link |
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Would it be hotter? Or would it just be slower due to thermal throttling.
I wouldn't be surprised if Intel's next big microarchitecture revision makes AVX512 useful in cases where it isn't today. We saw the same thing with Skylake and AVX2. |
17th October 2018, 03:52 | #6437 | Link | ||
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Monochrome Anomaly |
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17th October 2018, 11:10 | #6438 | Link |
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This will require 10nm process. 14nm++++++++++++ has reached its thermal limits. Upcoming 8C/16T CPUs already are very hot at 5GHz.
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17th October 2018, 15:51 | #6439 | Link | |
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so as long as you are only using it on x265 and use a safe thermal throttling setting u should be fine imho in case i am wrong and anyone else has different results please correct me |
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18th October 2018, 07:08 | #6440 | Link | |
Pig on the wing
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I'll post my results as soon as I finish the 720p tests. From what I can tell is that 1080p requires slightly different parameters, but of course it could be that things have changed so much under the hood that my set of parameters have been obsolete all the time What I already found strange is that deblock doesn't really affect bitrate. For example deblock 6:6 ended up around the same size as deblock 0:0.
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