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12th April 2018, 22:56 | #6022 | Link |
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Don't forget the "--asm avx512", it isn't enabled by default. This seems good if it is slower on most systems due to the multiplier offsets for AVX-512.
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madVR options explained |
12th April 2018, 23:28 | #6024 | Link |
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It is now, because they reigned in AVX2 use in some irrelevant functions with minimal speedups to reduce the effect of downclocks. They even had a presentation about that "adventure" and their findings on some conference once
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LAV Filters - open source ffmpeg based media splitter and decoders |
13th April 2018, 15:43 | #6025 | Link |
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no AVX512:
encoded 1780 frames in 169.38s (10.51 fps), 2541.97 kb/s, Avg QP:20.40 AVX512: encoded 1780 frames in 161.94s (10.99 fps), 2541.97 kb/s, Avg QP:20.40 makes a ~5% speed increase considering avx512 encode was almost 10°C cooler, so maybe i can get away with +100MHz. i like it |
14th April 2018, 03:01 | #6027 | Link | |
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Is anyone else having problems with getting it to work on Skylake Xeons?
x265 crashes on my Xeon Platinum 8176 server when I start it with the --asm avx512 flag. Quote:
And it works on my i9 7940X with the avx512 flag. |
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14th April 2018, 10:59 | #6030 | Link |
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i'm seeing very inconsistent results
CRF-20 preset-"medium" -------------------- Run1: encoded 1128 frames in 27.42s (41.14 fps), 3355.47 kb/s, Avg QP:20.21 Run2 (AVX512): encoded 1128 frames in 30.23s (37.32 fps), 3355.47 kb/s, Avg QP:20.21 Run3: encoded 1128 frames in 27.77s (40.62 fps), 3355.47 kb/s, Avg QP:20.21 Run4 (AVX512): encoded 1128 frames in 27.04s (41.71 fps), 3355.47 kb/s, Avg QP:20.21 but temps are still very low on avx512. i didn't expect this. probably x265 just uses very little avx512 and that's why we don't see much improvement - if any - running on lowered frequency. maybe we can run at default speed without getting too much heat/power, if we only use it on x265... i'll give it a try btw: i agree that avx512 is not worth getting a new cpu |
14th April 2018, 22:54 | #6031 | Link |
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x265 2.7+340-aa9102400f24
remove unused asmname from x265_param; added a newline in the help (fixed VMAF warning not applicable under Windows) Last edited by LigH; 15th April 2018 at 18:37. Reason: Not the fixed version yet |
15th April 2018, 18:31 | #6032 | Link | |
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Quote:
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15th April 2018, 19:33 | #6034 | Link |
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Thanks for more info. It looks like more serious bug (x265 works for a while). The error message is probably from decoding app that writes graphics data via pipe to x265.
There are many possible reasons for the crash, one of them is the OS (and msvcrt.dll file in your OS). Could you test VS 2015 and VS 2017 x265 binaries? They are not based on msvcrt.dll. |
15th April 2018, 21:24 | #6036 | Link |
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x265-2.7+336-07defe235cde.7z VS 17 x64, crt is statically linked so no install needed. Debug pdbs included.
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15th April 2018, 22:03 | #6037 | Link |
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Bisection is one of the most common method of finding bugs.
In source file common/x86/asm-primitives.cpp it is function pointers assignment with avx512 code -- from line # 4696 to 5385. We can turn off (comment) first half of this functions (x265-1.exe) and then second half (x265-2.exe). You can download avx512-bisect1.7z VS 2015 binaries with diff files -- if x265.exe (from clean sources) hangs, please try x265-1.exe and then x265-2.exe -- it should be that one of them hangs and second not. Please report back the results (which from the 3 binaries hangs and which not). |
15th April 2018, 22:38 | #6038 | Link | |
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Quote:
Is there additional information that can be provided for debug? |
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15th April 2018, 22:56 | #6039 | Link | |
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Quote:
Could you post results of the command x265 -V && x265 --asm avx2 -V && x265 --asm avx512 -V For example in my system it looks like Code:
F:\x265p\ma\avx512>x265 -V && x265 --asm avx2 -V && x265 --asm avx512 -V x265 [info]: HEVC encoder version 2.7+340-aa9102400f24 x265 [info]: build info [Windows][MSVC 1900][64 bit] 10bit x265 [info]: using cpu capabilities: MMX2 SSE2Fast LZCNT SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2 x265 [info]: HEVC encoder version 2.7+340-aa9102400f24 x265 [info]: build info [Windows][MSVC 1900][64 bit] 10bit x265 [info]: using cpu capabilities: MMX2 SSE2Fast LZCNT SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2 x265 [info]: HEVC encoder version 2.7+340-aa9102400f24 x265 [info]: build info [Windows][MSVC 1900][64 bit] 10bit x265 [info]: using cpu capabilities: MMX2 SSE2Fast LZCNT SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2 AVX512 ------------------------------------------------------ Your OS is Win 8.1 that do not support avx512. This bug in x265 is not technical but conceptual -- avx512 is not auto recognized by default so option '--asm avx512' should not turn on avx512 without any check. You can test file avx512-patch.7z with x265 that check what is supported by CPU & OS up to avx512 if option '--asm avx512' is used. On Win 8.1 it should work with '--asm avx512' exactly like without this option, on Win 10 it should turn on avx512 if you have CPU with avx512 and you use option '--asm avx512'. Last edited by Ma; 15th April 2018 at 23:58. |
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17th April 2018, 07:31 | #6040 | Link | |
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Quote:
We have observed that --refine-inter=3 and --refine-intra=4 gives the best quality, even better than standalone x265 encodes in some cases, with a performance gain of up to 1.8X. For 4K HDR content, you will have to modify the display settings based on the monitor. Please refer the docs for more information - http://x265.readthedocs.io/en/defaul...mation-options |
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