Can I measure time by counting frames and trusting on the ‘240 FPS’ that my iPhone 7+ slow motion camera is capable of record?

I’m using a slow motion video recorded using an iPhone 7+ to track something but would like to avoid recording a chronometer to know the time the process is taking. I need to measure about 10 seconds with an uncertainty of at most 0.1 s… Is this possible by just counting 2400 frames of my homemade video?

Ubuntu very slow boot after chaning driver (Nvdia)

I previously used X.Org driver for my Ubuntu desktop, and my graphic card is Nvdia GTX 1070, actually I’ve never been satisfied with my boot time because I use an high-end SSD and the boot time always takes more than 20 s (comparing to my Ubuntu laptop which is Radeon graphics and the same SSD, only takes 9 s).

However, recently I met some problem with compatibility issue of RStudio (always crashed) and I had to change to Nvdia driver as it was described here. So the Rstudio no longer crashes, however I face a very slow boot, after entering the grub (I have dual-boot), it freezes about 30s, and then the PC has a very transient beep (shorter than the boot one), and then I had to wait another 30 s until I can enter the login.

Does any one know how to solve this issue?

Ubuntu 18.04 LTS too slow after suspend and resume on dell

I have a dell vostro 5470, i7-4510U, 8gb ram, GeForce GT 740M 2gb and recently added ssd 240gb(it only has the ssd now) and i have just installed ubuntu 18.04 LTS. As you can see in this video: It takes a very long time to resume. I tried at least 10 approaches to solve this issue without sucess. I have nvidia driver(nvidia-390) installed I edited the GRUB_CMDLINE_LINUX variables in etc/default/grub I installed msr-tools and ran sudo wrmsr -a 0x19a 0x0 I checked this in dell website:

And so on…

I hope the video can help you understand what kind of problem it is. I really tried a lot before coming here. I hope someone could help, thanks

Why is ssh too slow when I access in Ubuntu 18.04?

I’ve recently installed Ubuntu 18.04 and set the network and I configured NIS client to get user information from the server.

The problem is when I access this server through ssh, it is too slow to get a shell from the server. I’ve been digging out to solve this problem and found this error message from /var/log/auth.log but I don’t know how to do that. What should I do?

Jun 13 08:55:08 server sshd[1716]: pam_systemd(sshd:session): Failed to create session: Connection timed out 

ffmpeg conversion is very slow – How to optimize it?

I am cropping and splitting a video of size 13476*1500 into 4 parts, below is the filters. The conversion is very very slow! Is there a faster way to convert the videos? please help! And also i want to know if there is an alternative way to do the same job or with handbrake.

ffmpeg -i input.mp4 -filter_complex "[0:v]crop=2691:1200:0:0[out1];[0:v]crop=4036:1200:2691:0[out2];[0:v]crop=2691:1200:6727:0[out3];[0:v]crop=4036:1200:9418:0[out4]" -map [out1] -map 0:a out1.mp4 -map [out2] -map 0:a out2.mp4 -map [out3] -map 0:a out3.mp4 -map [out4] -map 0:a out4.mp4 

Slow apt-get dist-upgrade

I just recently installed Kali Linux 2019.2 thru VMWare Workstation 15 on Windows 10 a day ago and I want to install OpenVas. However, it seems that I had to install it first and an error showed:

Unable to locate package openvas

So, I searched and found out that there might be something wrong with my sources.list. So I copied the commands below and pasted it on sources.list.

deb kali-rolling main contrib non-free # For source package access, uncomment the following line # deb-src kali-rolling main contrib non-free deb sana main non-free contrib deb sana/updates main contrib non-free # For source package access, uncomment the following line # deb-src sana main non-free contrib # deb-src sana/updates main contrib non-free deb moto main non-free contrib # For source package access, uncomment the following line # deb-src moto main non-free contrib 

After that, I did the update and upgrade which installed the missing files, I guess?

sudo apt-get update sudo apt-get dist-upgrade 

My question is: Is it normal if it is already taking more than a day to dist-upgrade? It’s only taking 28.2 Kb/s. Is there a way to speed up the upgrade process or did I miss something else where?

I’m just a beginner, hoping you could go easy on me. Thanks in advance.

Slow file transfer over SCTP internode link using SCP command

I am observing slow SCP file transfer over SCTP internode link after upgrading the lk-sctp version 1.0.17. The internode link is just between 2 gateway nodes which are in Active and Standby modes and has no connection to Service Routers.

It takes > 3mins for transferring a file at the rate of 3MB/sec.

Whereas the same SCP command execution for the same file transfer over the non SCTP link is quick only ~~8 sec at the rate of 13 MB/sec.

File size – 762835531.

This scp command execution slowness over sctp link was not observed prior SCTP Upgrade. The working lksctp version was 1.0.10. Our OS version is RHEL 7.6 Please let me know what has changed in the lksctp latest version w.r.t to SCP file transfer. Whether any SCTP settings or linux parameter needs to be fine tuned ?

Thanks, Murali

Loading a view page is very slow

On Drupal 8.7.3 and a very powerful VPS server with php 7.2, I have a view (page) that will list all available nodes of a specific content type.

The display of the view is “Footable” taken from the Footable module.

The view has 5 different relationships: _ to the logged in user. _ to the group where the node is assigned to. (Group Module) _ to two different taxonomy terms. _ to another content type.

In addition to a header.

PROBLEM: I have noticed a very slow page load of the view when the view has more than 100 nodes listed in it… noting that when the view has around 50 nodes, its loading time is just fine and acceptable…

The problem starts when the view has 100+ nodes.

Also noticed when I am on a different page than the view page and i click on the view link, at this time only the view is taking so much time to load but the rendering/display time of the view is fast.

The view is using caching on time-based of 6 hours for both loading and rendering.

Can someone please tell me what it could be the problem ?

Is there a method to check what is making the loading of the view very slow ?

Note that the caching system for the entire site is disabled from the site itself and from the server for many reasons out of scope of this question.

Thank you,

Probabilistic Weighted Moving Average (PEWMA) df.iterrows loop in python slow? Can Pandas speed it up?

Im implementing the Probabilistic Exponentially Weighted
Mean for real time prediction of sensor data in pandas but have issues with optimising the pandas notebook for quick iterations.

Is there a more optimal ways to completely remove the for loop as it currently runs longer than expected to… How can I take advantage of apply() etc here…

import sys import datetime import time  import pandas as pd import io import requests  Blockquote  import numpy as np     from itertools import islice from math import sqrt from scipy.stats import norm  # create a DataFrame for the run time variables we'll need to calculate pewm = pd.DataFrame(index=df.index, columns=['Mean', 'Var', 'Std'], dtype=float) pewm.iloc[0] = [df.iloc[0][value_col], 0, 0]  t = 0  for _, row in islice(df.iterrows(), 1, None):     diff = row[value_col] - pewm.iloc[t].Mean # difference from moving average     p = norm.pdf(diff / pewm.iloc[t].Std) if pewm.iloc[t].Std != 0 else 0 # Prob of observing diff     a_t = a * (1 - beta * p) if t > T else 1 - 1/(t+1) # weight to give to this point     incr = (1 - a_t) * diff      # Update Mean, Var, Std     pewm.iloc[t+1].Mean = pewm.iloc[t].Mean + incr     pewm.iloc[t+1].Var = a_t * (pewm.iloc[t].Var + diff * incr)     pewm.iloc[t+1].Std = sqrt(pewm.iloc[t+1].Var)     t += 1 ```