gpu cpu render time comparison

 https://blenderartists.org/t/blender-stats-cpu-gpu-comparison/1364344

i5 to 1080 GPU seems to be 888 to 325, approx 3x speed-up.

 

Edit: See also, posts which have a comparison with the Studio Mac, and using SheepIt render farm.

 

rendering tips for Blender - noise threshold

To speed up Blender rendering with cycles -

About noise threshold
https://medium.com/@samuelsullins/your-first-real-render-in-blender-a27d3049d659

(also mentions tip about Lock Camera to View for easily manipulating camera by viewing through it).

For 720p, 100 samples should be plenty,
https://blenderartists.org/t/cycles-how-many-sample-should-i-render/1466873

Recommended workflow now is to set a noise threshold, and allow the number of samples to be dynamically set. - You need to set a time limit.
https://blenderartists.org/t/question-about-noise-threshold-in-3-0/1354392

street view video

An interesting idea, maybe can be implemented using Google Apps Script?

https://andrewpwheeler.com/2018/04/02/drawing-google-streetview-images-down-an-entire-street-using-python/

Wordpress users unable to log in

Troubleshooting request - admin users got logged out of Wordpress, unable to log in, "reset password also not working".

Rebooting the server has not resolved the issue.

The users shared this page,

https://blog.hubspot.com/website/locked-out-of-wordpress

Reset the password by connecting to the database and editing the users table, getting the MD5 hash of the password using

echo -n testpasswrdreplacewithcorrectone | md5sum

which works fine, tested with

https://www.md5hashgenerator.com/

 

Still could not log in, so renamed the password security plugin directories as mentioned in the post above, located in public_html/wordpress/wp-content/plugins

password-protect-page

and

password-policy-manager 

in this case, renamed to the directoryname_deactivate or whatever.

Then login works.

 

frame repeat / drop bug

Found frames being repeated (or dropped?) with a ~20 minute video processed with OCVvid2fulldome - found duration had reduced from 24 minutes to 22, and also some jerkiness in motion. The github issue is here.  

Possibly this is due to using ffmpeg in the backend, and this issue?
https://superuser.com/questions/1255380/ffmpeg-duplicating-frames

ffmpeg seems to assume 25fps input as default for frame sequences, and adds duplicate frames if output is 30 fps. https://gist.github.com/hn-88/95dbd59767dcdff23eab2f2be5880c2f

-fps_mode passthrough

seems to be a workaround when using ffmpeg from the commandline, but when ffmpeg is used via OpenCV, how do we manage this? 

generate a video with frame numbers

 Using ffmpeg, can use the following

Generate a video of frame numbers. (github.com)

This can be used to test for bugs like this one, 

frames being repeated or dropped · Issue #10 · hn-88/OCVvid2fulldome

update to Moodle minor update post - stop git from complaining about file permissions changes

Found a couple of issues while upgrading using the steps given in my previous post regarding Moodle minor update using git -

1. If we uninstall the h5pactivity built-in plugin before the upgrade, the upgrade does not proceed - it complains about corrupted plugin. So, basically, we can't uninstall the default plugins without causing issues with upgrades.
   
   
2. If we change the file permissions, we need to add a command
   git config core.filemode false
   to prevent git from complaining about overwriting local files, listing all the files, and aborting the git pull. Via this post.

So, the updated list of commands:

cd /var/www/theLMSgit

sudo -u www-data /usr/bin/php admin/cli/maintenance.php --enable

git config core.filemode false

git pull

sudo chown -R azureuser:www-data .

sudo chmod -R 775 .

sudo -u www-data /usr/bin/php admin/cli/upgrade.php

(type y when prompted)

 

workflow and supported codecs

Workflow for creating files playable at our theatre using only cross-platform tools.

1. ffmpeg to create mp4 file if input is frame sequence - as in this post,
   ffmpeg -r 30 -f image2 -i "Our-frame_%06d.png" -vcodec libx264 -crf 15  -pix_fmt yuv420p Our-movie-4k-frames.mp4
   
   
2. OCVWarp to create warped file. Fourcc of avc1 results in x264 video, good quality.
   
   
3. Avidemux to edit the warped file, move the credits to the beginning and speed up credits. Also overlay Hindi / Telugu title text as graphics using the logo filter.
    
4. To note: Firestick 4K needs FAT32 formatted disk, which has a 4 GB file size limitation. So, re-encoding files with x265 (HEVC) using the options in the Configure button to choose file-size based codec quality. This takes around 8 hours to encode a half-hour 4K 30 fps video on an i5 laptop!
   
   
5. Similarly, the older BluRay player needs to have 1080p encoded with XVID fourcc. x263, I guess. 

Upcoming - perhaps try AV1 codec?

https://trac.ffmpeg.org/wiki/Encode/AV1

 

Moodle server down - restart db server fixed it

Uptimerobot alerted me that one of our Moodle servers was down.

The database server is not responding, that was the reason.

Initiated a restart, hoping this may solve the problem. 10 minutes later, systems were up.

Copy-pasting from an email exchange about the reasons:

 

It could have any of the following causes:
1. automated bot attack
2. some services not restarted properly after an automated system update
3. some other issue triggered by some user action

Right now I'm not digging into the logs for troubleshooting, in case the issue happens again, will do more digging.

We anyway would need a server upgrade some time in the first half of 2024 for operating system upgrades - at that time, I could tighten some of the parameters for better security (like the open ports with default services present currently).

Wordpress permalink issue

One of our servers' site admins reported a problem, with "remove the index.php from the URL" - the standard method of 
WordPress dashboard --> Settings --> Permalinks --> "Post Name" Permalink, Save Changes
did not work for them. "File not found" error.

Checked the .htaccess file, it seemed to be OK.

But looking at how Apache handles .htaccess files, found that AllowOverride would be needed for the .htaccess files to work.

Following

https://ubuntu.com/tutorials/install-and-configure-wordpress#4-configure-apache-for-wordpress

added the lines

<Directory /oursrv/path/to/www/wordpress>
        Options FollowSymLinks
        AllowOverride Limit Options FileInfo
        DirectoryIndex index.php
        Require all granted
    </Directory>

to the relevant files in /etc/apache2/sites-available and then did

sudo service apache2 reload

The admins report that this solved the issue.

Update your trusted root store for Azure Storage services

We got an email from Azure, asking us to update our trusted root store for Azure Storage services - "If you have client applications that still use certificate pinning, they'll be affected by this change and you'll need to take action by 29 February 2024 to avoid potential connection interruptions."

I don't think any of our apps or services use certificate pinning, so did not take any action.