can't update a git submodule from github web interface

Short answer - not currently possible to do it from the web interface. Discussion about this is at https://github.com/orgs/community/discussions/15079#discussioncomment-9292900

The same terminal commands are needed as referenced in the earlier post, https://hnsws.blogspot.com/2025/04/change-submodule-for-git-repository.html

In my case, since I'm using github actions to build OpenSpace (which I don't have commit access to), what I can do is to just 

cd whichever/submodule/parentdirectory

rm -Rf submoduledirectory

git clone https://fresh.git.subdirectory.url submoduledirectory
cd submoduledirectory

git checkout whatever-branch

before the configure and build steps. Or, of course, if just updating the branch is needed, only the git checkout line would be needed.

test a Mac app to see if it has everything it needs packaged

One way would be to remove all homebrew packages, which would not be recommended - apparently this can be done like

brew remove --force $(brew list --formula) --ignore-dependencies

(not tested)

But an easier way is to just rename the homebrew directory, for eg on Apple Silicon Macs,

sudo mv /opt/homebrew /opt/homebrew-backup

(and after finishing the tests, rename it back.)

adding a 'slow-send' functionality for Google Apps mailing list

I've updated the github repo Google-Apps-Script-mailing-list with a script file which does 'slow-send' for large mailing lists which can be sent over several days. 

Slow-send-one-by-one.gs

Features - 

• time-based trigger, programmatically created and removed
• sends emails to each recipient individually, ramping up from sending
  24 emails per day (once an hour)
  to 96 (once every 15 minutes)
  to 144 (once every 10 minutes)
  to 288 emails per day (once every 5 minutes). This could be increased further, too.
• uses GmailApp instead of MailApp, so we can have features like name (of sender), alias, reply-to, etc.

uninstalling coderabbit

I had signed up for the free trial of coderabbit, but did not find the free plan's functionality of "summarizing pull requests" to be of much use. In order to "uninstall" it, followed the method at 

https://docs.github.com/en/apps/using-github-apps/reviewing-and-revoking-authorization-of-github-apps

To revote authorization, on any github page after logging in, profile picture on top right > Settings > Integrations (on lhs) > Applications > Authorized GitHub Apps tab > click Revoke button for coderabbit.

how to do a homebrew install - avidemux - example

The workflow of installing an app with homebrew, with avidemux as an example, from https://www.avidemux.org/smf/index.php?topic=9960.msg53651#msg53651

After installation an App will be created in your Applications folder and there is finally a audio output device available (you have to select it in the preferences of the App: Edit -> Preferences -> Audio -> AudioDevice: "CoreAudio").

(1) Install XCode and the Command Line Tools of XCode.

(2) Install Homebrew using the following Terminal command:

ruby -e "$(curl -fsSL https://raw.github.com/Homebrew/homebrew/go/install)"

(Perhaps these steps 1 & 2 are now superceded by the instructions at brew.sh)

(3) Install the latest version of Avidemux (nightly version, recommended) using the following Terminal command:

brew install --HEAD avidemux

(4) When the installation has finished, you are asked to make an alias of the app in your Application folder using this command:

brew linkapps

--------------------------------

If you want to update Avidemux to the latest nightly version:

brew rm -f avidemux

brew install --HEAD avidemux

If you want to install the "stable" version of Avidemux (Milestone):

brew install avidemux

file transfer - Android to and from Mac

Macdroid for USB transfers, but only free for Android to Mac - 

https://www.macdroid.app/purchase/

JustBeamIt - works over wifi? but very slow, and link times out after 10 minutes. <1 Mbps. Suitable only for small files.

Filesharing - maybe if we connect both machines with wired connections (Android phone connected via USB to Linux box, and that to Mac with wired LAN), this might be fastest.

hardware accelerated encoding on mac

https://codetv.dev/blog/hardware-acceleration-ffmpeg-apple-silicon

-c:v h264_videotoolbox \ # use Apple Silicon hardware acceleration

Just like

ffmpeg -h encoder=hevc_nvenc

(Trying on Linux running on a PC, 

Codec 'h264_videotoolbox' is not recognized by FFmpeg - will work only on Mac.)

libx265 itself went at 20+fps.

hevc_videotoolbox with warping went at 33 fps.

using py-ffmpeg-warp on Mac

Trying to run py-ffmpeg-warp on the Mac mini, ran into module not found errors.

ModuleNotFoundError: No module named '_tkinter' on mac

had the simple solution as suggested in stackoverflow,

brew install python-tk 

But other modules like scipy, pillow, etc could not be installed this way. ChatGPT suggested a virtual environment to avoid breakage.

1. Create a venv (once per project)

python3 -m venv ~/venvs/gui_env

(this path is just an example.)

2. Activate it

source ~/venvs/gui_env/bin/activate

prompt changes to something like:

(gui_env) %

3. Install the required packages

python -m pip install --upgrade pip

python -m pip install numpy scipy pillow

So, when I want to run py-ffmpeg-warp, I could run the following manually - 

source ~/venvs/gui_env/bin/activate

cd /home/path/to/py/script

python3 py-ffmpeg-warp.py

Or maybe even put those lines in a script as mentioned at https://linuxconfig.org/how-to-use-a-bash-script-to-run-your-python-scripts

ntfs write on MacOS

Current Apple Silicon Macs only have read-only NTFS access out of the box. In order to write to NTFS, we need to jump through some hoops. 

https://machow2.com/read-write-ntfs-drives-on-mac/

free option seems to be via terminal

brew install --cask macfuse

But

brew install ntfs-3g

ntfs-3g: Linux is required for this software.

Then, ChatGPT suggested

https://mounty.app/

which has installation instructions lower down in that page. FUSE is a bit slow compared to the natively supported exFAT etc, but usually sufficient for our use since our low-cost NTFS external hard disks are also slow.  

sheepit renderfarm statistics for the M4 Mac Mini

Compared to the earlier stats, the CPU speed is nearly double, but lack of NVidia GPU prevents many projects from rendering. Copy-pasting from the session information page (My account > Connected machine > (clicking on the machine) - 

OS	macm1
CPU	Apple M4 x 10
RAM allowed	11.0 GB
RAM available	16.8 GB
Max render time per frame
Power CPU	208 %
Scheduler	default

force quit on Mac

https://www.wikihow.com/Force-Quit-an-Application-on-a-Mac

Click outside the problematic app - my test build of OpenSpace in this case - to change focus to another app, then click the Apple Menu > Force Quit ... which gives a choice, to choose the running app we should force quit.

running OpenSpace on Apple Silicon and modern Intel Macs

As written in the documentation, OpenSpace uses OpenGL double precision floating point operations extensively, and Apple Silicon does not have hardware support for it. Checking if it will downgrade gracefully to software rendering, found that OpenSpace would just crash, with Claude.ai telling me that the crash report 

Crashed Thread:        0  CrBrowserMain  Dispatch queue: com.apple.main-thread

Thread 0 Crashed:: CrBrowserMain Dispatch queue: com.apple.main-thread

0   libsystem_kernel.dylib                   0x190856388 __pthread_kill + 8

1   libsystem_pthread.dylib                  0x19088f848 pthread_kill + 296

2   libsystem_c.dylib                        0x1907989e4 abort + 124

3   libGLProgrammability.dylib               0x1f0ea63e4 glpPrimitiveTypeGetScalarType + 136

4   libGLProgrammability.dylib               0x1f0e8af20 glpLLVMLoadVector + 120

5   libGLProgrammability.dylib               0x1f0e7c8f0 glpLLVMCGLValue + 1160

6   libGLProgrammability.dylib               0x1f0e771b0 glpLLVMCGAssign + 112

7   libGLProgrammability.dylib               0x1f0e7788c glpLLVMCGCommaExpr + 268

8   libGLProgrammability.dylib               0x1f0e7788c glpLLVMCGCommaExpr + 268

9   libGLProgrammability.dylib               0x1f0e771b0 glpLLVMCGAssign + 112

10  libGLProgrammability.dylib               0x1f0e7788c glpLLVMCGCommaExpr + 268

11  libGLProgrammability.dylib               0x1f0e7788c glpLLVMCGCommaExpr + 268

12  libGLProgrammability.dylib               0x1f0e771b0 glpLLVMCGAssign + 112

13  libGLProgrammability.dylib               0x1f0e7788c glpLLVMCGCommaExpr + 268

14  libGLProgrammability.dylib               0x1f0e7b5f8 glpLLVMCGBlock + 516

15  libGLProgrammability.dylib               0x1f0e722c8 glpLLVMCGNode + 632

16  libGLProgrammability.dylib               0x1f0e7b234 glpLLVMCGFunctionDefinition + 2888

17  libGLProgrammability.dylib               0x1f0e70f30 glpLLVMCGTopLevel + 1444

18  libGLProgrammability.dylib               0x1f0e985f8 glpLinkProgram + 10092

19  libGLProgrammability.dylib               0x1f0eb1ea0 ShLink + 208

20  GLEngine                                 0x1f104a3b8 gleLinkProgram + 1140

21  GLEngine                                 0x1f0fc6350 glLinkProgramARB_Exec + 180

22  OpenSpace                                0x1021f8aa4 glbinding::BasicCallHelper<void, unsigned int>::call(glbinding::Function<void, unsigned int> const*, unsigned int&&) + 44

23  OpenSpace                                0x1021f87d0 glbinding::Function<void, unsigned int>::call(unsigned int&) const + 184

24  OpenSpace                                0x1021f3a24 glbinding::Function<void, unsigned int>::operator()(unsigned int&) const + 32

25  OpenSpace                                0x1023470c8 gl::glLinkProgram(unsigned int) + 32

26  OpenSpace                                0x101e5dc2c ghoul::opengl::ProgramObject::linkProgramObject() + 44

27  OpenSpace                                0x101e5e668 ghoul::opengl::ProgramObject::Build(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&, std::__1::__fs::filesystem::path const&, std::__1::__fs::filesystem::path const&, ghoul::Dictionary const&) + 1456

28  OpenSpace                                0x100a5dbac openspace::RenderEngine::buildRenderProgram(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&, std::__1::__fs::filesystem::path const&, std::__1::__fs::filesystem::path const&, ghoul::Dictionary) + 316

29  OpenSpace                                0x1016ce084 openspace::globebrowsing::RenderableGlobe::recompileShaders() + 6156

30  OpenSpace                                0x1016cc82c openspace::globebrowsing::RenderableGlobe::initializeGL() + 208

31  OpenSpace                                0x100b47b88 openspace::SceneGraphNode::initializeGL() + 584

32  OpenSpace                                0x100ae4bb0 openspace::Scene::update(openspace::UpdateData const&) + 132

33  OpenSpace                                0x100a5a6d0 openspace::RenderEngine::updateScene() + 196

34  OpenSpace                                0x1007eb428 openspace::OpenSpaceEngine::loadAssets() + 972

35  OpenSpace                                0x1007ed234 openspace::OpenSpaceEngine::preSynchronization() + 156

36  OpenSpace                                0x1004303ac (anonymous namespace)::mainPreSyncFunc() + 80

37  OpenSpace                                0x100ce8b90 sgct::Engine::exec() + 288

38  OpenSpace                                0x10042d170 main + 14684

39  dyld                                     0x1904eeb98 start + 6076

indicates that 

The crash is happening in Apple's OpenGL shader compiler (libGLProgrammability.dylib) when OpenSpace tries to compile shaders for the globe rendering. Look at the stack:

Frame 26-29: OpenSpace is compiling shaders for RenderableGlobe

Frame 19-21: Apple's OpenGL implementation tries to link the shader program

Frame 3: The shader compiler encounters something it can't handle and aborts 

Now, this could possibly be due to some filesystem issues, restrictions due to running OpenSpace from command-line from a sub-folder of my home folder instead of Applications folder, but I got a similar crash when running OpenSpace inside UTM on Ubuntu 24.04 (using the daily build deb file yesterday) if I enable hardware acceleration. 

Unfortunately, mesa on MacOS doesn't seem to enable software rendering - 
brew install mesa

# Set environment variables to use Mesa's software renderer

export LIBGL_ALWAYS_SOFTWARE=1

export GALLIUM_DRIVER=llvmpipe

# Run OpenSpace

./OpenSpace.app/Contents/MacOS/OpenSpace 

But the same crash is observed. Claude says,

Unfortunately, Mesa on macOS is limited. The Homebrew Mesa package primarily provides: OSMesa (off-screen rendering) and some utilities

But it won't override Apple's OpenGL framework the way it does on Linux. macOS applications are hardcoded to use /System/Library/Frameworks/OpenGL.framework. 

Then, tried disabling hardware acceleration and running the same OpenSpace deb file on Ubuntu 24.04, and that works. Around 8 fps, and the frame-rate does not seem to improve much beyond 20 fps or so even if we use something like onlyEarth.profile or loading individual assets to the empty profile, etc. But this could be still useful for offline work, validating single-precision builds and so on.

And so now to single-precision builds - I'll try to build for Mac Apple Silicon and see what happens.

Also, maybe I can try building for Intel Macs with these patches - with XCode for MacOS26, many of the incompatibilities and unsupported implementations are now ironed out, so we need far fewer patches. And github now has MacOS26 public runners.

Edit: 11 Jan 2026 - Finally OpenSpace for MacOS - Apple silicon - is up and running. Lots of shader patching, especially a tricky one here - Mac build - crashes when shader is called · Issue #75 · hn-88/OpenSpace-AppImage

tuning lossless ffmpeg command-line with Claude

The ffmpeg command

ffmpeg -y -r 30 -i in_%05d.jpg -i ../NormPeak-6dBENG.wav -c:v hevc_nvenc -preset lossless -global_quality 18 -pix_fmt nv12 -c:a aac -b:a 192k ~/Downloads/4kframes.mp4

gives the following warnings - 

[aist#1:0/pcm_s16le @ 0x59f7e96fbfc0] Guessed Channel Layout: stereo
....

[in#0/image2 @ 0x59f7e96f4e40] Thread message queue blocking; consider raising the thread_queue_size option (current value: 8)

[swscaler @ 0x59f7e97ae500] deprecated pixel format used, make sure you did set range correctly

    Last message repeated 3 times

[hevc_nvenc @ 0x59f7e9701880] The selected preset is deprecated. Use p1 to p7 + -tune or fast/medium/slow.

[hevc_nvenc @ 0x59f7e9701880] Using global_quality with nvenc is deprecated. Use qp instead. 

Claude's suggestion to fix - 

ffmpeg -y -r 30 -i in_%05d.jpg -thread_queue_size 512 -i ../NormPeak-6dBENG.wav -c:v hevc_nvenc -preset p7 -tune lossless -cq 0 -pix_fmt yuv420p -c:a aac -b:a 192k ~/Downloads/4kframes.mp4

MIDI-mapper for OpenSpace (or any javascript API)

With the help of Claude.ai, I've put up a MIDI-mapper for OpenSpace at OpenSpace MIDI mapping.

The readme.txt lists the prompts used, and usage. Copy-pasting from my post on OpenSpace Slack: With this, we can control OpenSpace using any MIDI control surface or MIDI instrument. Interesting effects like speeding up time for one (MIDI) violin string, slowing down for another string, etc can be thought of.

I've used our KORG nanokontrol - earlier version of this product - to do the development and testing.

By adding suitable functions, this could be extended to call any javascript API using a MIDI controller or MIDI instrument.

Bosch Wiper blades for Hyundai Santro

 PB helped me out with the following info:

Attached is the wiper blades size for Santro
List shows 20" on Driver side and 16" on Passenger side

TYPES OF BOSCH WIPERS
Bosch Clear Advantage — a flat-blade / beam-style wiper. Designed to give uniform pressure across the windshield, better contact, smoother wiping, and more streak-free clearing (especially good in heavy rain or at high speeds).

Bosch ECO (conventional / bracket-frame wiper) — a more traditional wiper with a metal (or mixed) frame + rubber blade. Usually more budget-friendly and covers basic everyday wiping needs.

AMAZON LINKS
Bosch Clear Advantage 16"

Bosch Clear Advantage 20"

Bosch ECO 16"

Bosch ECO 20"

I have been using Bosch ECO, and it works well. 

Will try Clear Advantage next time.

And, found that there were video guides on how to fit the blades, in the amazon listings. Also available on youtube, at Bosch ECO and Clear Advantage.

On my (new) Santro, the 20" blade seems a bit short. Perhaps I'll try the 21-inch blade next time.

hardware accelerated video encoding on Intel Iris graphics has issues with jpg frames input - resolved

 From ChatGPT,

ffmpeg -i filename_%05d.jpg -c:v hevc_qsv -preset veryslow -global_quality 0 output_lossless_qsv.mkv

For 4K (4096x4096) files, this was running at around 8 fps on my i5 laptop, as against 2 fps for non-accelerated libx264. The mistake I made earlier was to put the preset before the -c:v.

• -i must come before input options end.
• All encoder options (-c:v, -preset, -global_quality) must be placed after the input and before the output filename.

If you place -preset before -i filename_%05d.jpg, FFmpeg thinks it’s a decoder option, causing the error:

Codec AVOption preset ... is not a decoding option.

With audio, we would need something like

ffmpeg -r 30 -i KG-LS_%05d.jpg -i audio.wav \

  -c:v hevc_qsv -preset veryslow -global_quality 0 \

  -c:a aac -b:a 192k \

  -shortest \

  output_with_audio.mkv

# or on Windows,

ffmpeg -r 30 -i KG-LS_%05d.jpg -i audio.wav ^

  -c:v hevc_qsv -preset veryslow -global_quality 0 ^

  -c:a aac -b:a 192k ^

  -shortest ^

  output_with_audio.mkv

Edit - this produces a low-bitrate video with colour issues on VLC (and perhaps on other players. The python front-end presets, like the command below, might be useful - 

FFmpeg command to copy-paste:

ffmpeg -y -i in_%05d.jpg -i map_x_directp2.pgm -i map_y_directp2.pgm -i weight_alpha_mask.png -filter_complex '[0:v][1:v][2:v]remap[remapped];[3:v]format=gray,scale=4096:4096,colorchannelmixer=rr=1:gg=1:bb=1[mask_rgb];[remapped][mask_rgb]blend=all_mode=multiply[blended];[blended]scale=3840:2160,setsar=1,setdar=16/9,format=yuv420p[out]' -map '[out]' -map '0:a?' -c:v hevc_qsv -preset fast -crf 23 -pix_fmt yuv420p -c:a aac -b:a 128k D:/out-W4K.mp4

So, without warping, that would be - 

ffmpeg -y -i in_%05d.jpg -i audio.wav -c:v hevc_qsv -preset veryslow -crf 1 -pix_fmt yuv420p -c:a aac -b:a 128k out.mp4

But unfortunately, even the warping command produces a low bitrate video with colour issues. Green tinted instead of purple tinted for the earlier videos. Even changing the codec to libx265 did not help. So, some incompatibility in the input frames is suspected. Maybe I'll just use avidemux instead instead of trying to troubleshoot.

From ffmpeg -h

Getting help:

    -h      -- print basic options

    -h long -- print more options

    -h full -- print all options (including all format and codec specific options, very long)

    -h type=name -- print all options for the named decoder/encoder/demuxer/muxer/filter/bsf/protocol

ffmpeg -h encoder=hevc_qsv
....

  -preset            <int>        E..V....... (from 1 to 7) (default medium)

     veryfast        7            E..V.......

     faster          6            E..V.......

     fast            5            E..V.......

     medium          4            E..V.......

     slow            3            E..V.......

     slower          2            E..V.......

     veryslow        1            E..V.......

....

  -profile           <int>        E..V....... (from 0 to INT_MAX) (default unknown)

     unknown         0            E..V.......

     main            1            E..V.......

     main10          2            E..V.......

     mainsp          3            E..V.......

     rext            4            E..V.......

     scc             9            E..V.......

    

Claude.ai pointed out that the colour tint issues are probably due to wrong pixel format, and the low bitrate is probably because "QSV's CRF implementation is unreliable". So, suggestion is to use nv12 pixel format and global_quality instead of CRF, where quality of 15-20 is near lossless. Or force a high bitrate if that doesn't work - -b:v 20M -maxrate 25M

ffmpeg -y -r 30 -i in_%05d.jpg -i audio.wav -c:v hevc_qsv -preset veryslow -global_quality 18 -pix_fmt nv12 -c:a aac -b:a 128k out.mp4

And that solved the problem.

No colour tint, hevc_qsv encoder resulted in a 25 Mbps video, libx265 encoder with the same preset and quality settings but without the -pix_fmt nv12 resulted in a 7 Mbps video, both of good quality.

strategies for dealing with Google Workspace account filling up

Copy-pasting from an email:

Here are some ways to clear up space in <google workspace account>

1. From https://support.google.com/a/users/answer/14300711

You can go to drive.google.com/drive/quota. There, you see how much storage you use in Google Drive, Gmail, and Google Photos. It also lists the largest files in your google drive, which you can delete if not needed.

2. If GMail is the service which is using up most of the storage, then you can consider deleting files based on how large the attachments are, or based on how old the email is.

To find the emails with attachments greater than 10 MB, enter the following in the search box at the top of your GMail - 

has:attachment larger:10Mb

and hit Enter. 

Similarly for attachments greater than 5 MB etc. 

(You can also use the advanced search link on top of your GMail to achieve this.)

For finding emails older than a particular date, there is a drop-down, "Any time" just below the search email box. To find all emails earlier than 2015, say, you can first clear the "Search mail" box and then choose the "Any time" drop-down, and choose custom, like the screenshot below.

Using these search methods, you can try to delete unwanted emails, spam, internet forwards, outdated correspondence, and so on.

Once emails are deleted, you will then need to go to "Trash" and choose "Empty Trash Now" if you want the space savings to be applied ASAP. Even after this, Google might take some time before the % used decreases.

In case you are not able to free up space in this way, and need to back up old correspondence, here are some ways of doing that, by forwarding to another account, or by using a product called mailstore, etc, details in the link below - 

https://hnsws.blogspot.com/2019/04/mailstore-for-achiving-emails.html

Send user digests - Moodle task fails - sends hundreds of emails to Admin

On one of our Moodle instances, emails are supposed to go out through Google Workspace using Google SMTP servers. That being the case, we can't send an unlimited number of emails. So, email notifications had been globally - Site Administration > General > Messaging > Notification settings, which is located at server.url/admin/message.php

When there was a request to allow emails of a particular type to particular users, after enabling the email notification plugin at the above page, the next time a forum post was made, there was a cascade of Send user digests failed and Send user notifications failed messages.

For the immediate failure messages to stop, deleted all the adhoc tasks from mod_forum,

delete from prefix_task_adhoc  where prefix_task_adhoc.component = 'mod_forum';

I had previously set emailstop=1 on the database users table, for all users except the handful which should receive emails. Possibly the reason for the failures was that forcesubscribe=1 was set for many forums for many / all users. 

So, now I set it to zero (email disabled) for all forums on this instance, with

update prefix_forum set prefix_forum.forcesubscribe = 0;

and also updated the defaults,

Site administration > plugins > plugins overview > (chose mod_forum) > settings >

site.url/admin/settings.php?section=modsettingforum

and set subscription mode = subscription disabled for both defaults,

forum_announcementsubscription

and

forum_subscription 

Also, went to prefix_forum_subscriptions table and deleted all entries - which I suppose would be various users' subscriptions to various forums.

Hopefully this is sufficient to prevent the hundreds of failed send notification tasks. 

Update 13 Nov - Again received hundreds of task failed messages. Asked Claude.ai, and made the following changes as suggested, in addition to the above.

# Individual discussion subscriptions might still exist
DELETE FROM prefix_forum_digests;
DELETE FROM prefix_forum_discussion_subs;

UPDATE prefix_user SET maildigest = 0 WHERE emailstop = 1;

# Users might be getting auto-subscribed when they post
UPDATE prefix_forum SET trackingtype = 0;

TRUNCATE prefix_forum_track_prefs;

run 'Issue Certificates' task more often

There was a request for setting up email notifications for one Moodle course, a particular user to be notified when any user completes that course. I had earlier set many tasks to run less often due to our server being overloaded. 'Issue Certificates' task was one of them, especially since it needed some optimizations as per this thread. Checking the logs, I could see that issue certificates was taking between 30 and 120 seconds - so, increased the scheduled task cron frequency from once a day to once an hour, for two of our Moodle instances. 

Set to run every hour at the 30th minute (8:30, 9:30 etc) on one instance and at the 45th minute (8:45, 9:45, etc) on the other instance, in Site Administration > Server > Tasks > Scheduled tasks > \mod_customcert\task\issue_certificates_task 

installing python modules on Linux and Windows

For trying out LLM-generated python scripts for "warping", (still works in progress)

https://github.com/hn-88/python-ffmpeg-warp

https://github.com/hn-88/realtime_video_warper

https://github.com/hn-88/realtime_warp_c

On Windows, various python modules can be installed with 

pip install modulename

where we sometimes have to do an internet search to find the exact modulename. 

Eg. How to Fix "ModuleNotFoundError: No Module Named 'PIL'" in Python

pip install pillow

On my Linux Mint machine, where I've installed python using the default deb package with apt, 

ModuleNotFoundError: No module named 'imageio'

and when trying to install with pip,

× This environment is externally managed

╰─> To install Python packages system-wide, try apt install

    python3-xyz, where xyz is the package you are trying to

    install.

sudo apt install python3-imageio # this worked.

proctoring plugins for Moodle

Copy-pasting from an email exchange:

 ... would require us to conduct a proctored test. Moodle has several plug-ins. They are promoting 'Proctoring for Moodle'. I also find Quilgo to be good. Can we install these 2 plug-ins (and any other plug-in recommended by you) in (our dev server) for us to test them out?

Here is a list of proctoring plugins for Moodle, probably you would have seen this already. https://moodle.org/plugins/?q=proctor

'Proctoring for Moodle' is free software, but if you want to use the automated face-recognition, they ask us to contact them. "Moodle Proctoring plugin is a Quiz Access plugin designed to capture a user's picture via webcam to identify the individual attempting the Moodle quiz."

A demo is at https://www.youtube.com/watch?v=NcrE1OIj6_Q

In that video, it is mentioned that features like capturing student's screen for "suspicious behaviour" like copy-pasting into Google etc, requires Proctoring Pro.

But the "purchase" Proctoring Pro link seems to be broken. -

https://proctoring.elearning23.com/ 
https://elearning23.com/moodle-proctoring-pro-details/
https://elearning23.com/wp-content/uploads/2024/10/Proctoring-Pro-v2.0.0-User-Manual.pdf

(page not found etc)

"Quilgo® Proctoring for Moodle is a highly scalable plugin that allows you to include a camera, screen, track activity, and receive reports on test completion. Online assessments become easier and more reliable. Easy to use, no API customization or maintenance required." But the free plan is only for 20 tests, and the cheapest paid plan is $1200 for a year or $140 for a month.

https://quilgo.com/products/moodle 

A demo/tutorial is at https://www.youtube.com/watch?v=-pwwImIprSM

I have installed 'Proctoring for Moodle' and "Quilgo® Proctoring for Moodle" on (our dev server) now.

can QUIC be added to our dot net app

There was a request from the developers asking if we can enable QUIC support to the back end of an app for which we had disabled QUIC at cloudflare to prevent issues.

My reply was,

QUIC on Apache web server (which we use as the reverse proxy for dotnet) is experimental. 

https://www.linuxbash.sh/post/configuring-http3-quic-with-apache

We would have to use the experimental module, or shift to another web server like nginx etc. 

Since migration to a different web server is not simple, and the QUIC module is experimental on Apache, I would recommend against enabling QUIC for now. 

Also, QUIC security headaches for admins - 

https://www.networkstraining.com/what-is-quic-protocol/

handwriting recognition - ChatGPT is still the best

Uploading a page from my diary and checking how good the various LLMs are at handwriting recognition - ChatGPT is good for regular snaps.

ChatGPT -

JUN 7 FRI

 Social service instead of jogging as you're coming – making the Ashoka trees straight.

 Afternoon no class – we went to Mandir ~ 1:45, You came ~ 3:15. Vedaṁ, balloons, exerts, song – W/N pg writing & study this time Krishnamoorthy, IMI – problems in C...

Claude had done well at coding - better than ChatGPT and Gemini, but fared worse in handwriting recognition - Claude's version -

JUN 7 FRI

Bowl Service instead of dragging so forth coming - making the little trees sharply. Afternoon no class - we went to Nandu ~ 1:45, Su came ~ 3:15. Yadav, balloons, esotts, songs N/N pg writing & study his tone. Kishnamathy I/W - problems in C...

My corrected version - 

Social service instead of jogging as You're coming - making the Ashoka trees straight. Afternoon no class - we went to Mandir ~ 1:45 pm, You came ~ 3:15 pm. Vedam, balloons, escorts, song – WIN prg  during waiting at Mandir & study hours time. Krishnamoorthy, 1st MSc - problems in C...

Edit - 9 Nov - But when I edited together 5 pages to form a single long page, ChatGPT started hallucinating instead of transcribing!

Excerpt from ChatGPT's version of July 5-14 - 

JUL 5, FRI

 Toured Siddalingeshwar Plantation.

 Found good crop condition — 4½ acres of Amlan.

 Evening went to A.P.S. meeting at old students’ association.

 9:45 P.M. came home.

 Supper.

Actual corrected version,

"Pseudo heterodyning" - frustrating as could get only π phase change. Used signal analyzer to acquire data. S⁴ again seminars on 902...

Timetable again reverting to old schedule, 9 to 3, from Monday.

claude is good at coding

Pleasantly surprised to find that Claude.ai, running the Sonnet 4.5 model, with just a free plan and a single prompt, created a usable UI for a timeline editor in html / javascript, when supplied with javascript helper functions copy-pasted along with the prompt - the initial commit is at

https://github.com/hn-88/openspace-scripts/commit/79ff8dfcea16d7df944d1675f8ec3c6b4b9f3bd8

Edit - Subsequent commits were needed to make it actually functional, connect to OpenSpace, etc. using code copied from Jeff Nee,

https://github.com/hn-88/openspace-scripts/blob/main/OpenSpace-ConstellationsTonight_draft/00-readme.txt

The "finished product" is here,

https://github.com/hn-88/openspace-scripts/tree/main/OpenSpace-Keyframe-Timeline-editor

Moodle Course Completion

Extracts from an email thread, S asked the question and answered himself - 

...we have a custom report 'Course Completion Status' in one of our Moodle instances.

There is a field 'Course Completion - Completed' and this field should show 'Yes' when the course is completed and 'No' when the user is still doing the course. And then there is another field, 'Course Completion.Student Progress' and this field shows the percentage progress.

For (one particular) course many teachers have completed the course (the percentage is 100); certificates have been issued to them. However, the field 'Course completion - completed' is set to 'No' and not 'Yes'. What could be the problem? Even the system report 'Activity Completion' has all the activities ticked. 

Found out the issue - within the course, the course completion criteria weren't set up. To mark the course as completed, at least one criterion should be enabled. 

In the course page - More->Course Completion, enable one or more conditions. I have enabled 'Custom Certificate-Course Certificate'. And immediately, all the people who have received certificates have been marked as 'Completed'. 

hidden restrictions in Airtel's "unlimited 5G" plans

According to this youtube video, there are some terms and conditions which are shown only in the Airtel app, by which

1. If Airtel thinks it is being used for commercial purposes, they can restrict the "unlimited 5G"
2. If the data transferred exceeds 300 GB in a month, they can consider it "commercial"
3. Tethered use of 5G data - using a mobile hotspot - is not included in the "unlimited 5G"

And one of the comments in that video pointed out that the reason why at some times the 4G data cap gets used up even though 5G is displayed in the status area on the top right of Android phones, is because of Airtel's use of 4G infrastructure to deliver 5G - in which case, the 4G billing gets used. And apparently, the difference can be noticed on Samsung phones with the 5G logo which is displayed. 

It seems 5G with a white background = true 5G.

And 5G with white text = 4G masquerading as 5G.

And this seems to be confirmed by this page, 
https://androidsrc.net/android-samsung-phone-symbols/

Youtube 360 VR videos with a poor internet connection

Most of the time, our office internet connection can't support 2160s resolution for 360 VR videos on Youtube. My current solution is to download the youtube videos using yt-dlp - 

./yt-dlp_linux https://www.youtube.com/watch?v=yHQYd5i7CAE

and then watch.

internet problems with our old wifi router

Found that I had to restart the router often - sometimes more than once a day - when DNS would fail. So, instead of using the router's DNS, decided to use 8.8.8.8 - changed the IPv4 settings on the desktop (Linux Mint - "Advanced Network Configuration" - to use a static ip and added the DNS address. Did not make any changes on the router.

Google Apps Script - get the email of signed in user

There was a request to create a Google Apps Script which would do some spreadsheet lookups based on the email of the user, who would authenticate by signing in to the deployed web app - which would be deployed as having access to "Anyone with a Google account".

Apparently the script would work for anyone having an email id in the same workspace domain, but it would not work for users with generic @gmail.com email ids. 

Session.getActiveuser.getEmail() has the problem that it would need the script to run as the user who is logging in (and not as the creator of the script). Apparently this restriction does not apply for users within the same google workspace - 

https://developers.google.com/apps-script/reference/base/user

"the user's email address is not available in any context that allows a script to run without that user's authorization, like a simple onOpen(e) or onEdit(e) trigger, a custom function in Google Sheets, or a web app deployed to "execute as me" (that is, authorized by the developer instead of the user). However, these restrictions generally do not apply if the developer runs the script themselves or belongs to the same Google Workspace domain as the user."

So, made a workaround - first, a script which will run as the user who is logging in, which will get the email - and then POST it to the second script, which will run as the creator of the script, which will process the information. At the POST step, we could add our own authentication using some salted hash etc. 

The first script would be something like - 

function doGet(e) {

  let userEmail = Session.getActiveUser().getEmail();

  let targetUrl = "https://script.google.com/macros/s/AKfycbyx4CbCNIpgmLd2iaWF4buFh_WZtIyOY3vpwdht_Gillycyflpgu1C2bN-j77P2CD3j/exec"; // Replace with your other script's URL

  let html = `

    <!DOCTYPE html>

    <html>

      <body>

        <p>You are signed in as <b>${userEmail}</b></p>

        <form method="post" action="${targetUrl}" target="_blank">

          <input type="hidden" name="userEmail" value="${userEmail}">

  <!-- add other hidden inputs with salted hash or whatever for extra authentication -->

          <button type="submit">Proceed</button>

        </form>

      </body>

    </html>

  `;

  return HtmlService.createHtmlOutput(html);

}

// With deployment access to "Anyone with a Google account"

// Execute As "The User accessing the web app" 

And the second script would have a doPost() like -

function doPost(e) {

// e.parameter contains form fields

let userEmail = e.parameter.userEmail;

// do whatever other parameter checks for extra authentication

// Call your function to fetch data

let result = getData(userEmail);

let html;

if (result && result.found) {

let data = result.data;

html = `

<!DOCTYPE html>

<html>

<body>

<h3>Data Details</h3>

<p><b>Data1:</b> ${data.Namefield1}</p>

<p><b>Data Num:</b> ${data.Num}</p>

<p><b>Data Program:</b> ${data.Program}</p>

</body>

</html>

`;

} else {

html = `

<!DOCTYPE html>

<html>

<body>

<p>No data found for <b>${userEmail}</b></p>

</body>

</html>

`;

}

return HtmlService.createHtmlOutput(html);

}

warping with ffmpeg - and some filter_complex examples

Since OCVWarp uses OpenCV remap() and there does exist a remap filter in ffmpeg also, revisited ffmpeg remap in order to make use of the accelerated NVidia codecs, which ffmpeg supports. Asked ChatGPT to generate python code to create the required map files, debugged the code manually, and put the code at

https://github.com/hn-88/OCVWarp/tree/master/python

Currently it's just for the spherical mirror warping of fulldome content, but could potentially be extended to all of OCVWarp's functionality.

This ffmpeg command using the accelerated hevc_nvenc codec runs at 13 fps on a desktop running NVidia RTX 1060 as against 2.5 fps using OCVWarp saving to avc1 codec out.

ffmpeg -i input.mp4 -i map_x_directp2.pgm -i map_y_directp2.pgm -i weight_alpha_mask.png -filter_complex "
  [0:v]scale=3840:2160[scaled];
  [scaled][1:v][2:v]remap[remapped];
  [3:v]format=gray,scale=3840:2160,colorchannelmixer=rr=1:gg=1:bb=1[mask_rgb];
  [remapped][mask_rgb]blend=all_mode=multiply[out]
" -map "[out]" -map 0:a -c:v hevc_nvenc -preset p5 \

-cq 23 -rc vbr -maxrate 15M -bufsize 26M \
-c:a aac -b:a 128k output.mp4

Can potentially even create a UI using Tkinter in python, which would be cross-platform.

Some notes about the ffmpeg commands copy-pasted from the readme there - 

-ss for the start time should come before the input, and 
-t for the duration should come just before the filter_complex - 

For starting at two minutes and stopping after 10 seconds duration,

ffmpeg -ss 00:02:00 -i input.mp4 \

       -i map_x_directp2.pgm \

       -i map_y_directp2.pgm \

        -i weight_alpha_mask.png \

       -t 10 \

-filter_complex "

 [0:v]scale=3840:2160[scaled];

  [scaled][1:v][2:v]remap[remapped];

  [3:v]format=gray,scale=3840:2160,colorchannelmixer=rr=1:gg=1:bb=1[mask_rgb];

  [remapped][mask_rgb]blend=all_mode=multiply[out]

" -map "[out]" -map 0:a -c:v hevc_nvenc -c:a copy output.mp4

And a problematic video was fixed using an initial crop to 4096x4096 (although avidemux could show it as 4096x4096)

ffmpeg  -i "short_nometadata.mp4"        -i map_x_directp2.pgm        -i map_y_directp2.pgm         -i weight_alpha_mask.png      -filter_complex "[0:v]crop=4096:4096[cropped]; [cropped]scale=3840:2160[scaled]; [scaled][1:v][2:v]remap[remapped];[3:v]format=gray,scale=3840:2160,colorchannelmixer=rr=1:gg=1:bb=1[mask_rgb];

  [remapped][mask_rgb]blend=all_mode=multiply[out]

" -map "[out]" -map 0:a -c:v hevc_nvenc -preset p5 -cq 23 -rc vbr -maxrate 15M -bufsize 26M -c:a aac -b:a 128k short_w2.mp4

But unfortunately, the quality of the warped output is slightly lower than what is seen with OCVWarp - slightly less sharp. Perhaps changing the workflow to first remap and then resize (instead of resize to 3840x2160 first and then remap) might improve things.

Edit - 6 October 2025 - Yes - after doing the remap filter first, at the full resolution of the input video, and then the resizing to output resolution brings up the quality to as good or better than OCVWarp. ("Better" when OCVWarp's default avc1 video codec settings don't deliver as good quality as the hevc_nvenc settings above, I guess.) A separate repo has been created for this, incorporating a Python Tkinter UI,

https://github.com/hn-88/python-ffmpeg-warp/

screen capture or screen recording with Linux on NVidia cards

One more way of doing it, in addition to this earlier post which uses a compiled tool gpu-screen-recorder, there also seems to be a script which does ffmpeg capture of a particular window - 

https://github.com/karlomijaljevic/scrd

This seems to use ffmpeg with -x11grab to do the capturing. I've not yet tried it.

dd command to create linux boot disk

via https://linuxvox.com/blog/create-usb-boot-linux-mint/

sudo dd if='/path/to/linuxmint-22-cinnamon-64bit.iso' of=/dev/sdd bs=4M status=progress

2810183680 bytes (2.8 GB, 2.6 GiB) copied, 140 s, 20.1 MB/s

So, on my machine, it took less than three minutes to create a 2.8 GB boot disk.

Fujitsu mini PC not booting

I had a couple of Fujitsu mini PCs purchased cheaply, used from amazon - but neither of them would boot up now, a couple of years after I had used them last. Suspected the BIOS battery - used these videos to help with opening them up - similar, ours was Q920 without the DVD drive - 

Tearing down a Mini PC | Fujitsu Esprimo Q910

Mini PC Teardown - Fujitsu Espromo Q910

Got the CR2032 lithium cell bios batteries also from Amazon, put in new batteries, and they booted up fine. 

Edwiser Bridge Plugin for Moodle

There was a request to install Edwiser Bridge Plugin for Moodle which would enable integration between Moodle and WordPress. 

If this plugin is installed, for it to work, several settings need to be changed - 

https://edwiser.org/documentation/edwiser-bridge-pro/edwiser-bridge-pro/installation-and-user-guide-for-v3-0-0/steps-to-install-the-plugin-for-first-time-users/

I was spooked by some of these requirements, and also due to 

https://vulert.com/vuln-db/CVE-2025-32044

"vulnerability in Moodle that allows unauthenticated users to access sensitive user data through unauthenticated REST API calls. - fixed in 4.5.3"

So, I replied that I would not be responsible for security issues, if any, if this plugin is installed and asked for head of the institution approval if it was to be installed. The request was then withdrawn, so it was not installed.

the find command and mtime - finding disk space used by old files

 Asked ChatGPT, "linux commandline to list total disk space used of all files created or modified inside a directory more than one year ago" and got the following - 

You can do this with find + du or find + stat + awk.
Here’s a one-liner that lists the total disk space used by files in a directory older than one year:

find /path/to/dir -type f -mtime +365 -printf "%s\n" | \
awk '{sum+=$1} END {print sum/1024/1024 " MB"}'

Explanation:

• find /path/to/dir → search inside that directory.

• -type f → only files.

• -mtime +365 → modified more than 365 days ago (roughly one year).

• -printf "%s\n" → print file sizes in bytes.

• awk → sums up sizes and prints total in MB (divide by 1024/1024).

If you prefer human-readable output directly:

find /path/to/dir -type f -mtime +365 -print0 | du --files0-from=- -ch | tail -n1

This gives you a total in du’s human-readable format.

---

 Asked ChatGPT, "tree view of files and directories larger than 1 GB from linux command line" and got the following - 

You can combine find, du, and tree-style output to list only files/directories larger than 1 GB in a tree view. Here are a couple of approaches:

---

1. Using find with tree

find /path/to/search -type f -size +1G -print | tree --fromfile

• find ... -size +1G → finds files > 1 GB

• tree --fromfile → prints a tree structure from the list

If you want directories too (based on contents size), use du instead (see below).

---

2. Using du for directories/files with sizes

du -h --threshold=1G --max-depth=3 /path/to/search | sort -h

• --threshold=1G → only show entries larger than 1 GB

• --max-depth=3 → how deep to go

• sort -h → human-readable sort

This shows sizes and paths (not tree formatting, but size summary is clearer).

---

3. Pretty tree-like display with du

du -h --threshold=1G --max-depth=3 /path/to/search | sort -hr | 
awk '{print $2}' | tree --fromfile

This gives you a tree structure of directories/files whose total size is ≥ 1 GB.

---

✅ If you want only the largest offenders (say top 20 big files/directories over 1 GB), you can do:

find /path/to/search -type f -size +1G -exec du -h {} + | sort -hr | head -20

---

For this, I had to sudo apt install tree

started using github projects for task tracking

How to use github projects - a getting started video - 
https://www.youtube.com/watch?v=oPQgFxHcjAw 

Opened a private repo with issues, and with ChatGPT's help, linked it to a project. (Projects --> New Project in the github web UI for that repo). Automation to create a new issue worked after some tweaking - the github actions yml is copy-pasted below:

name: Instantiate Planetarium Show Task
on:
  workflow_dispatch:
    inputs:
      show_title:
        description: 'Title of the Planetarium Show'
        required: true
      deadline:
        description: 'Deadline'
        required: false

permissions:
  issues: write
  contents: read
  
jobs:
  create_task_issue:
    runs-on: ubuntu-latest
    steps:
      - name: Build issue content
        run: |
          echo "## Show Details" > issue.md
          echo " " >> issue.md
          echo "**Show Title:**  " >> issue.md
          echo "${{ github.event.inputs.show_title }}" >> issue.md
          echo "" >> issue.md
          echo "**Deadline:**  " >> issue.md
          echo "${{ github.event.inputs.deadline }}" >> issue.md
          echo "" >> issue.md
          echo "## Steps" >> issue.md
          echo "" >> issue.md
          echo "- [ ] Create script" >> issue.md
          echo "- [ ] Create Hindi translation" >> issue.md
          echo "- [ ] Create Telugu translation" >> issue.md
          echo "- [ ] Review Hindi translation" >> issue.md
          echo "- [ ] Review Telugu translation" >> issue.md
          echo "- [ ] Record Hindi VO" >> issue.md
          echo "- [ ] Record Telugu VO" >> issue.md
          echo "- [ ] Edit Hindi VO" >> issue.md
          echo "- [ ] Edit Telugu VO" >> issue.md
          echo "- [ ] Warp ready for our theatre" >> issue.md
          echo "- [ ] Eng-Hin-Tel audio" >> issue.md
          echo "- [ ] Final audio mix" >> issue.md
          echo "- [ ] Save backups" >> issue.md
          echo "- [ ] Post on website" >> issue.md
          echo "" >> issue.md
          echo "---" >> issue.md
          echo "" >> issue.md
          echo "" >> issue.md

        
      - name: Create issue from template
        uses: peter-evans/create-issue-from-file@v4
        with:
          title: "[Show] ${{ github.event.inputs.show_title }}"
          content-filepath: issue.md
          token: ${{ secrets.GITHUB_TOKEN }}
          labels: show,task

This script had to be re-written due to ChatGPT repeatedly using heredoc syntax which would clash with github's yml. I had to explicitly ask it to "Please use echo >> on each line, and no heredoc."

One more automation script to automatically move the items in the project from "TODO" to "In Progress" when any of the checkboxes above were clicked, failed. ChatGPT usually fails when the documentation is not complete and / or there are conflicting earlier documentation pages, as in this case. It would repeatedly suggest using

permissions:
  issues: write
  projects: write

when actually such a permission is no longer accepted by Github - it was part of "classic projects" - https://docs.github.com/en/enterprise-server@3.16/issues/planning-and-tracking-with-projects/creating-projects/migrating-from-projects-classic. 

Apparently with projectsV2, the REST api does not work, only GraphQL API works. And it needs a classic personal access token to work. And the code generated by ChatGPT had errors which I could not get it to fix after multiple iterations over multiple days, so I just left updates to be done manually by clicking on the drop-down seen in the linked project for each issue. I could probably read the GraphQL API documentation and try again, but right now, not motivated to do so.