Sunday, September 22, 2019

WhatsApp notification issue and solution

On my LG Q6 phone, running Android 8, there was a problem of WhatsApp notifications arriving only after I opened WhatsApp. WhatsApp voice call notifications were also not coming through. After some digging, found the setting which made the difference - under Battery -> Power saving exclusions, allowed WhatsApp as an exclusion. Problem seems to be solved.

Saturday, September 14, 2019

tutorial on 360 to dome with Vuo on Mac

 In the second half of this tutorial, Paul talks about warping 360 videos to dome -http://paulbourke.net/dome/vuo/

Edit: Can now use OCVWarp and do this ... 

Thursday, September 12, 2019

system program problem

Popup on startup - System Program Problem detected. The solution was to clear /var/crash as per this post.

Saturday, September 07, 2019

increasing font size in Octave legend

Some figures created in Octave had very small font sizes when added to the LaTEX manuscript. Trying to fix the text with Inkscape led to kerning issues similar to this post. So, found these solutions at
https://stackoverflow.com/questions/1532355/increase-font-size-in-octave-legend

Used commands like
print ("j0exp.eps", "-depsc", "-F:20")


Tuesday, September 03, 2019

starting offline processing in a new thread - C++

Tried various options to begin processing in a new thread for BscanFFT, without locking the UI - 

Just
std::system(offlinetoolpath);
// - this causes the BscanFFT program to wait for the offline tool to finish

Then,

pid = fork();

if (pid == 0)

{

// child process

std::system(offlinetoolpath);

}

else if (pid > 0)

{

// parent process

}

gives the error

 [xcb] Unknown sequence number while processing queue

[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called

[xcb] Aborting, sorry about that.

BscanFFTspinj.bin: ../../src/xcb_io.c:259: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed.

Apparently, system specific is safer, http://www.cplusplus.com/forum/beginner/13886/

"Actually, the most important disadvantage of system() is that it introduces security vulnerabilities. Using a system-dependent method (that skips the shell) is always safer.

In Windows, it is CreateProcess(), which is really straight-forward to use.

In POSIX (Linux, etc) it is a combination of fork() and one of the exec() functions.

http://linux.die.net/man/2/fork

http://linux.die.net/man/2/execve

http://linux.die.net/man/3/execv

These are also easy to use, but there are some caveats. Follow the example codes."

execve with the example code gave
(show:9323): Gtk-WARNING **: 10:47:16.601: cannot open display:

https://stackoverflow.com/questions/2437819/gtk-warning-cannot-open-display-when-using-execve-to-launch-a-gtk-progra/2437850#2437850

suggested using execv instead. This worked.


external hard disk prices

From amazon.in, current external USB hard disk prices which I collected for N -
1 TB = Rs. 3500 - per TB cost 3500
2 TB = Rs. 5100 - per TB cost 2550
3 TB = Rs. 6200 - per TB cost 2067
4 TB = Rs. 8100 - per TB cost 2025

The 3TB drives seem to be attractively priced due to the sharp drop in per TB price as compared to 2TB drives. 


Monday, September 02, 2019

gimp 16-bit caution

Gimp 2.8 opens 16-bit png files, but saves as 8-bit tif or png. Octave 4.2.2 on the other hand, does write 16-bit png with imwrite. Octave's behaviour depends on shared libraries, too, of course.

On Linux,
file filename.png
gives information about the file, like bit-depth and so on.