Monthly Archives: January 2018


The “Eiffel” (I fell) Tower and the “I did not fall” Tower

Eiffel tower image source: https://openclipart.org/detail/233894/detailed-eiffel-tower-trace-2

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I do not know what is worse, having high blood pressure or the fact that my mum and my wife know about it


ffmpeg: Create a video countdown 1

The code below was used to generate the video countdown timers that are available in the following playlist using ffmpeg:

#This example will create a 3 second video, with 100 frames per second and it will print the elapsed and remaining times using a two second accuracy.
fps=100;
seconds=3;
mantissaDigits=2;
upperFont=600;
lowerFont=100;
ffmpeg -loop 1 -i ~/Pictures/Black-Background.png -c:v libx264 -r $fps -t $seconds -pix_fmt yuv420p -vf "fps=$fps,drawtext=fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf':fontcolor=yellow:fontsize=$upperFont:x=(w-text_w)/2:y=(h-text_h)/2:text='%{eif\:($seconds-t)\:d}.%{eif\:(mod($seconds-t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}',drawtext=fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf':fontcolor=yellow:fontsize=$lowerFont:x=(w-text_w)/2:y=((h-text_h)/2)+$upperFont:text='Elapsed\: %{eif\:(t)\:d}.%{eif\:(mod(t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}'" "$seconds seconds countdown timer.mp4";

Notes:

  • We used a single black frame for the background that defined the size of the video frame as well.
  • Using the fps variable we defined the number of Frames per Second for the video.
  • The seconds variable defined the number of seconds the duration of the video should be.
  • The mantissaDigits variable defines how many decimal digits should be shown after the dot.
  • upperFont and lowerFont define the size of the fonts in the upper row and the lower one respectively.
  • We used the drawtext directive twice to write to the frames.

Notes on the first drawtext:

  • fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf' defines the font to be used for the text.
  • fontcolor=yellow defines the color of the font of the text.
  • fontsize=$upperFont defines the size of the font of the text.
  • x=(w-text_w)/2 defines the X-coordinate of the location for the text on the frame, here we center the text horizontally on the frame.
  • y=(h-text_h)/2 defines the Y-coordinate of the location for the text on the frame, here we center the text vertically on the frame.
  • text='%{eif\:($seconds-t)\:d}.%{eif\:(mod($seconds-t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}' We print the remaining seconds for the video to finish with specific decimal digit accuracy.

Notes on the second drawtext:

  • drawtext=fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf' defines the font to be used for the text.
  • fontcolor=yellow defines the color of the font of the text.
  • fontsize=$lowerFont defines the size of the font of the text.
  • x=(w-text_w)/2 defines the X-coordinate of the location for the text on the frame, here we center the text horizontally on the frame.
  • y=((h-text_h)/2)+$upperFont defines the Y-coordinate of the location for the text on the frame, here shift the text from the vertical center  of the frame.
  • text='Elapsed\: %{eif\:(t)\:d}.%{eif\:(mod(t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}' We print the elapsed seconds since the video started with specific decimal digit accuracy.

Qubes OS 3.2: Resize fedora-23 TemplateVM Root Image 1

Recently, we needed to increase the size of the root image for the fedora-23 TemplateVM.
We had to do this as we wanted to install in /opt a few IDEs, including android-studio which takes a lot of space when accompanied by the Android SDK.

Following the excellent guide at https://www.qubes-os.org/doc/resize-root-disk-image/, we did the following:

  1. Made sure that the fedora-23 TemplateVM and all VMs based on that template were shut down.
    This included stopping the sys-firewall and sys-net VMs as well (in this order).
  2. Then, in the VM Settings window at the Basic tab for the fedora-23 TemplateVM, we disabled the networking by selecting none on the NetVM: drop-down list and pressed OK to apply the settings changes.
  3. Following, in dom0 Terminal Emulator we run the following command:
    truncate -s 40G /var/lib/qubes/vm-templates/fedora-23/root.img;
  4. Afterwards we started the fedora-23 TemplateVM and run the following in the terminal:
    sudo resize2fs /dev/mapper/dmroot;
    Please note that if your output is Nothing to do! then most likely you forgot a VM that is based on the fedora-23 TemplateVM running. Normally your screen should print something along the lines of Resizing the filesystem...
  5. Next, we shut down the fedora-23 TemplateVM, and went to the VM Settings window to enable networking by selecting whatever we had there before (for us it was default (sys-firewall)).
  6. Finally, we could start using our VMs, their root.img were of the new extended size.